Effective Surface Area: Calculating & Understanding

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In summary, the difference between effective surface area and surface area of the emitting body in thermal radiations is that effective surface area takes into account the geometry and shape of the body, while surface area only considers the size of the body. To calculate the effective surface area, you need to know the shape factor and the surface area of the body. For a hollow cylinder with one side open to the outside and covered by insulating material, you can estimate the heat lost by convection and radiation by calculating the surface area of the cylinder and using the Stefan-Boltzmann law (E = σT^4A). The heat lost by convection can be estimated by determining the heat transfer coefficient and using Newton's law of cooling (Q =
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sadhu
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in thermal radiations what is the difference between effective surface area and surface area of emitting body ,and how to calculate effective surface area of ang body?
 
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What is the context of the question? You can assume that the MBR has an effective surface area of the entire universe, but that the surface area of the emitting body would be the size of the universe when the radiation was first released.
 
  • #3
consider a case of a hollow cylinder with one side open to outside &
external area is covered by insulating material, temperature is T
assuming perfect BB how to calculate heat lost by it in 1 sec,

E=[tex]\sigma[/tex]*T[tex]^{4}[/tex]*?

length is l, radius is r.as i think ?=[tex]\pi[/tex]*r[tex]^{2}[/tex]
 
  • #4
sadhu said:
consider a case of a hollow cylinder with one side open to outside &
external area is covered by insulating material, temperature is T
assuming perfect BB how to calculate heat lost by it in 1 sec,
E=[tex]\sigma[/tex]*T[tex]^{4}[/tex]*?

length is l, radius is r.

as i think ?=[tex]\pi[/tex]*r[tex]^{2}[/tex]

Your body loses heat by convection and radiation.
For convection you need to estimate H and then you can calculate how much heat you lose by convection.
your body also loses heat by radiation, but because you are dealing with cylinder , some of the radiation is reflected by the inner sides of the cylinder and only some of the radiation escape outside of the body. you need to know what fraction of the energy escapes to the outside (look for shape factor on any heat transfer book).
your heat transfer area by convection and radiation is the inner surface area of the cylinder. A=PI*D*L
 

What is the definition of effective surface area?

Effective surface area refers to the area of a solid object that is available for chemical reactions or interactions with other substances.

Why is calculating effective surface area important?

Calculating effective surface area is important because it allows scientists to determine the amount of available surface for reactions, which can impact the efficiency and effectiveness of chemical processes.

How is effective surface area calculated?

Effective surface area is typically calculated by using mathematical formulas based on the dimensions and geometry of the object, such as the surface area of a sphere or the surface area of a cube.

What factors can affect effective surface area?

The shape and size of an object, as well as its surface texture, can greatly impact its effective surface area. For example, an object with a rough surface will have a larger effective surface area compared to a smooth object of the same size.

How can understanding effective surface area help in real-world applications?

Understanding effective surface area can help in various industries, such as pharmaceuticals, materials science, and environmental science. It can aid in designing more efficient drug delivery systems, creating more effective materials, and improving pollution control methods, among others.

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