Viscosity and isobaric heat capacity of PEG 400-based phase change materials nano-enhanced with ZnO nanoparticles

Experimental work was performed in defining several properties for polyethylene glycol PEG 400 and nano-enhanced PEG 400 + ZnO in the range of mass percentages of up to 5 mass% ZnO. Thus, the article depicts several novel experimental data on viscosity and isobaric specific heat for PEG 400-ZnO nanoparticle enhanced fluids. The isobaric specific heat was investigated by differential scanning calorimetry. The rheological behavior of the nanofluids is explored through rotational rheometry. The properties are investigated in the temperature interval 283.15–333.15 K for nanoparticle mass concentrations of up to 5 mass% and data were compared with the open literature models and correlations. Experimental data were found to be in agreement with existing results and data interpretation was performed, while several correlations were proposed. Plus, the viscosity was modeled with the help of Vogel-Fulcher-Tammann equations, while the hysteresis was also checked. Concluding, no major hysteresis in viscosity was noticed, while the viscosity increase with nanoparticle addition and decrease by 10% when temperature is increasing. The isobaric heat capacity is increasing up to 5.4% with nanoparticle addition.