Eight reasons for small temperature difference in chillers

A sudden decrease in the temperature difference of a normal chiller can cause a decrease in the cooling effect of the production equipment or prevent it from working properly, resulting in product quality problems and wasting a lot of energy. So, what are the reasons for a small temperature difference in a chiller?

We have a basic understanding of the principle of a chiller, which is to generate chilled water through a refrigeration unit, enter the equipment cooling path through a water circulation pipeline, absorb the heat generated by the equipment's operation, and thus achieve cooling.
Any problem in the entire process will result in a small temperature difference and inability to cool down.
The refrigeration unit is a key link in the refrigeration process, and the reasons for the small temperature difference in the chiller are reflected in the following aspects.

No.1 refrigerant leakage
Generally, refrigerant leakage is caused by the following factors:
A、 Damage to the heat exchanger or refrigerant pipe connection pipeline
B、 The system comes into contact with corrosive liquids or gases
C、 Damage to refrigerant pipelines caused by vibration of mechanical moving parts
D、 Damage to refrigerant components caused by human factors
The problem of low pressure can be detected by observing the reading of the low pressure gauge. If such problems occur, they must be detected and handled by professional technical personnel.

No.2 evaporator blockage
Generally, evaporator blockage is caused by the following factors:
A、 The viscosity of chilled water is too high
B、 Insufficient cleanliness of chilled water
C、 The production of crystals in frozen water
The blockage of the evaporator can be determined by observing the return area of the compressor. When there is a large area of ice formation at the return port of the compressor, the blockage phenomenon of the evaporator can be determined.

No.3 Expansion valve damaged or blocked
The damage or blockage of the expansion valve is generally caused by the following factors:
A、 Physical damage caused by external conditions
B、 Self damage of model components
C、 Decreased system cleanliness
The malfunction of the expansion valve can be determined by listening to the sound of the liquid inlet pipe and whether the rear of the expansion valve is frozen.

No.4 Filter blockage
The blockage of general filters is caused by the following factors:
A、 Physical damage caused by external conditions
B、 Self damage of model components
C、 Decreased system cleanliness
The malfunction of the filter can be determined by whether there is a temperature difference in the refrigerant passing through the filter.

No.5 Return air network blockage
The blockage of the return air filter screen is generally caused by the following factors:
A、 The decrease in system cleanliness
B、 Qualitative changes in refrigeration oil
The fault of the return air filter can be determined by the temperature difference in the return air pipe, the temperature difference of the compressor body, and the discharge temperature of the compressor.

No.6 compressor damaged
The damage of a general compressor is caused by the following factors:
A、 Damage to electrical appliances
B、 Reaching the service life
C、 The harsh usage environment
D、 Internal fault of compressor
The compressor is equipped with an energy regulation device inside, which can automatically realize the operation of the compressor at high and low loads according to changes in cooling load. When it is necessary to strengthen refrigeration, if it is not automatically regulated, it will cause poor cooling effect. However, the absence of automatic adjustment is generally due to device failures such as compressor slide valves or plunger valves.

In general, as long as normal operation and maintenance are carried out, the service life of the compressor can be 10-15 years. The damage of the compressor can be judged by the ground resistance value of the motor and the fluctuation of the inlet and outlet pressure. You can contact the chiller manufacturer for after-sales service.

Then let's take a look at the water circulation pipeline. The water circulation pipeline is generally composed of a chilled water pump, valves, insulation boxes, etc. The excessive water flow rate is the direct cause of the small temperature difference in the chiller.

No.7 Water flow rate too high
When the heat absorption is constant, the larger the water flow rate, the smaller the temperature difference between the inlet and outlet. The water flow rate can be determined by observing the water pressure difference between the inlet and outlet of the evaporator, as well as the operating current of the water pump.

No.8 Increase in production equipment load
The increase in production equipment load will increase the refrigeration load of the chiller, and the required amount of chilled water will increase. When the number of units is fixed, the temperature difference will decrease, causing refrigeration difficulties.
Other reasons: Sensor malfunction
The water temperature sensor at the outlet is inaccurate, causing a small temperature difference. The troubleshooting method is to check if the sensor is in good condition and replace it immediately if there is any problem.

In summary, there are four reasons for the small temperature difference in the chiller: refrigerant leakage, evaporator blockage, expansion valve damage, filter blockage, return air network blockage, increased water flow rate, and increased load.