Consider a water pipe of length
Heat is generated in the pipe material uniformly by a 25-kW electric resistance heater. The inner and outer surfaces of the pipe are at
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Heat and Mass Transfer: Fundamentals and Applications
- 2.38 The addition of aluminum fins has been suggested to increase the rate of heat dissipation from one side of an electronic device 1 m wide and 1 m tall. The fins are to be rectangular in cross section, 2.5 cm long and 0.25 cm thick, as shown in the figure. There are to be 100 fins per meter. The convection heat transfer coefficient, both for the wall and the fins, is estimated to be K. With this information determine the percent increase in the rate of heat transfer of the finned wall compared to the bare wall.arrow_forward3.16 A large, 2.54-cm.-thick copper plate is placed between two air streams. The heat transfer coefficient on one side is and on the other side is . If the temperature of both streams is suddenly changed from 38°C to 93°C, determine how long it takes for the copper plate to reach a temperature of 82°C.arrow_forwardQ₁: Consider a large plane wall of thickness L = 0.4 m, thermal conductivity k-2.3 W/m °C, and surface area A= 20 m². The left side of the wall at x= 0 is subjected of T1 = 80°C. while the right side losses heated by convection to the surrounding air at T-15 °C with a heat transfer coefficient of h=24 W/m² °C. Assuming constant thermal conductivity and no heat generation in the wall, (a) express the differential equation and the boundary conditions for steady one-dimensional heat conduction through the wall, (b) obtain a relation for the variation of temperature in the wall by solving the differential equation, and (c) evaluate the rate of heat transfer through the wall Ans: (c) 6030 Warrow_forward
- Q1: Consider a large plane wall of thickness L = 0.4 m, thermal conductivity k=2.3 W/m °C, and surface area A= 20 m2. The left side of the wall at x= 0 is subjected of T1 = 80°C. while the right side losses heated by convection to the surrounding air at T-15 °C with a heat transfer coefficient of h=24 W/m2 C. Assuming constant thermal conductivity and no heat generation in the wall, (a) express the differential equation and the boundary conditions for steady one-dimensional heat conduction through the wall, (b) obtain a relation for the variation of temperature in the wall by solving the differential equation, and (c) evaluate the rate of heat transfer through the wall Ans : (c) 6030 Warrow_forwardConsider a long resistance wire of radius r₁ = 0.3 cm and thermal conductivity kwire = 18 W/m. °C in which heat is generated uniformly at a constant rate of g = 1.5 W/cm³ as a result of resistance heating. The wire is embedded in a 0.4-cm- thick layer of plastic whose thermal conductivity is kplastic = 1.8 W/m. °C. The outer surface of the plastic cover loses heat by convection to the ambient air at T = 25°C with an average combined heat transfer coefficient of h = 14 W/m². °C. As- suming one-dimensional heat transfer, determine the tempera- tures at the center of the resistance wire and the wire-plastic layer interface under steady conditions. Answers: 97.1°C, 97.3°C T Wire ·00 h Plastic coverarrow_forwardConsider a steel pan used to boil water on top of an electric range. The bottom section of the pan is L =0.5 cm thick and has a diameter of D =25 cm. The electric heating unit on the range top consumes 1.5k W of power during cooking, and 75 percent of the heat generated in the heating element is transferred uniformly to the pan. Heat transfer from the top surface of the bottom section to the water is by convection with a heat transfer coefficient of h=500W/m2 Assuming constant thermal conductivity and one-dimensional heat transfer, express the mathematical formulation (the differential equation and the boundary conditions) of this heat conduction problem during steady operation. Do not solve.arrow_forward
- Consider a large plane wall of thickness L=0.4 m, thermal conductivity k =1.8 W/m.K, and surface area A=30 m2. The left side of the wall is maintained at a constant temperature of T1= 900C while the right side loses heat by convection to the surrounding air at T∞= 250C with a heat transfer coefficient of h = 24 W/m2.K. Assuming constant thermal conductivity and no heat generation in the wall, (a) express the differential equation and the boundary conditions for steady one-dimensional heat conduction through the wall. (b) Obtain a relation for the variation of temperature in the wall by solving the differential equation and (c) evaluate the rate of heat transfer through the wall. Heat transfer coursearrow_forwardı need solutionarrow_forwardConsider a 40 mmx40 mmx 2 mm thick heat spreader with thermal conductivity of 160 W/m-°C. If the temperature difference across its thickness is 2°C, what is the heat transfer rate through it?arrow_forward
- A wall of length "L" m and height "H" m is made from a thick bricklayer of 20 cm with thermal conductivity of 0.59 W/mK is subjected to heat transfer due to the outside temperature as 38 oC and inside temperature 24 oC. If the energy loss is 12867 kJ in 9 hours. Determine the Heat transfer rate, Surface Area and Length and Height of the wall, if L = 2 H. Solution: Heat Transfer Rate (in Joule/Sec) = Surface Area of the Wall (in m2) = Height of the Wall (H in m) = Length of the Wall (L in m) =arrow_forwardheat transferarrow_forwardSOlve asap plzarrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning