Enhancement of pool boiling performance using MWCNT based nanofluids: A sustainable method for the wastewater and incinerator heat recovery

Abstract

Recovery of the wastewater heat and incinerator heat is an important stage of the design and optimization of the industrial thermal management system. Recovery and reuse of wastewater heat are also important for energy sustainability. Heat recovery boilers are mostly used in the industry for heat recovery. The performance of the heat recovery boilers is mainly depending on the Critical heat flux value of the cooling fluid. Various studies have suggested that the nanofluids are a better working fluid than conventional cooling fluids like water and ethylene glycol. Thus, in this study, we used MWCNT based nanofluids as a cooling fluid and compared its performance with the water. Because water is the conventional cooling fluid used in wastewater heat recovery. We have reported the bubble dynamics data, including the departure diameter, departure frequency, bubble growth time and bubble wait time. These results revealed that the incorporation of the MWCNT based nanofluids leads to the surface modification of the heater surface and the enhancement of critical heat flux.It was observed that by using a 0.005 vol% of MW-CNT in water, critical heat flux can be enhanced to 2.14 W/m2. This recorded critical heat flux enhancement is 62.12% more than the critical heat flux required for the water. At 0.005 vol% of MWCNT concentration, the heat-transfer coefficient is enhanced by 30%. The enhancement in the CHF is due to the enhanced surface wettability of the heating surface by a nanofluid. Furthermore, there is the deposition of the nanoparticles on the surface of the heater which causes CHF to enhance. This deposition also useful for critical heat flux enhancement.