Theoretical And Experimental Study On The Diffusion Absorption Refrigeration System Using Mixed Refrigerants

The development of society is threatened by the growing energy crisis and environmental problems, which lead to the worldwide attention to the technology of energy-saving and emission-reduction nowadays. The diffusion absorption refrigeration system is preferred and become a hot research topic again, because the system can be driven by low-grade heat with advantages of no noise, no moving parts and high reliability. Traditional absorption refrigeration systems use NH3/H2O or BrLi/H20working pairs, which are difficult for deep refrigeration due to the defects of the traditional working fluid. On the basis of summaries and analyses on the theoretical and experimental studies of the diffusion absorption refrigeration systems home and abroad, a diffusion absorption refrigeration system using the absorbent N,N-dimethylformamide (DMF), binary refrigerant R23/R134a and auxiliary inert gas helium is preposed this paper. Intensive theoretical and experimental studies are conducted on the thermophysical properties of multicomponent mixtures and the performance of refrigeration system.The main contents and conclusions are as follows:1. The parameters of the Patel-Teja equation of state (EOS) and Patel-Teja EOS+NRTL activity coefficient model were optimized with the Matlab, and the parameters of organic working fluids:R32-DMF、R134a-DMF、R22-DMF and R142b-DMF were obtained. Compared with the Patel-Teja EOS model, the Patel-Teja EOS+NRTL activity coefficient model is simpler and has higher accuracy in predicting the vapor-liquid equilibrium of the above mixtures. 2. The performance of refrigeration cycle was simulated using Patel-Teja EOS model. The relationships between the coefficient of performance (COP) and the following parameters:system pressure, concentration of rich solution, distillation effectiveness, absorption effectiveness, ambient temperature, generating temperature and cooling temperature were obtained. The results reveal that the matching of the capacity rates of the two fluids in the refrigerate recuperator plays a key role on the performance of system.3. A diffusion absorption refrigeration system using mixed refrigerants was designed and built up. In experiment it was verified that the diffusion absorption refrigeration system using mixed refrigerants is much easier to operate at low temperature than the pure refrigerant system.4. A new bubble pump with an annular channel generator was designed and built up. Experimental results show that it possesses advantages of quick start, small heat transfer temperature difference, low heat loss and large flowrate.