| The gas wave refrigeration technology is used to realize energy exchange between two streams through the movement of shock wave and expansion wave in the oscillating tube. Simple structure and high isentropic refrigeration efficiency are two main advantages of the gas wave refrigeration. Previous studies ignored the condition with phase transition. However, the condition with phase transition which is close to the reality. When the phase transition happens in the tube, it will release condensation latent heat, changing previous wave system in the tube and refrigeration efficiency.In this paper, numerical simulation and experimental test is adopted. And the paper carries on detailed research on non-equilibrium condensation mechanism in the refrigeration process. The influences of non-equilibrium condensation on flow field and refrigeration efficiency are investigated. The transparent observation oscillating tube platform and refrigeration platform is established to lay a foundation for future research. The main work and relevant conclusions are as follow:(1) Using C language to edit two common nucleation models and droplet growth model, the distribution of condensation parameters in the pressure oscillation tube is calculated. Based on the research, a suitable model used for non-equilibrium condensation of unsteady flow field in the tube is recommended. The research shows that the distributions of condensation parameters in the tube under two nucleation models are the same. While the difference between the two models becomes larger with the increase of steam content, the results show linear distribution, the fitting curve expression is y=1.40x+1.21 and the relevant parameter R2 is 0.931. Frenkel model is more preferable in the moving oscillation tube.(2) The influences of non-equilibrium condensation on wave system and refrigeration in the tube are investigated to draw wave graph with non-equilibrium condensation. The effect of non-equilibrium condensation on the match of wave system and the trajectory of condensation particles in the tube are analyzed Meanwhile, the reliable separation method of phase state is put forward. The research shows that the refrigeration efficiency of the tube decreases gradually with the increase of relative humidity. The efficiency decreases dramatically when the relative humidity is lager than 0.6 and decreases to 5%when the relative humidity reaches 0.8. The condensation shock wave is generated because non-equilibrium condensation releases latent heat which accelerates the propagation mach number and consequently change the match of wave system in the tube. Compared to the results of inlet medium without steam the optimized offset angle is reduced by 7%when the relative humidity reaches 0.8. The condensation particles move in the tube for a long distance, the second evaporation may appear when the particles move into high temperature section.(3) Building the visual oscillating tube platform, the experimental test on the formation and movement of inner particles is conducted. Building the oscillating tube platform with forced heat transfer, the effect of non-equilibrium condensation on the refrigeration performance is investigated experimentally. Plus, the main factor results in the change of refrigeration performance is studied through two types of heat transfer. The research shows that non-equilibrium condensation appears in the visual tube and is recorded in the pictures when using the mixture of air and steam as inlet medium. For the two types of heat transfer, on the one hand, the trends of refrigeration efficiency with the change of jet frequency are the same, but the extreme point of jet frequency corresponding to cooling water heat transfer moves forward. On the other hand, the refrigeration efficiency of the both types is decreased by 3%, therefore, the second evaporation of condensation particles as the main factor has a great influence on the refrigeration efficiency in the oscillating tube. |
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