Studyon Heat Transfer Performance and Targeted Control on Thermal Resistance in a Low-resistance Cross-flow Plate Heat Exchanger
Plate heat exchanger for flue gas waste heat recovery suffers from non-uniform temperature distribution.Improving the uniformity of temperature distribution can effectively suppress heat exchanger corrosion.This study experimentally investigates the performance of two low-resistance cross-flow plate heat exchangers.Meanwhile,the computational fluid dynamic(CFD)method is applied to predict the local heat transfer characteristics.By employing the targeting thermal resistance regulation strategy,a non-uniform fin structure is designed.Results demonstrate that,at a high temperature of 450℃,the total heat transfer coefficients of cross-flow plate heat exchangers made of carbon-steel and cast-iron reach 32.5 W/(m2·K)and 25.1W/(m2·K),respectively.The cross-flow heat transfer results in ex-tremely uneven temperature distribution concern.The regions at the cross-section of hot-side-outlet and cold-side-inlet,as well as the cross-section at the hot side outlet and the cold side outlet,show dominantly high thermal resistance,which can easily cause local flue gas temperatures dropping below its dew point temperature.As the result,a non-uniform fin structure based on thermal resistance analysis is involved based on the targeting local thermal resistance regulation analysis,the average temperature vari-ance at the outlet cross-section is significantly reduced from 6.9℃to 1.1℃while maintaining the flow resistance almost unchanged.The uniformity of fluid temperature distribution in the heat exchanger is sig-nificantly improved.
gas waste heatcross-flow plate heat exchangertargeting thermal resistance regulationnon-uniform fin structuretemperature uniformity
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