this paper focuses on the air conditioning design of this project, and gives the main design parameters and air conditioning system forms. The design experience is summarized according to the application effect.
1. General situation of the project
This project is a commercial and residential community, with a total land area of 38,319.4 square meters and a total construction area of 148,145.31 square meters. There are 5 23-storey high-rise residential buildings, 2 office buildings, 1 ~ 3-storey podium businesses and a 4-storey kindergarten in the site, among which, the towers of high-rise residential buildings are all about 69.95～71.25m in height.
2. Interior design parameters and ventilation design parameters
(1) Interior design parameters
(2) Ventilation design parameters
3. Air conditioning system design
3.1 The centralized commercial building area of some podium buildings in the office building of this project is about 17327.72m2, and central air conditioning system is adopted, with the total cooling load of 3465kW, and two sets of 1647kW are selected for water cooling. The average cooling load index is 1.93 W/m2.
3.2 split air conditioners are used in shops, houses, office buildings and kindergartens, and electricity consumption is reserved by electrical professionals.
3.3 chilled water system of air conditioner
Cold water is a primary pump variable flow system. The cold water cooled to 7℃ by the water chiller enters the water separator, and the cold water is sent to each terminal equipment according to their respective air conditioning ranges. The backwater at 12℃ flows into the water collector, is pressurized by the cold water pump through the water filter and electronic rust-proof descaler, and then returns to the water chiller. Horizontal pipes and risers are different programs. Each backwater riser is equipped with a static balance valve. The expansion water tank is located on the roof of the main building of Building 4, and its supplementary water comes from the water supply pipe. Overflow and sewage are connected to the roof drain. Automatic exhaust valves are set at the high point of the system, and water and sewage valves are set at the low point of the system.
3.4 cooling water system of air conditioner
The cooling water heated to 37℃ by the water chiller is sent to the cooling tower for cooling, and the water temperature is reduced to 32℃. After passing through the water filter and electronic rust-proof descaler, it is pressurized by the cooling water pump and then returned to the water chiller. Connecting pipes with shut-off valves are arranged between the water trays of the cooling tower, and the supplementary water comes from the high-level water supply tank, and the overflow and sewage are connected to the roof drainage ditch. Drains and collecting wells are arranged in the refrigerating machine room to eliminate the sewage, emptying or accidental water leakage of frozen water and cooling water.
3.5 air system
The supermarket on the first floor underground and the first to third floors of the podium adopt all-air constant air volume system.
The first basement and the third basement are commercial buildings, and centralized return air is adopted: indoor return air and outdoor fresh air are mixed in the wind cabinet, filtered by the wind cabinet, cooled by the coil, dehumidified and pressurized by the fan, and then sent to the room through the 71℃ fire valve duct and diffuser. Return air adopts centralized return air in the machine room. In order to save energy, outdoor fresh air should be used as much as possible in the excessive season. The fresh air inlet and its passage are all equipped with fresh air, and the air cabinet adopts the air cabinet with heat recovery, which can use the exhaust heat to precool the fresh air. The wind cabinet is located in the wind cabinet room, and the condensed water is discharged into the floor drain located in the wind cabinet room.
4. Design of ventilation, pressurized air supply and smoke control system
4.1 The 4# and 5# office buildings in this project belong to a class of public buildings, and mechanical positive pressure air supply systems are respectively provided for the smoke control stairwell and its front room or shared front room.
4.2 buildings 1#, 2#, 6#, 7# and 8# in this project can meet the requirements of natural smoke exhaust, so the stairwell and front room are windowed for natural smoke exhaust. For the smoke-proof stairwell and its front room or shared front room which cannot meet the requirements of natural smoke exhaust in this project, a mechanical positive pressure air supply system is set respectively, and a positive pressure fan is set on the first floor.
4.3 the first and second floors of the underground of this project are respectively provided with mechanical positive pressure air supply systems for smoke-proof stairwells and their antechambers or shared antechambers, which cannot meet the natural smoke exhaust conditions. The air volume is 16111CMH and 24111CMH respectively, and the fan is placed on the first floor.
4.4 residual pressure requirements of mechanical pressurized air supply system: a. smoke-proof stairwell: 41Pa to 51Pa,
b. front room, shared front room and fire elevator front room: 25Pa to 31Pa.
4.5 In this project, some shared forerooms have windows with a total area of more than 3m2. According to the relevant provisions of natural smoke exhaust in GB51116-2116, this kind of shared forerooms can adopt natural smoke exhaust.
4.6 In this project, there are smoke-proof stairs close to the external wall, and each floor has windows with a total area of more than 2m2. Therefore, according to the relevant provisions of natural smoke exhaust in GB51116-2116, In this project, this kind of smoke-proof staircase can adopt natural smoke exhaust method
4.7. Independent mechanical exhaust and smoke exhaust system and corresponding air supply system are set up for the underground parking garage according to the fire zone, and the smoke exhaust amount is not less than 6 times/hour. Each basement garage is equipped with mechanical exhaust system and smoke exhaust system, and the air exchange rate is 6 times/h. The fan is cabinet fan and hoisted in the machine room. There is no natural air supply at the entrance and exit of the driveway, and all fire zones are equipped with mechanical air supply system, and the air supply volume is designed to be no less than 3 times/h.
4.8 the power distribution room and generator room are equipped with mechanical exhaust system, which is used together with the exhaust system after gas fire extinguishing. The ventilation pipe is equipped with an electric fire damper, which is normally open, electrically closed before gas fire extinguishing, and electrically or manually opened at a long distance after fire extinguishing. Use explosion-proof fan for hoisting.
4.9 mechanical smoke exhaust system and mechanical air supply system are set in the basement equipment room and the inner walkway;
4.11 The skirt building of the office building shall be equipped with a smoke exhaust system according to the fire prevention zones, each smoke prevention zone shall have an area of not more than 511m2, and an independently controlled smoke outlet shall be provided, and the smoke exhaust quantity shall be calculated at not less than 61m3/h per square meter.
4.11 Independent mechanical smoke exhaust systems shall be set up for the inner walkways that cannot meet the requirements of natural smoke exhaust, and the smoke exhaust quantity shall be calculated at not less than 61m3/h per square meter.
4.12 the underground water pump house is equipped with an independent air supply and exhaust system, and the axial flow fan is used for hoisting.
4.13 the underground refrigerator room is equipped with an independent air supply and exhaust system, and the axial flow fan is used for hoisting.
4.14 The exposed part of the fan transmission device and the inlet and outlet of the fan leading to the atmosphere must be equipped with a protective cover (net) or other safety measures.
4.15 The wind speed of the mechanical pressurized air supply system pipeline, the smoke exhaust system pipeline and the air supply pipeline should meet the following requirements:
1. When using metal pipelines, it should not be greater than 21m/s;
2. When nonmetallic pipes are used, they should not be greater than 15m/s;
5. Automatic control of air conditioner:
5.1 System control:
(1) Chiller control: controlled by the microcomputer of the chiller itself.
(2) machine, pump and tower control: there are running water switches on the cold water and cooling water outlet pipes of water chillers, electric on-off valves on the cold water and cooling water return pipe of water chillers, and electric on-off valves on the water inlet pipes of cooling towers. The startup procedure is: each electric valve is opened → the cooling tower fan is started → the cooling water pump is started (the cooling water running switch is closed) → the cold water pump is started (the cold water running switch is closed) → (delayed) the main engine is started.
the shutdown procedure is the opposite.
(3) machine, pump and tower group control: temperature sensors are installed on the cold water main supply pipe and return pipe, and flow sensors are also installed on the cold water main supply return pipe. Through the above-mentioned cold water flow and the temperature difference between supply and return water, the microcomputer calculates the cooling capacity of the system, which is compared with the set value of the designed software to determine the optimal number of main engines to start and start the matching pumps and towers.
items (2) and (3) above can also be controlled by the manufacturers.
5.2 bypass valve group of cold water system: in order to solve the contradiction between the constant flow operation of water chillers and the variable flow operation of terminal equipment, a bypass valve group with bypass valve controlled by the pressure difference between main water supply and return water is set in this design.
5.3 Control of the air cabinet:
(1) Use the return air temperature of the air cabinet to control the water flow rate of the electric three-way valve (proportional and integral) located in the air cabinet refrigeration return pipe to maintain the indoor set temperature.
(2) The motor frequency conversion device of the fan is equipped, so as to change the speed of the fan according to the control requirements and achieve the purpose of changing the air volume and saving energy (the frequency converter has an interface for accessing the return air temperature signal).
6. Requirements for pipe equipment
6.1 Air ducts are made of galvanized iron sheets, and each section of air ducts is connected by flanges, with 8511 sealant tape between the flanges. When the diameter of water pipe is less than or equal to DN51, galvanized steel pipe and threaded connection shall be adopted; When the pipe diameter is greater than DN51, seamless steel pipes shall be used for welding, and flanges shall be used for connection where maintenance and replacement are required.
6.2 the exhaust fan shall be able to work continuously for 31min at 281℃.
6.3 The thickness of galvanized steel plate for air duct of air conditioning, ventilation and smoke control system is shown in the following table:
7. Energy-saving design requirements
7.1 Water-cooled screw chillers with high energy efficiency ratio are selected for the refrigeration unit, and the COP values are higher than 5.22 at full load and partial load, which meets the requirements of "Design Standard for Building Energy Efficiency".
7.2 the water pump adopts high efficiency and energy saving; The energy efficiency ratio (ER) of central air-conditioning water system is 1.12149, which meets the requirements of "Design Standard for Building Energy Efficiency".
7.3 The air conditioning cabinets in the podium are all air conditioning cabinets with heat recovery;
7.4 the fans shall be highly efficient and energy-saving, with the maximum power consumption per unit air volume ws = 1.28 <; 1.32W/（m /h）。 The large bay adopts cabinet air conditioning terminal, which can run in fresh air in transition season.
7.5 all bathrooms are equipped with exhaust air; Noise elimination and noise reduction measures shall be taken for the fan room, air conditioning room and fresh air room usually used.
7.6 some parts that need to be exhausted at the same time adopt total heat exchanger, which can eliminate indoor exhaust gas and recover the energy of exhaust air. Total heat recovery efficiency >: 61%.
7.7 Thermal resistance of air-conditioning duct insulation layer: 1.16 m k/w < P > 7.8 Cold water supply to return pipe needs non-combustible or flame-retardant materials for insulation. See the construction drawings for material selection. If flame-retardant materials are used for insulation, the outer surface needs to be protected by non-combustible materials. The thickness of insulation layer is proposed by the product supplier and checked and approved by the design institute.
this design selects the flame-retardant rubber sponge with the thickness of DN71～DN151 and the thickness of 35mm
> DN211 thickness: 41mm
air conditioning condensate pipe thickness: 21mm
7.9 Strictly implement the relevant national energy-saving codes, and meet the building's thermal insulation performance and energy-saving requirements from the architectural design.
7.11 natural ventilation is used as much as possible in the design.
7.11 the number of fans to be turned on in the underground garage according to the usage.
8. Noise treatment (environmental protection and energy saving)
8.1 All vibrating equipment, such as fans, shall be provided with vibration-damping bases or vibration-damping hangers; A flexible damping joint is arranged on the connecting pipe connected with the equipment.
8.2 The flue gas of diesel generator is equipped with a purification water tank for cooling and dust removal, and discharged to the roof of residential tower.
8.3 automatic and manual shut-off valves shall be set in the fuel flue of the generator set before entering the building and in the equipment room. The oil tank in the oil storage room shall be sealed, and a vent pipe leading to the outside shall be set. The vent pipe shall be provided with a breathing valve with a flame arrester.
9. Conclusion:
The design of building smoke control and exhaust is a complicated link in building fire protection design, and it is also the focus of building life safety system. Designers and construction managers of all disciplines must cooperate closely to strengthen the awareness of fire protection, so that the building air conditioning and ventilation system can meet the requirements of people's use and achieve the effect of fire prevention and safety.
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