Question

3. a) Describe and explain the differences between three different mechanisms of heat transfer. [3 marks] b) Define what is meant by a black body and state the key properties a black body possess. [1 mark] c) Air, at a temperature of 20 °C, blows over a hot steel plate. The steel plate is 0.5 m wide and 1 m long, and the surface of this plate is maintained at 250 °C. The Stefan Boltzmann constant ? = 5.67×10?? W/m²K?, and the thermal conductivity of the steel plate k = 43 W/mK. i) If the convection heat transfer coefficient for this process is measured to be 25 W/m²K, calculate the rate of convection heat transfer from the surface of the plate. [3 marks] ii) If the emissivity of the steel plate is ? = 0.72, calculate the radiation heat transfer from the surface of the plate. [3 marks]

          3. a) Describe and explain the differences between three different mechanisms of heat transfer. [3 marks]

b) Define what is meant by a black body and state the key properties a black body possess. [1 mark]

c) Air, at a temperature of 20 °C, blows over a hot steel plate. The steel plate is 0.5 m wide and 1 m long, and the surface of this plate is maintained at 250 °C. The Stefan Boltzmann constant ? = 5.67×10?? W/m²K?, and the thermal conductivity of the steel plate k = 43 W/mK.

i) If the convection heat transfer coefficient for this process is measured to be 25 W/m²K, calculate the rate of convection heat transfer from the surface of the plate. [3 marks]

ii) If the emissivity of the steel plate is ? = 0.72, calculate the radiation heat transfer from the surface of the plate. [3 marks]

3. a) Describe and explain the differences between three different mechanisms of heat transfer. [3 marks]

b) Define what is meant by a black body and state the key properties a black body possess. [1 mark]

c) Air, at a temperature of 20 °C, blows over a hot steel plate. The steel plate is 0.5 m wide and 1 m long, and the surface of this plate is maintained at 250 °C. The Stefan Boltzmann constant ? = 5.67×10?? W/m²K?, and the thermal conductivity of the steel plate k = 43 W/mK.

i) If the convection heat transfer coefficient for this process is measured to be 25 W/m²K, calculate the rate of convection heat transfer from the surface of the plate. [3 marks]

ii) If the emissivity of the steel plate is ? = 0.72, calculate the radiation heat transfer from the surface of the plate. [3 marks]

Added by Michael S.

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