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The coefficient of heat conductivity of heat-insulating materials does not exceed _________

The coefficient of heat conductivity of heat-insulating materials does not exceed _________ Correct Answer 0.18 kcal/m.hr.°C

The coefficient of heat conductivity of heat-insulating materials does not exceed 0.18 kcal/m.hr.°C. These materials are needed to give protection against heat and cold. They are generally porous.

Related Questions

Experimental results indicate that the local heat transfer coefficient h g for flow over a flat plate with an extremely rough surface is approximated by the relation h x = a x -0.12 Where a is a constant coefficient and x is distance from the leading edge of the plate. What is the relation between this local heat transfer coefficient and the average heat transfer coefficient for a plate of length x?
Fourier's law of heat conduction is (where Q = Amount of heat flow through the body in unit time, A = Surface area of heat flow, taken at right angles to the direction of heat flow, dT = Temperature difference on the two faces of the body, dx = Thickness of the body, through which the heat flows, taken along the direction of heat flow, and k = Thermal conductivity of the body)
Fourier's law of heat conduction is (where Q = Amount of heat flow through the body in unit time, A = Surface area of heat flow, taken at right angles to the direction of heat flow, dT = Temperature difference on the two faces of the body, dx = Thickness of the body, through which the heat flows, taken along the direction of heat flow and k = Thermal conductivity of the body)
Consider the following statements about thermal conductivity: 1) Thermal conductivity decreases with increasing molecular weight 2) Thermal conductivity of non-metallic liquids generally decreases with increasing temperature 3) Thermal conductivity of gases and liquids is generally smaller than that of solids Which of the above statements are correct?
An electronic semiconductor device generates 0.16 k J/hr of heat. To keep the surface temperature at the upper safe limit of 75 degree Celsius, it is desired that the heat generated should be dissipated to the surrounding environment which is at 30 degree Celsius. The task is accomplished by attaching aluminum fins, 0.5 square mm and 10 mm to the surface. Work out the number of fins if thermal conductivity of fin material is 690W/m K and the heat transfer coefficient is 45k J/square m hr K. Neglect the heat loss from the tip of the fin
Heat is being transferred by convection from water at 48 degree Celsius to glass plate whose surface is exposed to water at 40 degree Celsius. The thermal conductivity of water is 0.6 W/m K and the thermal conductivity of glass is 1.2 W/m K. The spectral gradient of temperature in the water at the water glass interface is 10 -4 K/m. The heat transfer coefficient in W/m2 K is
Consider the following statements regarding capability curves of a synchronous generator: 1. The MVA loading should not exceed the generator rating. 2. The field current should not be allowed to exceed a specified value determined by field heating. 3. The MW loading should not exceed the rating of the prime mover. 4. The load angle must be more than 90°. Which of the above statements are correct?
Maximum slenderness ratio of load bearing walls for a dwelling having more than 2 storeys
(i) Shall not exceed 12 if lime mortar is used
(ii) Shall not exceed 18 if cement lime mortar 1 : 2 : 9 is used
(iii) Shall not exceed 24 if cement mortar 1 : 6 is used
A Carnot heat engine receives heat at 750 K and rejects the waste heat to the environment at 300 K. The net work output of the heat engine is used to drive a Carnot refrigerator, whose COP is 6.14. If the heat removal rate from the refrigerated space is 6.6 kW, determine the rate of heat supply to the heat engine?
Mark the incorrect proposition:
1. Set-off is a statutory defence to a plaintiff's action, whereas a counterclaim is a cross-action.
2. Set-off and counter-claim arises out of the same transaction.
3. Set-off should not be barred on the date of the suit while counter-claim should not be barred on the date of filing of written statement.
4. Claim for set-off cannot exceed plaintiff's claim, whereas counterclaim can exceed the plaintiffs claim.
5. Both set-off and counter-claim cannot exceed the pecuniary jurisdiction of the court.