Cause analysis of high exhaust temperature and overload protection of modular machine

Author : sherry

Update time : 2020-10-30 13:24:23

Simply speaking, the air-cooled modular machine is a kind of air-cooled chiller and hot-water unit that can be freely combined. It can both cool and heat. It has the characteristics of flexible installation, reliable operation and convenient maintenance. It is suitable for building air conditioning projects, such as hotels, apartments, hotels, office buildings, shopping malls, cinemas, workshops, hospitals, etc.
1、 Cooling and heating cycle of modular machine
Refrigeration cycle: the low-temperature and low-pressure refrigerant gas from the indoor heat exchanger is inhaled by the compressor and compressed into high-temperature and high-pressure gas, and then discharged into the outdoor heat exchanger through the four-way valve. After heat exchange with the outdoor side air, it condenses into refrigerant liquid, enters the indoor heat exchanger after throttling and reducing pressure and cooling by capillary tube, and then enters the indoor heat exchanger after heat exchange with indoor air to be regulated It is low temperature and low pressure refrigerant gas. In this way, the cycle is repeated to achieve the purpose of refrigeration;
Heating cycle: the flow direction of refrigerant is opposite to that of refrigeration. The high-temperature and high-pressure refrigerant gas discharged from the compressor directly enters the indoor heat exchanger after passing through the four-way valve. Through the action of centrifugal fan, it releases heat to the indoor air and is condensed into refrigerant liquid. After throttling and depressurizing by the main and auxiliary capillaries of the external unit, it absorbs heat in the outdoor heat exchanger and becomes low temperature and low pressure Refrigerant gas, through the four-way valve back to the compressor, complete a heat pump heating cycle, so cycle again and again, to achieve the purpose of heating.
2、 Module compressor overload protection
Compressor overload protection includes compressor overload protection in refrigeration mode and compressor overload protection in heating mode, which are introduced respectively below.
Compressor overload protection in refrigeration mode: in case of refrigeration, if overload protection occurs, it can be judged from the following aspects;
1. Check whether the ambient temperature or water temperature is normal
① Check the local ambient temperature to see if it is abnormally high;
② The inlet and outlet water temperature of shell and tube, generally the ambient temperature will not exceed the normal range, mainly observe the inlet and outlet water temperature, if the inlet and outlet water temperature exceeds the operation requirements of the manual, reduce the water temperature;
2. Check whether the exhaust temperature of the system is normal
① Check the manual operator of the unit and check the "exhaust temperature". If the exhaust temperature is too high, connect the pressure gauge to the system. If the saturation temperature corresponding to the pressure value in the system is consistent with the current ambient temperature, the refrigerant in the system is normal; if the pressure value in the system is close to atmospheric pressure or the saturation temperature corresponding to the measured pressure value is more than 10 ℃ lower than the current ambient temperature, the system has insufficient refrigerant Check the leakage point of the system (Note: the detection should be carried out after the unit is shut down for more than 1 hour);
② Check whether the fins of the system are dirty and blocked. If the fins are dirty, clean the fins;
③ Observe the exhaust temperature of the manual operator. If the exhaust temperature is below 55 ℃, immediately measure the unit current with a multimeter. If the current is far greater than the current indicated on the nameplate, it indicates that the unit is filled with too much refrigerant; (if the compressor is damaged by overload caused by liquid hammer, there will also be abnormal sound of compressor "click", which usually occurs when the compressor is replaced or started without heating the unit ！）。
3. Check whether the operating voltage exceeds the requirements of the manual
① Use a multimeter to measure the input voltage of the unit, and the voltage shall not exceed the operation requirements of the manual (± 10% of the rated voltage).
Compressor overload protection in heating mode: if overload protection occurs in heating condition, it can be judged from the following aspects;

1. Check whether the water temperature and ambient temperature exceed the use scope of the manual;Check the water temperature. The outlet water temperature should not exceed 50 ℃ and the ambient temperature should not exceed 24 ℃.
2. Check whether the water pump and water system are normal
① Check whether there is water flow in the water pump, observe whether there is a big vibration sound in the water system, and observe the temperature difference between the inlet and outlet of the manual operator. If the temperature exceeds 8 ℃, the water flow is insufficient;
② Check whether there is air in the shell pipe water system. If there is a big vibration sound in the water system, it indicates that the emptying is not complete. Please continue to open the exhaust valve for evacuation;
③ Check whether the water pump is damaged. If the water pump is damaged, the noise of the water pump will be very loud. You can also start the standby water pump for flow comparison;
④ Check whether the water system filter is dirty and blocked. If the water flow is small, remove the filter and replace it.

3. Check whether the exhaust temperature of the system is normal
① Check the manual operator of the unit and check the "exhaust temperature". If the exhaust temperature is too high, connect the pressure gauge to the system. If the saturation temperature corresponding to the pressure value in the system is consistent with the current ambient temperature, the refrigerant in the system is normal; if the pressure value in the system is close to atmospheric pressure or the saturation temperature corresponding to the measured pressure value is less than 10 ℃ of the current ambient temperature, the system refrigerant is not Full, please check the system leakage point (Note: the detection needs to be carried out after the unit shutdown for more than 1 hour);
② Check whether the fins of the system are dirty and blocked. If the fins are dirty, clean the fins;
③ Observe the exhaust temperature of the manual operator. If the exhaust temperature is below 55 ℃, immediately measure the unit current with a multimeter. If the current is far greater than the current marked on the nameplate, it indicates that the refrigerant quantity injected into the unit is too much; (if the compressor is damaged by overload caused by liquid hammer, there will be abnormal noise of compressor "click". It is determined that it is the compressor problem, please replace the compressor!
4. Check whether the operating voltage exceeds the requirements of the manual，Use a multimeter to measure the input voltage of the unit, and the voltage shall not exceed the operation requirements of the manual (± 10% of the rated voltage).
3、 Protection of high exhaust temperature of module compressor
The high temperature of the exhaust gas of the modular compressor is very dangerous, and improper treatment will threaten the life of the compressor. The common reasons are as follows: 1. The refrigerant leaks and the refrigerant is insufficient, which leads to the over protection of the exhaust temperature during the compression operation; 2. The blockage of the thermal expansion valve leads to the insufficient suction pressure and high exhaust temperature of the compressor; 3. The dirty filter causes the insufficient suction pressure and exhaust temperature of the compressor 4. The electronic expansion valve is blocked, which leads to insufficient suction pressure and high exhaust temperature protection;

Previous : тип и расположение змеевиков вентилятора

Next : Pagpipilian at layout ng mga fan coil