| The process of industrial waste gas emission was associated with a lot of heat release. Atthe time of energy shortage, today waste heat recovery is an important way for energyrecycling. Regenerative heat exchanger is an important equipment used in waste heat recoverysysterm. Because of its big heat transfer coefficient at low flow rates, easy to clean, stronganti-scaling capabilities, high volumetric heat transfer coefficient, long service life etc., therandom ring regenerator of regenerative heat exchanger became one of promisingregenerative heat exchanger. At the same time as a kind of typical heat storage filler, ceramicring regenerators were applied in the packed bed regenerative heat exchanger. This graduatethesis has proposed a packed bed regenerative heat exchanger filled with ring regeneratorbased on the study on thermal characteristics of packed bed regenerator. Thermalcharacteristics of packed bed regenerator was studied by fluid dynamics software FLUENTand experiment. The main contents and conclusions are as follows:(1) Firstly, the research methods and the mathematical model of the packed bedregenerator were introduced. Secondly, the thermal characteristics were showed byexperiments comparing random ring regenerator with honeycomb ceramic regenerator.Thirdly, the packed bed regenerator was numerically simulated with porous media model inFLUENT software and the accuracy of its thermal characteristics was testified by experiment.Its charge and discharge performance of the entire packed bed regenerator was numericallysimulated with porous media model in FLUENT software. The effects of all parameters onthermal characteristics of the packed bed regenerators were researched by analyzingdistribution of temperature. Finally, the temperature variation of regenerators filled with oneand single layer ring regenerator numerically simulated by FLUENT were analyzed.(2) The experiments results showed: the outlet gas temperature of regenerative heatexchanger filled with random ring regenerator was almost the same as honeycomb ceramicregenerator at a low flow rate. Whlie the outlet air temperature and thermal efficiency were6℃and17.5%higher than those of honeycomb ceramic regenerator, nor the pressure drop was10Pa/m smaller than that of honeycomb ceramic regenerator. (3) The outlet gas and air average temperature of packed bed regenerative heat exchangernumerically simulated FLUENT was testified by experiment. There was a definite deviationbetween numerically simulation data and experiment, but the maximum deviation rate wasalmost16%. It showed that it was accurate and feasible for the numerical simulation methodto analyze regenerative heat exchanger. Numerical simulation of charge and discharge processfor the same size as the entire packed bed regenerators by changing parameters of structureand operation, the results indicated that:1) During charge process, the average heat transferrate of h=600mm regenerative heat exchanger filled with ceramic ring regenerator was1.2times than that of h=400mm. The outlet gas average temperature of h=600mm was27℃higher than that of h=400mm.2) During charge process, the average heat transfer rate of gasentrance velocity v=12m/s regenerative heat exchanger was1.3times than that of velocityv=8m/s. During discharge process, the average heat transfer rate of air entrance velocityv=10m/s regenerative heat exchanger was1.59times than that of velocity v=6m/s.3) Duringcharge process, the average heat transfer rate of swap time T=40s regenerative heat exchangerwas1.3times than that of swap time T=80s. The outlet gas average temperature of swap timeT=40s was37.8℃higher than that of swap time T=80s. During discharge process, theaverage heat transfer rate of swap time T=40s regenerative heat exchanger was1.04timesthan that of swap time T=80s. The outlet air average temperature of swap time T=40s was5℃higher than that of swap time T=80s.(4) Numerical simulation of charge and discharge process for the same size asregenerators filled with one and single layer ring regenerator, the results indicated that:1)During charge process, when the temperature of ring filler was the same as inlet gas, theaverage temperature of outlet gas was the highest. Yet during discharge process, when thetemperature of ring filler was the same as inlet air, the average temperature of outlet air wasthe lowest.2) The regenerator filled with single layer ring regenerator had a phenomenon ofthermal stress concentration due to uneven temperature distribution. |
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