Experimental analysis of the thermal-hydraulic performance of water based silver and SWCNT nanofluids in single-phase flow

•Experimental measurements of thermophysical properties of nanofluids.•Heat transfer coefficient is presented as a function of Reynolds number and mass velocity.•Pressure drop as a function of mass velocity and friction factor against Reynolds number.•A figure of merit was introduced to relate the heat transfer and pumping power. An experimental investigation was carried out on thermal-hydraulic performance of silver (Ag) and single-walled carbon nanotube (SWCNT) nanoparticles dispersed in distilled water in single-phase flow. An experimental facility was constructed to verify the heat transfer coefficient as well as the pressure drop in the transition and turbulent flows. The tests were performed maintaining the inlet temperatures in the section constant of 20°C for Ag and 25°C for SWCNT nanofluids, the constant heat flux applied on the wall was 20kW/m2 for Ag and 22kW/m2 for SWCNT and the mass flow rate varied between 30 and 100g/s. The nanofluids were tested at volume concentrations of 0.1%, 0.3% and 0.5% for Ag and 0.03%, 0.05% and 0.2% for SWCNT. The experimental heat transfer coefficient was evaluated as a function of mass velocity, G, and Reynolds number, where significant differences were observed. The Ag nanofluids showed increase whereas the SWCNTs showed decrement of the heat transfer coefficient. Regarding the pressure drop, the nanofluids exhibited pressure drops between 5 and 8.7% greater than that of the base fluid. Finally, a figure of merit was proposed to evaluate the obtained results, which relates the increase in heat transfer as a function of pumping power. The silver nanofluids presented a satisfactory thermal-hydraulic performance in contrast with the SWCNT results.