It’s so cold, the compressor of chiller is frozen!
Some netizens said that the compressor of the chiller was frozen! What’s going on here? What to do with it?
The compressor return air inlet frosting
The frosting of the compressor return air port indicates that the compressor return air temperature is too low. So what will cause this situation?
It is known that if the volume and pressure of the same quality of the refrigerant change, the temperature will have a different performance. That is to say, if liquid coolant absorbs more heat, then the coolant with the same mass will show high pressure, temperature and volume; if there is less heat absorption, the pressure, temperature and volume will be low.
So in other words, if the compressor return air temperature is low, it will generally show the low return air pressure and the same volume of high refrigerant. The root cause of this situation is that the refrigerant flowing through the evaporator cannot fully absorb the heat required to expand itself to the predetermined pressure temperature value, resulting in low temperature and pressure volume values of the return gas.
There are two reasons cause this temperature:
The lack of fluorine results in the frosting of the compressor
Actually most cases for frost phenomenon,we just need to adjust the hot gas bypass valve. The specific method is to open the rear end cap of the hot air bypass valve, and then use the no. 8 hexagon wrench to clockwise rotate the inside adjustment nut. The adjustment process should not be too fast. Generally, it will be paused after a half turn, and the system will run for a period of time before deciding whether to continue the adjustment. After the operation is stable and the frosting phenomenon disappears, screw the end cover tightly.
Cylinder head frosting
Always caused by large amounts of wet steam or refrigerant sucked into the compressor (crankcase frosting in serious cases). The main causes of this situation are:
The thermal expansion valve takes the degree of superheat at the evaporator outlet as the feedback signal, which produces the deviation signal after comparing with the given superheat value to adjust the direct acting proportional regulator of the refrigerant flows into the evaporator, which integrates the transmitter, regulator and actuator.
When the parameters measured by the transmitter deviate from the given value, the physical quantity of the transmitter changes, and sufficient energy is generated to directly drive the action of the actuator. The position change of the actuator is proportional to the parameter being tuned.
Thermal expansion valve can be divided into internal balance thermal expansion valve and external balance thermal expansion valve according to the different balance mode. The liquid coolant evaporates and absorbs heat in the evaporator. When it flows to the outlet of the evaporator, it has completely vaporized and has a certain degree of superheat. The thermodynamic expansion valve’s temperature tube is close to the evaporator outlet pipe and feels the temperature of the evaporator outlet. If the liquid filled in the temperature bulb is the same as the coolant, the liquid pressure above the thermal expansion valve diaphragm is greater than the liquid pressure below the diaphragm, and the higher the temperature of the evaporator outlet is , which is also can be said the higher the superheat, the higher liquid pressure above the diaphragm is.
This pressure difference is balanced by the tension between the stem and the adjusting spring below the diaphragm. If change or adjust the spring tension can change the upward force of the pushing rod, further to change the opening degree of the needle valve. Obviously, the evaporator superheat level will also lead to changes of the opening of the needle valve. When the regulating spring is adjusted in a certain position, the expansion valve will automatically change the pin valve opening according to the temperature of the evaporator outlet, so that the superheat degree of the evaporator outlet can be kept at a certain value.
The opening of the thermal expansion valve is over-regulated, the temperature sensor package is installed incorrectly or is fixed loose, so the temperature is too high and the valve core is unnormally opened. This can make a lot of wet steam suction compressor to cause the cylinder head frosting. The thermal expansion valve is used to adjust the superheat when working with the evaporator.
If the evaporator outlet superheat degree is too large, the overheating section at the back of the evaporator is too long, the refrigerating capacity will be significantly reduced.
But if the superheat at the outlet is too small, it may cause the compressor liquid hammer or even frost on the cylinder head. Generally, expansion valve should adjust the evaporator outlet superheat degree to 3℃-8℃.
The temperature sensing package of the temperature relay is placed in the cold storage. When the temperature of the cold storage is higher than the setting value limit, the contact point of the temperature relay is connected, the electromagnetic valve coil is energized, the valve is opened, and the refrigerant enters the evaporator for cooling. When the temperature is below the lower limit of the set value, the temperature relay contacts are disconnected, the solenoid coil current is cut off, the solenoid closes, and the refrigerant stops entering the evaporator, thus the temperature can keep in the desired range.
That is to say, the pressure before the expansion valve increases, and the cooling dose flowing into the evaporator increases. The liquid refrigerant cannot completely evaporate in the evaporator, so the compressor sucks in wet steam, the cylinder head is cold or even frosting, and may cause “liquid hammer”, and the evaporation pressure will also on the high side.
Winter air conditioning accurately add fluoridation (refrigerant) method!
The use rate of air conditioning increases in winter because of cold weather. However, various problems may occur when the air conditioning is used for a long time. A common cause of non – heating or poor heating effect of air conditioning in winter is lack of fluorine.
How to detect if the air conditioner is deficient in fluorine?
The most direct way to determine the lack of fluorine in winter is to see if the air conditioner does not produce heat, wind, or too small wind. The most direct method is to test the heating pressure of the air conditioner with the pressure gauge. Under normal heating, the working pressure is 1.6~ 2.1Mpa. If it is lower than this standard, it is fluorine deficiency.
For professionals, if they want to test the deficient in fluorine, turn on the air conditioner to start cooling, and let the air conditioner compressor run continuously for more than 15 minutes. If the refrigeration system is deficient in fluorine, the following phenomenon will occur:
Operation method of air conditioning fluoridation adding
Turn on the air conditioner and adjust it to the state of refrigeration, so that the fluorine can be added through the three-way valve.;
Because the winter is cold, air conditioning room temperature is likely to be lower than the set temperature, this time air conditioning will shut down;
How to make air conditioning run again?
Use the method of manual heating to raise the temperature of the heat detector!
In the state of heating, you can unplug the four-way valve of the external machine. In this way, the compressor of the air conditioner will operate in the state of refrigeration and the refrigerant can be added.
The method of adding refrigerant is the same as that of refrigeration condition. Here is a brief description:
Basis and method for accurately add fluorine
According to the indoor temperature, estimate the condensation temperature of system (such as indoor temperature 20 ℃ around, condensation temperature we estimate about 40-50 ℃), the high pressure at this time should be:
Measure the running current of the compressor with the clamp meter. If it is close to the rated running current, the refrigerant is sufficient. If it is less than the rated current, the refrigerant needs to be continued to fill.
The most accurate method is: quantitative add fluorine, according to the nameplate on the machine. Need how many kilograms we add how many kilograms.
Determine whether the refrigerant is sufficient by air pipe and liquid pipe
During the process of fluoridation, touch the temperature of the two tubes from time to time. If the thin tube is hot, and the thick tube is a little hot for hand it’s OK.
Refrigerant add wrongly has safe hidden troubles
There are many kinds of freon refrigerants, such as R22, R410A, R320, R209, and R134. Different refrigerant has different characters, and they cannot be mixed. If adding different kinds of freon, the refrigerant used in the compressor will deteriorate, or the system is blocked, resulting in not refrigeration or poor refrigeration effect. If a false freon is added, there is also the possibility that the pressure is too high, causing the connection pipe to explode and so on.
Function of chiller filter and common fault analysis and troubleshooting
The purpose of the filter is to collect solid impurities in the cooling system and lubricating oil, to prevent blocking of system, capillary or expansion valve, and ensure that the chiller’s piping system is unobstructed.
The special drying filter for water chiller is mainly composed of desiccant and metal mesh. The outer shell is made of copper tube with two different meridians at both ends. At the inlet there is a thick metal mesh and at the outlet is a thin metal mesh. The internal desiccant is used to absorb the moisture in the refrigerant, to ensure the capillary and expansion valve is unblocked, and to ensure the normal operation of the industrial cold water refrigerating system.
No matter the air-cooled water chiller, water-cooled water chiller or screw type water chiller, the impurities in water or lubricating oil shall be effectively filtered by drying filter. If the time of using the filter is too long, and there is no regular cleaning and replacement,it will result in dirty and plugging phenomenon, and then affect the cooling effect of the chiller. Its failure mainly manifest as that the outer shell of the filter turns from warm to cold or frost condensation, which will lead to insufficient liquid supply of the evaporator.
If there’s no temperature difference, we can know that the filter is completely clogged up. It is the same as the failure phenomenon when the capillary tube is completely blocked. If the drying filter and filter are slightly blocked or completely blocked, the main performance is that the refrigeration cycle condenser has no hot air discharge, the air outlet becomes normal temperature, and the running of the compressor is tedious. If the air-cooled chiller or the water-cooled chiller or the screw chiller is stopped, disconnect the capillaries/connection pipes attached to the dryer. Sufficient gas can be discharged at the side of the capillaries/connection pipes but the dryer has no gas discharge, that is, the dryer is blocked. Otherwise. the capillary or connection pipe side is blocked.
If the dry filter or filters are blocked, a new filter should be replaced. And vacuumize according to the nameplate on the water chiller to fill with predetermined amount of refrigerant to do machine test and observation, ensure the unit refrigeration system operate normally. Since most users are directly cooling the tap water and the unit operates 24 hours a day, the operator should check the filter regularly to ensure the cold water chillers cooling fast and operation stable.