辐射传热定律下外燃机最大输出功优化

Optimization of the Maximum Power Output of an External Combustion Engine Under the Law of Radiation-based Heat Conduction

以活塞式外燃机为研究对象,考虑工质与外热槽间传热服从辐射传热定律[q∝△(T4)],以循环输出功最大为优化目标进行了优化。给出了辐射传热定律下的数值算例,并与牛顿传热定律下的结果进行了比较。结果表明,热导率增加,最优完全循环和半循环的输出功和效率均减小,与完全循环相比,最优半循环的压缩比、输出功和效率较大;结果还说明虽然两种传热定律下最优完全循环和最优半循环的欧拉-拉格朗日(E-L)弧部分的工质体积随时间的变化曲线均类似于正弦曲线,并且均由3部分组成,但不同传热定律下工质体积随时间的变化曲线是不相同的。

With a piston-type external combustion engine serving as an object of study,optimized was an external combustion engine with the maximal power output of the cycle serving as the optimization target and the heat conduction between the working medium and the external heat channel abiding by the law of radiation-based heat conduction [q∝Δ(T1)].A numerical calculation case was given under the law of radiation-based heat conduction and compared with the results obtained under the Newton's heat law.The results of the numerical calculation case show that with an increase of the heat conductivity,the power output and efficiency of the optimal full and semi cycle will decrease.Compared with the full cycle,the compression ratio,power output and efficiency of the optimal semi-cycle are relatively big.Although the Euler-Lagrange(E-L) arc sections and the curves showing the change of the volume of the working medium with time are all similar to sine curves and composed of three sections under both heat conduction laws,the curves showing the change of the volume of the working medium under different heat conduction laws are not a same one.