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The equivalent thermal resistance for the thermal circuit shown here is
(e) None of them
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Heat and Mass Transfer: Fundamentals and Applications
- A plane wall 15 cm thick has a thermal conductivity given by the relation k=2.0+0.0005T[W/mK] where T is in kelvin. If one surface of this wall is maintained at 150C and the other at 50C, determine the rate of heat transfer per square meter. Sketch the temperature distribution through the wall.arrow_forwardQ1. Consider a plane wall (thermal conductivity, k = 0.8 W/mK, and thickness, fb1 = 100 mm) of a house as shown in Fig. Q1(a). The outer surface of the wall is exposed to solar radiation and has an absorptivity of a = 0.5 for solar energy, or=600 W/m². The temperature of the interior of the house is maintained at T1 = 25 °C, while the ambient air temperature outside remains at T2 = 5 °C. The sky, the ground and the surfaces of the surrounding structures at this location can be modelled as a surface at an effective temperature of Tsky = 255 K for radiation exchange on the outer surface. The radiation exchange inside the house is negligible. The convection heat transfer coefficients on the inner and the outer surfaces of the wall are h₁ = 5 W/m²-K and /1₂ = 20 W/m².K, respectively. The emissivity of the outer surface is = 0.9. T1 = 25 °C Ţ₁ Too1 = 25 °C T₁ k 100 mm Fig. Q1(a) Assuming the heat transfer through the wall to be steady and one-dimensional: (a) Solve the steady 1D heat…arrow_forwardA plane wall is 2 m high by 3 m wide by 20 cm thick. It is made of a material that has a thermal conductivity 0.84 W/m-K. A temperature difference of 60 Fahrenheit degree is imposed on the two large faces. Find the heat flux. A. 160 W/m^2 B. 145 W/m^2 C. 150 W/m^2 D. 140 W/m^2arrow_forward
- 4x F2 # 3 E 4, F3 54 $ R F4 Ac = 1m² ▬ H DII x= 1 m (4) Consider a wall (as shown above) of thickness L-1 m and thermal conductivity k-1 W/m-K. The left (x=0) and the right (x=1 m) surfaces of the wall are subject to convection with a convectional heat transfer coefficient h= 1 W/m²K and an ambient temperature T. 1 K. There is no heat generation inside the wall. You may assume 1-D heat transfer, steady state condition, and neglect any thermal contact resistance. Find T(x). % To,1 = 1 K h₁ = 1 W/m²K 5 Q Search F5 T T₁ A 6 x=0 F6 à = 0 W/m³ k= 1W/mK L=1m Y 994 F7 & 7 T₂ U Ton2 = 1 K h₂ = 1 W/m²K1 PrtScn F8 Page of 7 ) 0 PgUp F11 Parrow_forwardA 1000 m³ cubic building (meaning it is a cube with sides of length 10.0 m) has concrete walls 20 cm thick. Concrete has a thermal conductivity of 1.25 W/(mK). An indoor temperature of 21 C is maintained. If it is -15 C outside determine the rate of heat loss from the building. Answer: Check ✓ Choose... W Jarrow_forwardQ1/A long cylindrical shell of inner radius R, = 1 cm, outer radius R₂ = 2 cm, and length L = 10 m is shown in the Figure. The inner wall of cylindrical shell is maintained at constant temperature T₁ = 10 C and outer wall is maintained at constant temperature T2 Calculate the temperature at r = 1.5 cm (Consider radial conduction only). 20 C. Assumptions: System is in steady state. Thermal conductivity, k= 22.5 W/m C, is constant. System follows Fourier's law of heat conduction. Heat loss in axial direction is negligible, T₁ - R₂ T₂arrow_forward
- Find the total heat flux of the composite wall when: B F KA = KC = KF = 15 т. К A E KB = KD = 10 т. К KE = KG = 20 т. К D. Height of B = C = D 4 cm 3 cm 4 cm 6 cm Height of F = G AT = 30 K て)arrow_forwardQi: (50 marks) Find the total heat flux of the composite wall when: B KA = KC = KF = 15 m. K KB = KD = 10 m. K KE = KG = 20 %3D m. K D. Height of B = C = D 4 cm 3 cm 4 cm 6 cm Height of F = G AT = 30 Karrow_forwardThe inside wall of a furnace is at 2100oF and the outside wall is at 300oF. The wall of a furnace must be designed to transmit no more than 220 Btu/hr-ft2. Two types of bricks are available for construction:TYPE A: k = 0.38 Btu/ hr-ft-R with an allowable maximum temperature of 1400oFTYPE B: k = 0.98 Btu/ hr-ft-R with an allowable maximum temperature of 2300oF Both types of bricks have the same dimensions (9” x 4.5” x 3”) but the cost for Type B brick is twice the cost of Type A brick. Illustrate the order of arrangement of bricks A and B in the furnace wall (with thickness, estimated temperatures at the interface between walls A and B and at the interior and exterior surface, the transport area and direction of transfer included)arrow_forward
- The inside wall of a furnace is at 2100oF and the outside wall is at 300oF. The wall of a furnace must be designed to transmit no more than 220 Btu/hr-ft2. Two types of bricks are available for construction:TYPE A: k = 0.38 Btu/ hr-ft-R with an allowable maximum temperature of 1400oFTYPE B: k = 0.98 Btu/ hr-ft-R with an allowable maximum temperature of 2300oF Both types of bricks have the same dimensions (9” x 4.5” x 3”) but the cost for Type B brick is twice the cost of Type A brick. If a 15 ft2 wall is to be constructed, how many bricks will be used? how many brick A and how many brick B?arrow_forwardThe inside wall of a furnace is at 2100oF and the outside wall is at 300oF. The wall of a furnace must be designed to transmit no more than 220 Btu/hr-ft2. Two types of bricks are available for construction:TYPE A: k = 0.38 Btu/ hr-ft-R with an allowable maximum temperature of 1400oFTYPE B: k = 0.98 Btu/ hr-ft-R with an allowable maximum temperature of 2300oF Both types of bricks have the same dimensions (9” x 4.5” x 3”) but the cost for Type B brick is twice the cost of Type A brick. What is the rate of heat conduction through wall A? If a 15 ft2 wall is to be constructed, how many bricks will be used? how many brick A and how many brick B?arrow_forwardThe inside wall of a furnace is at 2100oF and the outside wall is at 300oF. The wall of a furnace must be designed to transmit no more than 220 Btu/hr-ft2. Two types of bricks are available for construction:TYPE A: k = 0.38 Btu/ hr-ft-R with an allowable maximum temperature of 1400oFTYPE B: k = 0.98 Btu/ hr-ft-R with an allowable maximum temperature of 2300oF Both types of bricks have the same dimensions (9” x 4.5” x 3”) but the cost for Type B brick is twice the cost of Type A brick. Model the wall as one-dimensional and determine the most economical arrangement of the bricks. Include:a drawing labeled with all given informationthe variables used in the appropriate places on the drawing (along with values and units, if provided)a thermal circuit showing the paths for heat transmissionequations and calculationsCalculations that show that the maximum temperature for Type A brick does not exceed 1400oFA recommendation for the number and orientation of the bricks. The inside temp is 2100f…arrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning