1, the refrigeration system exhaust temperature is too low:
Exhaust pressure is too low mainly due to the refrigeration system pipeline refrigerant flow is small or even stop. Exhaust pressure is too low, although the phenomenon is manifested in the high-pressure end, but the reason is mostly generated in the low-pressure end.
Common causes of low exhaust pressure:
Expansion valve hole clogging, liquid supply is reduced or even stopped, at this time the suction and discharge pressure are reduced.
Expansion valve ice blockage or dirty blockage and filter clogging, etc., is bound to make the suction and discharge pressure are down;
2, refrigeration system back to liquid:
For the use of capillary small refrigeration system: adding too much liquid will cause the return. Evaporator frost serious or fan failure when the heat transfer becomes poor, the liquid is not evaporated will cause liquid return. Frequent temperature fluctuations can also cause the expansion valve response failure and cause liquid return.
For the use of expansion valve refrigeration system: liquid return is closely related to the expansion valve selection and improper use. Expansion valve selection is too large, the superheat setting is too small, the temperature sensing package is installed incorrectly or adiabatic packing damage, expansion valve failure may cause liquid return.
For refrigeration systems where liquid return is difficult to avoid, the installation of gas-liquid separator control can effectively prevent or reduce the harm of liquid return.
3, the refrigeration system suction temperature:
The return air pipeline insulation is not good or the pipeline is too long, can cause suction temperature is too high. Under normal circumstances, the compressor cylinder head should be half cool, half hot.
Insufficient refrigerant charge in the system. Or the expansion valve opens too small, resulting in insufficient circulation of refrigerant in the system, the amount of refrigerant into the evaporator is small, the degree of superheat is large, and thus the suction temperature is high.
Expansion valve mouth screen clogging. Insufficient supply of liquid in the evaporator, the amount of refrigerant liquid is reduced, and a part of the evaporator is occupied by superheated vapor, thus the suction temperature rises.
4, liquid strike:
The suction temperature should be avoided to be too high or too low. Suction temperature is too low, the refrigerant evaporator evaporation in the evaporator is incomplete, both reduce the evaporator heat transfer efficiency, wet steam suction and the formation of compressor liquid strike. Suction temperature should normally be higher than the evaporation temperature 5 ~ 10 ℃.
In order to ensure the safe operation of the compressor, to prevent the phenomenon of liquid shock, the suction temperature is higher than the evaporation temperature, that is, there should be a certain degree of superheat.
Refrigeration equipment maintenance free hotline: 400-017-1110
5, the refrigeration system with liquid start:
With the liquid start of the blistering phenomenon can be clearly observed on the oil sight glass. The root cause is the lubricating oil dissolved and sunk in the lubricating oil below a large number of refrigerant, in the pressure suddenly lowered when the sudden boiling, and cause the lubricating oil blistering phenomenon, it is easy to cause liquid shock.
The installation of a crankcase heater (electric heater) on the compressor can effectively prevent refrigerant migration. The crankcase heater is energized when the compressor is shut down for a short period of time. After a long shutdown without use, heat the lubricant for a few or a dozen hours before starting the compressor. Install a gas-liquid separator on the return line to increase the resistance to refrigerant migration and reduce the amount of migration.
6, the refrigeration system appeared back to the oil:
The lack of oil will cause a serious lack of lubrication. The root cause of oil shortage does not lie in the compressor to run oil how much and how fast, but the system is not good back to the oil. Installation of an oil separator can quickly return to the oil, to extend the compressor without oil return operation time.
When the compressor is located higher than the evaporator, there is no oil return bend on the vertical return line. The return bends should be as compact as possible to minimize oil storage. The spacing between the return bends should be appropriate, and some lubricant should be added when the number of return bends is relatively large.
Frequent compressor starts. Frequent compressor startup is not conducive to the return of oil, due to the continuous operation of a short period of time compressor stopped, the return pipe to the formation of a stable high-speed air flow, lubricants can only stay in the pipeline. Return oil is less than the running oil, the compressor will be short of oil. The shorter the running time, the longer the pipeline, the more complex the system, the more prominent oil return problem.
7, the refrigeration system evaporating temperature is low:
Evaporating temperature has a greater impact on the refrigeration efficiency, it reduces every 1 degree, the same amount of cold need to increase power 4%. Therefore, under the conditions of permission, the appropriate evaporation temperature, to improve refrigeration efficiency is favorable, the evaporation temperature is generally lower than the air outlet temperature of 5 to 10 degrees.
A lower evaporating temperature although the temperature difference can be refrigerated, but the compressor cooling capacity is reduced, so the cooling speed is not necessarily fast. Not to mention that the lower the evaporating temperature, the lower the refrigeration coefficient, while the load has increased, the running time is extended, power consumption will increase.
8, refrigeration system exhaust overheating:
Exhaust overheating is mainly due to the following reasons: high return temperature, motor heating, high compression ratio, anti-expansion and gas mixing, compression temperature rise and refrigerant type, high condensing pressure.
On the specific causes and analysis of refrigeration system exhaust overheating, our refrigeration encyclopedia has previously released an article dedicated to detail, interested friends to view the previously released article.
9, the refrigeration system suction temperature is low:
Expansion valve opening is too large. Due to the temperature sensing element tied too loose, with the return air tube contact area is small, or the temperature sensing element is not wrapped with adiabatic material and its wrapping position error, etc., resulting in the temperature sensing element measured temperature inaccuracy, close to the ambient temperature, so that the expansion valve action of the openness of the expansion valve increases, resulting in the supply of liquid is too much.
Too much refrigerant charge. Refrigerant charge is too much, occupying part of the volume of the condenser and condensing pressure increases, the liquid into the evaporator increases. Evaporator liquid can not be completely vaporized, so that the compressor suction gas with liquid droplets. In this way, the temperature of the return gas pipeline drop, but the evaporating temperature because the pressure did not drop and did not change, the degree of superheat is reduced. There is no significant improvement even if the expansion valve is turned off.
10, the refrigeration system but fluorine:
Fluorine quantity is low or its regulating pressure is low (or partially blocked), the valve cover of the expansion valve (bellows), and even the inlet will be frost; fluorine is too low or basically no fluorine, the appearance of the expansion valve has no reaction, only a little bit of airflow can be heard silk sound.
Look at the icing from which end, from the liquid distribution head or from the press back to the air pipe, if from the liquid distribution head is the lack of fluorine, from the press is more fluorine.
Refrigeration equipment maintenance free hotline:: 400-017-1110