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QUESTION 1 The wall of a refrigerator is constructed of fiberglass insulation (k - 0.035 W/m...
Problem 21–20 pts.: “Kitchen Oven Fiberglass Thickness” • How much fiberglass insulation (k = 0.035 W/m-K) is needed to guarantee that the outer-surface temperature of a kitchen oven will not exceed 43°C? 1 The maximum air temperature of a kitchen oven to be maintained by the conventional type of thermostatic control is 290°C. The kitchen (or room) air temperature may vary from 15°C to 35°C, and the average convection heat transfer coefficient between the oven (inner and outer) surfaces and...
5-111 Consider a refrigerator whose outer dimensions are 1.80 m x 0.8 m × 0.7 m. The walls of the refrigerator are constructed of 3-cm-thick urethane insulation (k = 0.026 W m K and α = 0.36 × 10-6 m2/s) sandwiched between two layers of sheet metal with negligible thickness. The refrigerated space is maintained at 3°C and the average heat transfer coefficients at the inner and outer surfaces of the wall are 6 W/m2 K and 9 W/m2.K, respectively....
Questions 6-9 The walls of a refrigerator are typically constructed by sandwiching a layer of insulation between sheet metal panels. Consider a wall made from fiberglass insulation of thermal conductivity ki = 0.046 W/mK and thickness Li 50 mm and steel panels, each of thermal conductivity kp = 60 W/m. K and thickness Lp = 3 mm. If the wall separates refrigerated air at Too,i = 4°C from ambient air at T0o,0 = 25°C, what is the heat gain per...
A house has a composite wall of wood, fiberglass insulation, and plaster board, as indicated in the sketch. On a cold day, the temperature and the convection heat transfer coefficients are T∞,i =20°C, hi =30 W/m2K and T∞,o=−15°C, ho =60 W/m2K. The wall surface area is 350 m2. Determine the total heat loss through the wall. Conductivities are given as b k =0.038 W/m.K, s k =0.012 W/m.K, p k =0.17 W/m.K Glass fiber blanket (28 kg/m3), kn Plaster board,...
For such aircraft application (Figure 3), a wall is made from insulation material (k-0.030 W/m.K) and the insulation material is mounted between four layers of carbon steel (2 mm thickness), the carbon layers are separated by a 2 mm air gap (kair-0.025 W/mK). Figure 3, the thermal conductivity of the carbon steel is (k-15.5 W/m.K). The temperature inside the wall is maintained at 6 °C. The environmental temperature is 24°C. The engineer would like to avoid condensation occurring at outer...
Superheated steam flows steadily through steel tubing (k 35 W/m-K) applying a tube inner surface temperature of 575°C. The tubing has an inner diameter of 300 mm and a wall thickness of 30 mm. Insulation (k 0.10 W/m-K) is applied to the outer surface of the tube while thin aluminum sheet is applied around the insulation as a protective covering. The ambient air at 27°C provides a convection coefficient of 6 W/m2-K. Determine the minimum insulation thickness necessary (mm) to...
1. A house has a composite wall of wood, fiberglass insulation, and plaster board, as indicated below. On a cold winter day the convection heat transfer coefficients are ho = 60 W/m2K and hi = 30 W/m2K. The total wall surface area is 350 m2. (a) Determine the heat transfer rate through the wall in Watts. (b) If the wind were blowing violently, raising ho to 300 W/m2K, determine the percentage increase in the heat transfer rate. (c) What is...
3. CIN: A 50 m long section of a steam pipe at 15°C. The average temperature of the outer surface of combined heat transfer coefficient or the rate of heat loss from the steam plp generated in an natural gas furnance $0.52/therm (1 therm = 105, 0.035 W/mK) needed in order to say remain constant at 150°C. (10 marks) For a steam pipe whose outer diameter is 10 cm passes through an open space mperature of the outer surface of...
A house has a composite wall of wood (exterior) (k = 0.12 W m-1 K -1 , 20 mm thick), fibreglass insulation (k = 0.045 W m-1 K -1 , 70 mm thick) and plasterboard (interior) (k = 0.25 W m-1 K -1 , 10 mm thick). Determine the total heat loss through the wall when the inside temperature is 20 °C, the outside temperature is -10 °C, the inside heat transfer coefficient is 15 W m-2 K -1, and...
The wall of a furnace consists of two parts, a ceramic brick lining (k=1.1 W/m C,. l=20 mm) and an outer steel wall (k=50 W/ m C, l=10 mm). The inner heat transfer coefficient is 29 W/ m2 C and the outer heat transfer coefficient is 14 W/ m2 C. Taking the bulk temperature of the furnace to be 1000 C and the air temperature outside the furnace as 15 C calculate the temperature of the outer steel wall exposed...