Experimental and numerical investigation of thermal-hydraulic performance of supercritical nitrogen in airfoil fin printed circuit heat exchanger

摘要

Printed circuit heat exchangers (PCHE) are a new kind of high efficiency and compact plate heat exchangers, which can be used in extreme conditions, such as high pressure, high heat flux and volumetric limitation. Supercritical fluids have various favorable characteristics when used as working fluids in heat exchangers. In this paper, the thermal-hydraulic performance of supercritical nitrogen was studied both experimentally and numerically in an airfoil fin PCHE. The mass flow rate varied from 203 kg.m(-2).s(-1) to 228 kg.m(-2).s(-1) while the operating pressure ranged from 5 MPa to 8 MPa. The cold-side outlet temperature and pressure drop in the PCHE were investigated experimentally. The outlet temperature increased as pressure increased and the average outlet temperature at 8MPa was 7.81 K higher than that at 5 MPa for the same mass flow rate. The gradient of pressure drop increased as the mass flow rate increased. Moreover, a numerical analysis of nitrogen in the channel of airfoil fins PCHE was conducted. Nusselt number and Fanning friction factor correlations were developed for Reynolds number values from 10000 to 14500. The accuracy of the proposed correlations was validated using the experimental and numerical data obtained, and results showed that they have a good accuracy for predicting the thermal hydraulic performance of supercritical nitrogen in the channel of airfoil fin PCHE.