Example 3.4 (n) 90C An average convective heat transfer coefficient for flow of 90C air over a flat plate is measured by observing the temperature time history of a 40mm thick cooper slab exposed to 90C air. In one test run, the initial temperature of the plate was 200C and in 4.5 minutes the temperature decreased by 35C. Find the heat transfer coefficient for this case. Neglect the internal thermal resistance. Hint: Since thermal resistance is negligible, the lumped capacitance method is applicable. Then apply the temperature-time equation that relates h to temperature and time. i=TiTTT=exp[vCp(hA]t Example 3.4 (n) 90C An average convective heat transfer coefficient for flow of 90C air over a flat plate is measured by observing the temperature time history of a 40mm thick cooper slab exposed to 90C air. In one test run, the initial temperature of the plate was 200C and in 4.5 minutes the temperature decreased by 35C. Find the heat transfer coefficient for this case. Neglect the internal thermal resistance. Hint: Since thermal resistance is negligible, the lumped capacitance method is applicable. Then apply the temperature-time equation that relates h to temperature and time. i=TiTTT=exp[vCp(hA]t