Study On Heat Transfer Characteristics Of The Jacketed Heat Pipe And Numerical Simulation On Flow Field Of The Exchanger

Heat pipe exchanger uses the heat pipe as heat transfer element, and has the advantages of high efficiency, low pressure loss, good reliability and compact structure. But the traditional heat pipe exchanger has the serious problem of dew point corrosion in recovery of low grade waste heat. To solve this problem, the jacketed heat pipe exchanger is invented. This new type of heat pipe and heat pipe exchanger is investigated in the dissertation. The main contributions are listed as follows:The experimental investigation was conducted to explore the heat transfer characteristics of the jacketed heat pipe. The temperatures on the outer wall under different heat flux were collected, the distribution of the temperature on the outer wall was analyzed and the heat transfer coefficients of different heat pipes were calculated. According to the principle of the least square method, an experimental correlation was established to reveal the relationship among heat transfer coefficient, working fluid rate and heat flux. The system error of Heat Transfer Coefficient is less than±9.21%.Adopt the porous medium model to carry out the three dimensional numerical simulation on the flow field of the jacketed heat pipe exchanger using the computational fluid dynamic software FLUENT, and use the data from field test as the boundary conditions. The distribution of static pressure is nearly linear along the direction of the gas flow, and the total pressure increases with the gas flow velocity at the inlet. The simulation results of three different distributed resistances have the same tendency. And the relative error of simulation result from Taborek relation is less than 8%In order to make up the deficiency of local information of the heat pipe exchanger in detail by using the porous medium model, the solid model was adopted to calculate the representative volume element of the heat pipe exchanger. The relative error of the simulation result is 5.4%.The influence of pressure drop from the different structure parameters of the heat pipe exchanger was analyzed. The factors of process, installation and operation were comprehensive considered, so the results were gotten as follows. The fin height should be less than 26.5mm, the fin spacing should be more than 6.5mm, the transverse space of heat pipe should between 108 and 111mm, the longitudinal space of heat pipe should between 120 and 125mm.