Expansion valve - an important component in the refrigeration system.
The expansion valve is an important part of the refrigeration system, which is generally installed between the liquid storage cylinder and the evaporator. The expansion valve makes the liquid refrigerant of medium temperature and high pressure become low temperature and low pressure wet steam through its throttling, and then the refrigerant absorbs heat in the evaporator to achieve the refrigeration effect. The expansion valve controls the valve flow through the superheat change at the end of the evaporator to prevent the insufficient utilization of the evaporator area and the cylinder knocking phenomenon.
Temperature sensing bag
The refrigerant charged in the temperature sensing bag is in the state of gas-liquid equilibrium and saturation, and this part of the refrigerant is not communicated with the refrigerant in the system. It is generally tied to the evaporator outlet pipe, close contact with the pipe to feel the evaporator outlet superheated vapor temperature, because its internal refrigerant is saturated, so according to the temperature transfer temperature saturation state pressure to the valve body.
Equalizing tube
One end of the balance tube is connected to the evaporator outlet slightly away from the temperature envelope, and is directly connected to the valve body through a capillary tube. The function is to transfer the actual pressure of the evaporator outlet to the valve body. There are two diaphragms in the valve body, and the diaphragm moves upward under the action of pressure to reduce the refrigerant flow through the expansion valve and seek balance in the dynamic.
Quality judgment
The ideal operating state of the expansion valve should be to change the opening in real time and control the flow rate with the change of the evaporator load. However, in fact, due to the hysteresis of the temperature felt by the thermal envelope in the heat transfer, the response of the expansion valve is always half a beat slow. If we draw a time flow diagram of an expansion valve, we will find that it is not a smooth curve, but a zigzag line. The quality of the expansion valve is reflected in the amplitude of the twists and turns, and the larger the amplitude, the slower the reaction of the valve and the worse the quality.
The car air conditioner expansion valve is broken
01 The expansion valve is opened too large
Opening the expansion valve of automobile air conditioning too large may cause the cooling effect to decline. The main function of the expansion valve is to regulate the flow of refrigerant into the evaporator to maintain the low pressure in the evaporator. When the expansion valve is opened too wide, the refrigerant flow increases, which may cause the low pressure in the evaporator to be too high. This causes the refrigerant to be converted to liquid prematurely in the evaporator, which reduces the heat absorption effect in the evaporator. Therefore, the cooling effect of automobile air conditioning will be significantly reduced.
02 Cooling and heating are not good
The damage of the expansion valve of automobile air conditioning will lead to poor cooling and heating effect. The expansion valve plays a role in regulating the refrigerant flow in the air conditioning system. When the expansion valve is damaged, the refrigerant flow may be unstable or too large, thus affecting the cooling and heating effect. The specific performance is: in the refrigeration mode, the temperature inside the car may not be reduced to the set value; In heating mode, the temperature inside the car may not rise to the set value. In addition, damage to the expansion valve may also lead to damage to other components of the air conditioning system, further affecting the cooling and heating effect. Therefore, once the cooling or heating effect of the air conditioner is found to be poor, the expansion valve should be checked in time to see if it is damaged.
03 The expansion valve is too small or faulty
Opening the expansion valve too small or malfunctioning can cause problems in the car air conditioning system. When the expansion valve is opened too small, the refrigerant flow will be limited, making the cooling effect of the air conditioning system decreased. In addition, because the refrigerant does not adequately flow into the evaporator, it may cause the evaporator to freeze or frost the surface. When the expansion valve fails completely, the air conditioning system may not cool or heat at all. In this case, you need to replace the expansion valve as soon as possible to restore the normal working state of the air conditioning system.
04 Do not rest or sleep in the car with air conditioning for a long time
It is unwise not to rest or sleep for a long time in the car with the air conditioning on, especially if there is a problem with the expansion valve of the car air conditioning. Expansion valves are key components in automotive air conditioning systems and are responsible for regulating refrigerant flow and pressure. When the expansion valve is damaged, the cooling effect may be reduced or completely failed. In high temperatures, prolonged exposure to such an environment can lead to dehydration and fatigue, and even life-threatening conditions. Therefore, if you find a problem with the expansion valve of the car air conditioner, it is best to avoid resting or sleeping for a long time in the car to ensure safety and comfort.
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