Vapor-Liquid Equilibrium And Performance Assessment Of HFCs+Organic Absorbents Working Pairs Based Hybrid Refrigeration Cycle

The absorption-compression hybrid refrigeration cycles are important low-grade heat recovery utilization technologies, which can not only replace the consumption of primary energy, such as oil, gas and coal to reduce the carbon dioxide emission but also employ the environmentally friendly working pairs. However, the most common used in Hybird refrigeration cycles are NH3+H2O and CFCs or HCFCs-based systems, which have their own application of shortcomings. That restricted the development of Hybrid refrigeration cycle technology greatly. In order to solve these problems, the HFCs refrigerants together with suitable organic absorbents have been proposed as alternative working pairs for Hybrid refrigeration cycle in the study. With the aid of experimental measurement and computer simulation, the main content as follows have been carried out.Firstly, according to the working principle of Hybrid refrigeration cycle, the systems of R161+DMF and R161+DMEDEG with good affinity were proposed as novel working pairs based on two-step method. The VLE data of the two systems were measured in the temperature range293.15K to353.15K using the experimental apparatus. Experimental data were correlated using the NRTL activity coefficient model. For the R161+DMF and R161+DMEDEG systems, the average relative pressure deviations between experiment and calculated values are1.33%and1.46%, and the maximum relative pressure deviations are3.68%and3.90%, respectively. The results show good thermodynamic consistency between experimental data and calculated results. Both the two systems exhibit negative deviations from Raoult’s law. This work shows that the systems are potential working pairs for Hybird refrigeration cycle.The second, based on literature and experimental VLE data, the Hybrid refrigeration cycle performance of twelve different working pairs composed of HFC refrigerants and organic absorbents have been evaluated using Aspen Plus software. Then the systems R32+DMF, R32+DMAC, R152a+DMAC, R161+DMEDEG and R134a+DMF were selected as the potential working pairs for further simulation study. In addition, on the basis of two new cycle evaluation criterions, the heat powered coefficient of performance (ω) and electricity saving rate (ω), the effects of generator temperature, absorber temperature and compressor outlet pressure ratio (A) on the energy saving performance for the five systems were also discussed.Finally, an experimental setup is designed and built to measure the performance of Hybrid refrigeration system using R134a+DMF as working pair. And the detailed information of design and selection for key equipments such as evaporator, condenser, absorber, generator and solution exchanger were also introduced. The cycle performances of compression refrigeration system based on R134a have been investigated under variable working conditions.