不可逆矩形循环的功率和效率特性

Power and Efficiency Characteristics for an Irreversible Rectangular Cycle

用有限时间热力学的方法研究存在传热损失和摩擦的空气标准矩形循环,导出了功率与膨胀比、热效率与膨胀比以及功率和效率的最佳特性关系,同时分析了传热损失和摩擦对循环性能的影响。结果表明:功率及效率随膨胀比的变化曲线呈类抛物线型,功率-效率特性曲线呈回原点的扭叶型;随着摩擦的增大,循环的功率及效率减小;随着当量放热量的增大,摩擦、传热损失系数和初始温度的减小,最大功率和最高效率增大。

The performance of the air standard rectangular cycle with heat transfer and friction losses is investigated by using finite-time thermodynamics. The relations of power output versus expansion ratio and thermal efficiency versus expansion ratio, and the optimal relation of power output versus efficiency of the cycle are derived. Moreover, the effects of the heat transfer and friction losses on the cycle performance are analyzed. The results show that both the curves of power output versus expansion ratio and thermal efficiency versus expansion ratio are parabolic like type; the curve of power output versus efficiency is loop-shaped type returning to the origin. With the increase of the friction, both the power output and the efficiency increase. With the increase of the heat equivalent release or the decreases of the friction, the coefficient of heat transfer loss or the initial temperature, both the maximum power output and the maximum efficiency increase