【 Weak current College 】 refrigeration system failure symptoms (1)

Refrigeration system fails, generally not possible to directly see fault area where, it is impossible to be a part of the refrigeration system a decomposition and Anatomy, only from the outside, check out the anomaly, a comprehensive analysis. In the check in is generally through see, hear, touch to understand the system operational status. When the system's operating pressure and temperature exceeds the normal range, in addition to the Interior and external ambient deterioration, or else will be a problem, it is important to determine the root causes of failure.
1. refrigeration system pressure and temperature detection
(1) the concept of refrigeration system pressure refrigeration system at run time can be divided into two parts with high and low pressure. High pressure over the exhaust from the compressor to the throttle valve, this paragraph referred to as evaporation pressure. Compressor suction pressure is called inspiratory pressure, suction pressure close to evaporation pressure difference between the two is the pipe flow resistance. Pressure loss in the following general restrictions in 0.018Mpa.
For convenience, the evaporation of the refrigeration system and the condensing pressure is the pressure in the compressor suction and exhaust port detection. Commonly known as the compressor suction and discharge pressure. Detection of refrigeration system suction and exhaust pressure aims to get the evaporating temperature refrigeration system and the condensing temperature, a means of obtaining the health of the refrigeration system.
(2) the temperature of the cooling system concept refrigeration system wide temperature range, evaporating temperature te, suction temperature ts, condensing temperature, exhaust gas temperature, etc. The refrigeration system operating conditions decisive is evaporating temperature te and condensing temperature tc.
1) evaporation temperature te refers to liquid refrigerant in the evaporator boiling temperature gasification. For example, the air conditioning unit of te. 5 ~ 7OC best as the air conditioning unit, i.e. evaporation temperature conditioning design te 5 ~ 7OC, when maintenance of air conditioning units when debugging, if te to between 5 ~ 7OC, expansion valve for high speed, detecting compressor suction pressure. Its purpose is to understand the unit run by evaporating temperature, while te cannot directly detect that only through detection of evaporation pressure corresponding to the evaporating temperature (by a lookup table of thermodynamic properties of refrigerant).
2) condensing temperature tc is superheated vapor refrigerant in the condenser condensation heat back into the liquid temperature. Condensing temperature cannot directly detect, only by testing its corresponding condensing pressure, then through the lookup table and thermodynamic properties of refrigerant. Condensing temperature high, its relative rise in condensing, they correspond to each other. Condensing temperature ultra-high, unit load, motor overload, to run, its cooling capacity corresponding decline in the consumption of power increase, should be avoided.
3) exhaust temperature td is the compressor outlet temperature (the temperature of the exhaust nozzle), detection of exhaust temperature measuring device is a must, not to set up General minicomputer, the provisional measure available semiconductor thermometer error detection, but larger. Exhaust temperature from suction temperature and condensing temperature, air temperature, or cooling temperature, exhaust gas temperature also increased, so have to control the suction temperature and condensing temperature, exhaust gas temperature can be stable.
4) suction temperature ts is the compressor suction pipe gas temperature, there are suction temperature detection temperature measurement device, generally small unit not to set up a temperature measurement devices, general maintenance while debugging to touch estimation, the air conditioning unit of suction temperature generally require control ts = 15OC to left for good. Exceeding this value on the refrigeration effect has a certain influence.
2. inspiratory pressure changes the impact of the refrigeration system
Refrigeration system is running, the suction pressure and evaporation temperature and flow of the refrigerant there is a close relationship. For purposes of system expansion valve, suction pressure and expansion valve to open degree, refrigerant charge, compressor cooling efficiency, and the magnitude of the load. Capillary system, suction pressure and condensing pressure, cooling capacity, the compressor refrigeration efficiency, as well as the magnitude of the load. To do this in check cooling system, you should press the suction tube with manometer. Detection analysis of inspiratory pressure on failure.
(1) the factors of inspiratory pressure low inspiratory pressure lower than normal, which factors are insufficient cooling capacity, cooling load, expansion valve opening small, condensation pressure low (of a capillary system), and the filter is not clear.
(2) the factors of inspiratory pressure high inspiratory pressure higher than the normal value, the element has too many refrigerant, refrigeration load, expansion valve to open degree, condensing pressure (capillary system) as well as compressor efficiency differential, etc.