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The concrete slab of a basement is 11 m long, 8 m wide, and 0.20 m thick. During the winter, temperatures are nominally
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Chapter 1 Solutions
Introduction to Heat Transfer
- 2.34 Show that the temperature distribution in a sphere of radius . made of a homogeneous material in which energy is released at a uniform rate per unit volume , isarrow_forwardExample 10: Consider a long resistance wire of radius r1 = 0.2 cm and thermal conductivity kwire = 15 W/m·°C in which heat is generated uniformly as a result of resistance heating at a constant rate of g = 50 W/cm3. The wire is embedded in a 0.5-cm-thick layer of ceramic whose thermal conductivity is kceramic = 1.2 W/m·°C. If the outer surface temperature of the ceramic layer is measured to be Ts = 45°C, determine the temperatures at the center of the resistance wire and the interface of the wire and the ceramic layer under steady conditions.arrow_forwardDetermine the time needed to decrease the temperature of a solid cylinder from 40 C to 35 C if the ambient temperature is equal to 31 C. The cylinder has a length equals to 0.9 m and diameter equals to 100 mm. The heat convective coefficient is equal to 9 W/m^2.K. The cylinder has a conductivity equals to 2 W/m.K, a density equals to 1200 kg/m^3 and its Cp is equal to 4.700 kJ/kgK.arrow_forward
- A 6 in thick concrete wall, having thermal conductivity k =0.50 Btu/h ft F, is exposed to air at 70°F on one side and air at 20°F on the opposite side. The heat transfer coefficients are h=2.0 Btu/h. ft² ° F on the 70°F side and =10 Btu/h .ft².0 F on the 20°F side. Determine the heat transfer ratearrow_forwardA brass wire of 0.8 mm in diameter and 12 m long is annealed in an annealing furnace at a temperature of 400°C. Find the time required for the wire to reach the temperature of 150°C if the temperature of the wire before placing it inside the furnace is 30°C. Take h = 35 W/m2 K. Density = 8500 kg/m3. Specific heat = 0.335 kJ/kg K.arrow_forwardDetermine the time needed to decrease the temperature of a solid cylinder from 40 C to 35 C if the ambient temperature is equal to 31 C. The cylinder has a length equals to 0.9 m and diameter equals to 100 mm. The heat convective coefficient is equal to 1.3 W/m^2.K. The cylinder has a conductivity equals to 2 W/m.K, a density equals to 1200 kg/m^3 and its Cp is equal to 4.700 kJ/kgK. Select one: a. 83325 s O b. 10500s O c. 45360 s O d. 30050 sarrow_forward
- The wall of a house, 8.09 m wide and 6.70 m high is made from a thick bricklayer with thermal conductivity λ = 0.69 W/mK. The surface temperature on theinside & outside of the wall is 27ºC & 8 ºC respectively. Determine the heatenergy transfer rate and thickness of the wall, if energy loss is 10139 kJ in 9 hours.arrow_forwardA 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_forwardExample 2: The roof of an electrically heated home is 6 m long, 8 m wide, and 0.25 m thick, and is made of a flat layer of concrete whose thermal conductivity is k=0.8 W/m·°C. The temperatures of the inner and the outer surfaces of the roof one night are measured to be 15°C and 4°C, respectively, for a period of 10 hours. Determine the rate of heat loss through the roof that nightarrow_forward
- ı need solutionarrow_forwardA wall of length "L" m and height "H" m is made from a thick bricklayer of 31 cm with thermal conductivity of 0.5 W/mK is subjected to heat transfer due to the outside temperature as 38 °C and inside temperature 27 °C. If the energy loss is 12702 kJ in 10 hours. Determine the Heat transfer rate, Surface Area and Length and Height of the wall, if L = 4 H.arrow_forwardIt is desired to keep the interior of a refrigerator at 2 °C whose dimensions at the base are 0.8 x 0.8 m and the height is 1.9 m. The walls of the refrigerator are made of two sheets of steel, 0.28 cm thick with 3 cm of fiberglass insulation. The interior and exterior coefficients are, respectively, 10 W/m^2 °C and 15 W/m^2 °C. If the ambient temperature in the kitchen is 30°C, estimate the heat flux that must be extracted to maintain the specified conditions. Make a proposal to prevent heat from entering the refrigerator.arrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning
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