Abstract:

In this paper,the effects of ultrasonic waves on the mass transfer of the cryogen water in LiBr solution that acts as the working medium in an absorption refrigeration system were investigated. The results indicate that ( 1) ultrasonic waves obviously enhance the mass transfer of the cryogen water; ( 2) the enhancement is strongest at the intial phase,and then it gradually weakens and tends to be stable as the system becomes balanced; ( 3) in the refrigeration system with 50% LiBr solution as the working medium and with an initial pressure of 800 Pa,the transferring intensification rate is more than 20% when the heat source temperature is kept at 65 ～80℃, and it increases significantly with the decrease of the heat resource temperature; ( 4) the method of applying ultrasonic waves to the mass transfer enhancement can effectively improve the refrigeneration efficiency of the LiBr absorption refrigerator driven by low-temperature heat resources and can reduce the lowest temperature of heat source water for the refrigeration system without affecting the stable operation of the system; and ( 5) the propsed method is suitable for the solar absorption refrigeration system driven by low-temperature hot water and is capable of improving the refrigeration performance of solar air-conditioning.

Key words: ultrasonic waves, absorption refrigeration, mass transfer enhancement, solar energy