Q. The furnace of a boiler is laid from fire clay brick with outside lagging from the plate steel, the distance between the two is quite small compared with the size of the furnace. The brick setting is at an average temperature of 365 K whilst the steel lagging is at 290 K. Calculate the radiant heat flux. Assume the following emissivity values

For brick = 0.85
For steel = 0.65

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Q. Two black discs each of diameter 50 cm are placed parallel to each other concentrically at a distance of one meter. The discs are maintained at 1000 K and 500 K. Calculate the heat flow between the discs when no other surface is present

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Q. Two black discs each of diameter 50 cm are placed parallel to each other concentrically at a distance of one meter. The discs are maintained at 1000 K and 500 K. Calculate the heat flow between the discs when the disks are connected by a cylindrical black no-flux surface

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Q. A cavity in the shape of a frustum of a cone has diameter 30 cm and 60 cm and the height is 80 cm. If the cavity is maintained at temperature of 800 K, determine the heat loss from the cavity when the smaller diameter is at the bottom

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Q. A conical cavity of base diameter 15 cm and height 20 cm has inside surface temperature 650 K. If emissivity of each surface is 0.85, determine the net radiative heat transfer from the cavity

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Q. A cylindrical cavity of base diameter 15 cm and height 20 cm has inside surface temperature 650 K. If emissivity of each surface is 0.85, determine the net radiative heat transfer from the cavity

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Q. What is the unit of coefficient of radiant heat transfer?

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Q. Which of the following have a continuous spectrum?

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Q. Which of the following is/are known as selective absorbers?

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Q. Which layers participated in the process of thermal radiation through solids and liquids?

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Q. Some of the gases have low emissive power and absorptivity. They are considered practically diathermanous. Which of the following option is true?

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Q. Consider a beam of monochromatic radiation at wavelength λ that enters a layer of absorbing gas. As the beam passes through the gas layer, its intensity

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Q. When a gas or vapor is in the process of oxidation and combustion, it is called as

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Q. The monochromatic absorption coefficient depends upon

(i) Temperature

(ii) Time

(iii) Pressure

(iv) Wavelength

Identify the correct option

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Q. Which one of the following is not extremely inert to thermal radiation?

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Q. Consider a beam of monochromatic radiation at wavelength λ that enters a layer of absorbing gas. As the beam passes through the gas layer, its intensity is given by

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Q. Which one is having highest value of fouling factor?

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Q. What is the value of fouling factor for sea water?

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Q. What is the value of fouling factor for clean river?

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Q. Which one is having lowest value of fouling factor?

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