# HEAT TRANSFER?

1. A 10 mm OD pipe has cold fluid flowing inside which keeps the surface temperature at 3°C. The pipe is exposed to air at 30°C with a convection coefficient of 10 W/(m^(2)K) . Insulation with thermal conductivity of 0.15 W/mK is added in 5 mm layers . How much heat is transferred from outside? 2. A membrane type... show more 1. A 10 mm OD pipe has cold fluid flowing inside which keeps the surface temperature at 3°C. The pipe is exposed to air at 30°C with a convection coefficient of 10 W/(m^(2)K) . Insulation with thermal conductivity of 0.15 W/mK is added in 5 mm layers . How much heat is transferred from outside?

2. A membrane type electrical heater of 20,000 W/m^2 capacity is sandwiched between an insulation of 25 mm thickness with thermal conductivity of 0.029 W/mK and a metal plate with k = 12.6 W/mK of thickness 15 mm. The convection coefficient is 150 W/(m^(2) k ). The surroundings are at 5°C. Determine the surface temperature of the heater and the flow on either side .

3. The inside of a furnace wall is at 1000°C and with the existing wall of material with thermal conductivity of 1.7 W/mK looses 2.5 kW/m^2 when the outside is exposed to convection to air at 30°C with h = 27 W/(m^(2)K). Determine the wall thickness.