Experimental investigation on heat transfer characteristics and pressure drop of BPHE (brazed plate heat exchanger) using TiO2–water nanofluid

• Thermal performance, pressure drop in a plate heat exchanger is studied.
• TiO2/water nanofluid is used as a working fluid.
• Convective heat transfer coefficient enhancement was observed for nanofluid.
• The maximum increment in BPHE pressure drop by using nanofluid is about 20%.

In this research, the effect of using TiO2–water nanofluid on heat transfer enhancement and pressure drop in a Brazed Plate Heat Exchanger used in domestic hot water system is investigated experimentally. TiO2 nanoparticles with 20 nm diameter and 99+% purity are used for making the nanofluid at 0.3%, 0.8% and 1.5% weight concentration of suspended nanoparticles, in such experiments. This study is done on the brazed plate heat exchanger under turbulent flow condition. The effects of Reynolds number and weight concentration of nanoparticles on the heat transfer characteristics are investigated experimentally. This results in a significant increase in convective heat transfer coefficient through adding nanoparticles to distilled water. The results show that, the convective heat transfer coefficient and the overall heat transfer coefficient of TiO2–water nanofluid is increased with enhancement of Reynolds number and at a specified Reynolds number, heat transfer characteristics is enhanced by increasing weight concentration of nanoparticles in brazed plate heat exchanger. The maximum enhancement of the nanofluid convective heat transfer coefficient at 0.3%, 0.8% and 1.5% weight fraction of nanoparticles are about 6.6%, 13.5% and 23.7% respectively. Also the maximum enhancement of the nanofluid overall heat transfer coefficient at mentioned weight concentrations of nanoparticles are about 2.2%, 4.6% and 8.5% respectively. Finally, the nanofluid pressure drop at various levels of nanoparticles is measured experimentally. According to these results, increment in system pressure drop is negligible compared to the heat transfer improvement.