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Introduction to Heat Transfer
- The cylindrical pipe with a thread diameter of 0.070 m and an internal diameter of 0.050 m is insulated both internally and externally. Calculate the heat loss per unit length of the pipe (1 m) when the inner surface temperature of the pipe is kept at 50 °C and the outer surface temperature at 20 °C (Average thermal conductivity constant = Km= 0.172 J/cm.s.K).arrow_forwardThe temperature of a tank in the form of liquid nitrogen is -10 ° C. Tank diameter is 16 cm. The amount of heat lost by convection and radiation from the tank to the environment is 65.5 W / m. Calculate the temperature of the environment where the tank is located .h = 4.35 W / m2K, e= 1.arrow_forwardA 3 inch schedule 40 pipe is covered with two layers of insulations. The inner layer (k1 = 0.050) is 2 inches thick and the outer layer (k2 = 0.037) is 1(1/4) inches thick. Calculate the heat loss, in Btu/hr per unit length, if the outer surface temperature of the pipe is 670°F and the outer surface temperature of the outer layer of insulation is 100°F.arrow_forward
- Find the minimum amount of diameter for the insulation of a spherical water tank? Radius of the tank is 10 m, thermal conductivity is 25 W/(m^2*K) and convective coefficient is 5 W/(m*K) 8 m not sufficient information 10 m 20 m 15 marrow_forwardThe temperature of the flame in a furnace is 1277°C and the temperature of its surroundings is 277°C. Calculate the maximum theoretical quantity of heat energy radiated per minute per square meter to the surrounding surface area.arrow_forwardThe interior of a refrigerator whose dimensions are 0.05 x 0.05 dam base area and 1.25 m high, must be kept at 4 °C. The refrigerator walls are constructed of two steel sheets (k= 35 kcal/h.m.°C) 3 mm thick, with 65 mm of material insulation (k=0.213 kcal/h.m.°C) between them. The film coefficient of the inner surface is 10 kcal/h.m².°C, while on the external surface it varies from 8 to 12.5 kcal/h.m².°C. Calculate: a) The power (in HP) of the refrigerator motor so that the heat flux removed from the inside the refrigerator maintain the specified temperature, in a kitchen whose temperature can vary from 21 to 36 °C; b) The temperatures of the inner and outer surfaces of the wall. Given 1 HP = 641.2 Kcal/harrow_forward
- Steel pipe 5 cm thick, 1.0 m long and 12 cm deep, covered with 8 cm thick insulation. The wall temperature in the steel pipe is 100 ° C. The ambient temperature around the insulated pipe is 24 ° C. The convection heat transfer coefficient outside the insulation surface is 50 W / (m² K). The thermal conductivity of steel is 54 W / (m K), and the thermal conductivity of the insulation is 0.04 W / (m K). Count; a. Heat loss per meter of pipe ... (watts)b. temperature between steel pipe and insulation ... (° C)arrow_forwarda pipe with an outside diameter of 2.5 inches is insulated with 2 inches layer of asbestos ( K= 0.396(btu-in)/(hr-ft-F) followed by a layer of cork 1.5 inches thick ( K= 0.30 (btu-in)/ft (hr-ft-F). if the temperature of the outer surface of the cork and pipe is 90 F and 290 F RESPECTIVELY, calculate the heat loss per 100 ft of insulated pipe in btu/hrarrow_forwardA spherical container, with an inner radius r1= 1.4 m and an outer radius r2 = 1.45 m has its inner surface subjected to a uniform heat flux of q1= 7 kW/m2. The outer surface of the container has a temperature T2 = 25°C, and the container wall thermal conductivity is k = 1.5 W/m∙K. Determine the inner surface temperature of the container. (Round your answer to the nearest whole number.) The inner surface temperature is ____°C.arrow_forward
- A pipe with an outside diameter of 3.5 in. is insulated with a 3 in. layer of asbestos (ka=0.396 BTU-in/hr- ft2 - 0 F), followed by a layer of cork 1.5 in. thick (kc=0.30 BTU-in/hr-ft2 - 0 F). If the temperature of the outer surface of the cork and pipe is 1000 F and 3000 F, respectively, calculate the heat lost per 100ft or insulated pipe.arrow_forward3.6 Heat losses through windows in buildings are substantial. What would be the percentage reduction in heat loss that would be mitigated by replacing a window containing a single pane of glass with (a) double-pane low-E insulating glass or (b) a 3-inch-thick sheet of expanded polystyrene sheet? The quoted R values for these items are: • single pane of glass: 0.90 ft 2 hr ° F/Btu, • double pane of low-E insulating glass: 2.3 ft 2 hr ° F/Btu, • 1-inch-thick sheet of polystyrene sheet: 4.0 ft 2 hr ° F/Btu.arrow_forwardYou are asked to determine the heat loss from a very thin spherical cap containing a hot fluid at a temperature of 140.0°C. The outside diameter of the cap is 40.0 m and it is insulated by three layers of insulation of thickness 50.0 m each. The thermal conductivities of each layer are:?1 = 0.02 ?⁄??; ?2 = 0.06 ?⁄??; ?3 = 0.16 ?⁄?? These thermal conductivities are indicated from the inside out in the spherical space coordinate. On the other hand, the external temperature of the system is 30.0°C. Additionally, you are asked to determine the temperatures at the contact interfaces between the different materials. Finally, you are asked to make a freehand diagram of the system, indicating the temperatures obtained by you for each interface and the heat flux.arrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning