Shell and tube carbon dioxide gas coolers. Experimental results and modelling.

This paper experimentally compares the heat transfer performance of four different shell and tube gas coolers implemented in a 5 kW, R744 water/water heat pump controlled by a back pressure valve as expansion device. The tubes bundle consists of 10 tubes in a 30° arrangement for all the gas coolers with different tube geometries: smooth, corrugated, internally grooved, and corrugated and internally grooved, respectively. The results were carried out at fixed gas cooler inlet water temperature of around 25°C and by imposing two inlet gas cooling pressures: 8 MPa and 10 MPa, and by varying the water flow rate from 340 to 786 l h-1. A step-by-step procedure for the simulation of the heat transfer cooling process of the carbon dioxide in shell and tubes gas coolers is proposed and validated, allowing for a direct comparison of the heat transfer performance of the shell and tube gas coolers.