Experimental Investigation on Heat Transfer and Pressure Drop in Double Helically Coiled Tube Heat Exchanger with MWCNT/Water Nanofluid

In this experimental work, heat transfer and pressure drop analysis of a Double helically coiled tube heat exchanger by using Multi-walled carbon nanotube (MWCNT) /Water nanofluid as a coolant. The analysis is done under constant heat flux and turbulent flow condition. The double helically coiled tube heat exchanger (DHCTHX) is designed and fabricated. The MWCNT/water with ۰.۲% ۰.۴% & ۰.۶% volume concentration nanofluids are prepared by using two-step method. The nanofluid prepared is characterized by using SEM (Scanning Electronic Microscope). Initially, hot water and cold water with ۱۲۰,۱۴۰,۱۶۰& ۱۸۰LPH (liter per hour) of flow rates are tested. Secondly hot water and ۰.۲% ۰.۴% & ۰.۶% volume concentration of MWCNT/water nanofluid with the same mass flow rates are tested. On comparing, the MWCNT nanofluids have better heat transfer rate than that of water. It is found that the heat transfer rate increases with increasing volume concentration of nanofluids. The maximum heat transfer rate obtained is at ۰.۶% volume concentration of nanofluids at the ۱۲۰LPH mass flow rate at ۱۴۶۰ Dean Number. It is also studied that MWCNT /water nanofluid’s overall heat transfer rate is ۵۶% higher than water at ۰.۶% nanofluid at ۱۴۶۰ Dean Number. It is also found that the pressure drop of MWCNT/water ۰.۶% nanofluid is ۴۹% higher than that of water at ۱۴۶۰ Dean number.

Keywords:

MWCNT/water , Double Helically coiled tube Heat exchangers , Nusselt number , Thermal conductivity , Secondary flow , Dean number