Characteristics of carbon-based nanofluids and their application in a brazed plate heat exchanger under laminar flow

In this study, a graphite-powder-based heating and cooling processing method (GP-HCPM) was used to produce carbon-based nanofluids (CBNFs) as working fluid for a brazed plate heat exchanger (BPHE) system. Sodium dodecyl benzenesulfonate (SDBS) was added to CBNFs as a dispersant to enhance their stability, and the CBNF concentration was adjusted to 0.2 wt% (S1) and 0.6 wt% (S2). The thermal conductivity, viscosity, density, specific heat, and contact angle of the CBNFs were measured and analyzed. Finally, the CBNFs were tested in a BPHE system to evaluate the average heat exchange capacity (Q̇_ex,avg), pumping power consumption (P_p), and system efficiency factor (SEF) under various temperatures (35, 40, and 45 °C) and laminar flow conditions. Results show that the Q̇_ex,avg of S1 and S2 was higher than water under all experimental parameters, indicating that CBNFs exhibit a higher heat exchange performance than water. The P_p of S1 was slightly lower than that of water. The maximum Q̇_ex,avg and SEF enhancement ratio of S1 and S2 was 7.54% and 7.98% and 9.19% and 7.28%, respectively. Considering the overall system efficiency of experimental parameters of the BPHE system, S1 was deemed more suitable than S2.