Aspherical thermocouple measurement errors a spherical thermocouple made of constantin transfer coefficient between the gas and the thermocouple is h used to measure the temperature of a gas. the heat 400 w/m2 k. calculate the maximum diameter d of the thermocouple if the thermocouple's measurement error should be w 23 within 5% of the initial temperature difference in 5 seconds. for constantin, k 8920 kg/m3, and c 410 j/kg. k.