Effect of thermocouple electrical insulation on surface temperature measurement

The objective of this work is studying the effect of stripping thermocouple electrical insulation on peltier surface measurement. Analytical, numerical, and experimental analyses have been performed to investigate the effect of different stripped lengths on temperature measurement of peltier surface. Two sizes of type K thermocouple, 80μm and 200μm, with different stripped lengths (0 mm, 5mm, 10mm, 15mm and 20mm) are used to measure different peltier surface temperature of 4oC, 8oC, 15oC, 25oC and 35oC. During measurements thermocouple probe was in direct contact with peltier surface while the wires were extended vertically and exposed to natural convection from the external environment. Analytical results of thermocouple wire with insulation confirm that there is no specific value of the critical radius and the rate of heat flux around the thermocouple wire continuously increases with the wire diameter even though it is larger than the critical radius (or diameter). Numerical simulation using COMSOL Multiphysics software also confirms this that there is a negligible effect of the electrical insulation. Moreover, experimental results agree well with those obtained by the analytical and numerical methods and further reveal that the size of the thermocouple causes an impact on temperature measurement