High-rise buildings and sanitary installations in them are zoned: divided into parts - zones of a certain height, separated by technical floors. Equipment and communications are located on technical floors. In heating, ventilation and water supply systems, the permissible zone height is determined by the value of the hydrostatic water pressure in the lower heating devices or other elements and the possibility of placing equipment, air ducts, pipes and other communications on technical floors.
For a water heating system, the height of the zone depending on the hydrostatic pressure permissible as a working one for certain types heating devices(from 0.6 to 1.0 MPa), should not exceed (with some margin) 55 m when using cast iron and steel appliances (for MS type radiators - 80 m) and 90 m for appliances with steel heating pipes.
Within one zone, a water heating system is installed with water heat supply according to a scheme with independent connection to external heat pipelines, i.e. hydraulically isolated from the external heating network and from other heating systems. Such a system has its own water-to-water heat exchanger, circulation and make-up pumps, and expansion tank.
The number of zones along the height of the building, as well as the height of an individual zone, is determined by the permissible hydrostatic pressure, but not for heating devices, but for equipment in heating points located with water heat supply, usually in the basement. The main equipment of these heating points, namely conventional water-to-water heat exchangers and pumps, even those manufactured to special order, can withstand an operating pressure of no more than 1.6 MPa. This means that with such equipment, the height of the building for water-water heating with hydraulically isolated systems has a limit of 150...160 m. In such a building, two (75...80 m high) or three (50...55 m high) can be arranged. ) zonal heating systems. In this case, the hydrostatic pressure in the heating system equipment of the upper zone, located in the basement, will reach the design limit.
Rice. 5.8. Scheme of water heating of a high-rise building:
I and II – zones of the building with water-water heating; III – zone of the building with steam-water heating; 1 - expansion tank; 2 - circulation pump; 3 – steam-water heat exchanger; 4 – water-to-water heat exchanger
In buildings with a height of 160 to 250 m, water-water heating can be used using special equipment designed for an operating pressure of 2.5 MPa. If steam is available, combined heating can also be performed (Fig. 5.8): in addition to water-water heating in areas below 160 m, in areas above 160 m steam-water heating is installed.
The steam coolant, characterized by low hydrostatic pressure, is supplied to the technical floor under the upper zone, where another heating unit is installed. It is equipped with a steam-water heat exchanger, its own circulation pump and expansion tank, and devices for qualitative and quantitative regulation.
Rice. 5.9. Scheme of a unified water-water heating system for a high-rise building:
1 – water-to-water heat exchanger; 2 - circulation pump; 3 – zonal circulation booster pump; 4 – open expansion tank; 5 – pressure regulator “towards you”
The combined heating complex operates in the central part of the main building of the Moscow state university: in the lower three zones there is water-water heating with cast iron radiators, in the upper fourth zone - steam-water heating. In buildings with a height of more than 250 m, new steam-water heating zones are provided or resort to electric water heating.
To reduce cost and simplify the design, it is possible to replace the combined heating of a high-rise building with one water heating system, which does not require a second primary coolant. In Fig. 5.10 shows that the building can be arranged hydraulically general system with one water-to-water heat exchanger, common circulation pump and expansion tank. The building height system is still divided into zonal parts according to the above rules. Water is supplied to zone II and subsequent zones by zonal circulation booster pumps and returned from each zone to a common expansion tank. The required hydrostatic pressure in the main return riser of each zone section is maintained by a downstream pressure regulator. Hydrostatic pressure in the equipment of the heating point, including booster pumps, is limited by the installation height of the open expansion tank and does not exceed the standard operating pressure of 1 MPa.
Heating systems of high-rise buildings are characterized by dividing them within each zone along the sides of the horizon (along the facades) and automating the temperature control of the coolant.
Currently, the heating of the vast majority of existing residential multi-storey buildings in our country is carried out mainly by vertical single-pipe water heating systems. The advantages and disadvantages of such systems are noted in other sources. Among the main disadvantages, the following should be noted:
□ it is impossible to keep track of heat consumption for heating each apartment;
□ it is impossible to pay for heat consumption for actually consumed thermal energy(TE);
□ it is very difficult to maintain the required air temperature in each apartment.
Therefore, we can conclude that it is necessary to abandon the use of vertical systems for heating residential multi-storey buildings and use apartment heating systems (HS), as recommended. At the same time, it is necessary to install a heating element meter in each apartment.
Apartment CO in multi-storey buildings- these are systems that can be serviced by apartment residents without changing the hydraulic and thermal conditions of neighboring apartments and provide apartment-by-apartment metering of heat consumption. This increases thermal comfort in residential premises and saves heat for heating. At first glance, these are two contradictory tasks. However, there is no contradiction here, because Overheating of the premises is eliminated due to the absence of hydraulic and thermal misadjustment of CO. In addition, 100% of the heat from solar radiation and domestic heat input into each apartment is used. Builders and maintenance services are aware of the urgency of solving this problem. Existing apartment heating systems in our country are rarely used for heating multi-storey buildings for various reasons, including due to their low hydraulic and thermal stability. The apartment heating system, protected by the current RF patent No. 2148755 F24D 3/02, according to the authors, meets all the requirements. In Fig. 1 shows the CO scheme for residential buildings with a small amount of floors.
CO contains supply 1 and return 2 heat pipelines of network water, connected to an individual heating point 3 and connected, in turn, to supply heat pipe 4 CO. A vertical supply riser 5 is connected to the supply heat pipe 4, connected to the floor horizontal branch 6. Heating devices 7 are connected to the branch 6. In the same apartments where the vertical supply riser 5 is installed, a return riser 8 is installed, which is connected to the return heat pipe CO 9 and horizontal floor branch 6. Vertical risers 5 and 8 limit the length of floor branches 6 to one apartment. On each floor branch 6, an apartment heating unit 10 is installed, which serves to ensure the supply of the required coolant flow and take into account the heat consumption for heating each apartment and regulate the indoor air temperature depending on the outside temperature, heat input from solar radiation, heat release in each apartment , wind speed and direction. To turn off each horizontal branch, valves 11 and 12 are provided. Air valves 13 are used to remove air from heating devices and branches 6. Heating devices 7 can have valves 14 installed to regulate the flow of water passing through heating devices 7.
Rice. 1. Diagram of the heating system of buildings with a small number of floors: 1 - heating supply pipe of network water; 2 - return heat pipe of network water; 3 - individual thermal
paragraph; 4 - supply heat pipe of the heating system; 5 - vertical supply riser; 6 - floor horizontal branch; 7 - heating devices; 8 - return riser; 9 - return heat pipe of the heating system;
10 - apartment heating point; 11, 12 - valves; 13 - air valves; 14 - taps for regulating water flow.
In the case of a design system for a multi-storey building (Fig. 2), the supply vertical riser 5 is made in the form of a group of risers - 5, 15 and 16, and the vertical return riser 8 is made in the form of a group of risers 8, 17 and 18. In this design system, the supply riser 5 and the return riser 8, connected respectively with the heat pipes 4 and 9, combines into block “A” the horizontal floor branches 6 of several (in this particular case three branches) upper floors of the building. The supply riser 15 and the return riser 17 are also connected to heat pipelines 4 and 9 and combine the horizontal floor-by-floor branches of the next three floors into block “B”. The vertical supply riser 16 and the return riser 18 combine the floor branches 6 of the three lower floors into block “C” (the number of branches in blocks A, B and C can be more or less than three). On each horizontal floor branch 6, located in one apartment, an apartment heating unit 10 is installed. It includes, depending on the parameters of the coolant and local conditions, shut-off and control and control valves, a pressure (flow) regulator and a device for metering heat consumption (heat meter). To turn off the horizontal branches, valves 11 and 12 are provided. Valves 14 are used to regulate the heat transfer of the heating device (if necessary). Air is removed through taps 13.
The number of horizontal branches in each block is determined by calculation and can be more or less than three. It should be noted that vertical supply risers 5, 15, 16 and return risers 8, 17, 18 are laid in one apartment, i.e. the same as in Fig. 1, and this ensures high hydraulic and thermal stability of the CO of a multi-story building and, consequently, efficient operation of the CO.
By changing the number of blocks into which the CO is divided in height, it is possible to almost completely eliminate the influence of natural pressure on the hydraulic and thermal stability of the water heating system of a multi-story building.
In other words, we can say that with the number of blocks equal to the number of floors in the building, we will obtain a water heating system in which the natural pressure arising from the cooling of water in the heating devices connected to the floor branches will not affect the hydraulic and thermal stability of the CO.
The considered CO ensures high sanitary and hygienic indicators in heated premises, heat savings for heating, and effective regulation of indoor air temperature. It is possible to put the CO into operation at the request of the resident (if coolant is available) in heating point 3 at any time, without waiting for the CO to start up in other apartments or in the entire house. Considering that the thermal power and the length of the horizontal branches are approximately the same, when manufacturing a pipe blank, maximum unification of CO units is achieved, and this reduces the cost of manufacturing and installation of CO. The developed apartment heating system for multi-storey residential buildings is universal, i.e. Such CO can be used for heat supply:
□ from a central heat source (from heating networks);
□ from an autonomous heat source (including a rooftop boiler room).
Rice. 2. Diagram of the heating system of multi-storey buildings. 1 - supply heat pipeline of network water; 2 - return heat pipe of network water; 3 - individual heating point; 4 - supply heat pipe of the heating system; 5, 15, 16 - vertical supply risers; 6 - floor horizontal branch; 7 - heating devices; 8, 17, 18 - return risers; 9 - return heat pipe of the heating system; 10 - apartment heating point; 11, 12 - valves; 13 - air valves; 14 - taps for regulating water flow.
Such a system is hydraulically and thermally stable, can be single-pipe or double-pipe, and any type of heating device that meets the requirements can be used in it. The circuit for supplying coolant to the heating device may be different; when installing a tap at the heating device, it can be adjusted thermal power heating device. Such CO can be used not only for heating residential buildings, but also public and industrial buildings. In this case, a horizontal branch is laid near the floor (or in a recess in the floor) along the baseboard. Such a building can be repaired and reconstructed if there is a need to redevelop the building. The system described above requires less metal consumption. Installation of such CO can be carried out from steel, copper, brass and polymer pipes approved for use in construction. The heat transfer of heat pipes must be taken into account when calculating heating devices. The use of apartment-by-apartment CO provides a reduction in heat consumption by 10-20%.
The idea of using apartment-by-apartment systems for heating multi-storey residential buildings originated a long time ago. However, such heating systems were not used even in newly built residential buildings for many reasons, including the lack of a regulatory framework and design recommendations. Over the past 5 years, a regulatory framework has been created and recommendations for the design of such systems have been developed. In Russia, there is still no experience in operating apartment-by-apartment COs connected to various heat sources.
When designing such systems, many questions arise regarding the placement of horizontal branches and the locations of vertical supply and return drains. The consumption of pipelines for the installation of horizontal branches will be minimal if the apartment in plan is square or close to a square.
It should be noted that supply and return vertical risers can be laid in special shafts located in staircases or common corridors. In the shafts on each floor there should be installation cabinets in which apartment input units are placed.
For mass housing construction, it is advisable to make apartment-by-apartment COs single-pipe horizontal with closing sections and serial connection of heating devices. In this case, the pipe consumption is significantly reduced, but at the same time the heating surface of the heating devices increases (due to a reduction in thermal pressure) by an average of 10-30%.
Horizontal branches should be laid near external walls, above the floor, either in the floor structure or in special baseboards - boxes, depending on the height of the heating device, its type and the distance from the floor to the window sill board (the distance from the floor to the window sill board in new construction, if necessary, can be increased by 100-250 mm).
With long heating devices, for example convectors, it will be possible to use pass-through convectors and use versatile (diagonal) connection of devices to a horizontal branch, and this in many cases improves the heating of the devices and, therefore, increases their heat transfer. When horizontal branches are laid openly, their heat transfer into the room increases, and this ultimately leads to a decrease in the surface of heating devices and, consequently, a decrease in the consumption of metal for their manufacture.
This system is convenient for installation and, as a rule, pipelines of the same diameter are used for horizontal branches. In addition, with single-pipe CO, higher coolant parameters can be used (up to 105 °C). When using three-way taps (or another design solution), you can increase the amount of water flowing into the device, and this reduces the heating surface of the devices. With such a constructive design of the system, the possibility of its repair is ensured, i.e. replacement of pipelines, shut-off and control valves and heating devices in each apartment without opening the floor structure, etc.
Indisputable dignity of such heating systems is that only Russian-made materials and products can be used for their construction.
Literature
1. Scanavi A.N., Makhov L.M. Heating. Textbook for Higher Educational Institutions - M.: ASV Publishing House, 2002. 576 p.
2. SNiP. 41-01-2003. Heating, ventilation and air conditioning / Gosstroy of Russia. - M.: Federal State Unitary Enterprise TsPP, 2004.
3. Livchak I.F. Apartment heating. - M.: Stroyizdat, 1982.
Water heating system for high-rise buildings
High-rise buildings and sanitary installations are classified: divided into parts - zones of a certain height, separated by technical floors. Equipment and communications are located on technical floors. In heating, ventilation and water supply systems, the permissible zone height is determined by the value of the hydrostatic water pressure in the lower heating devices or other elements and the possibility of placing equipment, air ducts, pipes and other communications on technical floors.
For a water heating system, the height of the zone, depending on the hydrostatic pressure acceptable as working pressure for certain types of heating devices (from 0.6 to 1.0 MPa), should not exceed (with some margin) 55 m when using cast iron and steel devices (with radiators type MS - 80 m) and 90 m for devices with steel heating pipes.
Within one zone, a water heating system is installed with water heat supply according to a scheme with independent connection to external heat pipelines, i.e., hydraulically isolated from the external heating network and from other heating systems. Such a system has its own water-to-water heat exchanger, circulation and make-up pumps, and expansion tank.
The number of zones along the height of the building is determined, like the height of an individual zone, by the permissible hydrostatic pressure, but not for heating devices, but for equipment in heating points located with water heat supply, usually in the basement. The main equipment of these heating points, namely conventional water-to-water heat exchangers and pumps, even those manufactured to special order, can withstand an operating pressure of no more than 1.6 MPa.
This means that with such equipment, the height of the building with water-water heating by hydraulically isolated systems has a limit of 150-160 m. In such a building, two (75-80 m high) or three (50-55 m high) can be built ) zone heating systems. In this case, the hydrostatic pressure in the heating system equipment of the upper zone, located in the basement, will reach the design limit.
In buildings with a height of 160-250 m, water-water heating can be used using special equipment designed for an operating pressure of 2.5 MPa. Combined heating can also be carried out, if steam is available: in addition to water-water heating in the lower 160 m, in the area above 160 m, steam-water heating is installed.
The steam coolant, characterized by low hydrostatic pressure, is supplied to the technical floor under the upper zone, where another heating unit is installed. It is equipped with a steam-water heat exchanger, its own circulation pump and expansion tank, and devices for qualitative and quantitative regulation.
Each zone heating system has its own expansion tank, equipped with an electrical alarm system and system make-up control.
A similar combined heating complex operates in the central part of the main building of Moscow State University: water-water heating with cast iron radiators is installed in the lower three zones, and steam-water heating is installed in the upper zone IV.
In buildings with a height of more than 250 m, new steam-water heating zones are provided or electric water heating is used if a steam source is not available.
To reduce cost and simplify design, it is possible to replace the combined heating of a high-rise building with one water heating system, which does not require a second primary coolant (for example, steam). The building can have a hydraulically common system with one water-to-water heat exchanger, a common circulation pump and an expansion tank (Fig. 2). The building height system is still divided into zonal parts according to the above rules. Water is supplied to the second and subsequent zones by zonal circulation booster pumps and returned from each zone to a common expansion tank. The required hydrostatic pressure in the main return riser of each zone section is maintained by a downstream pressure regulator. Hydrostatic pressure in the equipment of a heating point, including booster pumps, is limited by the installation height of the open expansion tank and does not exceed the standard operating pressure of 1 MPa.
Heating systems of high-rise buildings are characterized by dividing them within each zone along the sides of the horizon (along the facades) and automating the temperature control of the coolant. The temperature of the water coolant for the zone heating system is set according to a given program depending on changes in the outside air temperature (disturbance control). At the same time, for the part of the system that heats rooms facing south and west, additional regulation of the coolant temperature is provided (to save thermal energy) in the case when the temperature of the rooms increases due to insolation (“deviation” regulation).
To empty individual risers or parts of the system, drainage lines are laid on technical floors. During the operation of the system, the drainage line is turned off to avoid uncontrolled leakage of water by the common valve in front of the drainage separation tank.
Decentralized hot water heating system
Among the water heating systems used, systems in which the surface temperature of heating devices is limited to 95 °C predominate. The above discussed common systems where the local coolant is centrally heated with high-temperature water, and is heated to a maximum of 95 °C in two-pipe systems and up to 105 °C in single-pipe systems. Meanwhile, a system in which high-temperature water would be supplied as close as possible to the heating devices, and their surface temperature kept low according to hygienic requirements, would have a certain economic advantage over a conventional system. This advantage would be achieved by reducing the diameter of the pipes to move a reduced amount of water at an increased speed under the pressure of the network (station) circulation pump.
In such a combined water-water system, heating of the coolant would occur in a decentralized manner. In the heating point of the building, equipment for heating and circulating water was not required; the operation of the system would only be controlled and the consumption of thermal energy taken into account.
Let us analyze some schemes of a system for decentralized heating of local coolant with high-temperature water, developed by Soviet engineers, dividing them into two groups: with independent and dependent connection of the system to external heat pipelines.
For decentralized heating of local water or oil according to an independent scheme, non-pressure steel or ceramic heating devices are proposed. These devices, like open vessels, are filled with water (oil) heated through the walls of the coil with high-temperature water. Evaporation from the surface of the water in the device increases the humidity in the room. The coil is included in a single-pipe flow-controlled system with “inverted” circulation of high-temperature water. High-temperature water can have a temperature of 110°C for ceramic blocks, and 130°C for steel appliances filled with mineral oil. In this case, the surface temperature of the devices does not exceed 95 °C.
Decentralized mixing of high and low temperature water, i.e. heating of the local coolant according to a dependent scheme, can be carried out in mains, risers and directly in heating devices.
When mixed in the mains, the heating system is divided into several series-connected parts (subsystems), each consisting of several single-pipe U-shaped risers. Associated mixing of high-temperature water with chilled water return water from subsystems (to increase the temperature from 70 to 105 °C) occurs through jumpers with diaphragms into intermediate lines between the individual subsystems.
In a system with water mixing at the base of single-pipe U-shaped risers, the line with high-temperature water, unlike known heating systems, is also single-pipe. The water in it lowers the temperature at the mixing points and enters the risers with different temperatures. In vertical risers, mainly natural circulation of water occurs, since the hydraulic resistance of the closing sections is relatively small.
To mix water at the base of two-pipe risers, special mixers are used 2 . Water in both mains moves under the pressure of the network pump, and natural circulation of water occurs in the risers.
With decentralized mixing and single-pipe risers, the heating system is divided into two parts: in the first, high-temperature water moves in the risers from bottom to top, cooling to a temperature of 95 ° C, in the second - from top to bottom. To ensure that the required amount of high-temperature water flows into the devices, diaphragms are installed at the closing sections.
With decentralized mixing in two-pipe risers, high-temperature water is supplied inside each heating device through a perforated manifold 4 or through a mixing nozzle, and cooled water is removed in the same amount into the return riser.
The described heating systems have not become widespread due to difficulties with laying high-temperature water pipes in rooms and the complexity of installation and operational regulation.
Currently, a direct-flow heating system is used with decentralized heating of water returning from three or four subsystems (groups of risers) connected in series. In this so-called staged temperature regeneration (CTR) system (high temperature water heats chilled water in two or three (between subsystems) temperature regenerators (RT). The temperature regenerators are counterflow pipe-in-pipe heat exchangers (for example, Dy25 pipe in housing Dy40).Water flows twice through each PT; first in the form of high-temperature water through the inter-tube space, then in the form of cooled water through inner tube. When returning from the last subsystem, water is heated by high-temperature water to 95-105 ° C, then enters the penultimate subsystem, etc., until it returns cooled from the first subsystem to the point of entry into the building of high-temperature water.
The SRT heating system is made of a single-pipe system with one-sided standardized instrument units, with upper or lower distribution of the supply line.
Apartment heating system
The problem of rational consumption and distribution of thermal energy by heating systems is still relevant, because under the climatic conditions of Russia, heating systems of residential buildings are the most energy-intensive of engineering systems.
In recent years, the prerequisites have been created for the construction of residential buildings with reduced energy consumption through the optimization of urban planning and space-planning solutions, the shape of buildings, by increasing the level of thermal protection of enclosing structures and through the use of more energy-efficient engineering systems.
Residential buildings erected since 2000 with thermal protection corresponding to the second stage of energy saving correspond in energy efficiency to regulatory requirements countries such as Germany and the UK. The walls and windows of residential buildings have become “warmer” - heat loss from enclosing structures has decreased by 2-3 times, modern translucent fences (windows, doors of loggias and balconies) have such low air permeability that there is practically no infiltration when the windows are closed.
At the same time, in residential buildings of mass construction, heating systems made according to standard designs are still designed and operated. The systems traditionally use high-temperature coolants with parameters of 105–70, 95–70°C. When providing thermal protection of buildings according to the second stage of energy saving and with the specified parameters of the coolant, the dimensions and heating surface of heating devices, the coolant flow through each device are reduced and, as a result, protection from back radiation in the area of windows, doors of balconies, loggias is not provided, and working conditions worsen and regulation of automatic thermostats of heating devices.
To create buildings with more efficient use of thermal energy, providing comfortable conditions for human habitation, modern, energy-efficient heating systems are needed. Adjustable apartment heating systems fully meet these requirements. However wide application The growth of apartment heating systems has been hampered in part by the lack of sufficient regulatory framework and design guidelines.
Currently, the technical standardization department of the Gosstroy of Russia is reviewing the Code of Rules “Apartment Heating Systems for Residential Buildings”. The set of rules was prepared by a group of specialists from FSUE SantekhNIIproekt, JSC Mosproekt, Gosstroy of Russia and includes requirements for systems, heating devices, fittings and pipelines, requirements for safety, durability and maintainability of apartment heating systems.
The set of rules supplements and develops the requirements for the design of apartment heating systems in accordance with SNiP 2.04.05-(2) and can be used for the design of apartment heating systems in residential buildings various types single- and multi-apartment, block and sectional during the construction of new and reconstructed buildings, provided with thermal energy from heating networks (CHP, RTS, boiler room), from autonomous or individual heat sources.
Apartment heating system is a system with piping within one apartment, ensuring the maintenance of a given air temperature in the premises of this apartment.
Analysis of a number of projects shows that apartment heating systems have a number of advantages compared to central systems:
Provide greater hydraulic stability of the heating system of a residential building;
They increase the level of comfort in apartments by ensuring the air temperature in each room at the consumer’s request;
Provide the ability to account for heat in each apartment and reduce heat consumption during the heating period by 10–15% with automatic or manual regulation of heat flows;
Satisfy the customer’s design requirements (the ability to choose the type of heating device, pipes, pipe laying scheme in the apartment);
Provide the ability to replace pipelines, shut-off and control valves and heating devices in individual apartments during redevelopment or when emergency situations without disturbing the operating mode of heating systems in other apartments, the ability to carry out adjustment work and hydrostatic tests in a separate apartment.
The level of thermal protection of residential buildings with apartment-by-apartment heating systems must not be lower than the required values of the reduced heat transfer resistance of the building’s external enclosures in accordance with SNiP II-3-79*.
The calculated air temperature for the cold period of the year in heated rooms of a residential building should be taken within the optimal standards according to GOST 30494, but not lower than 20°C for rooms with constant occupancy. In apartment buildings, it is allowed to lower the air temperature in heated rooms when they are not in use (during the absence of the apartment owner) below the standard by no more than 3–5°C, but not lower than 15°C. With such a temperature difference, heat loss through internal enclosing structures can be ignored.
IN apartment building With a central heating system, apartment heating systems should be designed for all apartments. It is not allowed to install apartment-by-apartment systems for one or more apartments in a building. Apartment heating systems in a residential building are connected to heating networks according to an independent circuit through heat exchangers, in a quarterly central heating point or in an individual heating point (IHP). It is allowed to connect apartment heating systems to heating networks using a dependent scheme, providing automatic control of the coolant parameters in the ITP.
In single-apartment and block houses with individual heat supply sources, both apartment heating systems with heating appliances and underfloor heating systems for heating individual rooms or areas of the floor can be used, provided that automatic maintenance of the set temperature of the coolant and the temperature on the floor surface is ensured.
For apartment heating systems, water is usually used as a coolant; other coolants may be used during a feasibility study in accordance with the requirements of SNiP 2.04.05-91*.
The coolant parameters for apartment heating systems, depending on the heat source, the type of pipes used and the method of their installation, are shown in the table.
In apartment heating systems of a residential building, the coolant parameters must be the same for all apartments. Upon technical justification or on the customer’s instructions, it is allowed to take the temperature of the coolant of the apartment heating system of one of the apartments below that accepted for the heating system of the building. In this case, automatic maintenance of the specified coolant temperature must be ensured.
Heating systems
In buildings with a height of two or more floors, to supply coolant to apartments, two-pipe systems should be designed with lower or upper distribution of main pipelines, main vertical risers servicing part of the building or one section.
The supply and return main vertical risers for each part of the section building are laid in special shafts of common corridors and staircase halls. In the shafts on each floor, built-in installation cabinets are provided, which should house floor distribution manifolds with discharge pipelines for each apartment, shut-off valves, filters, balancing valves, and heat meters.
Apartment heating systems can be implemented according to the following schemes:
Two-pipe horizontal (dead-end or associated) with parallel connection of heating devices (Fig. 1). Pipes are laid near external walls, in the floor structure or in special baseboard boxes;
Two-pipe radial with individual connection by pipelines (loops) of each heating device to the distribution manifold of the apartment (Fig. 2). It is allowed to connect two heating devices “on a coupling” within the same room. Pipelines are laid in the form of loops in the floor structure or along the walls under the baseboards. The system is convenient for installation, since pipelines of the same diameter are used and there are no pipe connections in the floor;
Single-pipe horizontal with closing sections and serial connection of heating devices (Fig. 3). Pipe consumption is significantly reduced, but the heating surface of heating devices increases by approximately 20% or more. The circuit is recommended for use at higher coolant parameters and smaller temperature differences (for example, 90–70°C). Due to the increase in the amount of water flowing into the device, the heating surface of the device decreases. The calculated temperature of the water leaving the last device should not be lower than 40°C;
Floor-mounted with installation of heating coils from pipes in the floor structure. Floor systems have greater inertia than systems with heating devices and are less accessible for repair and dismantling. Possible options for laying pipes in underfloor heating systems are shown in Fig. 4, 5. Scheme according to Fig. 4 ensures easy installation of pipes and uniform temperature distribution over the floor surface. Scheme according to Fig. 5 provides approximately equal average temperature on the floor surface.
Bathroom heated towel rails are connected to the hot water supply system - when the building is supplied with heat from heating networks or from an independent source, or to the heating system - when there is an individual heat source.
In residential buildings with more than three floors with a central or general autonomous heat supply source, it is necessary to design the heating of staircases, staircases and elevator halls. In buildings with more than three floors, but not more than 10, as well as in buildings of any number of floors with individual heat sources, it is allowed not to design heating for smoke-free staircases of the first type. In this case, the heat transfer resistance of the internal walls enclosing the unheated staircase from the living quarters is assumed to be equal to the heat transfer resistance of the external walls.
Hydraulic calculations of apartment heating systems are carried out using existing methods, taking into account recommendations for the use and selection of heating devices, developed based on the results of the Scientific Research Institute of Plumbing during testing and certification of heating devices from various manufacturers.
The connection of the heating device to the pipelines can be carried out according to the following schemes:
Lateral one-sided connection;
Radiator connection from below;
Lateral double-sided (multi-sided) connection to the lower radiator plugs. Versatile piping connections should be provided for radiators with a length of no more than 2,000 mm, as well as for radiators connected “on a coupling”. In a two-pipe heating system, it is allowed to connect two heating devices “on a coupling” within one room.
In apartment heating systems, as in traditional heating systems, heating devices, valves, fittings, pipes and other materials approved for use in construction and having certificates of conformity of the Russian Federation should be used.
In multi-apartment residential buildings, the service life of heating appliances and pipelines of heating systems must be at least 25 years; in single-family houses, the service life is taken according to the customer’s instructions.
As heating devices, it is advisable to use steel radiators or other devices with a smooth surface that ensures that the surface is cleaned from dust. It is allowed to use convectors with air control valves.
To regulate the heat flow in rooms, control valves should be installed near heating devices. In rooms with constant occupancy, as a rule, automatic thermostats are installed (with built-in or remote thermostatic elements), ensuring the maintenance of a given temperature in each room and saving heat supply through the use of internal excess heat (domestic heat release, solar radiation).
For hydraulic linking of individual branches of an apartment-by-apartment two-pipe heating system, pre-set valves are installed on all heating devices in the apartment.
For the hydraulic stability of the building's heating system, it is planned to install balancing valves on the main vertical risers for each part of the building, section, as well as at each floor distribution manifold.
In buildings with apartment heating systems, the following should be provided:
Installation in the ITP of a closed expansion tank and filter for the building system with heat supply from heating networks and an autonomous heat source;
Installation of a closed expansion tank and filter for each apartment with heat supply from an individual heat source.
When the expansion tanks are open, the water in the system is saturated with air, which significantly activates the process of corrosion of metal system elements, forming air jams in system.
Pipelines for an apartment heating system can be made of steel, copper, heat-resistant polymer or metal-polymer pipes. In heating systems with pipelines made of polymer or metal-polymer pipes, the coolant parameters (temperature and pressure) should not exceed the maximum permissible values specified in technical documentation for their production. When choosing coolant parameters, it should be taken into account that the strength of polymer and metal-polymer pipes depends on the operating temperature and pressure of the coolant. When the temperature and pressure of the coolant decrease below the maximum permissible values, the safety factor increases and, accordingly, the service life of the pipes increases. Pipelines for apartment heating systems, as a rule, are laid hidden: in grooves, in the floor structure. Open laying of metal pipelines is allowed. When laying hidden pipelines, hatches or removable panels should be provided at the locations of dismountable connections and fittings for inspection and repair.
When calculating heating devices in each room, at least 90% of the incoming heat from pipelines passing through the room should be taken into account. Heat losses due to cooling of the coolant in uninsulated openly laid horizontal pipelines are taken according to reference data. The heat flow of openly laid pipes is taken into account within the following limits:
90% when laying pipes horizontally near the floor;
70–80% when laying horizontal pipes under the ceiling;
85–90% for vertical pipe laying.
Thermal insulation is provided for pipelines laid in the grooves of external walls, in shafts and in unheated rooms, on floor areas with close placement of four or more pipes in the floor, ensuring acceptable surface temperatures.
Accounting for thermal energy consumption
Apartment heating systems, on the one hand, provide the most comfortable living conditions that satisfy the consumer, and on the other hand, they allow you to regulate the heat transfer of heating devices in the apartment, taking into account the family’s mode of residence in the apartment, the need to reduce heating costs, etc.
In a building with apartment-by-apartment heating systems, it is necessary to take into account the heat consumption of the building as a whole, as well as separately for each apartment and public and public premises. technical purpose located in this building.
To account for the heat consumption of each apartment, the following may be provided: heat consumption meters for each apartment system; evaporative or electronic type heat distributors on each heating device; heat consumption meter at the entrance to the building. For any type of heat metering devices, the tenant's payment must include the total heat costs of the building (heating stairwells, elevator halls, service and technical premises).
In buildings with increased thermal protection of enclosing structures, apartment heating systems (with automatic thermostats for heating devices and heat consumption meters both at the entrance to the building and for each apartment) create additional features and incentives for more efficient use of thermal energy. Thanks to the automatic regulation of the heat transfer of heating devices when the heat load in the premises changes and the ability of residents to adjust the heat transfer of heating devices taking into account the family's living conditions (reducing the air temperature in the premises during the absence of residents, reducing heat loss), thermal energy savings of 20 to 30% can be achieved. At the same time, consumer payments for heat will decrease, since the established standards for thermal energy consumption significantly exceed actual consumption.
Hydraulic calculation of a water heating system. Methods for hydraulic calculation of a water heating system. Calculation based on specific linear pressure loss; calculation based on resistance and conductivity characteristics; calculation based on drawn lengths and dynamic pressures. - 1 hour.
Loss of pressure in the network.
The movement of liquid in heat pipes occurs from a section with high pressure to a section with lower pressure due to the pressure difference. When moving a liquid, potential energy is consumed, i.e., hydrostatic pressure to overcome resistance from friction against the walls of pipes and from turbulence and shock when changing the speed and direction of movement in fittings, devices and fittings.
The pressure drop caused by frictional resistance against the pipe walls is a linear loss; pressure drop caused by local resistance - local loss.
The pressure drop Ap, Pa, caused by friction and local resistance, is measured in fractions of dynamic pressure and is expressed by a formula known from the hydraulics course
If, when calculating heating systems, we assume the density of the coolant (liquid) to be constant, which leads to an error that lies beyond the practical accuracy of the calculation, then the values can be determined as constant for a heat pipe of a given diameter.
Using a constant ratio in calculations allows, based on a given coolant flow rate and heat pipe diameter, to determine the coolant speed by dividing the flow rate by this value; the use of a constant value allows you to determine the pressure loss in the heat pipeline at a given flow rate, bypassing the determination of speed.
Hydraulic calculation of water heating systems.
Pipelines in the heating system perform the important function of distributing coolant to individual heating devices. They are heat conductors whose task is to transfer a certain calculated amount of heat to each device.
The heating system is a highly branched and complexly looped network of heat pipes, through each section of which a certain amount of heat must be transferred. Performing an accurate calculation of such a network is a complex hydraulic task associated with solving a large number of nonlinear equations. In engineering practice, this problem is solved by the selection method.
In water systems, the amount of heat brought by the coolant depends on its flow rate and the temperature difference when cooling the water in the device. Usually, when calculating, they set the general coolant temperature difference for the system and strive to ensure that this difference is maintained in two-pipe systems - for all devices and the system as a whole; in single-pipe systems - for all risers. If there is a known temperature difference in the coolant, the water flow determined by calculation must be supplied to each heating device through the heat pipes of the system.
With this approach, performing a hydraulic calculation of the network of heat pipelines of the heating system means (taking into account the available circulation pressure) to select the diameters of individual sections so that the calculated coolant flow passes through them. The calculation is carried out by selecting diameters based on the available range of pipes, so it is always associated with some error. For various systems and individual elements certain discrepancies are allowed.
In contrast to the method discussed above, the method with a variable temperature difference in the risers, proposed by A.I. Orlov in 1932, is now widely used in relation to the calculation of single-pipe heating systems.
The principle of calculation is that water flow rates in the risers are not specified in advance, but are determined in the process of hydraulic calculation based on the complete correlation of pressures in all rings of the system and the accepted diameters of the heating pipes of the network. The temperature difference of the coolant in individual risers is different - variable. The area of the heat-releasing surface of heating devices is determined by the temperature and water flow determined by hydraulic calculation. The calculation method with a variable temperature difference more accurately reflects the actual picture of the system’s operation, eliminates the need for installation adjustments, and facilitates the unification of the pipe workpiece, as it makes it possible to avoid the use of various combinations of diameters of radiator units and composite risers. This method became widespread after G.I. Fikhman proved the possibility of using average values of friction coefficients when calculating heat pipelines of water heating systems and conducting the entire calculation according to the quadratic law.
General instructions according to the calculation of the water heating system
The artificial pressure Arn created by the pump is assumed to be:
a) for dependent heating systems connected to heating networks through elevators or mixing pumps, based on the available pressure difference at the inlet and the mixing coefficient;
b) for independent heating systems connected to heating networks through heat exchangers or to boiler houses without the prospect of connecting to heating networks, based on the maximum permissible speed of water movement in heat pipelines, the possibility of linking pressure loss in the circulation rings of the systems and technical and economic calculations.
Based on the value of the average specific linear pressure loss Rcр, the preliminary and then (taking into account losses due to local resistance) the final diameters of the heat pipes are first determined.
The calculation of heat pipes begins with the main most unfavorable circulation ring, which should be considered:
a) in pumping system with dead-end water movement in the mains - a ring through the most loaded riser and the one farthest from the heating point;
b) in a pumping system with associated movement of water - a ring through the middle, most loaded riser;
c) in a gravitational system - a ring in which, depending on the available circulation pressure, the value of Rсp will be the smallest.,
Linking pressure losses in circulation rings should be made taking into account only those areas that are not common to the rings being compared.
The discrepancy (discrepancy) in the calculated pressure losses in parallel-connected sections of individual rings of the system is allowed for dead-end water movement of up to 15%, and for associated water movement in the mains ±5%.
Students, graduate students, young scientists who use the knowledge base in their studies and work will be very grateful to you.
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Ministry of Education of the Republic of Belarus
Belarusian National Technical University
Faculty of Energy Construction
Department of Heat and Gas Supply and Ventilation
on the topic: "Heat supply and heating of high-rise buildings"
Prepared by: student gr. No. 11004414
Novikova K.V.
Checked by: Nesterov L.V.
Minsk - 2015
Introduction
If the temperature conditions in a room or building are favorable, then heating and ventilation specialists are somehow not remembered. If the situation is unfavorable, then specialists in this field are criticized first.
However, the responsibility for maintaining given parameters indoor maintenance is not solely the responsibility of heating and ventilation specialists.
The adoption of engineering decisions to ensure the specified parameters in the room, the volume of capital investments for these purposes and subsequent operating costs depend on space-planning decisions taking into account the assessment of wind conditions and aerodynamic parameters, construction solutions, orientation, building glazing coefficient, calculated climatic indicators, including including quality, level of air pollution based on the totality of all sources of pollution. Multifunctional high-rise buildings and complexes are extremely complex structures from a design point of view engineering communications: heating systems, general and smoke ventilation, general and fire water supply, evacuation, fire automatics, etc. This is mainly due to the height of the building and the permissible hydrostatic pressure, in particular in water heating, ventilation and air conditioning systems.
All buildings can be divided into 5 categories based on height:
* up to five floors where installation of elevators is not required - low-rise buildings;
* up to 75 m (25 floors), within which vertical zoning into fire compartments is not required - multi-storey buildings;
* 76-150 m - high-rise buildings;
* 151-300 m - high-rise buildings;
* over 300 m - super-tall buildings.
The gradation is a multiple of 150 m due to a change in the calculated temperature of the outside air for designing heating and ventilation - every 150 m it decreases by 1 °C.
Features of the design of buildings above 75 m are related to the fact that they must be divided vertically into sealed fire compartments (zones), the boundaries of which are enclosing structures that provide the required fire resistance limits to localize a possible fire and prevent it from spreading to adjacent compartments. The height of the zones should be 50-75 m, and it is not necessary to separate vertical fire compartments with technical floors, as is customary in warm countries, where technical floors do not have walls and are used to collect people in case of fire and their subsequent evacuation. In countries with harsh climates, the need technical floors due to the requirements for the placement of engineering equipment.
When installing it in the basement, only part of the floor located on the border of the fire compartments can be used to accommodate smoke protection fans, the rest - for work rooms. With a cascade scheme for connecting heat exchangers, as a rule, they, together with pumping groups, are placed on technical floors, where they require more space, and occupy the entire floor, and in super-tall buildings sometimes two floors.
Below we will give an analysis of design solutions for heat and water supply and heating of the listed residential buildings.
1. Heat supply
Heat supply internal systems heating, hot water supply, ventilation, air conditioning of high-rise buildings, it is recommended to provide:
From district heating networks;
from an autonomous heat source (AHS), subject to confirmation of the admissibility of its impact on the environment in accordance with current environmental legislation and regulatory and methodological documents;
from a combined heat source (CHS), including hybrid heat pump heat supply systems using non-traditional renewable energy sources and secondary energy resources (soil, building ventilation emissions, etc.) in combination with heat and/or electrical networks.
Heat consumers of high-rise buildings are divided into two categories based on the reliability of heat supply:
the first - heating, ventilation and air conditioning systems for premises in which, in the event of an accident, interruptions in the supply of the calculated amount of heat and a decrease in air temperature below the minimum permissible according to GOST 30494 are not allowed. The list of these premises and the minimum permissible air temperature in the premises must be given in the Technical Specifications;
the second - other consumers for whom it is allowed to reduce the temperature in heated premises for the period of liquidation of the accident for no more than 54 hours, not lower than:
16C - in residential premises;
12C - in public and administrative premises;
5C - in production premises.
The heat supply of a high-rise building should be designed to ensure uninterrupted heat supply in case of accidents (failures) at the heat source or in the supply heating networks during the repair and restoration period from two (main and backup) independent inputs of the heating networks. The main input must supply 100% of the required amount of heat for a high-rise building; from the backup input? supply of heat in an amount not less than that required for heating and ventilation and air conditioning systems of consumers of the first category, as well as heating systems of the second category to maintain the temperature in heated premises not lower than that specified above. By the beginning of the operating cycle, the air temperature in these rooms must correspond to the standard.
Internal heating systems should be connected:
with centralized heating? according to an independent circuit to heating networks;
with AIT? according to a dependent or independent scheme.
Internal heat supply systems must be divided according to the height of buildings into zones (zoned). The height of the zone should be determined by the value of the permissible hydrostatic pressure in the lower elements of the heat supply systems of each zone.
The pressure at any point in the heat supply systems of each zone under hydrodynamic conditions (both at the design flow rates and water temperature, and with possible deviations from them) must ensure that the systems are filled with water, prevent boiling of water and not exceed the value permissible in terms of strength for equipment (heat exchangers, tanks, pumps, etc.), fittings and pipelines.
Water supply to each zone can be carried out in a sequential (cascade) or parallel circuit through heat exchangers with automatic control of the temperature of the heated water. For heat consumers of each zone, it is necessary, as a rule, to provide their own circuit for the preparation and distribution of coolant with a temperature regulated according to an individual temperature schedule. When calculating the temperature schedule of the coolant, the beginning and end of the heating period should be taken at the average daily outside air temperature of +8C and the average design air temperature in heated rooms.
For heat supply systems of high-rise buildings, it is necessary to provide equipment redundancy according to the following scheme.
In each coolant preparation circuit, at least two heat exchangers (working + backup) should be installed, the heating surface of each of which should provide 100% of the required heat consumption for heating, ventilation, air conditioning and hot water supply systems.
When installing backup capacitive electric heaters in the hot water preparation circuit, redundancy of heat exchangers of DHW systems may not be provided.
It is allowed to install three heat exchangers (2 working + 1 reserve) in the coolant preparation circuit for the ventilation system, the heating surface of each of which must provide 50% of the required heat consumption for ventilation and air conditioning systems.
With a cascade heat supply scheme, the number of heat exchangers for heat supply to the upper zones is allowed to be 2 working + 1 reserve, and the heating surface of each should be 50% or according to the technical specifications.
Heat exchangers, pumps and other equipment, as well as fittings and pipelines should be selected taking into account the hydrostatic and operating pressure in the heating system, as well as the maximum test pressure during hydraulic testing. The operating pressure in the systems should be 10% below the permissible operating pressure for all system elements.
The coolant parameters in heat supply systems, as a rule, should be taken taking into account the temperature of the heated water in the zonal heat exchangers of the water preparation circuit of the corresponding zone along the height of the building. The coolant temperature should be no more than 95 C in systems with pipelines made of steel or copper pipes and no more than 90 C - from polymer pipes approved for use in heat supply systems. Coolant parameters in internal heat supply systems are allowed to be more than 95 C, but not more than 110 C in systems with pipelines made of steel pipes, taking into account the check that the water being moved does not boil over the height of the building. When laying pipelines with a coolant temperature of more than 95 C, they should be laid in separate or shared with other pipelines, fenced off shafts, taking into account appropriate safety measures. Laying of the specified pipelines is possible only in places accessible to the operating organization. Measures should be taken to prevent steam from entering outside the technical premises if pipelines are damaged.
A feature of the design of heat and water supply systems is that everything is pumping and heat exchange equipment The high-rise residential buildings in question are located at ground level or minus the first floor. This is due to the danger of placing superheated water pipelines on residential floors, uncertainty about the adequacy of protection from noise and vibration of adjacent residential premises during operation of pumping equipment, and the desire to preserve scarce space to accommodate a larger number of apartments.
This solution is possible thanks to the use of high-pressure pipelines, heat exchangers, pumps, shut-off and control equipment that can withstand operating pressures of up to 25 atm. Therefore, when piping heat exchangers from the local water side, they use butterfly valves with collar flanges, pumps with a U-shaped element, and direct-acting “upstream” pressure regulators installed on the make-up pipeline, solenoid valves, designed for a pressure of 25 atm. in the heating system filling station.
When the height of buildings is above 220 m, due to the occurrence of ultra-high hydrostatic pressure, it is recommended to use a cascade scheme for connecting zonal heat exchangers for heating and hot water supply. Another feature of the heat supply of implemented high-rise residential buildings is that in all cases the source of heat supply is city heating networks. Connection to them is made through a central heating point, which takes quite large area. The central heating system includes heat exchangers with circulation pumps for heating systems of different zones, heat supply systems for ventilation and air conditioning heaters, hot water supply systems, pumping stations for filling heating systems and pressure maintenance systems with expansion tanks and auto-regulation equipment, emergency electrical storage water heaters hot water supply. Equipment and pipelines are located vertically so that they are easily accessible during operation. A central passage with a width of at least 1.7 m passes through all central heating centers to allow the movement of special loaders, allowing the removal of heavy equipment when replacing it (Fig. 1).
This decision is also due to the fact that high-rise complexes, as a rule, are multifunctional in purpose with a developed stylobate and underground part, on which several buildings can be located. Therefore, in the complex, which includes 3 high-rise residential buildings with 43-48 floors and 4 buildings with a height of 17-25 floors, united by a five-level stylobate part, technical collectors with numerous pipelines depart from this single central heating center, and to reduce them, they placed booster water supply pumping stations that pump cold and hot water into each zone of high-rise buildings.
Another solution is also possible - the central heating station serves to introduce urban heating networks to the facility, place a pressure differential regulator "after itself", a heat metering unit and, if necessary, a cogeneration installation and can be combined with one of the individual local heating points (ITP), employees for joining local systems heat consumption close in location to this heating point. From this central heating station, superheated water is supplied through two pipes, and not through several from the comb, as in the previous case, to local ITPs located in other parts of the complex, including on the upper floors, according to the principle of proximity to the thermal load. With this solution, there is no need to connect the internal heat supply system to the supply air heaters according to an independent circuit through a heat exchanger. The heater itself is a heat exchanger and is connected directly to the superheated water pipelines with pump mixing to improve the quality of load control and increase the reliability of the heater protection from freezing.
One of the solutions for reserving centralized heat and power supply to high-rise buildings may be the construction of autonomous mini-CHPs based on gas turbine (GTU) or gas piston (GPU) units that simultaneously generate both types of energy. Modern means protection from noise and vibration allow them to be placed directly in the building, including on the upper floors. As a rule, the power of these installations does not exceed 30-40% of the maximum required power of the facility and in normal mode these installations operate, complementing centralized energy supply systems. With greater power of cogeneration plants, problems arise in transferring excess energy carriers to the network.
There is literature that provides an algorithm for calculating and selecting mini-CHPs for power supply to an object in autonomous mode and an analysis of the optimization of the choice of mini-CHPs using the example of a specific project. If there is a shortage of only thermal energy for the object under consideration, an autonomous heat supply source (AHS) in the form of a boiler room with hot water boilers can be accepted as a source of heat supply. Attached, located on the roof or protruding parts of the building, or free-standing boiler rooms designed in accordance with SP 41-104-2000 can be used. The possibility and location of AIT should be linked to the entire complex of its impact on environment, including for a residential high-rise building.
The temperature situation in the room is significantly influenced by the area and thermal performance of the glazed surface. It is known that the standard reduced heat transfer resistance of windows is almost 6 times less than the reduced heat transfer resistance of external walls. In addition, through them per hour, if there are no sun protection devices, up to 300 - 400 W/m2 of heat due to solar radiation. Unfortunately, when designing administrative and public buildings, the glazing factor can be exceeded by 50% if there is appropriate justification (with a heat transfer resistance of at least 0.65 m2°C / W). In fact, it is possible to use this assumption without appropriate justification.
2. Heating
The following heating systems can be used in high-rise buildings:
water two-pipe with horizontal wiring by floors or vertical;
air with heating and recirculation units within one room or combined with a mechanical supply ventilation system;
electrical according to design specifications and upon receipt technical specifications from the energy supply organization.
It is allowed to use underfloor (water or electric) heating to heat bathrooms, locker rooms, swimming pool areas, etc.
The parameters of the coolant in the heating systems of the corresponding zone should be taken according to SP 60.13330 no more than 95C in systems with pipelines made of steel or copper pipes and no more than 90C? from polymer pipes approved for use in construction.
The height of the heating system zone should be determined by the permissible hydrostatic pressure in the lower elements of the system. The pressure at any point in the heating system of each zone in hydrodynamic mode must ensure that the systems are filled with water and not exceed the permissible strength value for equipment, fittings and pipelines.
Devices, fittings and pipelines of heating systems should be selected taking into account the hydrostatic and operating pressure in the heating system of the zone, as well as the maximum test pressure during hydraulic testing. The operating pressure in the systems should be 10% below the permissible operating pressure for all system elements.
Air-thermal regime of a high-rise building
When calculating the air regime of a building, depending on the configuration of the building, the influence of vertical wind speed on the facades, at the roof level, as well as the pressure difference between the windward and leeward facades of the building are assessed.
The design parameters of outdoor air for heating, ventilation, air conditioning, heat and cold supply systems of a high-rise building should be taken according to the technical specifications, but not lower than parameters B according to SP 60.13330 and SP 131.13330.
Calculations of heat loss by external enclosing structures, air conditions of high-rise buildings, parameters of external air at the locations of air intake devices, etc. should be carried out taking into account changes in the speed and temperature of external air along the height of buildings in accordance with Appendix A and SP 131.13330.
Outdoor air parameters should be taken taking into account the following factors:
decrease in air temperature in altitude by 1 °C for every 100 m;
increased wind speed during the cold season;
the appearance of powerful convective flows on building facades irradiated by the sun;
placement of air intake devices in the high-rise part of the building.
When placing receiving devices for outside air on the southeast, south or southwest facades, the outside air temperature in the warm season should be taken 3-5 C higher than the calculated one.
Calculated parameters of the indoor air microclimate (temperature, movement speed and relative humidity) in residential, hotel and public spaces high-rise buildings should be taken within the optimal standards according to GOST 30494
During the cold season in residential, public, administrative and industrial premises ( refrigeration units, elevator machine rooms, ventilation chambers, pump rooms, etc.), when they are not in use and during non-working hours, it is allowed to reduce the air temperature below the normalized one, but not less than:
16C? in residential premises;
12C? in public and administrative premises;
5C? in production premises.
By the beginning of working hours, the air temperature in these rooms must correspond to the standard.
At the entrance vestibules of high-rise buildings, as a rule, double airlocking of the hall or vestibule should be provided. It is recommended to use airtight devices of a circular or radius type as entrance doors.
Measures should be taken to reduce air pressure in vertical elevator shafts, which is formed along the height of the building due to the gravitational difference, as well as to eliminate unorganized flows of internal air between individual functional areas building.
Water heating systems of high-rise buildings are zoned by height and, as already mentioned, if fire compartments are separated by technical floors, then the zoning of heating systems, as a rule, coincides with fire compartments, since technical floors are convenient for laying distribution pipelines. In the absence of technical floors, the zoning of heating systems may not coincide with the division of the building into fire compartments. Fire inspection authorities allow pipelines of water-filled systems to cross the boundaries of fire compartments, and the height of the zone is determined by the value of the permissible hydrostatic pressure for the lower heating devices and their piping.
Initially, the design of zone heating systems was carried out as for conventional multi-storey buildings. As a rule, two-pipe heating systems with vertical risers and lower distribution of supply and return lines running along the technical floor were used, which made it possible to turn on the heating system without waiting for the construction of all floors of the zone. Such heating systems have been implemented, for example, in residential complexes" Scarlet Sails", "Vorobyovy Gory", "Triumph Palace" (Moscow). Each riser is equipped with automatic balancing valves to ensure automatic distribution of coolant throughout the risers, and each heating device is equipped with an automatic thermostat with increased hydraulic resistance to provide the resident with the opportunity to set the temperature he needs air in the room and minimizing the influence of the gravitational component of the circulation pressure and turning on/off thermostats on other heating devices connected to this riser.
Further, in order to avoid imbalance of the heating system associated with the unauthorized removal of thermostats in individual apartments, which has repeatedly occurred in practice, it was proposed to switch to a heating system with an overhead distribution of the supply line with a parallel movement of the coolant along the risers. This equalizes the pressure loss of the circulation rings through the heating devices, regardless of which floor they are located on, increases the hydraulic stability of the system, guarantees the removal of air from the system and facilitates the setting of thermostats.
However, subsequently, as a result of analyzing various solutions, the designers came to the conclusion that the best system heating systems, especially for buildings without technical floors, are systems with apartment-by-apartment horizontal wiring, connected to vertical risers, passing, as a rule, along staircase, and made according to a two-pipe scheme with lower routing of lines. For example, such a system was designed in the crowning part (9 floors of the third zone) of the Triumph Palace high-rise complex and in a 50-story building under construction without intermediate technical floors.
Apartment heating systems are equipped with a unit with a shut-off valve, regulating valves using balancing valves and drain valves, filters and a heat energy meter. This unit should be located outside the apartment on the staircase for unhindered access by the maintenance service. In apartments over 100 m2, the connection is made not through a loop perimeter laid around the apartment (since as the load increases, the diameter of the pipeline increases, and as a result, installation becomes more complicated and the cost increases due to the use of expensive large fittings), but through an intermediate apartment distribution cabinet, in which a comb is installed, and the coolant flows from it beam scheme pipelines of smaller diameter are sent to heating devices according to a two-pipe scheme.
Pipelines are used from heat-resistant polymeric materials, usually from cross-linked polyethylene PEX, the laying is carried out in floor preparation. The calculated parameters of the coolant, based on the technical conditions for such pipelines, are 90-70 (65) °C due to the fear that a further decrease in temperature leads to a significant increase in the heating surface of heating devices, which is not welcomed by investors due to the rising cost of the system. Application experience metal-plastic pipes in the heating system of the complexes was considered unsuccessful. During operation, as a result of aging, the adhesive layer is destroyed and inner layer the pipe “collapses”, as a result of which the flow area narrows and the heating system stops working normally.
Some experts believe that for apartment wiring, the optimal solution is to use automatic balancing valves ASV-P (PV) on the return pipeline and shut-off and measuring valves ASV-M (ASV-1) on the supply pipeline. The use of this pair of valves makes it possible not only to compensate for the influence of the gravitational component, but also to limit the flow rate for each apartment in accordance with the parameters. Valves are usually selected according to the diameter of the pipelines and are set to maintain a pressure drop of 10 kPa. This valve setting value is selected based on the required pressure loss on radiator thermostats to ensure their optimal operation. The limitation of flow per apartment is set by the settings on the ASV-1 valves, and it is taken into account that in this case the pressure loss on these valves must be included in the pressure difference maintained by the ASV-PV regulator. heat supply temperature water heating
The use of apartment-by-apartment horizontal heating systems compared to a system with vertical risers leads to a reduction in the length of the main pipelines (they are suitable only for the staircase riser, and not for the most distant riser in corner room), reducing heat loss through pipelines, simplifying the floor-by-floor commissioning of the building and increasing the hydraulic stability of the system. The cost of installing an apartment-by-apartment system is not much different from standard ones with vertical risers, but the service life is longer due to the use of pipes made of heat-resistant polymer materials.
In apartment heating systems, heat energy metering can be carried out much easier and with absolute clarity for residents. We must agree with the opinion of the authors that although the installation of heat meters does not relate to energy-saving measures, however, payment for actually consumed thermal energy is a powerful incentive forcing residents to use it carefully. Naturally, this is achieved, first of all, by the mandatory use of thermostats on heating devices. The experience of their operation has shown that in order to avoid influencing the thermal conditions of adjacent apartments, the thermostat control algorithm should include a limitation on reducing the temperature in the room they serve to no lower than 15-16 ° C, and heating devices should be selected with a power reserve of at least 15%.
These are the solutions for heat supply and heating systems of the tallest residential buildings built to date. They are clear, logical and do not fundamentally differ from the solutions used in the design of conventional multi-storey buildings less than 75 m in height, with the exception of the division of heating and water supply systems into zones. But within each zone, standard approaches to implementing these systems are retained. Greater attention is paid to installations for filling heating systems and maintaining pressure in them, as well as in circulation lines from different zones before connecting them to a common comb, automatic regulation of heat supply and distribution of coolant to implement comfortable and economical modes, redundant operation of equipment to ensure uninterrupted supply heat consumers.
The disadvantages of the decisions made include ignoring the use of energy-saving solutions, such as partial replacement of energy demand through the use of autonomous energy-producing gas turbine or gas piston units, solar photovoltaic or water heating elements, heat pumps using low-potential soil energy, and ventilation emissions. It should also be noted that there is insufficient use of centralized refrigeration to improve the comfort of living in apartments and eliminate the negative impact on the architecture of the building of external split-system units haphazardly hung on the facade. High-rise buildings, being advanced in terms of architectural and structural solutions, should be an example for the implementation of promising technologies in engineering systems. During the installation and manufacture of units and parts of heat supply and heating systems with water temperatures above 388 K (115 ° C) and steam with a working pressure of more than 0.07 MPa (0.7 kgf/cm).
To protect against electrochemical corrosion and stray currents, fastening devices for metal elements of all systems and passage units through building structures must be electrically insulated. Main pipelines and risers must be grounded. A combination of materials forming an electrochemical couple is not allowed.
The durability of equipment must be at least 12 years, materials - 25 years.
Development project documentation must be preceded by the development and approval of special technical conditions.
Bibliography
1. Anapolskaya L.E., Gandin L.S. Meteorological factors thermal regime buildings. Gidrometeoizdat. Leningrad. 1973.
2.SNiP 21-01-97* "Fire safety of buildings and structures."
3.Shilkin N.V. Problems of high-rise buildings // ABOK No. 6, 1999.
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abstract, added 06/11/2011
Duration of standing intervals of outdoor air temperature according to climatological data of the city of Astrakhan. Calculation of heating modes, heat pump installation in heat supply system mode. Cooling mode of the air conditioning system.
test, added 02/07/2013
Heat supply methods administrative buildings. Schemes and equipment of heating networks. Properties of coolants. Hydraulic calculation of heating network gas pipelines. Characteristics of a gas boiler room, calculation of its parameters depending on the heat loss of the room.
thesis, added 03/22/2018
High-rise buildings and the history of their construction. Building classification criteria. Classification of structural systems of skyscrapers. Features of the technology for constructing high-rise buildings of the shell system. Characteristics of materials required for construction.
essay, added 09/24/2016
Basic requirements for modern industrial buildings. Space-planning solutions for industrial buildings. Types of multi-storey industrial buildings. Cellular and hall industrial building. Unified parameters of one-story industrial buildings.
presentation, added 12/20/2013
Selection, placement and laying of main pipes, risers and heating devices. Placement of shut-off and control valves. Removing air from the heating system. Compensation for thermal expansion of pipes. Calculation of the main and small circulation rings.
course work, added 03/26/2012
Fundamentals of industrial plant design. In-shop lifting and transport equipment. Unification in industrial construction. Modular system and building parameters. Steel frame of one-story buildings. Requirements for walls and their classification.
When designing large-scale heating systems (in particular, calculating the adjustment of the heating system of an apartment building and its full functioning), especially close attention is paid to the external and internal factors of equipment operation. Several heating schemes for central heating have been developed and are successfully used in practice, differing from each other in structure, working fluid parameters and pipe routing patterns in apartment buildings.
Depending on the installation of the heat generator or the location of the boiler room:
Heating schemes depending on the parameters of the working fluid:
Based on the piping diagram:
Autonomous heating systems of a multi-storey residential building perform one function - timely transportation of heated coolant and its adjustment for each consumer. To ensure the possibility of general control of the circuit, a single distribution unit with elements for adjusting the parameters of the coolant, combined with a heat generator, is installed in the house.
An autonomous heating system for a multi-storey building necessarily includes the following units and components:
A practical heating scheme for a residential multi-storey building includes a set of documentation: design, drawings, calculations. All documentation for heating in an apartment building is drawn up by the responsible executive services (design bureaus) in strict accordance with GOST and SNiP. Responsibility for ensuring that the centralized system central heating will be operated correctly is the responsibility of the management company, as well as its repair or complete replacement of the heating system in an apartment building.
The normal operation of the heating of an apartment building depends on compliance with the basic parameters of the equipment and coolant - pressure, temperature, wiring diagram. According to accepted standards, the main parameters must be observed within the following limits:
The choice of piping in a five-story or multi-story building depends on the number of floors, total area building, and the thermal output of the heating system, taking into account the quality or availability of thermal insulation of all surfaces. In this case, the difference in pressure between the first and ninth floors should not be more than 10%.
The most economical option for piping is a single-circuit scheme. A single-pipe circuit works more efficiently in low-rise buildings and with small area heating As a water (rather than steam) heating system, single-pipe wiring began to be used from the early 50s of the last century, in the so-called “Khrushchev buildings”. The coolant in such a distribution flows through several risers to which apartments are connected, while the entrance for all risers is one, which makes installation of the route simple and quick, but uneconomical due to heat losses at the end of the circuit.
Since the return line is physically absent, and its role is played by the working fluid supply pipe, this gives rise to a number of negative aspects in the operation of the system:
In new buildings, the single-pipe scheme has not been implemented for a long time, since it is almost impossible to effectively monitor and account for coolant flow for each apartment. The difficulty lies precisely in the fact that for each apartment in a Khrushchev building there can be up to 5-6 risers, which means that you need to install the same number of water meters or hot water meters.
A correctly drawn up estimate for heating a multi-storey building with a single-pipe system should include not only maintenance costs, but also the modernization of pipelines - the replacement of individual components with more efficient ones.
This heating scheme is more efficient, since in it the cooled working fluid is taken through a separate pipe - the return pipe. The nominal diameter of the return coolant supply pipes is chosen to be the same as for the supply heating main.
The double-circuit heating system is designed in such a way that the water that has given off heat to the apartment is supplied back to the boiler through a separate pipe, which means it does not mix with the supply and does not take away the temperature from the coolant delivered to the radiators. In the boiler, the cooled working fluid is heated again and sent to the supply pipe of the system. When drawing up a project and during operation of heating, the following features should be taken into account:
The pressure parameters in the heating pipes in an apartment building depend on the number of floors, but are in the range of 3-5 Atm, which should ensure the delivery of heated water to all floors without exception. In high-rise buildings, intermediate pumping stations can be used to lift the coolant to the top floors. Radiators for any heating systems are selected according to design calculations, and must withstand the required pressure and maintain the specified temperature.
The layout of heating pipes in a multi-storey building plays a big role in maintaining the specified parameters of the equipment and working fluid. Thus, the upper distribution of the heating system is more often used in low-rise buildings, the lower - in high-rise buildings. The method of coolant delivery - centralized or autonomous - can also affect the reliable operation of heating in the house.
In overwhelming cases, a connection is made to the central heating system. This allows you to reduce the current costs in the estimate for heating a multi-storey building. But in practice the level of quality of such services remains extremely low. Therefore, if possible, preference is given to autonomous heating multi-storey building.
Modern new buildings are connected to mini-boiler houses or to centralized heating, and these schemes work so efficiently that it makes no sense to change the connection method to autonomous or another (communal or apartment-by-house). But the autonomous scheme gives preference to apartment-by-apartment or house-wide heat distribution. When installing heating in each individual apartment, autonomous (independent) pipe distribution is carried out, a separate boiler is installed in the apartment, control and metering devices are also installed for each apartment separately.
When organizing a common house wiring, it is necessary to build or install a common boiler room with its own specific requirements:
In a communal heating system, heat consumption is monitored and metered apartment by apartment. In practice, this means that a meter is installed on each coolant supply pipe from the main riser.
If you connect the pipes to the central heating supply, what difference will there be in the wiring diagram? The main working unit of the heat supply circuit is the elevator, which stabilizes the liquid parameters within the specified values. This is necessary due to the long length of heating mains in which heat is lost. The elevator unit normalizes temperature and pressure: for this, in the heating station, the water pressure is increased to 20 Atm, which automatically increases the temperature of the coolant to +120 0 C. But, since such characteristics of the liquid medium for pipes are unacceptable, the elevator normalizes them to acceptable values.
The heating point (elevator unit) operates both in a double-circuit heating system and in a single-pipe heating system of a multi-apartment high-rise building. Functions that it will perform with this connection: Reduce working pressure liquids using an elevator. The cone-shaped valve changes the flow of fluid into the distribution system.
When drawing up a heating project, do not forget that the estimate for installation and connection of centralized heating to an apartment building differs from the costs of organizing autonomous system to a lesser extent.
