Abstract
The thesis emphasizes on the investigations of single-phase and two-phase flow fluid dynamics and heat transfer of porous media in CPL evaporators. Because the structure of the CPL evaporator is composed of porous media, a rather extensive exploration on fluid dynamics and heat transfer behaviors inside a porous media was conducted in the thesis. The original Darcy's Law and some of its modifications such as the implementation of no-slip boundary condition were examined. Meanwhile, solutions (with no-slip boundary condition) on flow distribution inside an cylindrical pipe were obtained and compared with the results from Darcy's Law model. Larger discrepancies are expected for large permeabilities. Because inside CPL evaporators, the working fluid undergoes phase change and exhibits unique transport phenomena, the current work also looks into the associated important parameters such as fluid saturation, and interphase microscale transport mechanisms. In addition, CPL fundamentals and operating principle are briefly introduced. The 2-D and 3-D numerical analyses of flat type evaporators are also discussed to further understand their fluid dynamics and heat transfer inside CPL evaporators. Finally, the present research also investigates the applications of the computational fluid dynamics code, CFX, to examine those commands and settings as applied in the calculations related to porous media transport behaviors. Some sensitivity analysis, such as the effects of evaporator geometry on their performance are conducted. Preliminary results showed satisfactory temperature, velocity, and pressure distributions in flows inside a porous media. It was found that the temperature gradients inside the thermal layer were consistent with the imposed heat flux from the temperature distribution. The velocity and pressure distributions also indicated as the width of heating plate increases, the velocity at the outlet becomes faster and the pressure drop between the inlet and outlet becomes larger, which is substantiated by the profiles of velocity and pressure obtained from the numerical analysis of 2-D flat type evaporator. Due to a large number of commands and modeling parameters involved in CFX modeling of porous media two-phase flow, it is proposed that a systematic investigation be carried out in the future to fully understand its applications in CPL evaporator design.<end>論文目次: