Investigation Of Heat Exchanger On Thermal Enhancement

Energy conversation is a long-term strategy in the national economic development.In the PHD thesis,the flow and heat transfer problems related with thermal enhancement are investigated,which expects to contribute to save energy and decrease energy consumption in related industries.First,in order to develop commerical cooking utensils,the S-type air preheater is put forward by series of experimental studies.The heat transfer performance is systematically studied by the theoretical simulation and experimental validation method,including the measurement of basic data,the optimization of constructional dimension,the analysis of fluid flow and the exploration of mechanism of heat transfer et al.Base on the view of economic system,the relationship between the objective function and the target parameters is analyzed,while the consolidated profit is treated as the objective function and the effective length,flow rate of hot and cold entrance,area of heat transfer are treated as the target parameters.The fitting formulas are used to guide the industrial design of heat exchanger.Then,in order to further optimize the heat transfer performance,the configuration and structure of traditional vortex generators are simulated and optimized,such as arrangement of fins(downstream,upstream),layout of vortex generators(ABA type,AB type),size of vortex generators and holes on vortex generators et al.Compared with the traditional vortex generators(delta wing,rectangular wing),a novel type of vortex generator is proposed,which is defined as the double delta winglet vortex generator(DDWT).By the ways of simulated optimization and experimental validation,the thermal mechanism of DDWT is investigated and the structure is optimized.What?s more,combined the novel structure(DDWT)with the traditional structure(delta wing,rectangular wing),it is demonstrated that the combined vortex generator performs better thermal enhancement.Finally,the diversion structures are applied to enhance the heat exchanger and a novel plate heat exchanger is proposed.Experiments and theoretical simulation of the plate heat exchanger are discussed for the heat exchange between liquids,the condensation and evaporation on film flow.The effect of different types of diversion on thermal enhancement,such as vertical corrugated board,oblique corrugated board and fenestrate corrugated board,are compared.Meanwhile,compared with the single and double diversion structures,the experimental results indicate that the fenestrate diversion structure has better heat transfer performance.