E-PolyLearning

Discussion Forum

Que. Three metal walls of same thickness and cross sectional area have thermal conductivities k, 2k and 3k respectively. The temperature drop across the walls (for same heat transfer) will be in the ratio
a. 3:2:1
b. 1:1:1
c. 1:2:3
d. Given data is insufficient
Correct Answer:3:2:1
Abishek :(February 24, 2020) Explanation anyone?
Reply
Confused About the Answer? Ask fellow aspirants for Details Here
Already Know Explanation? Add it Here to help others.

More Questions Like this:

A pipe of outside diameter₂0 mm is to be insulated with asbestos which has a mean thermal conductivity of 0.1 W/m degree. The local coefficient of convective heat to the surroundings is 5 W/square meter degree. Find the critical radius of insulation for optimum heat transfer from pipe?
Find the heat flow rate through the composite wall as shown in figure. Assume one dimensional flow and take

k 1 = 150 W/m degree
k 2 = 30 W/m degree
k 3 = 65 W/m degree
k 4 = 50 W/m degree
AB = 3 cm, BC = 8 cm and CD = 5 cm.
The distance between middle horizontal line from the top is 3 cm and from the bottom is 7 cm
A plane wall of thickness δ has its surfaces maintained at temperatures T₁ and T₂. The wall is made of a material whose thermal conductivity varies with temperature according to the relation k = k₀ T². Find the expression to work out the steady state heat conduction through the wall?
The shape factor for complete rectangular furnace is
Where a, b and c are the inside dimensions and d x is the wall thickness
A composite wall is made of two layers of thickness δ₁ and δ₂ having thermal conductivities k and 2k and equal surface area normal to the direction of heat flow. The outer surface of composite wall are at 100 degree Celsius and 200 degree Celsius. The minimum surface temperature at the junction is 150 degree Celsius. What will be the ratio of wall thickness?
For insulation to be properly effective in restricting heat transmission, the pipe radius r0 will be
For the same amount of fabrication material and same inside capacity, the heat loss is lowest in
The rate of heat transfer for a plane wall of homogenous material with constant thermal conductivity is given by
A homogeneous wall of area A and thickness δ has left and right hand surface temperatures of 0 degree Celsius and 40 degree Celsius. Determine the temperature at the center of the wall
A pipe carrying steam at 215.75 degree Celsius enters a room and some heat is gained by surrounding at 27.95 degree Celsius. The major effect of heat loss to surroundings will be due to
The quantity d t/Q for conduction of heat through a body i.e. spherical in shape is
With variable thermal conductivity, Fourier law of heat conduction through a plane wall can be expressed as
Heat is transferred from a hot fluid to a cold one through a plane wall of thickness (δ), surface area (A) and thermal conductivity (k). The thermal resistance is
Typical examples of heat conduction through cylindrical tubes are not found in
A stainless steel tube with inner diameter₁2 mm, thickness 0.2 mm and length 50n cm is heated electrically. The entire 15 k W of heat energy generated in the tube is transferred through its outer surface. Find the intensity of current flow
A plane slab of thickness 60 cm is made of a material of thermal conductivity k = 17.45 W/m K. Let us assume that one side of the slab absorbs a net amount of radiant energy at the rate q = 530.5 watt/m². If the other face of the slab is at a constant temperature t₂ = 38 degree Celsius. Comment on the temperature with respect to the slab?
The thermal resistance for heat conduction through a hollow sphere of inner radius r1 and outer radius r2 is
The rate of conduction heat flow in case of a composite sphere is given by
The accompanying sketch shows the schematic arrangement for measuring the thermal conductivity by the guarded hot plate method. Two similar 1 cm thick specimens receive heat from a 6.5 cm by 6.5 cm guard heater. When the power dissipation by the wattmeter was 15 W, the thermocouples inserted at the hot and cold surfaces indicated temperatures as 325 K and 300 K. What is the thermal conductivity of the test specimen material?
A composite wall generally consists of

View All Questions on: Steady State Conduction

Management and Accounting

Human Resource Management Marketing and Marketing Management Financial Management and Financial Markets Cost Accounting Business Statistics