Transient surface heat flux measurement for short duration using K-type, E-type and J-type of coaxial thermocouples for internal combustion engine

Abstract

The surface heat flux measurement in the internal combustion engine is imperious work, because the heat transfer rate is changing very quickly during combustion process in the internal combustion engine and has very transitory heat transfer in nature. Due to this, a fast response measuring thermal sensor is required to trace the heating rate in the internal combustion engine. The coaxial thermocouples are appropriate to measure extremely transitory surface heat flux due to having the response time in the range of in millisecond or less and can invariantly use for short time observation facilities due to their meticulousness measurements. The transient heat flux recovered from transient temperature is one of the conventional techniques and used in many engineering application such as internal combustion engine, aerodynamic vehicles cooling device, etc. In this existent exploration, the surface heat flux has measured of a four-stroke diesel engine at cylinder surface. In this backdrop, three (K-type, E-type and J-type) types of coaxial thermocouples have been contrived and calibrated to measure transient surface heat flux of engine cylinder. A field emission scanning electron microscopy (FESME) technique has been used for microstructural analysis of measuring the surface of these handmade coaxial thermocouples and an energy dispersive X-ray analysis (EDXA) technique used to qualitatively appraise of the coaxial surface junction thermocouples (CSJTs) materials composition. Using these coaxial thermocouples, the transient surface temperature has been recorded at four different experimental shot for short duration as well as its heat flux has been recovered using one-dimensional heat conduction modelling for a semi-infinite body. The average value of surface heat flux recovered for all experiment have a reasonable deviation of 3% to each other and have 0.075% for transient surface temperature. This investigation states that these hand-made coaxial thermocouples are the efficient candidate to measure surface heat flux in the application internal combustion engine.