Background: Researchers working in the field of nanofluid have done many studies on
the thermophysical properties of nanofluids. Among these studies, the number of studies on specific
heat is rather limited. In the study of the heat transfer performance of nanofluids, it is essential to
raise the number of specific heat studies, whose subject is one of the important thermophysical properties.
Objective: The authors aimed to measure the specific heat values of Al2O3/water, Cu/water nanofluids
and Al2O3-Cu/water hybrid nanofluids using the DTA procedure, and compare the results with
those frequently used in the literature. In addition, this study focuses on the effect of temperature and
volume concentration on specific heat.
Methods: The two-step method was tried to have nanofluids. The pure water selected as the base
fluid was mixed with the Al2O3 and Cu nanoparticles and Arabic Gum as the surfactant, firstly mixed
in the magnetic stirrer for half an hour. It was then homogenized for 6 hours in the ultrasonic homogenizer.
Results: After the experiments, the specific heat of nanofluids and hybrid nanofluid were compared
and the temperature and volume concentration of specific heat were investigated. Then, the experimental
results obtained for all three fluids were compared with the two frequently used correlations
in the literature.
Conclusion: Specific heat capacity increased with increasing temperature, and decreased with increasing
volume concentration for three tested nanofluids. Cu/water has the lowest specific heat capacity
among all tested fluids. Experimental specific heat capacity measurement results are compared
by using the models developed by Pak and Cho and Xuan and Roetzel. According to experimental
results, these correlations can predict experimental results within the range of ±1%.