Performance analysis of an isothermal piston in the case of air compression

A critical aspect for isothermal compression is the rapid transfer of heat, which also represents a key challenge. The heat transfer and resistance characteristics of an isothermal piston were examined through a dimensionless analysis, and the findings were compared with the experimental results. Two parameters, Ka and Xu, were established in the dimensionless model. Ka is an index reflecting the heat transfer performance, and Xu describes the temperature variation of porous media. As the heat transfer increases, the fluid resistance increases irreversibly. The parameter X_por is proposed to indicate the effect of resistance; specifically, this parameter depends on the properties of the porous media and influences the theoretical minimum total work. The relation between the theoretical minimum total work and X_por is presented, which can provide guidance for the optimal design of isothermal pistons.