Q1: A house has a composite wall of wood, fiberglass insulation, and plaster board, as indicated in the sketch. On a cold winter day the convection heat transfer coefficients are ho3D60 W/m2. C and h; = 30 W/m2. °C. The total wall surface area is 350 m2. Take k= 0.038 W/m. °C, k,= 0.17 W/m. °C, k,= 0.12 W/m. °C, and k= 0.026 W/m. °C. (a) Determine a symbolic expression for the total thermal resistance of the wall, including inside and outside convection effects for the prescribed conditions. (b) Determine the total heat loss through the wall.

Q1: A house has a composite wall of wood, fiberglass insulation, and plaster board, as indicated in the sketch. On a cold winter day the convection heat transfer coefficients are ho3D60 W/m2. C and h; = 30 W/m2. °C. The total wall surface area is 350 m2. Take k= 0.038 W/m. °C, k,= 0.17 W/m. °C, k,= 0.12 W/m. °C, and k= 0.026 W/m. °C. (a) Determine a symbolic expression for the total thermal resistance of the wall, including inside and outside convection effects for the prescribed conditions. (b) Determine the total heat loss through the wall.

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.

Chapter8: Natural Convection

Section: Chapter Questions

Problem 8.38P

See similar textbooks

Similar questions

The air-conditioning system in a Chevrolet van for use in desert climates is to be sized. The system is to maintain an interior temperature of 20C when the van travels at 100 km/h through dry air at 30C at night. If the top of the van is idealized as a flat plate 6 m long and 2 m wide and the sides as flat plates 3 m tall and 6 m long, estimate the rate at which heat must be removed from the interior to maintain the specified
The 4-mm-thick rear window of an automobile is defogged by passing warm air over its inner surface. Warm air temperature is at T,1 = 40C and corresponding convection coefficient is h1 =30 W/(m2·K). Outer ambient temperature T,2 = 5C and corresponding convection coefficient is h2 = 70 W/(m2·K). The size of the window is 0.5 m (height)  1.5 m (width). A. Draw two thermal circuits (one based on heat rate and one based on heat flux) considering the convection occurring over inner and outer surfaces and the conduction through the window. Show the equations for the thermal resistances in the circuits.B. Determine the total thermal resistance based on heat flux in m2K/W andoverall heat transfer coefficient U in W/m2K. Find the thermal conductivity of glass (sodalime at 300K)C. Determine the inner and outer temperatures of the glass (that are Ts,1 and Ts,2 shown above).
A domestic refrigerator with inner dimensions of 0.7 m by 0.7 m at the base and height 1 m was designed to maintain a set temperature of 6 ˚C. The bodies consist of two 10-mm-thick layers of Aluminium (k = 225 W/mK) separated by a 30 mm polyurethane insulation (k=0.028 W/mK). If the average convection heat transfer coefficient at the inner and outer surfaces are 11.6 W/m2K and 14.5 W/m2K respectively, calculate: Data: Hgt = , W = , L1 = L3 = = m, k1= k3 = , L2 = = , k2 = , T∞1 = , T∞2 = , ho= , hi = .
Consider the vertical heat sink (see the figure) used to cool a surface at 70 0C. The room temperature is 30 0C. The dimensions are given as (H=2 cm, L=5 cm, t=1 mm, W=15 cm). If the space between the fins is arranged so that the heat transfer rate is maximum, what is the heat transfer rate from the heat sink? Properties of air: ρ=1 kg/m3, k=0.03 W/mK, ν=1.5x10-5 m2/s, cp=1 kJ/kg0C, Pr=0.7
A modern cabin has a concrete floor that is 4.50 inches thick. Aroaring fire keeps the interior of the cabin at 21.0 0C while the airtemperature below the cabin is a chilly 2.00 0C. How much heat(J) is lost through the concrete floor in 4 hrs if the cabin measures4.50 m by 6.50m to 3 sig fig?
A domestic refrigerator with inner dimensions of 0,7 m by 0,7 m at the base and height 1m was designed to maintain a set temperature of 6 degrees Celsius. The bodies consist of two 10 mm thick layers of Aluminum (k=225 W/mK) separated by a 30 mm polyurethane insulation (k=0,028 W/mK). If the convection heat transfer coefficient at the inner and outer surfaces are 11,6 W/m²K and 14,5 W/m²K respectively, calculate the outer surface temperature of Aluminum in degrees Celsius to 2 decimal places. 2)calculate the resistance (R) for the insulation layer in K/W to 4 decimal places. 3)calculate the steady rate of heat transfer from the interior to maintain the specified temperature in the kitchen at 25 degrees Celsius in W to 2 decimal places. 4)calculate the total resistance (R) for the refrigerator in K/W to 4 decimal places
It 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.
Convection heat transfer from a plate (2 m x 2 m) is 450 W. If surface temperature of plate is 450 K and surrounding temperature is 300 K, what will be value of heat transfer coefficient?
A domestic refrigerator with inner dimensions of 0,7 m by 0,7 m at the base and height 1m was designed to maintain a set temperature of 6 degrees Celsius. The bodies consist of two 10 mm thick layers of Aluminum (k=225W/mK) separated by a 30 mm polyurethane insulation (k=0,028W/mK). If the average convection heat transfer coefficient at the inner and outer surfaces are 116W/m²K and 14,5W/m²K respectively. Calculate : 1)The individual resistance (R) for each thermal layer, as well as for the refrigerator 2)The steady rate of heat transfer from the interior to maintain the specified temperature in the kitchen at 25 degrees Celsius 3)The outer surface temperature of the Aluminum 4)Sketch the sectional view of the refrigerator showing thermal circuit
A domestic refrigerator with inner dimensions of 0.7 m by 0.7 m at the base and height 1 m was designed to maintain a set temperature of 6 ˚C. The bodies consist of two 10-mm-thick layers of Aluminium (k = 225 W/mK) separated by a 30 mm polyurethane insulation (k=0.028 W/mK). If the average convection heat transfer coefficient at the inner and outer surfaces are 11.6 W/m2K and 14.5 W/m2K respectively, calculate: Total inner surace area in m2 to 2 decimal places.
Given a plaster of paris (PoP) slab with L = 0.052 cm, W = 0.052 cm, and H = 0.0095 cm, what is the heat transfer coefficient if the biot number is 0.19682? Other data (if necessary):Initial Temperature: 328.2 CSurrounding Temperature: 27.9 CPoP Density: 680 kg/m^3Heat Capacity: 1090 J/kgKThermal Conductivity: 0.1185 W/mK
A domestic refrigerator with inner dimensions of 0.7 m by 0.7 m at the base and height 1 m was designed to maintain a set temperature of 6 ˚C. The bodies consist of two 10-mm-thick layers of Aluminium (k = 225 W/mK) separated by a 30 mm polyurethane insulation (k=0.028 W/mK). If the average convection heat transfer coefficient at the inner and outer surfaces are 11.6 W/m2K and 14.5 W/m2K respectively, calculate: the outer surface temperature of the Aluminum in 0C to 2 decimal places