Experimental investigation of the subcooled flow boiling heat transfer of water and nanofluids in a horizontal metal foam tube

The present article experimentally explored heat transfer through a horizontal metal foam tube with a constant wall heat flux during the subcooled flow boiling of water, Al2O3/H2O, and CuO/H2O nanofluids. To investigate the effect of using metallic foam on the subcooled flow boiling heat transfer, the results have been compared with a simple tube. Besides, The impacts of significant parameters, including subcooled inlet temperature (25–60 °C), mass flux (150–310 kg m−2 s−1), wall heat flux (100–230 kW m−2), particle type (CuO and Al2O3), and nanofluids concentration (0.5% wt., 1% wt.) were investigated on the transfer of boiling heat while measuring pressure loss and rate of heat transfer. The results show that the use of metal foam increases the heat transfer rate by 3.5–5.8 times compared to the simple tube. Comparing the subcooled flow boiling heat transfer of water and nanofluids in both metal foam and simple tubes, it was found that water has superiority over the nanofluids. Besides, the value of the thermal performance index defined as a ratio of the heat transfer enhancement to the pressure loss degradation is more than one for water and the nanofluids.