为了回收内燃机排气余热能,提出气动/内燃复合循环.该复合循环利用内燃机排气过程提前开启,以提高排气压力,保证内燃机排气和压缩空气顺利混合.基于热力学理论建立复合循环p-V图,分析复合循环工作过程和循环效率,对循环效率进行初步计算.结果表明:随着排气提前角的增大,复合循环热力学第一定律效率和第二定律效率均呈现先增加后减小的趋势;随着内燃循环转速的增加,复合循环最佳排气提前角呈现减小趋势,而复合循环热力学第一定律效率和第二定律效率呈现逐渐增加的趋势,但增加幅度逐渐减小.
The pneumatic and internal combustion combined cycle was proposed in order to recycle the exhaust heat of internal combustion engine. The exhaust valve open timing was advanced in this combined cycle,which can raise the exhaust pressure and lead to smoothly full mix of compressed air and exhaust gas. The p-V diagram of combined cycle was built based on the thermodynamics theory, and it was used to analyze the working process and cycle efficiency. The cycle efficiency was preliminarily calculated. Results show that the first law and second law thermodynamics efficiency grow in the beginning and decrease with the increasing of the exhaust valve open timing. The optimum exhaust valve open timing drops as the internal combustion engine speed increases, while the first law and second law thermodynamics efficiency of combined cycle increase in the same condition, but with its increasing rate falling gradually.