Apply these 5 parameters to easily determine whether the refrigeration and air conditioning system is operating normally!

Apply these 5 parameters to easily determine whether the refrigeration and air conditioning system is operating normally!

1. Condensing temperature

Condensing pressure is the pressure at which the refrigerant condenses into liquid in the condenser. Since the pressure inside the condenser in the refrigeration system cannot be measured, in fact, the pressure drop of the refrigerant in the exhaust pipe and the condenser is actually very small. Therefore, regardless of design debugging or maintenance, it is generally considered that the exhaust pressure is approximately equal to the condensing pressure.

　　 The condensation temperature corresponds to the condensation pressure, which is the saturation temperature during condensation. The condensation temperature is not equal to the temperature of the cooling medium, and there is also a heat transfer temperature difference between the two.

　　 Then, how to determine the condensation temperature?

　　According to experience, the condensing temperature of the system = ambient temperature + (10~15℃); we take an air conditioner with an ambient temperature of 35℃ in summer as an example.

　　 The outdoor ambient temperature of the air conditioner in summer is about 35 degrees, we can estimate the condensation temperature at this time: condensation temperature = 35 + (10 ~ 15 degrees) = 45 degrees.

　　 The pressure corresponding to the condensing temperature is the condensing pressure, (you can check the temperature and pressure gauge provided by the public number of Refrigeration Encyclopedia) If the discharge pressure of the refrigeration system is lower than this pressure, please consider whether the refrigerant charge is too small, etc.;

　　 If the exhaust pressure of the system is higher than this pressure, please consider whether the refrigerant charge is too large, whether the condenser heat exchange is sufficient, whether the expansion valve opening is too small, etc.

　　 2. Evaporating temperature

　　 The evaporation temperature is the temperature at which the liquid refrigerant boils. When the refrigerant flow rate is constant, the lower the evaporation pressure, the lower the evaporation temperature. However, if the evaporation temperature of the system is continuously reduced, the refrigeration capacity of the refrigeration compressor will also continue to decrease, and the cooling speed may not necessarily be faster. Moreover, the lower the evaporation temperature, the lower the refrigeration coefficient of the system. .

　　 Then, how to judge whether the evaporation pressure of the system is normal?

　　According to experience, the evaporating temperature of the air-conditioning system = ambient temperature—(10~15℃); we take the summer (set temperature in the room 22℃) air conditioner as an example:

　　 The indoor unit temperature of the air conditioner in summer is 22 degrees, we can estimate the evaporation temperature at this time: evaporation temperature = ambient temperature-(10~15℃); that is, evaporation temperature = 22-(10~15℃)≈12℃;

The pressure corresponding to the evaporating temperature is the evaporating pressure, (you can query through the temperature pressure gauge provided by the Refrigeration Encyclopedia public account). If the evaporating pressure of the refrigeration system is lower than this pressure, please consider whether the evaporator has a problem with the heat exchange and the expansion valve is open Is the degree too low?

　　 If the evaporation pressure of the system is higher than this pressure, please consider whether the refrigerant charge is too high, whether the expansion valve opening is too large, etc.

　　 Three, suction temperature

　　Suction temperature refers to the refrigerant temperature at the compressor suction valve or compression button. In order to ensure the safe operation of the compressor and prevent the phenomenon of liquid hitting the cylinder, the suction temperature is required to be slightly higher than the evaporation temperature, which means that the refrigerant vapor becomes a superheated gas.

　　 Whether the suction temperature is normal, it can directly feedback whether the opening of the expansion valve is appropriate. Many people know the degree of inhalation superheat, and also know that the degree of inhalation superheat* is 5~7℃;

　　 But many novices do not know the actual meaning of the existence of this parameter; knowing the degree of inhalation superheat, we can calculate the normal inhalation temperature of the system.

　　 suction temperature = suction superheat + evaporation temperature, for example:

　　 We know that the evaporating temperature of a refrigeration system is 12℃; according to the suction superheat of *5~7℃; we can calculate that the suction temperature of the system* is about 17℃;

　　 We can judge whether the suction temperature at this time is normal according to the temperature of the hand. For example, the suction pipe feels colder than 17℃, we can judge that the opening of the expansion valve is larger or the refrigerant charge is too large; if the suction temperature is hotter than 17℃, we can judge that the expansion valve is hot at this time The opening of the valve is small or the refrigerant charge is small.

　　 If the suction pipe does not condense, it means that the suction temperature is too high. Please check whether the refrigerant charge is low or the expansion valve opening is small. If the suction pipe is frosted (ice), it means the suction temperature is low. Please check whether the refrigerant charge is too large or the expansion valve opening is too large.

　　 Fourth, exhaust temperature

　　The exhaust temperature is the temperature of the exhaust gas after the compressor has worked, which can be measured from the exhaust pipe with a thermometer. The exhaust temperature is directly proportional to the pressure ratio and the suction temperature. The higher the pressure ratio, the higher the suction temperature, the higher the exhaust temperature

　　 Many colleagues have never heard of the concept of "exhaust superheat", "exhaust superheat": the difference between the compressor's exhaust pipe (or condenser inlet temperature) and the saturation temperature corresponding to the condensation pressure.

　　 A normal refrigeration system exhaust superheat is 20~30℃. Therefore, we can judge whether the exhaust temperature is normal based on this empirical value; for example: an air conditioner with a condensation temperature of 45°C, the normal value of the exhaust temperature at this time should be:

　　Exhaust temperature=exhaust superheat degree+condensing temperature=25+45=70℃;

　　 5. Running current

　　 There are many factors affecting the operating current of the compressor, such as:

　　 Poor heat dissipation of the external machine;

　　 The external power supply voltage is abnormal;

　　 The refrigeration system has air;

　　The oil return is not good, resulting in high shell/internal temperature;

　　 Impurities in the system, too much water,

　　 In addition, let’s talk about the influence of refrigerant and compression ratio on current:

　　 how much refrigerant is compressed

　　 The degree of refrigerant compression (compression ratio)

　　 In fact, it is easy to understand, for the first one: the more refrigerant the compressor compresses, the harder it is for the compressor to compress, and the larger the current. For the second one: the higher the degree of refrigerant compression (the greater the compression ratio), the more work the compressor will do, and the corresponding current will be larger.

　　 Therefore, the operating current of the compressor can largely reflect whether the refrigeration charge of the refrigeration system is normal. Generally, there is a current value on the nameplate of the refrigeration equipment.