Investigating the effect of coolant on cooling rate of engine oil used in automobile industry using Arduino interfaced temperature sensor

Abstract Heat is lost by the system due to temperature difference between the hot object and surroundings. Two models which explain cooling are conduction-convection method and radiation method. During an automobile engine operation, both engine and engine oil get heated up. To overcome the problem of excessive heat generated, coolant is used to cool down the system. In present study, cooling rate of engine oil kept at high temperature was studied in the absence and presence of coolant. In the absence of coolant, engine oil follows the natural law of cooling stated by Newton and follows the exponential decay in temperature. Cooling rate constant was estimated through fitting first order and second order exponential decay with experimental data and found to be 3.35 × 10 − 4 s − 1 and 2.39 × 10 − 4 s − 1 (in first 50 min) respectively. Cooling rate in the presence of coolant was studied which shows rapid decrease in temperature for first few minutes which may be attributed to high heat capacity of coolant which surrounds the hot engine oil. After 50 min of cooling, temperature of both fluids found to decrease exponentially. Thus, the use of coolant was found to absorb the heat content from the engine oil rapidly in comparison to natural environment. Cooling rate constant were estimated through fitting experimental data and found to be 2.44 × 10 − 4 s − 1 and 2.43 × 10 − 4 s − 1 for engine oil and coolant respectively. The percentage change in temperature of oil in first two minutes in the presence of coolant was about 70% which is much higher in comparison to cooling without the use of coolant which was about 16% only. For data acquisition of temperature of engine oil and coolant, MAX6675 module with K-type thermocouple is used which were interfaced with the Arduino board.