E-PolyLearning

Discussion Forum

Que. The quantity d t/Q for conduction of heat through a body i.e. spherical in shape is
a. ln (r2/r1)/2πLk
b. ln (r2/r1)/πLk
c. ln (r2/r1)/2Lk
d. ln (r2/r1)/2πk
Correct Answer:ln (r2/r1)/2πLk
Confused About the Answer? Ask fellow aspirants for Details Here
Already Know Explanation? Add it Here to help others.

More Questions Like this:

A steel pipe of 20 mm inner diameter and 2 mm thickness is covered with 20 mm thick of fiber glass insulation (k = 0.05 W/m degree). If the inside and outside convective coefficients are 10 W/m² degree and 5 W/m² degree, calculate the overall heat transfer coefficient based on inside diameter of pipe. In the diagram, the diameter of small circle is 20 mm
A spherical vessel of 0.5 m outside diameter is insulated with 0.2 m thickness of insulation of thermal conductivity 0.04 W/m degree. The surface temperature of the vessel is – 195 degree Celsius and outside air is at 10 degree Celsius. Determine heat flow
A wire of radius 3 mm and 1.25 m length is to be maintained at 60 degree Celsius by insulating it by a material of thermal conductivity 0.175 W/m K. The temperature of surrounding is 20 degree Celsius with heat transfer coefficient 8.5 W/ m² K. Find percentage increase in heat loss due to insulation?
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
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?
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?
Which is true regarding a complete rectangular furnace?
The temperature distribution associated with radial conduction through a sphere is represented by
Maximum value of critical radius is
A cylinder of radius r and made of material of thermal conductivity k 1 is surrounded by a cylindrical shell of inner radius r and outer radius 2r. This outer shell is made of a material of thermal conductivity k 2. Net conductivity would be
A heat exchanger shell of outside radius 15 cm is to be insulated with glass wool of thermal conductivity 0.0825 W/m degree. The temperature at the surface is 280 degree Celsius and it can be assumed to remain constant after the layer of insulation has been applied to the shell. The convective film coefficient between the outside surface of glass wool and the surrounding air is estimated to be 8 W/m² degree. What is the value of critical radius?
Shape factor for cylinder is
For insulation to be properly effective in restricting heat transmission, the pipe radius r0 will be
The thermal resistance for heat conduction through a spherical wall is
The value of critical radius in case of cylindrical hollow object is
A composite slab has two layers having thermal conductivities in the ratio of 1:2. If thickness is same for each layer then the equivalent thermal conductivity of the slab would be
Chose the correct one with respect to critical radius of insulation
The thermal resistance for heat conduction through a hollow sphere of inner radius r1 and outer radius r2 is
The temperature distribution in a large thin plate with uniform surface temperature will be
(Assume steady state condition)
The oven of an electric store, of total outside surface area 2.9 m² dissipates electric energy at the rate of 600 W. The surrounding room air is at 20 degree Celsius and the surface coefficient of heat transfer between the room air and the surface of the oven is estimated to be 11.35 W/m² degree. Determine the average steady state temperature of the outside surface of the store

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