Heat Transfer Performance of Propylene Glycol Versus Ethylene Glycol Coolant Solutions in Laboratory Testing 1999-01-0129

This paper describes the results of laboratory testing comparing the heat transfer performance of heavy duty radiators with Propylene Glycol and Ethylene Glycol based coolants. Solutions of 50/50 Propylene Glycol/ water (50/50 PG/water) and 50/50 Ethylene Glycol/water (50/50 EG/water) were tested in radiators of different geometries. The tests showed that the performance of 50/50 PG/water is degraded at higher flow rates to a greater degree than either 50/50 EG/water or 100% water. Specifically, it was found that in typical truck radiators the cooling performance of water drops off below 2.52 L/s (40 gpm), while that of 50/50 EG/water drops off below 3.78 L/s (60 gpm) and that of 50/50 PG/water drops off below 5.05 L/s (80 gpm). It is recommended that crossflow radiator designs be used for short, wide radiator applications to maximize the fluid flow rate in the radiator tubes.