Comparison of temperature difference measurement technologies used in vehicular heat exchangers

Abstract

In the vehicle industry, thermal balance experiments are extensively conducted on engines to determine energy distribution from fuel to engine power. The temperature differences between the hot and cold sides of the vehicular heat exchanger are the key data used to calculate heat quantity. However, in certain gas–liquid heat exchangers, the temperature difference of the liquid side is significantly smaller than that of the gas side. Measuring error is increased when adopting an inappropriate measurement method. To minimize error, a temperature difference measurement method based on compound thermocouple (CTC) is introduced in this paper. This method is calibrated using a thermostatic oil tank. An empirical formula is used to calculate cases in which the basic temperature ranges from 20°C to 120°C, and a temperature difference of less than 20°Cisgained. The proposed method is applied in a practical thermal balance experiment using a vehicle radiator, and the results are compared with that obtained by measuring with pairing calibrated resistance temperature detectors. Results show that the CTC can reduce thermal balance error in vehicular cooling systems to less than 4%.