电场强化对流传热的热力学机理

Thermodynamic Mechanism of Convective Heat Transfer Enhanced by Electric Field

外场作用能够有效地强化传递过程,电场强化传热便是其中的一个研究热点.为揭示电场强化对流传热过程的热力学机理,文中利用能量公理建立了电场作用下的基本热力学关系,定义了电场作用下的焓和吉布斯函数,导出了等温条件下焓随电场的变化以及绝热条件下温度随电场的变化关系.结果表明:对于常用的液体物质,在有效的工作温度范围内,焓在等温过程中随电场增加而减小,温度在绝热过程中随电场增加而上升;如果在系统放热过程中施加电场作用,焓减小意味着系统能够放出更多的热量,温度上升意味着更利于向低温热源放热,因此电场作用能够提高传热效率.文中还基于此热力学机理提出了一个电场强化对流传热过程的原理图.

Transfer processes can be effectively enhanced by external fields,and the heat transfer process enhanced by electric field is a research hotspot in nowadays.In order to reveal the thermodynamic mechanism of convective heat transfer enhanced by electric field,fundamental thermodynamic equations including the influence of electric field are put forward based on the energy postulate,enthalpy and Gibbs function are redefined with the effect of electric field,and the expressions of the partial derivatives of enthalpy and temperature with respect to electric fields are derived.The results indicate that,for most liquids in a valid temperature range,the enthalpy decreases in isothermal process and the temperature increases in adiabatic process with the increase of external electric field. When an external electric field is applied on the heat release stage,the decreased enthalpy of the liquid medium means that more heat can be released,while the increased temperature of it means that the heat release to lower reservoir tends to be more effective.Thus,it is concluded that the electric field effectively enhances the convective heat transfer.Based on the proposed thermodynamic mechanism,a principle diagram is finally presented to de-scribe the convective heat transfer enhanced by electric field.