A 2 cm diameter plastic rod has a thermocouple inserted to measure temperature at the center of the rod The plastic rod ( Iuml 1190 kg m 3 , c p 1465 J kg middot K, and k 0 19 W m middot K) was initially heated to a uniform temperature of 70 deg C, and allowed to be cooled in ambient air temperatur...

The convection heat transfer coefficient for a plastic rod being cooled is to be determined As ...

A 2-cm-diameter plastic rod has a thermocouple inserted to measure temperature at the center of the rod.

Question:

A 2-cm-diameter plastic rod has a thermocouple inserted to measure temperature at the center of the rod. The plastic rod (Ï = 1190 kg/m³, c_p= 1465 J/kg·K, and k = 0.19 W/m·K) was initially heated to a uniform temperature of 70°C, and allowed to be cooled in ambient air temperature of 25°C. After 1388 s of cooling, the thermocouple measured the temperature at the center of the rod to be 30°C. Determine the convection heat transfer coefficient for this process. Solve this problem using analytical one-term approximation method (not the Heisler charts).

Air, 25°C Thermocouple Plastic rod wires