1. Design position of water pump in the system:
Generally speaking, the chilled water pump should be located at the front end of the chiller, and the chilled water coming back from the end will be pumped back to the chiller through the chilled water pump; The cooling water pump is arranged on the water path where the cooling water enters the unit, and the cooling water from the cooling tower is pumped back to the unit through the cooling water pump; The hot water circulating pump is arranged on the backwater main pipe, and the hot water returned from the end returns to the plate heat exchanger through the hot water circulating pump.
2. Valve design on cooling tower:
2. Add an electromagnetic valve to the water inlet pipe of 1 cooling tower (manual valve is not recommended).
2, 2 pipeline drain valve should be set indoors, (if placed outdoors, because there is some water in the pipeline, it is easy to freeze in winter).
3. The installation position of the electronic water treatment instrument is placed behind the water pump and in front of the main engine.
4. Pressure gauges before and after the filter valve and filter.
5. Valves before and after the water pump
5. 1 The inlet pipe of the water pump is connected in sequence: butterfly valve-pressure gauge-soft connection.
5.2 Connection sequence of water pump outlet pipe: soft connection-pressure gauge-check valve-butterfly valve.
6. Distribution manifold
6. Add an electric differential pressure bypass valve and a bypass pipe (generally DN50 in diameter) between 1 distribution manifold.
6. A thermometer should be installed on the return pipe of the water collector.
7. Location of various instruments: Thermometers, pressure gauges and other measuring instruments should be arranged in places convenient for observation. The height of the valve from the ground is generally 1.2- 1.5m, and a working platform should be set up.
8. Unit location: the distance between the protruding parts of the two compressors is less than 1.0m, the distance between the refrigerator and the wall and the distance between the non-main channels is not less than 0.8m, and the distance between large and medium-sized refrigeration units (centrifugal, screw and absorption refrigerators) is1.5-2.0m. It is better to reserve a hook for lifting the largest part or set up electric lifting equipment at the upper part of the refrigeration room of the refrigeration unit.
(2) Summary of waterway design problems
Question 1: The slope of water pipes should be reasonable.
1, horizontal branch pipes and main pipes, with a slope of not less than 0.002 along the water flow direction;
2. The slope of the water tray drainage branch pipe of the unit shall not be less than 0.0 1.
3. Due to conditions, it can be laid without slope, but the pipeline velocity shall not be less than 0.25m/s. ..
Question 2: Design of condensate main pipe
1, condensed water should be discharged nearby, usually in the bathroom floor drain.
2. The length design of condensate main pipe should consider the height caused by slope, and the height difference between the two ends of the pipe should not be greater than the ceiling height.
Question 3: Choose the appropriate pipeline valve.
1, and the regulating valve is installed at the joint of riser and horizontal pipe.
3. Exhaust devices should be installed at each highest point of the water pipeline (at the end of the horizontal pipe flow when there is no slope).
3. The lowest part of the riser is connected with a cut-off valve, which is convenient for maintenance. 4. The thermal compensation of water pipes can be naturally compensated by elbows, and an expansion compensator can be added when it is insufficient.
Question 4: Water pipe layout
1, the riser should not be misplaced in the pipeline well, but should be placed by the corner against the wall.
2. Pipes are prohibited from crossing stairs, shear walls and power distribution rooms in the horizontal plane.
Question 5: Water pipe insulation
1 Thermal insulation structure generally consists of thermal insulation layer and protective layer.
2 The thickness of insulation layer shall be determined according to thermal calculation. For the experience value, please refer to P279 of Air Conditioning Design for Civil Buildings.
3 thermal insulation materials can be adapted to local conditions and taken from the nearest place. Non-combustible or flame retardant materials shall be used, which must conform to the code for fire protection design of buildings.
Question 6: Hydraulic calculation
1 The pressure loss difference of each parallel loop of air conditioning water system should not be greater than15%;
2 The specific friction resistance of water pipelines should be controlled at100-300 Pa/m..
Question 7: Water system replenishment
1 the make-up water of air conditioning water system should be treated with softened water, and the electronic water treatment instrument can only be used in the refrigeration system in summer;
2. The system water supply is 2% of the system water capacity.
3 water supply point should be located in the suction section of circulating water pump.
(3) Problems needing attention in wharf design:
1. tuyere design of air duct fan tray.
1) The distance between the first air supply outlet and the air outlet of the fan disc should be appropriate;
2) The fan tray air supply pipe with two air outlets should be reduced in diameter;
3) The distance between the air supply outlet and the air return outlet of the fan disk should be appropriate. (≤ 5m)
2. Design of inlet and outlet pipes of fan coil unit.
1) The inlet and outlet pipes are "upward and downward";
2) The relative elevation between the fan tray and the main supply return pipe is not less than 200mm；;
3) the water inlet pipe is sequentially connected with a filter, a gate valve and a soft joint;
4) The water outlet pipe is connected with the soft joint and the gate valve.
3. Determination of the number of air outlets of the same type of fan disk
The number of air outlets of the same type of fan disk can be determined according to the different air conditioning areas.
4. The two small rooms are organized by the airflow of the fan tray.
Two small rooms use a fan tray, each room can be provided with an air outlet, and the air return ports of the two rooms can be connected in series to the air return ports of the fan tray.
5. Arrangement of the fan tray near the window:
In order to resist the infiltration of outdoor cooling load, the fan coil units should be arranged as close as possible to the external walls and windows.
6. Layout of fan coil in large space:
When arranging fan coils in a large space, it is advisable to adopt the air distribution mode of "air return in the middle and air supply on both sides", as shown in the attached figure 1-6.
7. Arrangement of embedding machine
When installing the embedded device, the distance from the side wall should not be greater than 3m;
When arranging embedded machines, such as meeting rooms and multi-function halls, multiple machines with small refrigeration capacity should be selected and arranged evenly.
8. Internal machine selection:
Embedded machines can be used in large spaces, and card machines are best used in rectangular offices.
9. tuyere selection
Diffuser is not suitable for air supply in high space (the wind should not reach the working area), and it is best to use adjustable double-layer louver air supply outlet.
10. Back to the bellows:
Return air design of air processor: make a relatively large return air box at the return air place, and open a return air outlet at one side of the return air box, which can adjust the air volume and reduce noise), as shown in the attached figure 1-7.
1 1. Design an appropriate fan tray according to the room function and cooling load.
The selection of fan tray should be based on the design load, and the layout of fan tray should consider the characteristics of air-conditioned room and be as beautiful as possible. (See attached figure 1-8)
(4) Matters needing attention in wind system design:
1. The distance between the air outlet and the air outlet should be appropriate.
Keep a distance of at least 3 meters between the air outlet and the air supply outlet to prevent short circuit of air flow.
2. Select the appropriate air valve.
In principle, the error of wind pressure balance of the system is within 10%- 15%, and there is no need to set a regulating valve, but in fact it is very difficult to adjust the wind pressure only by the size of the air duct, and it is necessary to set a air volume control valve to adjust it.
(1) The air duct branch pipe shall be provided with an air flow control valve. The three-way regulating valve can be arranged at the three-way branch or at the branch.
(2) obviously unfavorable loop can not set regulating valve, in order to reduce the resistance loss.
③ Fire dampers can be used instead of control valves where fire dampers are needed; (4) The louver tuyere at the air supply outlet shall be provided with a control valve; For those with low requirements, double louver tuyeres can be used, and the air volume can be adjusted by adjusting the tuyere angle.
⑤ The fresh air inlet should be equipped with an air valve that can be tightly opened and closed, and a heat preservation air valve should be installed in cold areas. When there is automatic control, electric air valve should be used.
3. Arrangement of air ducts.
① Minimize local resistance, that is, reduce the number of elbows, tees and reducers.
(2) The radius of curvature at the center of the elbow should not be less than the diameter or side length of the conduit, which is generally available.
1.25 times diameter or side length
(3) In order to facilitate the adjustment of the air duct system, pressure taps should be reserved before and after the branch points of the main pipeline. The distance between the pressure measuring hole and the local pipe fittings in front should be greater than 5b(b is the long side of rectangular duct or the diameter of circular duct), and the distance between the pressure measuring hole and the local pipe fittings in rear should not be less than 2b. Pressure measuring holes should be reserved on the pipe section with stable airflow at the outlet of ventilator.
4. Location of fresh air inlet
(1) The air inlet should be located in a place where the outdoor air is relatively clean to ensure the air quality.
(2) It should be located in the north wall, avoiding the roof and the west wall, and should be located in the shade of the building, so that the outdoor air temperature inhaled in summer can be lower.
(3) The bottom of the air inlet shall not be less than two meters away from the outdoor ground. When the air inlet is arranged in the green belt, it should not be less than one meter.
(4) It shall be arranged on the windward side of the exhaust port as far as possible and below the exhaust port, and the spacing shall be kept at least10m as far as possible.
5. Requirements for new tuyeres
(1) Fixed shutters should be adopted.
② Waterproof shutters should be used in rainy areas to prevent rainwater from entering.
(3) In order to prevent birds from entering, a metal mesh should be set in the blinds.
6. The new practice of exhaust pipeline
The design of the exhaust system for similar hotel rooms can be considered as follows: the indoor air is discharged into the ceiling of the corridor by using an exhaust fan, and an exhaust pipe is installed in the corridor to exhaust air. In order to effectively use the waste heat, an exhaust fan can be installed in the bathroom.
Illustration:
7. Distance between tuyere and sidewall
The distance between the tuyere and the wall should not be less than1m.
8. Selection of tuyere.
(1) The new air outlet and air supply outlet adopt double louver air outlets.
(2) the return air grille tuyere.
③ Double louvers at the air outlet.
(4) Because the air volume of fluorine system is generally small, if heating is needed in winter, double louvers should be used instead of diffusers.
⑤ When the fan-coil unit has two tuyeres, double louvers with regulating valves should be selected.
9. tuyere condensation
Dew condensation at tuyere is due to small tuyere and low temperature. The size of the tuyere can be increased to prevent condensation.
Illustration:
10. Calculation of static pressure box
(1) The wind speed controlled by the plenum should not be greater than1.5m/s.
(2) The cross-sectional area of the air outlet is A=G/V(G is the air supply volume), and the cross-sectional areas in all directions should be the same.
③ In general systems, tuyere reducer and muffler can be used to replace the static pressure box.
1 1. Determination of ventilation times of smoke control and exhaust.
(1) between fire pumps is not less than 4 times.
(2) the transformer room 5-8 times
(3) substation room 5-8 times.
12. Layout of smoke outlet.
(4) When the corridor is more than 60 meters, do smoke exhaust.
⑤ The elevator front room adopts a normally open multi-leaf air supply outlet, one on each floor.
⑥ The stairwell adopts self-hanging louver tuyeres, one for each floor 2-3.
13. Air pressure state of the room.
(1) The air-conditioned room in the building should maintain positive pressure.
(2) The toilet, bathroom and various equipment rooms in the building should be kept under negative pressure.
(3) The hotel room should be kept under positive pressure, and the bathroom should be kept under negative pressure.
(4) Positive pressure should be maintained in the dining room lobby and negative pressure should be maintained in the kitchen. The air pressure in the dining room should be between the front hall and the kitchen.
14. Layout principle of air duct in ceiling
From top to bottom: smoke exhaust duct, exhaust duct, air supply duct and water pipe.
15. Relative position of air supply outlet and air exhaust outlet
When the air supply and exhaust pipes in air-conditioned rooms are arranged in parallel, the air supply and exhaust ports should not be arranged in parallel as far as possible, and it is best to stagger them.
16. Design of air supply pipeline:
Try to avoid the reverse flow of wind in the air supply pipeline and ensure good airflow and air outlet effect in the pipeline.
17. Lapping of tee and air duct:
The pipe diameter connected with the tee pipe shall be consistent with the diameter of the tee pipe, and the diameter shall not be changed to avoid excessive local loss.