Effect of tangled channels on the heat transfer in a printed circuit heat exchanger

The heat exchangers used in thermoelectric power generation are required to achieve an optimal efficiency by comparing heat transfer that is related to the power generation into the consumption of pump power. The main objective of this study is to enhance heat transfer at a lower flow rate using a tangled channel. The newly introduced channel was designed to increase heat transfer through the entangled shape despite the low Reynolds numbers. Both experimental and numerical analyses were used to investigate the thermal-hydraulic characteristics of the present printed circuit heat exchanger (PCHE). The computational fluid dynamics analysis using ANSYS CFX 15.0 successfully predicted the experimental data with average errors of 1.25% and 4.51% for temperature and pressure differences between the inlet and the outlet, respectively. The present PCHE with a tangled channel showed the improvement of heat transfer when the Reynolds number ranges from 1000 to 3000. Based on the numerical calculation, the geometric effect was investigated by using the concept of temperature uniformity. The temperature uniformity in mixing zones might be a reason for the improvement in heat transfer at a relatively low range of Reynolds number.