Factors influencing the evaporation capacity of air-cooled chiller evaporator

Factors influencing the evaporation capacity of air-cooled chiller evaporator

Whether it is an air-cooled chiller, an air-cooled screw chiller, or an air-cooled low-temperature chiller, an evaporator is needed. Today we are discussing: What is an evaporator? What are the factors that affect the evaporation capacity of an air-cooled chiller evaporator?

　　 One, what is an evaporator

　　 The evaporator is one of the four major components of the air-cooled chiller refrigeration system. It is a component or equipment that specifically provides liquid refrigerant in which it boils and evaporates. Since evaporation is a heat-absorbing process, the evaporator is the ultimate manifestation of the cooling capacity and function of the air-cooled chiller refrigeration system, including the indoor unit of the household air conditioner, and its main component is the evaporator. In fact, depending on whether the object to be cooled is air or liquid, the evaporator is commonly called an air cooler or a liquid cooler.

　　 2. What are the factors that affect the evaporation capacity of the air-cooled chiller evaporator?

　　 The main indicators to measure the evaporator of the air-cooled chiller are the heat transfer coefficient and the heat transfer surface. In order to improve the efficiency of the evaporator, the heat transfer coefficient should be improved first. Then the key to improving the heat transfer coefficient is to improve the convective heat transfer between the refrigerant and the heat transfer tube wall.

　　Because the surface heat transfer coefficient of the refrigerant boiling is far greater than the heat transfer coefficient between the vapor and the tube wall, the contact surface between the liquid and the tube wall in the evaporator should be large, and the vapor generated during boiling should be quickly discharged. In fact, it is more difficult to improve the heat transfer coefficient.

　　When the heat transfer coefficient is constant, the size of the heat exchange surface determines the evaporation capacity of the air-cooled chiller evaporator. Increasing the number of heat transfer tubes and using finned tubes (finned tubes) can effectively increase the heat transfer surface, which are common measures to improve the evaporation capacity.

　　How to cool the air-cooled chiller

Industrial chillers can be divided into water-cooled chillers and air-cooled chillers according to the cooling method. Technically, water-cooled chillers have an energy efficiency ratio of 300 to 500 kcal/h higher than air-cooled chillers; In terms of price, water-cooled chillers are much lower than air-cooled chillers; in terms of installation, water-cooled chillers need to be incorporated into the cooling tower and an external water pump can be used, while air-cooled chillers are mobile and do not need It occupies space and does not require other auxiliary equipment. It can be used only when it is connected to the power supply. However, the air-cooled chiller only relies on the fan to dissipate heat, and has some requirements for the environment: such as ventilation, humidity, temperature not higher than 40℃, air pH, etc.