1- The heat flux through a slab made of wood with 50 mm thick, whose inner and outer surface temperatures are 40 oC and 20 oC respectively, has been measured to be 40 W/m2. What is the thermal conductivity of the wood

Two parts and label (A) & (B) Solve carefully! Question : The roof of a car in a parking lot absorbs a solar radiant flux of 600 W/m2, while the underside is perfectly insulated. The convection coefficient between the roof and the ambient air is 15 W/m2.K and the roof’s surface emissivity is 0.5. If the ambient air temperature is 25C, answer the following questions: PART (A) Neglecting radiation heat transfer, find the temperature of the roof under steady state conditions. Part ( B) Neglecting convective heat transfer, find the steady state temperature of the roof [Tsur =0]?

6. a. The heat flux applied to the walls of the biomass combustion furnace is 20 W/m2. The furnace walls have a thickness of 10 mm and a thermal conductivity of 12 W/m.K. If the wall surface temperature is measured to be 50oC on the left and 30oC on the right, prove that conduction heat transfer occurs at a steady state!b. Heating the iron cylinder on the bottom side is done by placing the iron on the hotplate. This iron has a length of 20 cm. The surface temperature of the hotplate is set at 300oC while the top side of the iron is in contact with the still outside air. To reach the desired hotplate temperature, it takes 5 minutes. Then it takes 15 minutes to measure the temperature of the upper side of the iron cylinder at 300oC. Show 3 proofs that heat transfer occurs transiently

The thermal conductivities of human tissues vary greatly. “Fat” and “skin” have conductivities of approximately 0.200 W /m 0K and 0.0200 W /m 0K, respectively, while other “tissues” inside the body have conductivities of approximately 0.500 W /m 0 Assume that between the core region of the body and the skin surface lies a “skin” layer of 1.00mm, a “fat” layer of 0.500 cm., and 3.20 cm. layer of other “tissues”. A)Find the R-factor for each of these three layers, and the R-factor for all layers taken together