NUMERICAL STUDY ON SUPERCRITICAL CO2 IN PRINTED CIRCUIT HEAT EXCHANGER WITH ASYMMETRICAL AIRFOIL FINS
In this paper, the printed circuit heat exchangers (PCHEs) with airfoil fins (AFFs) working as a sCO2 condenser are analyzed by computational fluid dynamic (CFD) method. Due to the measurement difficulty of local temperature and pressure, the entire average method is usually applied in experimental study data reduction, which may lead to errors in data reduction. Thus, the difference between the entire average method and the staged integral method is analyzed. It can be found that the error in heat transfer performance calculation is increased as the flow distance increases because of the great change of the sCO2 thermal properties over short distances in the heat exchanger. However, the pressure resistance calculation error is not significantly affected by flow distance. So, for experimental study, it is proposed that a PCHE sample used for sCO2 heat transfer should be designed with short length and tested by varying inlet temperature in order to improve the accuracy of empirical correlations. Meanwhile, PCHE models with asymmetrical AFFs are studied by CFD method and compared to a PCHE model with NACA0015 AFFs. NACA8415, NACA8615 and NACA8815 AFFs are all simulated with different layouts. These simulations show that the heat transfer performance and pressure loss increase as the location of maximum camber shifts aft on the asymmetrical AFFs. With the staged integral data reduction method, the result shows that the asymmetrical AFFs with staggered-direction layout can improve the thermal performance with reasonable pressure loss.