A study of boiling heat transfer via an aqueous solution of commercial-grade engine coolant and pure water

Abstract

Commercial grade motor radiator coolant is a mixture of glycol, corrosion inhibitors, inorganic compounds, and water. These type of radiator coolants formulations are used to enhance the thermal efficiency and lifespan of internal combustion engines. In this study we added a radiator coolant solution in a distilled water to investigate potential improvements in the heat transfer rate during boiling. Thus, the heat dissipation from a coiled Nichrome wire (electrically operated) was analyzed in open air, pure water, and various concentrations of aqueous coolant solutions. The boiling of coolant aqueous solution at concentrations of 5% wt./wt., 10% wt./wt., 15% wt./wt., and 20% wt./wt. were compared with pure water. In general, a heat transfer coefficient values increases with coolant concentration. For example, at 5% wt./wt., the heat transfer coefficient is 40 W/m²·K, whereas at 20% wt./wt. concentration, it rises to 140 W/m²·K. Moreover, qualitatively the bubble size in pure water is significantly larger than that of bubbles of the coolant solutions. Turbidity and total dissolved solids increase with coolant concentrations, whereas at a 20% wt./wt. concentration, the surface tension decreases to 68.8 mN/m. This study suggests that adding an engine coolant solution into standard boiler feed water or similar cooling system devices will improve the overall heat transfer rate and hence reduces the operational fuel expenses.