Analysis: functions of three types of throttling devices for air source heat pump
After understanding the four major components of the air source heat pump and their main functions, we know that one of the four major components is a throttling device. Why should throttling devices be added to air source heat pumps?
Because the air source heat pump throttling device has the function of throttling and depressurization and regulating the superheat and refrigerant circulation of the refrigeration system, in other words, the throttling device is one of the four indispensable components of the refrigeration and heat pump system, it plays an important role in regulating refrigerant flow and establishing high and low pressure difference of the system.
The following small series will show you the throttling device of air source heat pump--Electronic expansion valve, thermal expansion valve, capillary tube.
The structure of throttling device can be relatively complex, such as thermal expansion valve, electronic expansion valve, etc. It can also be very simple, such as capillaries.
Therefore, the throttling devices of air source heat pump can be divided into three categories: the first category, electronic expansion valve is a throttling device that directly controls the current or voltage on the expansion valve by using electrical signals to change the movement of the needle valve, the reaction is sensitive and accurate, the flow control range is large, and the program can be scheduled to control according to the evaporator signal when the system actually works.
It can * control the evaporation temperature, and can be completed in a few seconds in a fully closed or fully open state. In areas where Frost is not very serious, bypass defrosting can be carried out in a fully open manner with an electronic expansion valve.
The second category, thermal expansion valve, thermal expansion valve (Temperature regulating valve, automatic regulating valve)
The refrigerant flow rate into the evaporator can be adjusted according to the refrigerant temperature flowing out of the evaporator.
Thermal expansion valve is suitable for small and medium-sized heat pump systems. Some heat pumps using new working medium or mixed working medium may not be able to buy corresponding thermal expansion valves in the market. It is necessary to determine their specifications and models through experiments, buy expansion valves with close thermal properties.
The third type, capillary is a length of 0. 5m ~ 5 m, inner diameter 0.
5mm ~ The 3mm thin copper tube has a very simple structure and low cost. It is welded between the condenser and the evaporator and generally does not cause leakage and other faults.
Capillary has the function of automatically adjusting refrigerant flow to a certain extent, and is suitable for small and medium-sized heat pump devices.
However, due to the small pipe diameter and long and narrow passage, dirty blockage and ice blockage are easy to occur, and the ability to regulate the flow is also limited.