The Research Of Heat Pipe Heat Exchanger Based On The Sewage Thermal Utilization

Sewage which is a kind of renewable and clean resources with high quality hasbecome a key object of the “increase income and reduce expenditure” in the field ofbuilding energy efficiency when the policy of energy conservation and emissionreduction was practiced widely in today’s society. Sewage source heat pump system isan important technology in the utilization of sewage heat. The solution of inefficiencyand jam in the sewage heat exchangers has become the key problem in sewage sourceheat pump system for indirect sewage source heat pump system which was commonlyused. A new type of sewage heat pipe exchanger which was researched by sewage heatexchangers in indirect sewage source heat pump system was introduced in this paper.As a phase-change heat transfer component, heat pipe has become one of the mostefficient in known areas of heat transfer components, with its excellent heat transfer,higher heat transfer limit and other advantages. But it cannot be widely used in the fieldof renewable energy use until now. In order to promote the wider use of sewage sourceheat pump technology, the heat pipe, as a heat transfer component in sewage heatexchangers, is suggested to be used in sewage source heat pump system in this paper.Internal heat pipe which conduct heat by the phase change of working mediuminvolving two-phase flow boiling condensation and some other heat transfer mechanism,is a complex flow and heat transfer systems. Theoretical analysis and experimentalphysics methods was designed to validate the feasibility and optimize the heat transfereffect of heat pipe exchanger applied in sewage source heat pump system. The researchresults were analyzed to explore the design method of heat pipe exchanger applied insewage source heat pump system.In this paper, an in-depth study was made from theoretical and experimentalaspects which were based on the research and development of phase change heatexchanger in the utilization of sewage heat. The theory was studied at three differentlevels:①The theoretical design of heat pipe which was based on rated temperatureconditions in sewage source heat pump system mainly includes the choice of the heatpipe working medium, the design of shell and end cover, the calculation of quantity ofliquid and the design of the heat pipe structure size.②The heat transfer performance ofevaporator section and condensation section in heat pipe exchanger was analyzed fromtheoretical aspects to find the formula of the heat transfer limit during operation in gravity heat pipe. And this can provide theoretical basis for the subsequent papers.③The heat transfer coefficient, temperature difference and the heat transfer area of heatexchanger pipe were analyzed which were based on heat transfer theory to lay thetheoretical foundation for the subsequent heat exchanger design, production andexperiments.④After the comprehensive theoretical analysis, the heat pipe exchangertube spacing design was suggested by using fluent,under the premise that theproduction process of heat pipe can be met, to optimize heat transfer and reduce theresistance loss.The experiments were carried out experiments in three different types:①Sewageheat pipe exchanger model was designed. And a sewage source heat pump system testplatform model was built.②The start feasibility experiments, a single heat pipecondenser section to optimize heat transfer fluid flow experiments and the effect of heatpipe heat exchanger optimization experiments under rated temperature conditions insewage source heat pump were designed.③A series of experiments related work-design of the experimental under different conditions, quantitative experimental test andanalysis and discussion of the experimental data-was conducted.Through theoretical analysis and experimental analysis, it is founded that:①Theutilization of heat pipe in sewage source heat pump system is feasible. Heat pipe has theadvantages that high heat transfer efficiency, not easy jam, small resistance, and easycleaning management operation.②The heat exchanger effect is better when the fluidoutside heat pipe is contranatant than it is downstream in heat pipe within the process ofheat transfer.③The heat exchanger effect is better when the fluid outside heat pipe whenthe heat pipes are180°horizontal sweep bundles than there are90°horizontal sweepbundles or vertical sweep bundles in heat pipe exchanger during operation.