重力热管蒸汽发生器热力学分析

为挖掘热管蒸汽发生器回收余热的潜能,基于耗散理论,对不考虑黏性耗散影响和考虑黏性耗散影响的两种情况,分别推导出无量纲参数(耗散数和耗散数)的表达式,并结合工程案例,分析了热管蒸汽发生器烟气侧入口处迎风面流速、热管外径及热管蒸发段长度等参数对耗散数和耗散数的影响,并给出一些有关热管蒸汽发生器设计的建议.研究表明:当不考虑黏性耗散影响时,耗散数和耗散数的变化趋势与温度耗散的变化趋势相同;当考虑黏性耗散影响时,耗散数和耗散数的变化趋势与温度耗散和压力耗散乘积的变化趋势相同,且耗散数比耗散数对迎风面流速、热管外径和热管蒸发段长度等参数变化的响应更敏感.上述方法为热管余热回收装置的热力学性能研究提供了参考.

Thermodynamic analysis of gravity heat-pipe steam generator

In order to excavate the potential of recovering waste heat for heat-pipe steam generator,based on the entransy dissipation theory,the expressions of dimensionless parameters(exergy dissipation number(EXDN) and entransy dissipation number(ENDN)) were derived,respectively,when considering or not the viscous dissipation.After that,some influence factors including the velocity of wind side at the inlet in the flue gas side of heat-pipe steam generator,the outer diameter and the length of evaporation section of heat pipe,for EXDN and ENDN were analyzed according to an engineering case,and some suggestions about the design of heat-pipe steam generator were given.Analysis shows that the change trends of EXDN and ENDN are the same with the temperature-exergy dissipation when not considering the viscous dissipation,and when considering the viscous dissipation,the change trends of EXDN and ENDN are the same with the product of temperature-exergy dissipation and pressure-exergy dissipation,and ENDN is more sensitive to the changes of the above mentioned influence factors than EXDN.These explain that it is feasible for EXDN and ENDN to be used as the evaluation indexes of the irreversibility during the heat transfer process between cold and hot working fluids for heat-pipe steam generator.The method mentioned above can offer beneficial references for the research of thermodynamic performance of heat pipe equipments recovering waste heat.