Influencing factors of refrigeration system pressure

1. Factors of low suction pressure:

The suction pressure is lower than the normal value. The factors include insufficient cooling capacity, small cooling load, small expansion valve opening, low condensing pressure (referring to the capillary system), and the filter is not smooth.

Factors of high suction pressure:

The suction pressure is higher than the normal value. The factors include excessive refrigerant, large refrigeration load, large expansion valve opening, high condensing pressure (capillary tube system), and poor compressor efficiency.

2. Exhaust pressure, high exhaust pressure factors:

When the exhaust pressure is higher than the normal value, there are generally small flow of the cooling medium or high temperature of the cooling medium, too much refrigerant charge, large cooling load and large expansion valve opening.

These caused the circulation flow of the system to increase, and the condensing heat load also increased correspondingly. Since the heat cannot be dissipated in time, the condensing temperature will rise, and all that can be detected is the rise in exhaust (condensing) pressure. When the flow rate of the cooling medium is low or the temperature of the cooling medium is high, the heat dissipation efficiency of the condenser decreases and the condensation temperature rises.

When the cooling medium flow rate is low or the cooling medium temperature is high, the heat dissipation efficiency of the condenser decreases and the condensation temperature rises. The reason for the excessive refrigerant charge is that the excess refrigerant liquid occupies a part of the condenser tube, which reduces the condensing area and causes the condensing temperature to rise.

Factors of low exhaust pressure:

The exhaust pressure is lower than the normal value due to factors such as low compressor efficiency, insufficient refrigerant quantity, low cooling load, small expansion valve opening, and filter failure, including the expansion valve filter screen and low cooling medium temperature.

The above factors will cause the cooling flow rate of the system to drop, the condensation load is small, and the condensation temperature is reduced.

From the above-mentioned changes in suction pressure and discharge pressure, there is a close relationship between the two. Under normal circumstances, when the suction pressure increases, the exhaust pressure increases accordingly; when the suction pressure decreases, the exhaust pressure also decreases accordingly. The general situation of the discharge pressure can also be estimated from the change of the suction pressure gauge.