Study On Key Technology Of Air-Cooled Adiabatic Absorption Refrigeration

Energy and environment has been issues concerned all over the world. Rapid expansion in the use of electricity-powered air conditioning and refrigeration devices not only has been a strong reason for occurrence of electricity demand peaks in the summer and winter seasons, but also has caused serious environmental problems such as ozone depletion and global warming effect. Owing to its advantages such as cleanness, environment-protection and less electricity comsumption, air-cooled gas-fired air conditioning contributes to relieving inconsistency between electric supply and demand, besides, optimizing and improving the structure of energy consumption. Application in households, villas and office buildings is very promising. However, traditional air-cooled gas-fired air-conditioners caused increase of risk of crystallization, acceleration of corrosion and lower COP because of boost of temperature, concentration and pressure in the systems. To be worse, poor absorption effect in traditional falling film absorber brought about too large absorber size, and it is difficult to make the device smaller.In view of the facts that many problems caused by air-cooled falling film absorption, an air-cooled adiabatic absorption refrigeration cycle has been developed, where the working fluid is lithium bromide-water solution. The conventional air-cooled falling film absorber is replaced by an adiabatic absorber with an air-cooler. There is a packed bed in the adiabatic absorber, which ensures the reliability of operation and improves the cycle performance. The vapor-absorbing process is a simultaneous heat and mass transfer process in the traditional air-cooled absorber. Because mass transfer inside is limited by space and time, the effects of mass transfer is poor. However, heat and mass transfer process is separated in adiabatic absorber with an air-cooler. It is possible to enhance the mass transfer in the adiabatic absorber and heat transfer in the air-cooler respectively. The adiabatic absorber and the packed bed can provide enough space and time for mass transfer process. The packed bed augments interface between vapor and spray solution to enhance the mass transfer further, thus reducing the adiabatic absorber size. It is easier to improve heat transfer between circulation solution and air in the air-cooler. It helps increase subcooling of spray solution at the outlet of the air-cooler, which improves absorption process. Another key feature is that waste heat of saturated refrigerant water from low pressure generator is recovered in low temperature heat exchanger by weak solution from the absorber. Heat recovery can save heat supplied by gas-fired heater and a higher COP can be obtained.The research on the performance of small-size air-cooled gas-fired adiabatic absorption refrigeration cycle was made theoretically. Principle of cycle operation was explained, and the mathematical model for each component making up the cycle system was presented. The optimization design for the normal system is made on thermodynamic parameters and area of heat...