Thermal and hydraulic performance of a heat exchanger working with carbon-water nanofluid

In the present paper, the heat transfer and fluid flow characteristics of a copper-made heat exchanger were experimentally studied. The configuration of the heat exchanger was a double pipe and carbon-water nanofluid was utilised as a heat-exchanging medium within the heat exchanger. Experiments were conducted at volume fractions 0.1–1% and Reynolds number 800–10500. Plausible effect of various parameters including the nanofluid flow rate, nanoparticles’ volumetric concentration and film temperature on the overall heat transfer coefficient (HTC) were investigated. Results showed that carbon/water nanofluid can offer a great potential for cooling applications. It was found that the flow rate of nanofluid; concentration and temperature of nanofluid can enhance the HTC. Interestingly, the presence of carbon nanoparticles within the base fluid resulted in the augmentation of pressure drop. This was because of the enhancement in friction factor parameter between layers of the base fluid and the augmentation in fluid viscosity, which is attributed to the presence of nano-carbons, which increased the pressure drop. Significant improvement in overall HTC was registered (44% enhancement) achieved at vol.% =1. The penalty of 14% was reported for the pressure drop at vol.% = 1, which offers a trade-off between the increase in the value of HTC and augmentation in the value of pressure drop. The maximum value for thermal hydraulic performance of the system was 42.2% at Reynolds number 10200 and vol.% = 1.