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建立了不可逆diesel循环的热力学模型 ,对diesel循环进行了有限时间热力学分析。推导出在内可逆、内外均不可逆时diesel循环在给定热力学模型下输出功率与热效率之间的关系式 ,并证明了内可逆diesel循环有一最大输出功率 ,而此时循环热效率即为著名的CA效率 ,并求出了最大输出功率表达式 ,证明了在具有最大输出功率时循环压缩比及预胀比有确定的关系。当具有内外双重不可逆时 ,相应公式只是对内可逆时的公式用不可逆系数I进行修正 ,即用ITL 代替原公式中的TL 即可。给出了计算实例 ,并通过实例计算分析了内不可逆系数、热源温度对最大输出功率、热效率的影响及循环压缩比、预胀比对热效率的影响。本文的研究对内燃机的设计和性能评估有理论意义。
The thermodynamic model of irreversible diesel cycle was established and a finite time thermodynamic analysis of the diesel cycle was carried out. The relationship between output power and thermal efficiency of a diesel cycle under a given thermodynamic model is deduced when the inner reversible and the inner reversible both are irreversible and the maximum output power of the inner reversible diesel cycle is proved. However, the circulating thermal efficiency is known as CA Efficiency, and obtained the maximum output power expression, proved that the maximum output power cycle compression ratio and pre-bulging ratio have a definite relationship. When both internal and external irreversible, the corresponding formula is only reversible formula with irreversible coefficient I to be amended, that is, the ITL can be used to replace the original formula TL. The calculation example is given. The influence of internal irreversibility coefficient, heat source temperature on the maximum output power and thermal efficiency and the influence of cycle compression ratio and pre-expansion ratio on the thermal efficiency are also analyzed through examples. The research in this paper has theoretical significance for the design and performance evaluation of internal combustion engine.