Theoretical And Experimental Studies On A Diffusion Absorption Refrigeration System Using Mixed Refrigerants

Diffusion-absorption refrigeration system has the advantages of no moving parts and driven by low grade waste energy, however traditional diffusion absorption refrigeration cycle has the limitation that it cannot achieve low refrigeration temperature. Auto-cascade absorption refrigeration cycle can achieve low refrigeration temperature, but the solution pump consumed too much power due to the large circulation ratio in this system. A diffusion absorption refrigeration cycle using mixed refrigerants was proposed in this thesis to overcome these two cycles' deficiency and both theoretical and experimental studies were carried out in this thesis to achieve low refrigeration temperatures only with low grade thermal energy.The main research contents are as below:1. The research history and present status of diffusion absorption refrigeration system and auto-cascade absorption refrigeration system at home and abroad are reviewed.2. The auto-cascade diffusion absorption refrigeration cycle is proposed and modified. Using modified Patel-Teja type equation and virial mixing rule, a calculation program is made to calculate the vapor-liquid equilibrium and other thermodynamic properties of the mixed working fluid He/R23/R134a/DMF. The thermodynamic calculation of the diffusion absorption refrigeration cycle using mixed refrigerants is also carried out. 3. Based on the thermodynamic calculation, the design of system structure and the calculation of components are described soundly. The location of each component is also designed and optimized.4. Replacing the bubble pump with a mechanical pump, an experimental device of diffusion absorption refrigeration cycle is built up. Based on large numbers of experimental studies, the reasons for the fluctuation of the evaporator temperature are analyzed; the experimental device is also improved.5. A series of experimental studies are carried out on the effect of the parameters such as the system pressure, heat flux and working fluid components on the lowest temperature. The device achieved a lowest refrigeration temperature of-30.3℃in experiment.