A comparative study on thermal behavior of PEG 400 and two oxide nanocolloids

• PEG 400 thermal conductivity was experimental investigated. • Thermal conductivity variation with temperature and nanoparticle loading of PEG 400 + MgO and TiO 2 is discussed. • Thermal diffusivity for all samples was analyzed. • Pr number for all samples follows the behavior of fluids viscosity. • Heat transfer performance evaluation criteria are outlined and discussed. Fluids plays a significant role in all heating and cooling processes, while their thermal conductivity is extremely relevant for a large number of heat exchange applications. This paper mainly discusses the results of an experimental study on thermal conductivity of PEG 400 and two oxide nanocolloids with MgO and TiO 2 , together with an analysis on Prandtl number, thermal diffusivity and performance evaluation criteria. Several samples (i.e. 11), with different nanoparticle concentration, were manufactured, analyzed and all the experimental data were discussed and further compared with current findings on new heat transfer fluids. Collected experimental data outlined that the thermal conductivity increases with nanoparticle addition and highly depends on the nanoparticle type. Plus, temperature variation does not affect the thermal conductivity of studied samples, while Pr number for all samples follows the behavior of fluids viscosity. For example, Pr number is decreasing with MgO concentration, while the diffusivity increases by 33.86 % for PEG + 2.50 MgO. Concluding, the combined analysis on Prandtl number and thermal diffusivity revealed that the suspensions with MgO have a better behavior at heat transfer if compared with nanocolloids with TiO 2 .