Development And Evaluation Of A Non Invasive Core Temperature Measurement System PDF Download

While the surface temperature of a heat-generating solid body can be measured using a variety of methods, there is a scarcity of techniques that exist for non-invasively measuring the temperature inside the solid body. Internal temperature measurement is very desirable as mere measurement of surface temperature gives no indication of the internal temperature. The highest temperature, usually located at the core of the body, dictates system performance and safety. For example, Li-ion cells provide good energy storage and conversion characteristics, but unfortunately suffer from safety problems related to overheating due to insufficient heat removal during operation. The following thesis presents a technique to non-invasively measure the core temperature of a heat generating solid body for both steady state and transient cases, utilizing the theoretical relationship between the core and surface temperatures of the body. This method is experimentally validated by determining the core temperature of various heat generating cylindrical bodies - a thermal test cell and a Li-ion cell - using infrared temperature measurement on the surface, and comparing with measurements from embedded thermocouples within each cell. There is excellent agreement throughout the heat generation period between the predicted core temperature and measurements from the embedded thermocouple. These measurements demonstrate an accurate, non-invasive measurement method for real-time, core temperature monitoring. This thesis also investigates thermal performance of a Li-ion cell with a heat pipe inserted into the core. It is shown that active cooling of the protruding tip of the heat pipe results in maximum thermal benefit, which is shown to reduce the core temperature to as low as, or even lower than the surface temperature. This work contributes towards fundamental thermal metrology, and toward effective thermal management techniques for future Li-ion cell manufacturer designs, with possible applications in a wide variety of engineering systems.