The inner surface of a plane brick wall is at 60°C and the outer surface is at 35°C. Calculate the rate of heat transfer per m' of surface area of the wall, which is 220 mm thick. The thermal conductivity of the brick is 0.51 W/m°C.

College Physics
11th Edition
ISBN:9781305952300
Author:Raymond A. Serway, Chris Vuille
Publisher:Raymond A. Serway, Chris Vuille
Chapter1: Units, Trigonometry. And Vectors
Section: Chapter Questions
Problem 1CQ: Estimate the order of magnitude of the length, in meters, of each of the following; (a) a mouse, (b)...
icon
Related questions
icon
Concept explainers
Question
h=
= 10
100
m² °q
3- Radiation heat transfer:
This is when heat is transferred by radiating off of an object.
• All bodies send out energy in the form of electromagnetic radiation.
• The wavelength and intensity is dependent on the temperature of the
surface.
• Radiation may be transferred through vacuum, but also through air.
HW1
The inner surface of a plane brick wall is at 60°C and the outer surface is at 35°C. Calculate the rate of heat
transfer per m of surface area of the wall, which is 220 mm thick. The thermal conductivity of the brick is
0.51 W/m°C.
HW2
A reactor's wall 320 mm thick, is made up of an inner layer of fire brick (k = 0.84 W/m°C) covered with a layer
of insulation (k = 0.16 W/m°C). The reactor operates at a temperature of 1325°C and the ambient temperature is
25°C. (i) Determine the thickness of fire brick and insulation which gives minimum heat loss. (ii) Calculate the
heat loss presuming that the insulating material has a maximum temperature of 1200°C.
HW3
Q1
A 0.1-m-thick brick wall is exposed to a cold wind at 270 K through a convection heat transfer coefficient of 40
W/m K. On the other side is calm air at 330 K, with a natural-convection heat transfer coefficient of 10 W/m?
K. Calculate the rate of heat transfer per unit area (i.e., the heat flux).
Q2
A mild steel tank of wall thickness 12 mm contains water at 95°C. The thermal conductivity of mild steel is 50
W/m°C, and the heat transfer coefficients for the inside and outside the tank are 2850 and 10 W/m°C,
respectively. If the atmospheric temperature is 15°C, calculate:
(i) The rate of heat loss per m of the tank surface area;
(ii) The temperature of the outside surface of the tank.
Q3
The interior of a refrigerator having inside dimensions of 0.5 m x 0.5 m base area and 1 m height, is to be
maintained at 6°C. The walls of the refrigerator are constructed of two mild steel sheets 3 mm thick (k = 46.5
W/m°C) with 50 mm of glass wool insulation (k = 0.046 W/m°C) between them. If the average heat transfer
coefficients at the inner and outer surfaces are 11.6 W/m2°C and 14.5 W/m2°C respectively, calculate:
(i) The rate at which heat must be removed from the interior to maintain the specified temperature in the kitchen
at 25°C, and
(ii) The temperature on the outer surface of the metal sheet.
Transcribed Image Text:h= = 10 100 m² °q 3- Radiation heat transfer: This is when heat is transferred by radiating off of an object. • All bodies send out energy in the form of electromagnetic radiation. • The wavelength and intensity is dependent on the temperature of the surface. • Radiation may be transferred through vacuum, but also through air. HW1 The inner surface of a plane brick wall is at 60°C and the outer surface is at 35°C. Calculate the rate of heat transfer per m of surface area of the wall, which is 220 mm thick. The thermal conductivity of the brick is 0.51 W/m°C. HW2 A reactor's wall 320 mm thick, is made up of an inner layer of fire brick (k = 0.84 W/m°C) covered with a layer of insulation (k = 0.16 W/m°C). The reactor operates at a temperature of 1325°C and the ambient temperature is 25°C. (i) Determine the thickness of fire brick and insulation which gives minimum heat loss. (ii) Calculate the heat loss presuming that the insulating material has a maximum temperature of 1200°C. HW3 Q1 A 0.1-m-thick brick wall is exposed to a cold wind at 270 K through a convection heat transfer coefficient of 40 W/m K. On the other side is calm air at 330 K, with a natural-convection heat transfer coefficient of 10 W/m? K. Calculate the rate of heat transfer per unit area (i.e., the heat flux). Q2 A mild steel tank of wall thickness 12 mm contains water at 95°C. The thermal conductivity of mild steel is 50 W/m°C, and the heat transfer coefficients for the inside and outside the tank are 2850 and 10 W/m°C, respectively. If the atmospheric temperature is 15°C, calculate: (i) The rate of heat loss per m of the tank surface area; (ii) The temperature of the outside surface of the tank. Q3 The interior of a refrigerator having inside dimensions of 0.5 m x 0.5 m base area and 1 m height, is to be maintained at 6°C. The walls of the refrigerator are constructed of two mild steel sheets 3 mm thick (k = 46.5 W/m°C) with 50 mm of glass wool insulation (k = 0.046 W/m°C) between them. If the average heat transfer coefficients at the inner and outer surfaces are 11.6 W/m2°C and 14.5 W/m2°C respectively, calculate: (i) The rate at which heat must be removed from the interior to maintain the specified temperature in the kitchen at 25°C, and (ii) The temperature on the outer surface of the metal sheet.
Expert Solution
trending now

Trending now

This is a popular solution!

steps

Step by step

Solved in 2 steps

Blurred answer
Knowledge Booster
Energy transfer
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, physics and related others by exploring similar questions and additional content below.
Similar questions
Recommended textbooks for you
College Physics
College Physics
Physics
ISBN:
9781305952300
Author:
Raymond A. Serway, Chris Vuille
Publisher:
Cengage Learning
University Physics (14th Edition)
University Physics (14th Edition)
Physics
ISBN:
9780133969290
Author:
Hugh D. Young, Roger A. Freedman
Publisher:
PEARSON
Introduction To Quantum Mechanics
Introduction To Quantum Mechanics
Physics
ISBN:
9781107189638
Author:
Griffiths, David J., Schroeter, Darrell F.
Publisher:
Cambridge University Press
Physics for Scientists and Engineers
Physics for Scientists and Engineers
Physics
ISBN:
9781337553278
Author:
Raymond A. Serway, John W. Jewett
Publisher:
Cengage Learning
Lecture- Tutorials for Introductory Astronomy
Lecture- Tutorials for Introductory Astronomy
Physics
ISBN:
9780321820464
Author:
Edward E. Prather, Tim P. Slater, Jeff P. Adams, Gina Brissenden
Publisher:
Addison-Wesley
College Physics: A Strategic Approach (4th Editio…
College Physics: A Strategic Approach (4th Editio…
Physics
ISBN:
9780134609034
Author:
Randall D. Knight (Professor Emeritus), Brian Jones, Stuart Field
Publisher:
PEARSON