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

•The shell and tube heat exchanger is proposed as gas cooler.•Four different shell and tube gas coolers are experimentally characterized.•A step-by-step procedure to simulate the gas cooling process is proposed and validated.•The gas coolers are compared using the developed procedure.

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.