Refrigeration repair commissioning , first understand these basic knowledge ....

Condensing Temperature
The condensing temperature of the compressor system is the temperature at which the refrigerant condenses in the condenser, and the refrigerant vapor pressure corresponding to this temperature is the condensing pressure.
Condensing temperature is one of the main operating parameters in the refrigeration cycle, for the actual refrigeration device, due to the small range of changes in other design parameters, condensing temperature can be said to be the most important operating parameters, which is directly related to the refrigeration effect of the refrigeration device, safety and reliability and energy consumption level.
Evaporation temperature
Evaporation temperature refers to the temperature of the refrigerant in the evaporator when it evaporates and boils, which corresponds to the corresponding evaporation pressure, and the evaporation temperature is also an important parameter in the refrigeration system.
The evaporating temperature is the refrigeration temperature in the ideal state, but the evaporating temperature of the refrigerant in actual operation is 3 to 5 degrees lower than the refrigeration temperature.
Suction temperature
Suction temperature refers to the temperature of the refrigerant when it enters the compressor, which is generally higher than the evaporation temperature. Because the evaporating temperature is the saturation temperature of the refrigerant, while the suction temperature is the temperature of the superheated gas, when the refrigerant becomes superheated gas. The difference between the suction temperature and the evaporation temperature is the suction superheat.
Superheat
Definition of superheat: The temperature difference between the low pressure side and the vapor in the temperature sensing package.
Measurement of superheat: Measure the evaporating pressure as close as possible to the temperature-sensing package, convert the reading to temperature, and then subtract the temperature from the actual temperature measured at the temperature-sensing package. The degree of superheat should be between 5 and 8°C.
Degree of subcooling
Definition of subcooling: the difference between the saturated liquid temperature corresponding to the condenser condensing pressure and the actual temperature of the condenser outlet liquid.
In engineering, the exhaust pressure is generally approximated as the condensing pressure, and the difference between the saturated liquid temperature corresponding to the exhaust pressure and the temperature of the condenser outlet liquid is taken as the degree of subcooling. The reason for this approximation is that the pressure drop of the condenser is relatively small compared to the evaporator. For air-cooled condenser, 3 to 5 degrees of subcooling is more appropriate. When the refrigeration system circulates normally, the outlet of the condenser will generally have a certain degree of subcooling.
The role of suction superheat
If the suction is completely without superheat, it is possible to produce the return gas with liquid, or even cause wet stroke liquid shock damage to the compressor. In order to avoid this phenomenon, a certain degree of suction superheat is required to ensure that only dry steam into the compressor (due to the nature of the refrigerant, the existence of superheat indicates the complete evaporation of liquid refrigerant).
However, too high a degree of superheat also has the disadvantage of high degree of superheat will cause the compressor exhaust temperature (exhaust superheat) rise, the compressor operating conditions deteriorate life reduced. Therefore, the suction superheat should be controlled within a certain range.
Expansion valve placed in the compressor return pipe or evaporator outlet temperature-sensitive part to sense the return temperature and the actual evaporative pressure (corresponding to the saturation temperature) between the temperature difference (the temperature difference is the degree of suction superheat), and set the degree of superheat as the basis for adjusting the expansion valve opening, which is equivalent to the amount of liquid supply to regulate the evaporator, and ultimately can control the degree of suction superheat.
Now some models (such as inverter multi-connected machine) also has a special control condensing subcooling degree of the expansion valve. When the degree of subcooling is insufficient, increase the opening of the subcooling circuit expansion valve, increase the amount of liquid spray to cool the main circuit refrigerant, improve the condensing effect.
Refrigerant evaporates in the evaporator temperature, the greater the impact on the refrigeration efficiency, it reduces every 1 degree, the same amount of cold need to increase the power 4%, so in the case of conditions permitting, appropriate to improve the evaporation temperature to improve the efficiency of the refrigeration system is advantageous.
Evaporation temperature adjustment
Evaporative temperature regulation, in practice, is to control the evaporative pressure, that is, to adjust the pressure value of the low-pressure pressure gauge, the operation of the thermal expansion valve by adjusting the degree of opening (or throttle) to adjust the low-pressure pressure. Expansion valve opening degree is large, the evaporating temperature rises, the low pressure also rises, the refrigeration capacity will increase; if the expansion valve opening degree is small, the evaporating temperature decreases, the low pressure also decreases, the refrigeration capacity will be reduced.
Factors affecting the evaporating temperature
In the actual operation of the refrigeration device, the evaporating temperature change is very complex, it is directly affected by the expansion valve (throttle valve) control, and the object to be cooled by the heat load, the heat transfer area of the evaporator and the compressor capacity. These three conditions of a change, the refrigeration system evaporative pressure and temperature will inevitably occur corresponding changes, so the operator to ensure that the evaporative temperature in the prescribed range of stable operation, it is necessary to understand the evaporative temperature changes in a timely manner, according to the law of change of the evaporative temperature, timely, correctly for the adjustment of the evaporative temperature.
The heat load to the evaporation temperature influence
The heat load refers to the exothermic quantity of the cooled thing. When the heat load increases, other conditions remain unchanged, the evaporation temperature will rise, the low pressure will also rise, suction superheat will also increase. In this case can only open the expansion valve, increase the refrigerant circulation, but not because of the low pressure rise off the expansion valve, reduce the low pressure. Doing so will make the suction gas superheat greater, exhaust gas temperature increases, the operating conditions deteriorate. Adjustment of the expansion valve, each time the amount of adjustment should not be too large, after adjustment must be run for a certain period of time, in order to reflect the heat load and refrigeration capacity is balanced.
Refrigeration compressor energy changes on the evaporation temperature, when increasing the energy of the refrigeration compressor, the compressor's suction increases accordingly, in the case of other conditions remain unchanged, there will be a high-pressure rise, low-pressure reduction, the evaporation temperature will also fall. In order to continue to maintain the evaporation temperature required by the production process, it is necessary to open the expansion valve, so that the low pressure rises to the prescribed range. Refrigeration compressor to increase the energy to run for a period of time, as the temperature of the cooled material decreases, the evaporating temperature, low pressure will be gradually reduced (expansion valve does not make any adjustments), this is because of the temperature of the cooled material decreases in the heat load to reduce the cause. In this case should not be mistaken for a drop in pressure, is not enough to open the expansion valve to increase the amount of liquid supply, but should be closed to reduce the expansion valve, reduce the refrigeration compressor energy operation.
Heat transfer area changes on the evaporative temperature effect
Heat transfer area mainly refers to the evaporator's evaporative area, changes in heat transfer area mainly refers to changes in the size of the evaporative area. In the complete refrigeration device, the evaporating area is usually fixed, but in actual operation, due to insufficient liquid supply or oil accumulation in the evaporator, the evaporating area is constantly changing. The effect of increase and decrease of evaporating area on evaporating temperature is basically similar to the effect of increase and decrease of heat load on evaporating temperature. When the evaporation area increases, the evaporation temperature will rise; When the evaporation area decreases, the evaporation temperature will decrease. In order to maintain the required temperature, the energy and expansion valve should be adjusted, and the evaporator should be drained and cleaned to maintain the relative balance between the heat transfer area and the cooling capacity.
Relationship between evaporating pressure and evaporating temperature
The lower the evaporating pressure (low pressure), the lower the evaporating temperature.
The relationship between evaporating temperature and cooling capacity is: when the refrigerant flow rate is certain, the lower the evaporating temperature, the greater the temperature difference with the heat load (hot air), the greater the cooling capacity, in other words, the lower the evaporating pressure, the greater the cooling capacity, and the same quality of the same refrigerant, the same refrigerant, evaporated at different temperatures, its latent heat of evaporation is not the same, the lower the evaporating temperature, the greater the latent heat of evaporation, the stronger the heat-absorbing capacity.
In the condensing temperature: 40 ℃, degree of superheat: 10 ℃, degree of subcooling: 5 ℃, other conditions remain unchanged in the case of evaporation temperature changes on the compressor refrigeration capacity, power, the impact of COP.
Xinxiang Yukun Refrigeration Technology Co. is a production and sales of refrigeration two apparatus parts and sheet metal products, mainly engaged in condenser, evaporator, heat exchanger, reservoir, filter drier, Fin Evaporator (condenser), Stamping Parts, sheet metal parts, aluminum tubes for refrigeration, etc.

Our company has always had strict quality control standards in the market of refrigeration and heat exchange equipment, focusing on providing customised services to our customers. Not only do we have high requirements for the selection of raw materials, but we also keep up to date with the latest production processes and have high testing standards.

Our company mainly produces products for:Fin Evaporator.Fin Type Condenser.Capillary Tube. Coolant Reservoir.Plate Reinforcement Parts. Stamped Parts .Aluminum Tube.Instrument Testing Equipment.

Supermarket Refrigeration Show Case Copper Condenser Coil
1. OEM or ODM can be accepted
2. Fin type: Louver or corrugated
3. Be customerized according to samples and drawings.
4. High quility and low price and energy saving 60% (CE, RoHS, EMC and ISO9001 certification) The CD series products can be used in Various specificantion Condensing Units .
They are air cooled heat exchangers for refrigeration system. They are divided in 4 group:CD,CDC,CDS and CDV.All the products have been tested on 2.8MPa air leakage,and the system is disposed of pollution,applicable to R22,R134a,R404A,R407C systems.

Our company mainly produces products for:Fin Evaporator.Fin Type Condenser.Capillary Tube.Aluminum Coolant Reservoir.Plate Reinforcement Parts.Stamped Parts.Aluminum Tube.Instrument Testing Equipment.
Supermarket Refrigeration Show Case Copper Condenser Coil
1. OEM or ODM can be accepted
2. Fin type: Louver or corrugated
3. Be customerized according to samples and drawings.
4. High quility and low price and energy saving 60% (CE, RoHS, EMC and ISO9001 certification) The CD series products can be used in Various specificantion Condensing Units .