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Industrial chillers, also known as chillers, refrigeration units, ice water units, cooling equipment, etc., have different requirements for chillers due to their widespread use in various industries. The chiller unit consists of four main components: compressor, evaporator, condenser, and expansion valve, thereby achieving the refrigeration and heating effect of the unit.
1. Evaporation pressure and temperature
In the operation of a chiller, the evaporation temperature, pressure, and heat brought into the evaporator by cold water are closely related. When the heat load is high, the return water temperature of the cold water in the evaporator increases, causing an increase in the evaporator temperature and corresponding evaporation pressure. On the contrary, when the heat load decreases, the temperature of the cold water return decreases, and its evaporation temperature and pressure both decrease. When the heat load of the air-conditioned room decreases in actual operation, the temperature of the cold water return water decreases, and its evaporation temperature and pressure will both decrease.
According to the national standard GB/T18403.1-2001, the rated operating conditions of the chiller are 12 ℃/7 ℃ for the inlet and outlet water temperature of the chilled water, and 30 ℃/35 ℃ for the inlet and outlet water temperature of the cooling water. So the working conditions of the chiller at the factory are 12 ℃/7 ℃ for the inlet and outlet water temperature of the chilled water, and 30 ℃/35 ℃ for the inlet and outlet water temperature of the cooling water.
During operation, the cold water outlet temperature should be raised as much as possible while meeting the requirements for air conditioning use. In general, the evaporation temperature is 2 ℃~4 ℃ lower than the outlet temperature of cold water. The evaporation temperature is often controlled within the range of 3 ℃ to 5 ℃. Excessive evaporation temperature often makes it difficult to achieve the required air conditioning effect, while low evaporation temperature not only increases the energy consumption of the unit, but also easily causes freezing and cracking of the evaporation pipeline.
2. Condensation pressure and temperature
In a chiller, the pressure indicated by the high-pressure gauge is called the condensation pressure, and the temperature corresponding to this pressure is called the condensation temperature. The level of condensation temperature, while the evaporation temperature remains constant, has a decisive significance for the power consumption of the unit. During the operation of the chiller unit, attention should be paid to ensuring that the cooling water temperature, water quantity, water quality, and other indicators are within the qualified range. When air is present in the condenser, the temperature difference between the condensation temperature and the outlet of the cooling water increases, while the temperature difference between the inlet and outlet of the cooling water decreases. At this time, the heat transfer effect of the condenser is not good, and the outer part of the condenser feels hot to the touch. In addition, the scaling and sludge on the water side of the condenser tube also play a significant role in heat transfer.
3. Pressure and temperature of cold water
The cold water flow rate of the evaporator is inversely proportional to the temperature difference between the supply and return water, that is, the larger the cold water flow rate, the smaller the temperature difference; On the contrary, the smaller the flow rate, the greater the temperature difference. So, the operating conditions of the chiller set the temperature difference between the cold water supply and return to 5 ℃, which actually regulates the cold water flow rate of the unit. The control of cold water flow is manifested by controlling the force drop of cold water passing through the evaporator.
Under standard operating conditions, the cooling water supply and return pressure on the evaporator is set to decrease by 0.5 kgf/cm2. The pressure drop setting method is to adjust the opening of the cold pump outlet valve and the opening of the evaporator supply and return water valves.
4. Cooling water pressure and temperature
The chiller operates under standard operating conditions, with a condenser return water temperature of 30 ℃ and an outlet temperature of 35 ℃. Under standard operating conditions, the condenser outlet pressure drop is set to around 0.75kgf/cm2. The pressure drop setting method also adopts adjusting the opening of the cooling water pump outlet valve and the condenser inlet and outlet water pipe valve.
In order to reduce the power consumption of the chiller, the condenser temperature should be minimized as much as possible. There are two feasible measures: one is to reduce the return water temperature of the condenser, and the other is to increase the cooling water volume.
For centrifugal chillers, high or low condensation pressure can cause surge. When a centrifugal chiller encounters this situation, it should be noted that the difference between the condensation pressure and the evaporation pressure should not be too small and should meet the requirements to prevent surge, otherwise surge may occur. In autumn when the temperature is low, it is more advantageous to operate a reciprocating chiller because the condensing pressure is lower and the power consumption is greatly reduced.
Industrial chillers, also known as chillers, refrigeration units, ice water units, cooling equipment, etc., have different requirements for chillers due to their widespread use in various industries. The chiller unit consists of four main components: compressor, evaporator, condenser, and expansion valve, thereby achieving the refrigeration and heating effect of the unit.
1. Evaporation pressure and temperature
In the operation of a chiller, the evaporation temperature, pressure, and heat brought into the evaporator by cold water are closely related. When the heat load is high, the return water temperature of the cold water in the evaporator increases, causing an increase in the evaporator temperature and corresponding evaporation pressure. On the contrary, when the heat load decreases, the temperature of the cold water return decreases, and its evaporation temperature and pressure both decrease. When the heat load of the air-conditioned room decreases in actual operation, the temperature of the cold water return water decreases, and its evaporation temperature and pressure will both decrease.
According to the national standard GB/T18403.1-2001, the rated operating conditions of the chiller are 12 ℃/7 ℃ for the inlet and outlet water temperature of the chilled water, and 30 ℃/35 ℃ for the inlet and outlet water temperature of the cooling water. So the working conditions of the chiller at the factory are 12 ℃/7 ℃ for the inlet and outlet water temperature of the chilled water, and 30 ℃/35 ℃ for the inlet and outlet water temperature of the cooling water.
During operation, the cold water outlet temperature should be raised as much as possible while meeting the requirements for air conditioning use. In general, the evaporation temperature is 2 ℃~4 ℃ lower than the outlet temperature of cold water. The evaporation temperature is often controlled within the range of 3 ℃ to 5 ℃. Excessive evaporation temperature often makes it difficult to achieve the required air conditioning effect, while low evaporation temperature not only increases the energy consumption of the unit, but also easily causes freezing and cracking of the evaporation pipeline.
2. Condensation pressure and temperature
In a chiller, the pressure indicated by the high-pressure gauge is called the condensation pressure, and the temperature corresponding to this pressure is called the condensation temperature. The level of condensation temperature, while the evaporation temperature remains constant, has a decisive significance for the power consumption of the unit. During the operation of the chiller unit, attention should be paid to ensuring that the cooling water temperature, water quantity, water quality, and other indicators are within the qualified range. When air is present in the condenser, the temperature difference between the condensation temperature and the outlet of the cooling water increases, while the temperature difference between the inlet and outlet of the cooling water decreases. At this time, the heat transfer effect of the condenser is not good, and the outer part of the condenser feels hot to the touch. In addition, the scaling and sludge on the water side of the condenser tube also play a significant role in heat transfer.
3. Pressure and temperature of cold water
The cold water flow rate of the evaporator is inversely proportional to the temperature difference between the supply and return water, that is, the larger the cold water flow rate, the smaller the temperature difference; On the contrary, the smaller the flow rate, the greater the temperature difference. So, the operating conditions of the chiller set the temperature difference between the cold water supply and return to 5 ℃, which actually regulates the cold water flow rate of the unit. The control of cold water flow is manifested by controlling the force drop of cold water passing through the evaporator.
Under standard operating conditions, the cooling water supply and return pressure on the evaporator is set to decrease by 0.5 kgf/cm2. The pressure drop setting method is to adjust the opening of the cold pump outlet valve and the opening of the evaporator supply and return water valves.
4. Cooling water pressure and temperature
The chiller operates under standard operating conditions, with a condenser return water temperature of 30 ℃ and an outlet temperature of 35 ℃. Under standard operating conditions, the condenser outlet pressure drop is set to around 0.75kgf/cm2. The pressure drop setting method also adopts adjusting the opening of the cooling water pump outlet valve and the condenser inlet and outlet water pipe valve.
In order to reduce the power consumption of the chiller, the condenser temperature should be minimized as much as possible. There are two feasible measures: one is to reduce the return water temperature of the condenser, and the other is to increase the cooling water volume.
For centrifugal chillers, high or low condensation pressure can cause surge. When a centrifugal chiller encounters this situation, it should be noted that the difference between the condensation pressure and the evaporation pressure should not be too small and should meet the requirements to prevent surge, otherwise surge may occur. In autumn when the temperature is low, it is more advantageous to operate a reciprocating chiller because the condensing pressure is lower and the power consumption is greatly reduced.
