Improvement of the cooling performance of a reciprocating compressor cylinder by a conjugate heat transfer and deformation analysis

The cooling system of a reciprocating compressor has a big impact on the total cost of the unit, depending on the total head and the capacity of the system. Considering that current regulations API618 for reciprocating compressor impose the refrigeration of the cylinder, cooling water passages inside cylinder shall be designed to limit as much as possible thermal dilatation and to avoid hot spots, while lowering down capacity and pressure losses. In this paper, a conjugate heat transfer (CHT) analysis on a double-acting water-cooled reciprocating compressor cylinder is presented. The aim of the study was the simulation of simultaneous heat transfer in both the solid metal and the water circuit, where the conduction in the solid and the convection in the fluid are analysed concurrently. A detailed overview on some critical issues for the assessment of the proper boundary conditions for the metal body is given. Two different geometrical configurations of the refrigerating system were studied in order to improve the cooling performance. Moreover, a thermal deformation analysis to check the induced dilatations was carried out. Finally, the most suitable geometrical layout was assessed and a sensitivity analysis was performed on the influence of the mass flow rate on the cooling efficiency.