The so-called solar refrigeration, is the use of solar collectors for absorption chiller to provide its generator needs of hot water. The higher the temperature of the thermal medium water, the higher the performance coefficient (also known as COP) of the refrigerator, the higher the refrigeration efficiency of the air-conditioning system. For example, if the temperature of thermal medium water is about 60℃, the COP of refrigerator is about 0~40. If the temperature of thermal medium water is about 90℃, the COP of refrigerator is about 0~70. If the temperature of thermal medium water is about 120℃, the COP of refrigerator can reach more than 110.
It has been proved that the technology scheme of solar air conditioning combining heat pipe vacuum tube collector and lithium bromide absorption refrigerator is successful, which opens up a new application field for solar thermal utilization technology.
One: basic working principle
The solar absorption air conditioning system is mainly composed of solar collector and absorption refrigerator.
Working principle of absorption refrigeration
Absorption refrigeration is performed by using a binary solution of two substances as the working medium. The two substances have different boiling points at the same pressure. The components with high boiling points are called absorbent, and the components with low boiling points are called refrigerants. There are two kinds of absorbents and refrigerants in common use: one is lithium bromide and water, which is usually suitable for large central air conditioners; The other is water-ammonia, which is usually used in small air conditioners.
Absorption chiller is mainly composed of generator, condenser, evaporator and absorber.
This paper takes lithium bromide absorption chiller as an example. During the operation of refrigerator, when lithium bromide aqueous solution is heated by hot medium water in the generator, the water in the solution will vaporize continuously. Steam enters the condenser, which is cooled by cooling water and condenses. With the constant vaporization of water, the solution concentration in the generator increases continuously and enters the absorber; When the water in the condenser enters the evaporator through the throttle valve, it expands rapidly and vaporizes, and absorbs a large amount of heat from the refrigerant water in the evaporator during the vaporization process, so as to achieve the purpose of cooling and refrigeration. In this process, low-temperature water vapor enters the absorber and is absorbed by concentrated lithium bromide solution in the absorber. The solution concentration gradually decreases and is sent back to the generator by the solution pump to complete the whole cycle.