Concept explainers
Calculate the rate of heat loss per foot and the thermal resistance for a 15-cm schedule 40 steel pipe covered with a 7.5-cm-thick layer of
Trending nowThis is a popular solution!
Chapter 2 Solutions
Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)
- 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_forwardSteam at a temperature of 723 K is flowing through a pipe with an outer diameter of 100 mm. The pipe is insulated with 30-mm thick mineral wool, the average thermal conductivity of which is 0.065 W/m.K. Determine the outside surface temperature of mineral wool if the ambient air temperature is 300 Assume the hot-surface temperature of the mineral wool is the same as that of the flowing steam and the value of the surface coefficient of the insulating material is 33 W/m2.K.arrow_forwardA 50-cm-diameter pipeline in the Arctic carries hot oil at 30◦C and is exposed to a surrounding temperature of −20◦C. A special powder insulation 5 cm thick surrounds the pipe and has a thermal conductivity of 7 mW/m · ◦C. The convection heat-transfer coefficient on the outside of the pipe is 9 W/m2 · ◦C. Estimate the energy loss from the pipe per meter of length. (Please give step-by-step solution)arrow_forward
- A 50-cm-diameter pipeline in the Arctic carries hot oil at 30°C and is exposed to a surrounding temperature of −12°C. A special powder insulation 5 cm thick surrounds the pipe and has a thermal conductivity of 7 mW/m°C. The convection heat transfer coefficient on the outside of the pipe is 9 W/m2°C. Estimate the energy loss from the pipe per meter of length.arrow_forwardCan u continue the question 5 to 7 5. Calculate the change in heat energy of the submarine’s outer haul, when it descends from the surface to a depth of 3,500m (with an average temperature of 20°C). 6. Calculate the power of the submarine’s electrical heater needed, to maintain the interior of outer hull at 30°C. The exterior of outer hull is 10°C. (Assume heat of the submarine is only lost across the outer hull) 7. Suggest aerospace applications of ballast.arrow_forwardA steel tube with 6 cm ID, 8.2 cm OD and k=18 W/m-C is covered with an insulative covering of thickness 3 cm and k = 0.3 W/m-C . A hot gas at 330 C with h = 400 W/m^2-C flows inside the tube. The outer surface of the insulation is exposed to cooler air at 28 C with h = 60 W/m^2-C. Calculate the heat loss from the tube to the air for 12 m of the tube and the temperature drops resulting from the thermal resistances of the hot gas flow, the steel tube, the insulation layer and the outside air.arrow_forward
- Fins, or extended surfaces, commonly are used in a variety of engineering applications to enhance cooling. Common examples include a motorcycle engine head, a lawn mower engine head, extended surfaces used in electronic equipment, and finned tube heat exchangers in room heating and cooling applications. Consider aluminum fins of a rectangular profile, which are used to remove heat from a surface whose temperature is100° C . The temperature of the ambient air is 20° C. We are interested in determining how the temperature of the fin varies along its length and plotting this temperature variation. For long fins, the temperaturedistribution along the fin is given byarrow_forwardEstimate the natural convection heat transfer coefficient of the horizontal pipe. The outer surface temperature of the pipe is 100 ° C. The ambient air temperature is 35 ° C. The outer diameter of the pipe is 15 cm. Convection coefficient = W / m² ° C.arrow_forwardAir at 300 degrees Celsius flows over a plate of dimension 0.5 m by 0.25 m. If the convection heat transfer coefficient is 250 Watts per Sq.m Kelvin, determine the heat transfer rate from the air to one side of the plate if the plate is to be maintained at 40 degrees Celsius.arrow_forward
- To maximize production and minimize pumping costs, crude oil is heated to reduce its viscosity during transportation from a production field. (1) Consider a pipe-in-pipe configuration consisting of concentric steel tubes with an intervening insulating material. The inner tube is used to transport warm crude oil through cold ocean water. The inner steel pipe ( ks = 40 W/m·K) has an inside diameter of Di,1 = 150 mm and wall thickness ti = 20 mm while the outer steel pipe has an inside diameter of Di,1 = 250 mm and wall thickness . Determine the maximum allowable crude oil temperature to ensure the polyurethane foam insulation ( kp = 0.0425 W/m·K) provides an external convection heat transfer coefficient of ho = 500 W/m2·K. The convection coefficient associated with the flowing crude oil is hi = 450 W/m2·K. (2) It is proposed to enhance the performance of the pipe-in-pipe device by replacing a thin ( ta =10 mm) section of polyurethane located at the outside of the inner pipe with an…arrow_forwardTo maximize production and minimize pumping costs, crude oil is heated to reduce its viscosity during transportation from a production field. (1) Consider a pipe-in-pipe configuration consisting of concentric steel tubes with an intervening insulating material. The inner tube is used to transport warm crude oil through cold ocean water. The inner steel pipe (ks= 40 W/m·K) has an inside diameter of Di, 1= 150 mm and wall thickness ti= 20 mm while the outer steel pipe has an inside diameter of Di, 2= 250 mm and wall thickness to=ti. Determine the maximum allowable crude oil temperature to ensure the polyurethane foam insulation (kp= 0.0675 W/m·K) between the two pipes does not exceed its maximum service temperature of Tp, max= 70°C. The ocean water is at ∞ T∞, o= -5°C and provides an external convection heat transfer coefficient of ho= 500 W/m2·K. The convection coefficient associated with the flowing crude oil is hi= 450 W/m2·K. (2) It is proposed to enhance the performance of the…arrow_forwardTo maximize production and minimize pumping costs, crude oil is heated to reduce its viscosity during transportation from a production field. (1) Consider a pipe-in-pipe configuration consisting of concentric steel tubes with an intervening insulating material. The inner tube is used to transport warm crude oil through cold ocean water. The inner steel pipe (ks= 40 W/m·K) has an inside diameter of Di, 1= 150 mm and wall thickness ti= 20 mm while the outer steel pipe has an inside diameter of Di, 2= 250 mm and wall thickness to=ti. Determine the maximum allowable crude oil temperature to ensure the polyurethane foam insulation (kp= 0.0675 W/m·K) between the two pipes does not exceed its maximum service temperature of Tp, max= 70°C. The ocean water is at ∞ T∞, o= -5°C and provides an external convection heat transfer coefficient of ho= 500 W/m2·K. The convection coefficient associated with the flowing crude oil is hi= 450 W/m2·K. (2) It is proposed to enhance the performance of the…arrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning