Temperature has a great influence on refrigeration and air-conditioning systems, don’t you know

Temperature has a great influence on refrigeration and air-conditioning systems, don’t you know

The relevant temperature of the components of the refrigeration and air-conditioning system has a normal temperature range, and it is an abnormal state if it exceeds this range. The cause of these abnormalities may be malfunctions or incorrect adjustments, but the reasons must be analyzed and processed or checked in time. These temperature points are difficult to measure with a thermometer. Generally, they can only be estimated by hand and then judge whether they are normal.

　　 1. The influence of exhaust temperature

　　 In summer, the compressor's discharge temperature is relatively high and cannot be touched by hands. According to national standards, the exhaust temperature of the R22 refrigeration system should not exceed 150°C, which is an abnormal condition. The reason for the excessively high exhaust temperature is the excessively high suction temperature of the compressor or the excessively high condensing temperature, which must be paid attention to. The exhaust temperature is too low, and the exhaust pipe is not hot when touching the exhaust pipe by hand. This indicates that the suction temperature is extremely low, and the compressor may be running in a wet stroke or the operating state of the system with relatively little working fluid. The wet stroke of the compressor is easy to damage the valve structure; the refrigerant runs under unusual circumstances, which will affect the heat dissipation of the motor winding and accelerate the aging of the insulating material.

　　 2. The influence of the temperature change of the casing on the compressor and refrigeration system

The temperature field of the casing of the fully enclosed reciprocating piston compressor can be divided into two parts: a. The upper casing is affected by the inhaled vapor, and the temperature is relatively low. It is in the slightly hot or slightly cooler range. It is estimated to be around 30°C. There may be dew condensation on the surface of the casing around the pipe. b. The heat generated by the motor in the lower casing and the frictional heat carried by the refrigerating oil are mainly carried out of the casing by steam.

　　 1. The influence and reason of the case temperature is too high:

　　 The surface temperature of the case exceeds the normal range, mainly because the suction temperature of the refrigeration system is too high (above 15°C). Excessively hot steam enters the compressor and absorbs the heat in the casing to make the temperature of the steam higher, thereby increasing the temperature of the casing. The temperature of the superheated steam rises very high, and the temperature of the casing also rises very high, which is unfavorable to the cooling of the oil, which will affect the lubrication of the moving parts, accelerate the wear, and cause the bearing to seize (seize) in severe cases. It will also cause the exhaust temperature to rise.

　　2. The influence and reason of the case temperature is too low:

　　The surface temperature of the case is lower than the normal range. The reason is that the suction temperature is too low (below 15°C). It is beneficial to the cooling of refrigerating oil and motor windings, but the cooling capacity is reduced. When the suction temperature is particularly low, it will cause most of the casing to condense, and there is a danger of liquid strike. This is a fatal blow to the compressor, and special attention should be paid. At the same time, a large amount of refrigerant is dissolved in the refrigerating oil, which is not conducive to the lubrication of moving parts.

　　 3. The temperature of the condenser

　　1. The temperature of the condenser:

　　 The normal situation is that the front half of the radiating pipe is very hot, and its temperature has a slow and gradual decrease in equilibrium. The heat sensation of the second half of the radiating pipe is lower than that of the first half. This is because the refrigerant in the second half of the pipe has gradually liquefied and reached the condensation temperature and supercooling temperature. When an abnormal situation occurs, one is that the first half is not too hot, and the second half is close to normal temperature (ambient temperature). The reason is that the compressor absorbs wet vapor refrigerant or the amount of refrigerant is insufficient. The other is that the entire condenser tube is very hot. The reason is that the amount of refrigerant is too much or the ventilation is small, or the ambient temperature is high.

　　2, water-cooled condenser:

　　 Shell and tube condenser shell is normally hotter in the upper half and warmer in the lower half. Under abnormal conditions, the entire shell is not too hot, and the reason is that the amount of refrigerant is insufficient. Another situation is that the entire shell is very hot, which is due to insufficient cooling water or poor heat dissipation (fouling in the water pipe). Under normal circumstances, the outer surface of the sleeve type condenser is very hot, the reason is that the cooling water volume is too small or the heat dissipation effect is poor; the other is that the outer surface of the entire sleeve is not too hot, and the reason is that the amount of refrigerant is insufficient.

　　 Fourth, the temperature of the reservoir

　　 Under normal circumstances, the suction tube feels very cold to the touch with dew. The reason is that the condenser has poor heat dissipation, high condensing temperature or excessive refrigerant charge.

　　 5. Liquid tube temperature condition

　　Under normal circumstances, the liquid tube is warm. Under abnormal conditions, the liquid tube is relatively hot. The reason is that the condenser has poor heat dissipation, high condensation temperature or excessive refrigerant flow.

　　 6. Filter temperature condition

The basic condition is the same as that of the infusion tube, but it has a prominent abnormal phenomenon, that is, the filter may become cold. The reason is that the filter mesh is blocked by sludge, which makes the filter not unblocked. When the refrigerant flows through the filter, A throttling phenomenon occurs, that is, a part of the liquid vaporizes and absorbs heat, which makes the filter cool, and in severe cases, condensation occurs. Another abnormal phenomenon is that the filter is not hot, which is equivalent to the ambient temperature. The reason is that the filter is completely blocked and the refrigerant cannot flow.

　　 Seven, the temperature of the suction pipe

　　 Under normal circumstances, the suction tube feels cold to the touch with dew. Under abnormal conditions, one is that the suction pipe is cold and there is too much dew, which causes condensation on a large area of the casing. The reason is that the refrigerant flow is too large, the liquid cannot be completely vaporized in the evaporator, and there is a phenomenon of liquid reflux. The hazard is that the compressor may run on a wet stroke. In severe cases, liquid shock will occur and the valve plate will be threatened. The second is that the suction pipe is not cold, does not condense, and the casing is very hot. The reason is that the refrigerant flow is too small or the amount of refrigerant is insufficient. The consequence is that the exhaust temperature rises and the cooling capacity drops.