4. The section of a vertical wall is made up of fiberglass insulation slabs separated by wooden studs. The thermal conductivity of fiberglass and wood are 0.04 W/m-K and 0.18 W/m-K, respectively. The thickness of the wall is 160 mm. The temperatures of the inner and outer surfaces of the wall section are 22 °C and 4 °C, respectively. The ratio of the insulation area to the total wall area is 0.8. Calculate the total heat flow rate (in W/m2) through the wall per unit area. Wooden Stud Fiberglass Insulation Follow-up question to Question 4, calculate the rate of heat flow (in W/m2) through unit area of studs.

4. The section of a vertical wall is made up of fiberglass insulation slabs separated by wooden studs. The thermal conductivity of fiberglass and wood are 0.04 W/m-K and 0.18 W/m-K, respectively. The thickness of the wall is 160 mm. The temperatures of the inner and outer surfaces of the wall section are 22 °C and 4 °C, respectively. The ratio of the insulation area to the total wall area is 0.8. Calculate the total heat flow rate (in W/m2) through the wall per unit area. Wooden Stud Fiberglass Insulation Follow-up question to Question 4, calculate the rate of heat flow (in W/m2) through unit area of studs.

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.

Chapter1: Basic Modes Of Heat Transfer

Section: Chapter Questions

Problem 1.37P: 1.37 Mild steel nails were driven through a solid wood wall consisting of two layers, each 2.5-cm...

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1.1 On a cold winter day, the outer surface of a 0.2-m-thick concrete wall of a warehouse is exposed to temperature of –5°C, while the inner surface is kept at 20°C. The thermal conductivity of the concrete is 1.2 W/m K. Determine the heat loss through the wall, which is 10-m long and 3-m high. Problem 1.1
1.37 Mild steel nails were driven through a solid wood wall consisting of two layers, each 2.5-cm thick, for reinforcement. If the total cross-sectional area of the nails is 0.5% of the wall area, determine the unit thermal conductance of the composite wall and the percent of the total heat flow that passes through the nails when the temperature difference across the wall is 25°C. Neglect contact resistance between the wood layers.
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.
1.4 To measure thermal conductivity, two similar 1-cm-thick specimens are placed in the apparatus shown in the accompanying sketch. Electric current is supplied to the guard heater, and a wattmeter shows that the power dissipation is 10 W. Thermocouples attached to the warmer and to the cooler surfaces show temperatures of 322 and 300 K, respectively. Calculate the thermal conductivity of the material at the mean temperature in W/m K. Problem 1.4
A composite refrigerator wall is composed of 5 cm of corkboard sandwiched between a 1.2-cm-thick layer of oak and a 0.8-mm-thick layer of aluminum lining on the inner surface. The average convection heat transfer coefficients at the interior and exterior wall are 11 and 8.5W/(m2K) respectively. (a) Draw the thermal circuit. (b) Calculate the individual resistances of the components of this composite wall and the resistances at the surfaces. (c) Calculate the overall heat transfer coefficient through the wall. (d) For an air temperature of 1C inside the refrigerator and 32C outside, calculate the rate of heat transfer per unit area through the wall.
20-m pipe has an outside diameter of 50 mm. Pipe is insulated with a layer of asbestos, then followed by a layer of cork. Inside and outside diameter of the cork is 77 mm and 80 mm, respectively. If the temperature drop from pipe to cork is 1165°C, calculate the inside diameter of the pipe (mm). The rate of the heat transfer is 8778 W. The thermal conductivity of steam pipe, asbestos and cork are 0.045 kW/m-K, 0.058 W/m-K and 0.043 W/m-K respectively.
The section of a vertical wall is made up of fiberglass insulation slabs separated by wooden studs. The thermal conductivity of fiberglass and wood are 0.04 W/m-K and 0.18 W/m-K, respectively. The thickness of the wall is 160 mm. The temperatures of the inner and outer surfaces of the wall section are 22 °C and 4 °C, respectively. The ratio of the insulation area to the total wall area is 0.8. Calculate the total heat flow rate (in W/m2) through the wall per unit area. Wooden Stud Fiberglass Insulation Round your answer to 2 decimal places. Add your answer Follow-up question to Question 4, calculate the rate of heat flow (in W/m2) through unit area of studs. Round your answer to 2 decimal places.
How many inches of insulation are required to insulate a ceiling such that the surface temperature of the ceiling facing the living area is within 2°C of the room air temperature? Assume a heat transfer coefficient on both sides of the ceiling of 2.84 W/(m2 • K) and a thermal conductivity of 0.0346 W/(m . K) for the insulation. The ceiling is 1.27 cm thick plasterboard with a thermal conductivity of 0.433 W/(m . K). Room temperature is 20°C and attic temperature is 49°C.
2. A refrigerated cold room wall has a thickness of 100mm and a thermal conductivity 0.14 W/m-K. The room wall has a 60mm thick internal lining of cork having a thermal conductivity of 0.05 W/m.K. The thermal conductance between the exposed faces and the respective atmosphere is 12 W/m²-K. If the room is maintained at 0°C and the external atmospheric temperature is 20°C, Calculate the heat loss rate through 1m² of the wall.
The wall of the furnace is 30.48 mm thick and is insulated from outside. Thermal conductivity of the wall material is 0.1 W/m K and the insulation material is 0.01 W/m K. The furnace operates at 650 0C and the ambient temperature is 30 0 Allowable temperature on the outer side of the insulation is 1000C. Determine the overall heat transfer by conduction per unit area occurring across a furnace wall made from clay.If the air side heat transfer coefficient is 0.4 W/m2 K, calculate the minimum insulation thickness requirement. please provide the answers with proper steps along with clear explanations and pictures
The oven of a stove must have a sufficient insulation so that the surface temperature of the stove is not greater than 50 oC. To accomplish this, insulation, k = 0.11 W/m-K, is used between the inside and outside metal surfaces. The room temperature is 20 oC, and the outside unit convective coefficient is 8 W/m2-K. Neglecting the resistance of the metal, what is the minimum thickness of insulation required, if the outside temperature reaches 315 oC?
A container has a 4 mm thick metal wall and is lined insider with a 1.5 mm-thick plastic. The inside temperature is 80oC and the outside ambient temperature is 25oC. When ambient air flow is high, heat loss on the outside is a combined convection and radiation and the overall coefficient is 50 W/m^2·K. Thermal resistance inside is negligible. Thermal conductivity of the metal is 60 W/m·K and that of the plastic is 0.08 W/m·K. "Wind chill temperature" is defined as the air temperature under calm conditions with the same heat loss rates. 1)Calculate the heat loss rate. 2) What is the "wind chill" temperature for the above scenario if the outside combined coefficient is 20 W/m K when the wind is calm