Comparison of temperature difference measurement technologies used in vehicular heat exchangers

Abstract

In the vehicle industry, thermal balance experiments have been 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 parameters used to calculate the 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. Measurement errors can be increased if an inappropriate measurement method is adopted. To minimize the measurement errors, a new temperature difference measurement method based on compound thermocouple (CTC) is introduced in this study. This method is calibrated using a thermostatic oil tank. An empirical formula is used to evaluate cases in which the basic temperature ranges from 20°C to 120°C, and a temperature difference of less than 20°C is gained. The proposed method has been implemented in a practical thermal balance experiment using a vehicle radiator, and the results are compared with that of pairing calibrated resistance temperature detectors (RTDs). The results show that the CTC-based method can reduce the averaged thermal balance error in vehicular cooling systems to less than 4%.