熵产生最小时不可逆Otto循环热机活塞运动最优路径  

Optimal paths of piston motion of irreversible Otto cycle heat engines for minimum entropy generation

作　　者：戈延林[1] 陈林根[1] 孙丰瑞[1] 

机构地区：[1]海军工程大学研究生院,武汉430033

出　　处：《中国科学：物理学、力学、天文学》2010年第9期1115-1129,共15页Scientia Sinica Physica,Mechanica & Astronomica

基　　金：国家自然科学基金(批准号:10905093);教育部新世纪优秀人才支持计划(编号:NCET-04-1006);全国优秀博士论文作者专项资金(编号:200136)资助项目

摘　　要：给定循环总时间和耗油量的情况下,以存在传热、摩擦等内、外不可逆性的Otto循环热机为研究对象,考虑工质与环境之间的传热分别服从牛顿传热规律q∝Δ(T)和线性唯象传热规律q∝Δ(T-1),以循环熵产生最小为目标对整个循环活塞运动的最优路径进行了研究.利用最优控制理论得出了两种传热规律下无加速度约束和限制加速度时对应于循环最小熵产生时各冲程活塞最优运动规律及循环总时间的最优分配.限制加速度时各个冲程的活塞运动最优构型均由三段组成,均包含了一个初始最大加速段和一个末端最大加速段.给出了最优构型的数值算例,并与牛顿传热规律和线性唯象传热规律时最大输出功条件下的最优构型进行了比较.计算结果表明优化活塞运动规律后可使热机熵产生减小30%以上,这主要是通过减少功率冲程初始段传热损失引起的熵产生实现的.An Otto cycle heat engine with internal and external irreversibilities of heat transfer and friction, in which the heat transfer between the working fluid and the environment obeys Newton＇s heat transfer law [ q∝Δ（T） ] and linear phenomenological heat transfer law [ q∝Δ（T-1） ], respectively, is studied in this paper. The optimal piston motion trajectories for minimizing entropy generation per cycle are derived for the fixed total cycle time and fuel consumed per cycle. Optimal control theory is applied to determine the optimal piston trajectories for the cases of with and without piston acceleration constraint on each stroke and the optimal distribution of the total cycle time among the strokes with two heat transfer laws. The optimal piston motions with acceleration constraint for each stroke consist of three segments, including initial maximum acceleration and final maximum deceleration boundary segments, respectively. Numerical examples for optimal configurations are provided, and the results obtained are compared with those obtained when maximizing the work output with Newton＇s and linear phenomenological heat transfer laws. The results also show that optimizing the piston motion could reduce engine entropy generation by more than 30%. This is primarily due to the reduction of heat transfer loss on the initial portion of the power stroke.

关 键 词：牛顿传热规律 线性唯象传热规律 不可逆Otto循环热机 最小熵产生 活塞最优运动路径 有限时间热力学 

分 类 号：O414.11[理学—理论物理]