In order to evaluate the influence of ultrasonic cavitation on mixing, based on the method of UFD (User Defined Function), the flow field in the mixer（KSM）was numerical simulated by using FLUENT software and verified by experiment. The results showed that the fluid in the KSM mixed faster and more uniform due to the ultrasonic cavitation. The pressure drop of the mixer increased slightly. The flow rate of the fluid increased from 0.50 m/s to 0.55 m/s at the inlet of the mixer and it increased by 10%. The turbulence intensity of the fluid was enhanced, and the strengthening effect was most significant at the first mixing element. And more important, the strengthening effect was most significant for the first element which is basically stable after second mixing elements. The result of experiment also is basically consistent with the simulation results. The fluid mixed more uniform and the mixing was better. With the addition of ultrasonic cavitation, the mixing of the fluid in the static mixer was more uniform and the mixing effect was better.

In order to improve the heat transfer efficiency of the twophase closed thermosyphon, different working conditions of the twophase closed thermosyphon under different working condition were simulated by the FLUENT software. Including,the twophase closed thermosyphon under the working condition of different influence of wall temperature of the evaporation zone, and the different filling factor of the evaporation zone on heat transfer efficiency was studied. The results showed that when the wall temperature of the evaporation was 570 K and the filling factor of the evaporation was 50%, the best heat transfer efficiency of the twophase closed thermosyphon was best.

The process of generating the freeze wall was simulated by a numerical method. The energy conservation equation to describe the heat transfer of oil shale and water was established, including the freezing of water. The configuration of the freeze wall was designed. The temperature decrease of the rock near the freeze well was calculated, and the temperature profiles were presented. As the freezing time passed, temperature variation of the underground oil shale was simulated numerically. The numerical results show that the frozen wall will be generated after 180 days of freezing. The minimum thickness of the freeze wall is 1.0 m. The results are the important references for determining the scheme of oil shale insitu conversion, and provide reliable data for the environmental assessment.