Abstract
The main aim of the present research is to measure the nucleate boiling heat transfer coefficient (BHTC) of aqueous glycol nano-suspension as a coolant around a horizontal heater. Alumina nanoparticles were added to the base fluid at a volumetric concentration of 1% to improve the thermal conductivity of the nano-suspension. The pressure of the system was set to the atmospheric pressure, and the coolant was tested at different applied heat fluxes (HF) ranged from 0 to 90 kW m(-2)and volumetric concentration of 0-40% of the heavier component. Two zones of heat transfer were identified, including a natural convection zone and nucleate boiling one mixed with bubble formation and bubble interactions. Results also showed that the HTC of the nano-suspension is smaller than those recorded for the pure water. A rough comparison was made to examine the accuracy of the developed equations for estimating the BHTC value against the experimental data. It was found that the developed equations are not accurate for the data measured in the free convection region. Thus, the Churchill-Chu correlation was recommended for estimating the BHTC in the free convection area of heat transfer. Also, the effect of operating parameters such as HF and volumetric concentration on the pool boiling HTC of the solution was studied.