Estimate the temperature gradient at the surface by convection over a surface of 4.6m2 area if the surface is at 232.3°C and fluid is at 46.6°C. The value of convective heat transfer coefficient is 5 W/m².K. k=6.5W/mk.

A glass window of width W = 1 m and height H = 2 m is 5 mm thick and has a thermal conductivity of k 1.4 W/m K. If the inner and outer surface temperatures of the glass are 15°C and -20°C, respectively, on a cold winter day, what is the rate of heat loss through the glass? To reduce heat loss through windows, it is cus- tomary to use a double pane construction in which adjoining panes are separated by an air space. If the spacing is 10 mm and the glass surfaces in contact with the air have temperatures of 10°C and -15°C, what is the rate of heat loss from a 1 m x 2 m window? The thermal conductivity of air is k, = 0.024 W/m.K.

Air at 25 ° C blows over the hot steel plate whose surface temperature is maintained at 200 ° C. The plates have dimensions of 50 cm x 50 cm and a thickness of 2.5 cm. The convection heat transfer coefficient on the upper surface is 25 W / (m² ° C). The thermal conductivity of steel is 45 W / (m ° C). Calculate the hourly heat loss from the plate surface. a. heat loss per hour = AnswerkJ. b. If the reverse side surface temperature is maintained, specify hourly heat loss = AnswerkJ.

5. A laboratory water bath has an immersed horizontal (cylindrical) water element, 2.54 cm. in diameter and 35cm in length, with a power input of 500 W. If the bulk water temperature is 40 °C and heat transfer occurs by free convection only, calculate the surface temperature of the heater.