1 1. Composition of HVAC system
5( 1) HVAC system is mainly composed of refrigeration system, cooling system and condensation system. The refrigeration system is involved in cooling.
7 heat exchange, the main system realizes refrigeration and heating; The cooling system is a system for cooling the running host; The condensing system is
7. System for collecting and discharging condensed water in the system.
The final device of 7-terminal cold and heat exchange. After cold and heat exchange, it enters the main engine of cold and heat source through the backwater pipeline in the transmission and distribution system for recycling.
1 cycle, more than 95% of HVAC systems are closed cycle systems.
4 Second, cold and hot.
3. The host generates cold and hot, and the terminal releases, in which cold and hot media are needed as carriers. Hot and cold medium
5 can be steam, water, glycol solution, etc. Water is mainly used in HVAC systems.
4 hot and cold L=QxOT= flow multiplied by temperature difference.
0=, constant flow and variable flow
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Draw the pressing surfaces of the mouth separator and the mouth filter.
(2) The main engine side energy saving is to realize the change of the number of main engine start-ups through the bypass flow of the differential pressure bypass valve. if
When the bypass flow of the differential pressure bypass valve reaches the main engine flow, notify the control system to shut down the main engine. But in the open Lord
The temperature difference between them is constant, and we mainly rely on changing the system flow to realize the change of refrigeration capacity.
(4) If the user adopts a constant flow system, that is, no electric valve is installed, variable air volume (changing the fan speed) is adopted.
Small) to adjust the indoor temperature; Or install an electric three-way valve to realize constant flow. Constant current system, the initial investment of the owner is small,
But it doesn't save energy. The system always runs at the maximum flow, and the running cost is high.
(5) The actual demand for cooling capacity at the user side will change with the number of users (switches) or the change of ambient temperature (settings).
Constant temperature changes, resulting in valve opening changes, causing flow changes). At this time, the change can be realized by installing an electric two-way valve.
Flow, to achieve the purpose of energy saving.
Four, primary pump system and secondary pump system
(1) primary pump system (also known as primary secondary circulation)
The main engine, auxiliary water pump and cooling tower are in a corresponding relationship:-A main engine is equipped with a main water pump and a cooling tower.
By installing an electric two-way valve, the bypass pipeline realizes the constant flow on the host side and the variable flow on the user side, so: the host and the primary water
The pump runs at a constant flow rate, and the number of the main engine and the pump is adjusted by the automatic control system through the change of the flow rate at the user end, so as to realize energy saving.
The process of adjusting the number of main engine and water pump;
A. Through the electronic differential pressure bypass valve (Note: A800 self-operated differential pressure bypass valve cannot be used at this time, because A800 cannot.
Feedback differential pressure electric signal), the differential pressure sensor transmits the electric signal of the working differential pressure in and out of the water to the control system of the host computer or water pump.
System. We assume that when the number of users decreases, the flow through the user side decreases, the differential pressure bypass valve automatically opens and the flow increases.
You can turn off the host to save energy. On the other hand, when the feedback AP of the differential pressure sensor drops to △Pmin, the control
The system can start the host.
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Through the flowmeter installed in the bypass system (A800 can be used at this time), the meteor meter feeds back the Huang Liu signal to the host and.
When the flow of the bypass system reaches the running flow of the main engine, the water pump control system shuts down the main engine; When the bypass system
When the system traffic is less than the minimum traffic required by the current host, restart the host.
1 ...
(2) Secondary pump system (secondary circulation system)
Secondary pump system is widely used in high-rise buildings, mainly considering a wide range of user flow. In order to save more energy, it is necessary
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-The secondary pump is a constant current system and must be a constant frequency pump; The secondary pump can choose frequency conversion pump.
The number of primary pumps is controlled by the flow profit and loss mode of bypass system: when the flow demand at the customer end decreases, the secondary pumps pass.
Verb (abbreviation for verb) valve of main pumping station
Of course, our understanding of the system mainly depends on the valves used in each system.
Automatic switching of cooling or heating, see remarks),
Remarks: Two controls mean that the transmission and distribution system has only one set of pipes, which provide cooling in summer and heating in winter, and is suitable for China.
Emotion and economy are the main applications now, so the two control systems are mainly used for air conditioning supply in summer and winter, spring and autumn.
It is necessary to switch the air conditioner; Four-control system refers to a heating and cooling transmission and distribution system. In a large-scale project, it consists of
In season, the core area inside the building may need to be cooled down, so the four control systems supply cold and heat all year round, which is suitable for super-large buildings.
The initial investment of the project and the places where air conditioning must be supplied all the year round are very high. )
note:
Large-diameter short-body silent check valve
Valve. At this time, if a manual regulating valve (also called a static balancing valve) is installed, it is unnecessary to install a dynamic balancing valve.
If the check valve at the outlet of the water pump is not equipped with a manual regulating valve, a dynamic balancing valve must be installed to protect the water pump and the main engine to ensure that
It operates under rated flow conditions.
It is a better scheme to replace check valve and flow regulating valve with constant current multifunctional valve. While saving space.
At the cooling tower, it is strongly recommended that the design institute choose the electric butterfly valve. If the number of hosts is turned off, the cooling tower cannot be used at the same time.
Closed, it will waste energy and reduce the cooling efficiency; Selecting dynamic balance valve can also improve cooling efficiency.
6. If the main engine and water pump have control requirements, the differential pressure bypass valve shall adopt electronic differential pressure controller. (The caliber is above 200.
This function can be realized by electric adjustable butterfly valve, which has small installation space and low price.
6. Problems easy to occur in HVAC construction
If the quality management is not strict in the construction process, it is easy to cause serious consequences in the use process. This requires our scientific application.
Work, strict management, the whole construction process, closed monitoring.
Positioning and elevation crossing of pipelines and equipment
1. 1 Comprehensive design principle of pipeline engineering
According to the different performances and uses of pipelines, pipelines in buildings can be roughly divided into the following categories:
1. Water supply pipeline: including domestic water supply, fire water supply and production water;
2. Drainage pipes: including domestic sewage, domestic wastewater, fire fighting drainage, rainwater and other drainage;
Reclaimed water pipeline: including reclaimed water collection and supply;
4. Thermal pipeline: including steam or hot water needed for heating, hot water supply, air conditioning and air handling equipment;
Gas pipeline: gas fuel and liquid fuel;
6. Air duct: including all kinds of air ducts in ventilation engineering and air conditioning system, as well as compressed air required by some production equipment.
Power supply and distribution lines or cables: including power distribution, lighting distribution, weak current system distribution, etc. , in which the weak current part includes * * *
1.2 Attention should be paid to the design of air duct.
The height of the ceiling depends largely on the size of the duct section in the height direction. The air duct route should not be too long, otherwise the construction will be very difficult.
Large, other pipelines are also difficult to arrange. For example, the largest cross-sectional area of the air duct in a shopping mall is 2400mmx500mm, and the cross-sectional area of the air duct is large.
The computer room must be big, and the noise is also big when the computer room is big, and it is difficult to organize the return air. If the air duct runs insufficiently, the power of the fan may be small.
Yes, you can choose to hang the horizontal unit at this time, and the computer room is more flexible. In addition, the air duct laid in the ceiling should also:
Try to change the cross-sectional size of the pipeline according to the change of air volume, so as to facilitate the decoration and locally increase the height of the ceiling;
Comprehensive design of pipeline engineering should be carried out for all kinds of pipelines in buildings, and comprehensive details of pipelines should be provided for complex buildings.
To sum up, it takes a lot of efforts to improve the ceiling height.
Coordinate with each other. Under the unified coordination of the construction unit, each construction unit and decoration unit finally unified control to meet their respective requirements.
Artistic requirements, in order to make the building meet the requirements of economy, rationality, hygiene and comfort, and improve the suspension under the premise of ensuring the decorative effect.
Maximum height.
Second, the HVAC equipment noise exceeds the standard.
Noise-splitting symphony
Excessive operating noise of air conditioning terminal equipment is a common problem in HVAC engineering. Because the fan coil technology is relatively successful
Familiar with, many domestic manufacturers' fan coil products can meet the noise standard, but the situation of Dafeng Star air conditioning unit is not satisfactory.
The measured noise value is much higher than the product sample parameters provided by the manufacturer.
2. 1 Equipment installation
Sound treatment, such as using sound insulation materials as enclosure structure in air-conditioned rooms to prevent the noise of equipment from being transmitted to the outside or to the room.
Sticking sound-absorbing materials: using concave-convex sound-absorbing board as the wall or ceiling of the computer room to enhance the sound-absorbing effect; The computer room should be as small as possible.
Set up doors and windows. Sound-absorbing doors and windows or sound-absorbing shutters should be used to minimize equipment noise.
22 water system installation
If it can't be fixed on the floor, it should be fixed on the beams as far as possible, or a channel beam should be erected between the beams to fix it. The water pipe runs through the floor.
23 Installation of air system
Impedance silencers should be installed at the inlet and outlet of the fan, silencing louvers should be used at the inlet of fresh air, and silencers and air ducts should be arranged in appropriate positions.
The elbow is equipped with muffler elbow, and the outside of the air conditioner fresh air muffler is insulated with high-quality thermal insulation material, similar to the static pressure box.
Paste high-quality sound-absorbing materials inside. Because the return air duct uses low wind speed and large air volume to reduce noise, the cross-sectional area of the duct is relatively large.
If the installation strength and overall stiffness of the air duct are not enough, friction and vibration noise will occur. It is recommended to use duct hangers as much as possible.
Rubber damping pad ensures that the air duct will not produce vibration and noise.
Circulation problem of three-gas water delivery system
Action at two o'clock. "Electricity 58 L will do.
Water system is the most critical link in construction, and problems will directly affect the normal operation of the system. Central air conditioning cold water system is the most common.
Good, causing a lot of gas praise in the pipe network, affecting the circulation of the pipe network; Second, the air conditioning water system pipeline was not cleaned, so it was done directly.
Aiming at the problem of 1, the solution is to strengthen the management before construction, reasonably arrange the elevation and slope of the pipeline, and try to avoid it.
Before the equipment is connected, the equipment should be cleaned by stages in combination with the water pressure test. After the cleaning work is completed, the water system circulation test should be carried out.
Operation, the purpose of which is to concentrate the sewage flushing in the pipe network on the filter, and then disassemble and clean the filter to remove the sewage.
Four condensation and dripping problems
There are many reasons for condensation and dripping in the debugging and operation of air conditioning system, which can be summarized as follows: pipeline installation and heat preservation
The solution to the problem is to drain the nearby condensed water as much as possible to avoid water accumulation in the condensed water pipeline or "fighting" with hanging items.
Phenomenon; The condensed water pipeline of the cabinet machine should be sealed according to the negative pressure inside the machine, so that the condensed water can be discharged smoothly.
The main methods to solve the above problems are:-strengthening the inspection of thermal insulation materials and strengthening the technical disclosure and construction before construction.
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