Do you know what are the main factors that affect the operation of the air source heat pump system host?We know that in air source heat pump heating and cooling systems, different types of indoor loads are usually docked. This is also the place where air source heat pumps are significantly different from other heat sources. For example, central air conditioning usually only needs to be connected to the air pan, while air source heat pumps will For ground heating, fan coils, radiators, etc., and other radiant cooling terminals. When the air source heat pump is connected to different ends, as a designer and an installer, there will be such a question. In the case of stable work, the system will be very efficient? What factors will affect the efficiency of the work? To answer these two The problem also needs to return to the design of the heat pump itself.
When designing an air source heat pump, there will be a working condition, including the ambient temperature, water flow, water temperature, etc. at the time of design. The best working point of the air source heat pump is debugged under this working condition. It is actually a Variable conditions. The water flow rate is an important parameter of the air source heat pump system. It is a design condition that must be determined in every air source heat pump system. The same output capacity, different water flow rates, may be different in the selection of heat exchanger size, evaporation temperature and The condensing temperature is also different, and these factors will affect the operation of the air source heat pump. A simple estimate can be made. If the water flow is reduced by 20% and the evaporation and condensation temperatures remain unchanged, the evaporator may increase by 20%-30%. In the application, it is hoped that the water flow is sufficient, and the running water flow is greater than the designed water flow, because the water flow is too small, which will affect the power consumption of the heat pump.
Under the guidance of this kind of thinking, when doing a system design, it is difficult to accurately calculate the resistance characteristics of the end load, especially when different types of ends have many features such as valves, elbows and filters.
Because of this design tendency and consideration, when the water pump is selected, the flow rate is often small. In addition to the reduced efficiency of the air source heat pump, if the deviation is too large, it will also cause the exhaust temperature to rise, high pressure protection, etc. It even causes the heat exchanger to freeze or freeze.
In order to protect the unit, a water flow switch is usually added, most of which use the chip type and the press brake type. After the water flow switch is added, the protection is increased for the heat pump unit, but it also brings another problem. When the flow rate is small, how to ensure the scientific operation of the entire system, such as only a part of the indoor end, how to meet the requirements of the host? In the primary system, the large system usually uses a differential pressure bypass valve, and the small system can be without a valve. For flow control, a three-way valve can also be installed.
In the heating system, if the end of the room is not in use, it is okay not to install the valve, at least there is no harm. However, in the refrigeration system, if the end is not opened, and the water flow is not blocked by a valve, then a very serious situation will occur, which will cause condensation in the end and related pipelines, and it is not easy to find.
Therefore, in the refrigeration system, if the indoor end is not open, the cold water should not pass through the pipes and equipment. In the primary system, in order to ensure the stability of the system, the selection of the pump is generally too large.
In addition, when the terminal system changes, the flow rate of the air source heat pump host must be ensured. Assuming that all the air disc system uses two-way valves, there is no problem when the system is debugged. The flow of the main engine and the end is sufficient, and the water pump is also selected according to the total load. However, when only one fan is turned on, the water resistance will be large, and the flow rate of the air source heat pump host will be greatly reduced. In this case, the water flow switch of the host may report a failure. In the air source heat pump system, considering the consistency of the host flow rate and the flow rate after the end load changes, it is necessary to install a three-way valve or a differential pressure bypass valve to solve the problem.