An engineer constructs a refrigerator having a cubical shape that is 2 m on a side. If the bottom and the top are perfectly insulated. What is the minimum thickness of insulation (k = 0.06 W/m.K) that the engineer should apply to the side walls to ensure a heat load of less than 500 W, when the inner and outer surfaces are - 10 C and 35 C. a. 86 mm b. 54 mm C. 14 mm d. 156 mm Clear my choice

An engineer constructs a refrigerator having a cubical shape that is 2 m on a side. If the bottom and the top are perfectly insulated. What is the minimum thickness of insulation (k = 0.06 W/m.K) that the engineer should apply to the side walls to ensure a heat load of less than 500 W, when the inner and outer surfaces are - 10 C and 35 C. a. 86 mm b. 54 mm C. 14 mm d. 156 mm Clear my choice

Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)

8th Edition

ISBN:9781305387102

Author:Kreith, Frank; Manglik, Raj M.

Publisher:Kreith, Frank; Manglik, Raj M.

Chapter2: Steady Heat Conduction

Section: Chapter Questions

Problem 2.30P: 2.30 An electrical heater capable of generating 10,000 W is to be designed. The heating element is...

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A 10-m-long, 5-cm-outer-radius cylindrical steam pipe is covered with 3-cm thick cylindrical insulation with a thermal conductivity of 0.05 W/m. °C. If the rate of heat loss from the pipe is 1000 W, what would be the temperature drop (in °C) across the insulation? Select one: O a. 163°C b. 48°C c. 79°C d. 150°C e. 600°C
1. For a steam pipe with a given diameter of 10 cm covered by two (2) layers of insulation. The first insulation has a thickness of 4 cm and a coefficient of thermal conductivity of 0.08 W/m.K. and the second insulation has a thickness of 3 cm and a thermal conductivity of 0.15 W/m.K. The steam main conveys steam at a pressure of 1.70 MPa with 25°C superheat. Outside temperature is 27°C. The pipe is 30 meters in length. (tsat @ 1.70 MPa = 204°C). Determine the following: a) The heat loss in KW b) Explain the concepts/principles that were considered and the factors that affected the condition of the above mentioned items (a & b).
The thermal conductivities of wood is kwood = 0.1W/(m°C)and air is kair = 0.0234W/(m°C). Part A If the temperature of the room is 20°C and outside is 10°C, find the rate of heat flow for a wall of wood with area = 10 m² and thickness of 5cm. O 60 W O 304 W O 34 W O 200 W O 100 W Submit Request Answer Part B The wall of wood with thickness of 5cm is now replaced with two layers of wood and a gap of air between the wood. Each layer of wood has a 2.5cm thickness and the gap is 1cm. The rate of heat flow will, decreases. increases. stay the same. Submit Request Answer Part C The temperature in the air gap will be, O 20°C, between 10°C and 20°C, O 10°C,
An office space contains one (6`x 3`) well- fitted door made of nominal 2" wood. The heat loss through door is (517.2 Btuh) if Tb.l.=80 F and To= -10 F. ? True or false
The cooling load for a house is determined in part by using the same formulaused to find the heat load. The temperature difference used in designing acooling system is 25°F. The corner room shown does not face the sun so noadditional cooling load is required. The windows are single pane, and thewalls are brick veneer with 31⁄2 inches of insulation (R-11). The ceiling has31⁄2 inches of insulation (R-11), and the floor has no insulation. The room isbuilt over a vented crawl space with a vented attic above it. Find the coolingload for this room.
QUESTION 8 A 1m by 2m glass wool insulation wall (k=0.036 W/mK) with a thickness of 5cm has an inside temperature of 70°C. If the heat flow rate through the wall is 85.5w, the lower temperature is O a. 1.7 °C O b. 17.4 °C OC. 6°C O d. 0.6 °C O e. 10.6 °C O f. None of them
An office space of 14 ft x114 ft x12 ft height. The heat loss through roof is (5131.3 Btuh) if Tb.l.=70 F, To= 5 F , and Uwall=0.35 Btu/hr.ft2.F * O True O False
A wall (0.5 m x 1.2 m), having thermal conductivity of 1.7 W/m.K. The temperatures at the inner and outer surfaces are 1000K and 900 K, respectively. The heat flux through the wall is: Select one: a. 1020 W b. 1020 W/ m2 c. 10.2 W d. 10.2 W / m2 e. None of the mentioned
6. a. The heat flux applied to the walls of the biomass combustion furnace is 20 W/m2. The furnace walls have a thickness of 10 mm and a thermal conductivity of 12 W/m.K. If the wall surface temperature is measured to be 50oC on the left and 30oC on the right, prove that conduction heat transfer occurs at a steady state!b. Heating the iron cylinder on the bottom side is done by placing the iron on the hotplate. This iron has a length of 20 cm. The surface temperature of the hotplate is set at 300oC while the top side of the iron is in contact with the still outside air. To reach the desired hotplate temperature, it takes 5 minutes. Then it takes 15 minutes to measure the temperature of the upper side of the iron cylinder at 300oC. Show 3 proofs that heat transfer occurs transiently
An office space of 15 ft x12 ft x10 ft height. The heat loss through walls is (6949.8 Btuh) if Tb.l.=80 F , To= -10 F , and Uwall=0.143 Btu/hr.ft2.F ? True or false
6. Make a diagram and show the step-by-step process. Do not use shortcut methods. Make it as detailed as it can be. Encode (not hand-written)!