Study And Optimization On Performance Of Over-Expanded Gas Wave Refrigerator

Over-Expanded Gas Wave Refrigerator (OE-GWR) is a new type of Pressure Exchanging Refrigerator (PER). Compared with ECD-GWR (External-Circulation Dissipative Gas Wave Refrigerator), an old type of PER, OE-GWR adds the step of recovering pressure energy which greatly increases the efficiency. What’s more, it inherits the properties of small volume, easily assembling, conveniently maintaining and so on which PER has. So OE-GWR has a broad application prospect. However, at present, the study of OE-GWR is not deep enough and the performance of OE-GWR is not clear. The optimization of OE-GWR is not beginning also.Based on the condition above, the study of the performance of OE-GWR is done with gas dynamic knowledge, thermodynamic knowledge and numerical simulation through which some useful proposals are come up with. The working performance of OE-GWR is also experimentally studied. The main working contents and results are shown as below:(1) The inside flow condition of OE-GWR is studied with gas dynamic knowledge. The way how the shock wave and expansion wave is formed is introduced and the way to calculate the shock wave speed is deduced then. At last, the perfect shock wave pattern is plotted and the way to match the HP port and MP port is shown based on the introduction above.(2) The working process of OE-GWR is simulated with HYSYS through which the main performance of OE-GWR is studied. The influence of pressure ratio, expansion efficiency, compression efficiency and HP temperature to the global efficiency and temperature drop is concluded based on the simulation. The performance contraction of OE-GWR and ECD-GWR is also studied and the conclusion that the efficiency of OE-GWR is much higher than ECD-GWR in small pressure ratio while as the pressure ratio increases, the difference becomes smaller is drawn.(3) The OE-GWR is simulated with FLUENT firstly using the model in which the LT port and the LP port are connected. The error brought by the setting of LP port and LT port parameters is eliminated using this model. Based on the simulation, the property of pressure and temperature distribution is studied. Through the study of the formation of the pressure of the low temperature gas, the way of setting a WP port to increase the temperature drop is proposed and it is then proved to be effective by the simulation. (4) The influence of the fan frequency to the global efficiency is studied and explained in detail with thermodynamic knowledge which shows that when the mass flow rate of low temperature gas is equal to the middle pressure gas, the global efficiency is the highest. The way of using high pressure gas to drive low temperature gas instead of the fan is proposed then and it is proved to be feasible by the simulation of FLUENT.(5) The actual property of OE-GWR in small pressure ratio and offset angle is studied experimentally by updating the old experiment system. The influence of pressure ratio, rotor speed, offset angel and MP port size to the global efficiency is studied. The experiment result is discussed and analysed. By adjusting the parameters, the global efficiency of OE-GWR can be increased to355.8%from90%which is the highest efficiency that the former gets.