Che Zhu

Unsteady Behavior of Real Gas in Wave Rotor Refrigerators

Real gas effect has great impact on unsteady flow behaviors in wave rotor refrigerator (WRR). In this work, the main thermal separation effect and propagation speed of gasdynamic wave of real gases are briefly studied. Numerical results have shown the large deviations between perfect gas model and real gas model for gasdynamic waves. A corrected wave diagram of WRR has been achieved based on real gas PVT relations, through which the problem of offset design of port timing can be completely solved.

Study on Hydrated Operation Performance of Wave Rotor Refrigerators

Because of bilateral pulse tubes, wave rotor refrigerators (WRRs) have excellent fluidic operation performance. In this work, a WRR experimental rig with throughput of 3×104Nm3/d and expansion ratio 3 for hydrated gases has been built. A number of experiments show that the temperature of low pressure port of WRR has little influence on refrigeration efficiency. This makes possible of maintaining excellent refrigeration efficiency when WRR operating with high-liquid gases. Actual liquid experiments do show the excellent fluidic operation performance: the refrigeration performance remains almost unchanged even if WWR operates with 13.7 %( w) liquid ratio.

Study on Flow Field Intensification of Dynamic Pre-Cyclone Separators

Abstract Because of external driving, dynamic pre-cyclone separators have excellent operational performances in areas of pressure vary occasionally. In this work, a numerical model of the dynamic separator been built and the flow field is thoroughly studied. The distribution results of angular velocity show that an appropriate structure of pre-cyclone vanes is of great importance to get a relative uniform flow angular velocity field. A novel structure of pre-cyclone vanes under different separation requirements is developed and verified by a number of experiments.

Real Gas Effect on Unsteady Flow of Natural Gases in Shock Tubes

The unsteady flow behaviors in devices like gas wave machines, wave rotor refrigerators and so on are complex due to real gas effect at high operational pressure and low temperature. In this work, a detail computational model for unsteady flow analysis of real natural gases is established. The real effect on unsteady behaviors of natural gases in shock tubes have been studied extensively. Results show that the non-classical flow of the gases will not exist. The discipline of reflection and refraction of various gas waves or discontinuities remain unchanged for natural gases. Attention should be paid only to the deviations between perfect gas model and real gas model for gasdynamic waves.

Propagation and Reflection of Gas Waves in a Close Tube

The gas and shock wave’s motion in a receiving tube is investigated numerically and experimentally. The results show that, the velocity of the contact face rises rapidly as gas is injected into the receiving tube, and drops sharply after a steady propagation. However, the velocity of the shock wave in the tube is almost linear and the shock wave can be reflected at the close end of the receiving tube. The shock wave and the injecting wave propagate in the different direction. When the reflected wave sweeps, it can heat the gas about 20K under the pressure ratio of 2. If the exhausted gas is used to refrigeration, the reflected wave has negative effect. With increasing of inlet pressure, the velocity of the shock wave and steady velocity of contact face also increase. There is obvious thermal effect as the shock wave sweeps the gas. The reflected shock wave can heat the exhausting gas in the open end. The exhausting gas’ temperature for low pressure ratio is higher than the temperature for high pressure ratio. But as the pressure ratio rises to a value, the temperature drop little. The result shows that the numerical value is a little higher than the experimental value, especially under lower pressure ratio. The reason may lie in the operation condition and the heat exchange. Under lower pressure ratio, the shock wave can heat the gas in the closed end and the heat can easily be transferred to the open end. As a whole, the experimental results are consistent with the numerical simulation. Open image in new window Shock wave’s reflection