The effect of pH on stability and thermal performance of graphene oxide and copper oxide hybrid nanofluids for heat transfer applications:Application of novel machine learning technique

This paper investigates the effects of pH on stability and thermal properties of copper oxide(CuO),graphene oxide(GO),and their hybrid nanofluid(HNF)at different mixing ratios.Initially,sol-gel and Hummer’s method was employed for the synthesis of CuO and GO nanoparticles(NPs),and they are characterized with various techniques.The effects of two different surfactants were analyzed on nanofluid’s(NF’s)stability at different pH values.The properties like thermal conductivity(TC)and viscosity(VST)of NFs were measured at different volume concentration(0.1 vol%to 1.0 vol%)and temperature range of 30-60℃,respectively.The TC and VST of GO/CuO(50:50)HNF are higher than that of GO/CuO(20:80).The figure of merit(FOM)is determined for the studied HNFs.The correlations were presented to calculate the TC as well as VST of HNFs.Two modern novel machine learning-based ensemble approaches were employed for predictive model development for TC and VST of considered HNFs.The comparison of prognostic models with Taylor’s diagram revealed that Bayesian optimized support vector machine(BoASVM)was superior to Bayesian optimized boosted regression trees(BoA-BRT)for both TC and VST models.

Impact of indoor heat load and natural ventilation on thermal comfort of radiant cooling system:An experimental study

Construction and operation of buildings are responsible for about 20%of the global energy consumption.The embodied energy of conventional buildings is high due to the utilization of energy-intensive construction mate-rials and traditional construction methodology.Higher operational energy is attributed to the usage of power-consuming conventional air-conditioning systems.Therefore,moving to an energy-efficient cooling technology and eco-friendly building material can lead to significant energy savings and CO 2 emission reduction.In the present study,an energy-efficient thermally activated building system(TABS)is integrated with glass fiber rein-forced gypsum(GFRG),an eco-friendly building material.The proposed hybrid system is termed the thermally activated glass fiber reinforced gypsum(TAGFRG)system.This system is not only energy-efficient and eco-friendly but also provides better thermal comfort.An experimental room with a TAGFRG roof is constructed on the premises of the Indian Institute of Technology Madras(IITM),Chennai,located in a tropical wet and dry climate zone.The influence of indoor sensible heat load and the impact of natural ventilation on the thermal comfort of the TAGFRG system are investigated.An increase in internal heat load from 400 to 700 W deteriorates the thermal comfort of the indoor space.This is evident from the increases in operative temperatures from 29.8 to 31.5℃ and the predicted percentage of dissatisfaction from 44.5%to 80.9%.Natural ventilation increases the diurnal fluctuation of indoor air temperature by 1.6 and 1.9℃ for with and without cooling cases,respectively.It reduces the maximum indoor CO 2 concentration from 912 to 393 ppm.