Question

An enclosure measures 1.5 m x 1.7 m with a height of 2 m. The wall and celling
are maintained at 350°C and the floor at 130°C. The walls and celling have an
emissivity of 0.82 and the floor 0.7. Determine the net radiation to the floor.

Answer 1

The net radiation to the floor is 233.8 W.

To determine the net radiation to the floor, we need to calculate the net heat gain (or loss) from the walls, ceiling, and floor. This can be done using the formula for net radiation:

Net radiation = $(Emissivity * Stefan-Boltzmann constant * (Temperature^4 - T_surroundings^4)) * Area$

Where:

Emissivity is the ratio of the energy emitted by a surface to the energy that would be emitted by a perfect black body at the same temperature.

Stefan-Boltzmann constant is a physical constan $t (5.67 x 10^-8 W/m^2K^4)$ that relates the energy emitted by a surface to its temperature.

Temperature is the temperature of the surface in degrees Celsius.

T_surroundings is the temperature of the surroundings in degrees Celsius.

Area is the area of the surface.

The net radiation is the difference between the radiation emitted by the floor and the radiation received by the floor from the walls and ceiling.

First, we need to find the radiation emitted by the walls and ceiling and received by the floor:

Net radiation from walls and ceiling = $(0.82 * 5.67 x 10^-8 W/m^2K^4 * (350^4 - 130^4)) * (1.5m * 2m + 1.7m * 2m) = 554.7 W$

Next, we need to find the radiation emitted by the floor

Net radiation from floor = $(0.7 * 5.67 x 10^-8 W/m^2K^4 * (130^4 - T_surroundings^4)) * (1.5m * 1.7m) = -320.9 W$

Net radiation to the floor =$554.7 W + (-320.9 W) = 233.8 W$

So the net radiation to the floor is 233.8 W. This means that the floor is receiving 233.8 W more energy than it is emitting, resulting in a net heat gain.

To know more about the concept please go through the links

brainly.in/question/9257389

brainly.in/question/14790360

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