工质变比热和传热损失对内可逆矩形循环性能的影响

用有限时间热力学理论和方法分析空气标准矩形循环,由数值计算给出了存在传热损失和工质变比热时循环功与压缩比、效率与压缩比以及功和效率的特性关系,并分析了传热损失和工质变比热对循环性能的影响特点,通过分析可知传热和变比热特性对矩形循环性能有较大影响。     

内可逆工质恒比热Meletis-Georgiou循环有限时间热力学建模与性能优化

应用有限时间热力学理论建立内可逆工质恒比热Meletis-Georgiou(MG)循环模型,导出循环各点温度、循环功、效率等性能参数表达式,并对MG循环性能进行分析和优化。应用数值计算方法,得到循环功与效率特性关系;分别以循环功和效率为目标,对压缩比、转换比、过膨胀比进行优化并得到一系列优化结果;分析了传热损失及循环各参数对循环性能与优化结果的影响。所得结果对实际MG发动机的设计优化有一定指导作用。     

不可逆Dual循环的功率效率特性

用有限时间热力学的方法考虑空气标准 Dual循环 ,导出了存在摩擦及传热损失的空气标准 Dual循环的功率与压缩比、效率与压缩比以及功率和效率的最佳特性关系 ,同时由数值计算分析了摩擦和传热对循环性能的影响特点。     

工质变比热和传热损失对Otto循环性能的影响

用有限时间热力学的方法分析空气标准Otto循环，由数值计算给出了存在传热损失和工质变比热时循环功率与压缩比、效率与压缩比以及功率和效率的特性关系，并分析了传热损失和工质变比热对循环性能的影响特点。通过分析可知传热和变比热特性对Otto循环性能有较大影响，所以在实际循环分析中应该予以考虑。     

工质变比热对内可逆Lenoir循环性能的影响

用有限时间热力学理论和方法分析内可逆Lenoir循环,建立了存在工质变比热和传热损失时的循环模型,由数值计算得到了循环的临界压缩比范围,给出了功与压缩比、效率与压缩比以及功和效率的特性关系,并分析了传热损失和工质变比热对循环性能的影响特点,通过分析可知变比热特性和传热损失对Lenoir循环性能有较大影响,对该循环的应用具有一定指导意义。     

包含多变过程的内可逆Otto循环有限时间热力学分析

应用有限时间热力学理论分析了包含多变过程的内可逆Otto循环,由数值计算给出了考虑传热损失时循环输出功与压缩比、效率与压缩比以及输出功与效率的特性关系,分析了多变指数和传热损失对循环性能的影响,通过分析可知多变指数和传热对Otto循环性能有较大影响。计算所得的结果对实际Otto热机的设计和改进有一定的指导意义。     

工质变比热对不可逆矩形循环性能的影响

考虑工质线性变比热特性、传热损失和摩擦损失,用有限时间热力学方法研究了不可逆矩形循环。循环功率与压缩比、效率与压缩比和功率与效率的特性关系均由数值计算给出,分析可知矩形循环性能受工质变比热特性及传热、摩擦损失影响较大。考虑工质变比热特性的循环模型更加接近工程实际,所得结果对矩形循环的应用具有一定的理论指导意义。     

不可逆Miller循环的功率效率特性

用有限时间热力学的方法考虑空气标准Miller循环，导出存在摩擦及传热损失的空气标准Miller循环的功率与压缩比、效率与压缩比，以及功率和效率的最佳特性关系；同时由数值计算分析了摩擦和传热对循环性能的影响特点。结论包含了各种特定条件下不同循环的特性，具有一定的普适性。     

工质非线性变比热比不可逆Dual-Miller循环生态学目标函数优化

考虑工质非线性变比热比特性,存在气缸传热损失、活塞摩擦损失和其他内不可逆性损失,应用有限时间热力学理论分析和优化空气标准Dual-Miller循环性能,推导出了功率、效率和生态学目标函数等性能参数表达式,并由数值计算得到功率和效率与压缩比、功率与效率、生态学目标函数与功率和效率的特性关系,分析升压比和活塞冲程对各性能指标的影响,并分析比较各种不同优化目标下的性能特点。     

工质非线性变比热比内可逆Dual-Miller循环功率、效率和生态学函数优化

考虑工质非线性变比热比和传热损失,应用有限时间热力学理论分析和优化空气标准内可逆DualMiller循环性能。推导功率、效率和生态学函数等性能参数表达式,并通过数值计算得到了功率、效率、生态学函数与压缩比的特性关系;当设计参数取某些特定值时,比较了Dual-Miller循环与Otto、Dual和Miller循环的功率、效率和生态学函数等性能差异;分析了预胀比和Miller循环比对功率、效率、生态学函数等性能的影响。     

Effects of heat transfer and friction on the performance of an irreversible air-standard miller cycle

The performance of an air standard Miller cycle with heat transfer loss and friction-like term loss was analyzed by using finite-time thermodynamics. The relation between the power output and the compression ratio, between the thermal efficiency and the compression ratio as well as the optimal relation between the power output and the efficiency of the cycle are derived. Moreover, the influences of heat transfer loss and friction loss on the cycle performance are analyzed by detailed numerical examples. The results obtained herein include the performance characteristics of different cycles in given conditions, which have universal guidance.     

Performance of irreversible Meletis–Georgiou vane rotary engine cycle with variable specific heats of working fluid

An irreversible cycle model of Meletis–Georgiou (MG) engine consisting of an isochoric heating branch, isochoric and isobaric cooling branches, two non-isentropic compression and two non-isentropic expansion branches and with heat transfer loss, internal irreversibility and the linear relation between specific heat of the working fluid and its temperature is established by using the theory of finite time thermodynamics. The analytical relations of the work output versus compression ratio, the efficiency versus compression ratio, as well as the work output versus efficiency are obtained by using numerical examples. The results show that the work output versus the efficiency characteristic of the irreversible MG cycle is a loop-shaped curve which is consistent with the general heat engine performance, and the cycle model considering the internal irreversibility and linear relation between specific heats of the working fluid and its temperature is closer to practice than the endo-reversible model with constant specific heats of the working fluid.     

多孔介质发动机再热循环有限时间热力学分析

建立了多孔介质（PM）发动机循环的有限时间热力学模型，对PM循环进行了分析，导出了存在摩擦及传热损失时循环功率与压缩比、效率与压缩比以及功率效率的特性关系，同时由数值计算分析了压缩比、预胀比、传热损失和摩擦损失对循环性能的影响特点。将PM循环与Otto循环进行了比较，结果表明：PM循环的性能要优于Otto循环的性能。     

Performance analysis and parametric optimum criteria of an irreversible Atkinson heat-engine

Multi-irreversibilities, mainly resulting from the adiabatic processes, finite-time processes and heat loss through the cylinder wall, are considered in the cycle model of an Atkinson heat engine. The power output and efficiency of the cycle are derived by introducing the pressure ratio and the compression and expansion efficiencies. The performance characteristic curves of the cycle are presented. The bounds of the power output and efficiency are determined. The optimum criteria of some important parameters, such as the power output, efficiency and pressure ratio are given. The influences of the various design parameters on the performance of the cycle are analyzed in detail. The results obtained may provide a theoretical basis for both the optimal design and operation of real Atkinson heat engines.     

Finite-time thermodynamic modelling and analysis of an irreversible Otto-cycle

The performance of an air standard Otto-cycle is analyzed using finite-time thermodynamics. In the irreversible cycle model, the non-linear relation between the specific heat of the working fluid and its temperature, the friction loss computed according to the mean velocity of the piston, the internal irreversibility described by using the compression and expansion efficiencies, and the heat-transfer loss are considered. The relations between the power output and the compression ratio, between the thermal efficiency and the compression ratio, as well as the optimal relation between the power output and the efficiency of the cycle are indicated by numerical examples. Moreover, the effects of internal irreversibility, heat-transfer loss and friction loss on the cycle performance are analyzed. The results obtained in this paper may provide guidance for the design of practical internal-combustion engines.