Experimental and CFD simulation of a printed circuit heat exchanger design

A 4×4 mm straight square channel printed circuit heat exchanger is designed and manufactured for applications in nuclear facilities. Thermal and hydraulic characteristics of the heat exchanger are evaluated on a test rig using water as the coolant on both sides over a mass flux range from 62.5 kg/m²s to 562.5 kg/m²s. The pressure loss is measured across the hot and cold channels. The friction factor of the hot side is 4 times and the cold side is 3 times higher compared to the straight circular pipe. A friction factor correlation based on experimental data is developed for both sides of the channel. Heat transfer experiments are conducted with the hot inlet temperature varied from 331.15 K to 349.15 K. The heat transfer rate rises with an increase in hot inlet temperature and mass flux. The heat transfer rate increases linearly with the mass flux for a fixed hot inlet temperature. The heat transfer rate also depends on the hot inlet temperature. A 1.9 % and 4.6 % increase in the hot inlet temperature results in a 28 % and 72.2 % increase in the heat transfer rate, respectively, for a mass flux of 281.25 kg/m²s on the hot side and 562.5 kg/m²s on the cold side. Computational fluid dynamics simulations are performed for the printed circuit heat exchanger. The simulations are validated through experimental data. The simulation results are used to study the heat transfer characteristics of the heat exchanger. For the maximum mass flux and hot inlet temperature, the hot and cold sides exhibit a Nusselt number of 26.6 and 28.8, respectively. Correlations for the hot and cold side Nusselt number for the square channel are also developed. The friction factor and the Nusselt number are used to evaluate the Performance Evaluation Criteria. For the maximum operating conditions of the study, a Performance Evaluation Criteria of 8.5 is achieved on both the hot and cold sides, respectively. The heat exchanger design is highly compact and efficient in heat transfer, making it suitable for reducing the size and enhancing the efficiency of small modular reactors.