What is the difference between the fin effectiveness and the fin efficiency?

What is the difference between the fin effectiveness and the fin efficiency?

Therefore, the fin effectiveness can be determined easily when the fin efficiency is known, or vice versa. The thermal conductivity k of the fin material should be as high as possible. The overall effectiveness is a better measure of the performance of a finned surface than the effectiveness of the individual fins.

Why are fins provided on heat transferring surfaces?

Explanation: Fins are provided to a heat exchanger surface to augment the heat transfer by increasing the surface area exposed to the surroundings.

What are different types of fins?

• Fish Fins. Fins are one of the most distinctive features of a fish and appear in several different forms.
• Dorsal Fins.
• Tail Fin or Caudal fin.
• Ventral or Pelvic Fins.
• Anal Fin.
• Pectoral Fin.
• Finlets or Scutes.

How does the gray body differ from the black body?

black body is an object that absorbs all the radiant energy reaching its surface with all the wavelengths. WHILE A gray body is defined as a body whose absorption does not change with variation in temperature & wavelength of the incident radiation.

What is the difference between emissivity and absorptivity?

Absorptivity (α) is a measure of how much of the radiation is absorbed by the body. Reflectivity (ρ) is a measure of how much is reflected, and transmissivity (τ) is a measure of how much passes through the object. Emissivity (ε) is a measure of how much thermal radiation a body emits to its environment.

Does emissivity increase with temperature?

Yes, Emissivity changes with temperature because of energy that is tied up in the behavior of the molecules that form the surface. As the material gets to a higher temperature, the molecules move more and more, this means they will usually emit more energy.

Does emissivity and absorptivity vary with temperature?

So at that the beginning, the emissivity of plate two higher than its absorptivity. But when both bodies have the same temperature, then the emissivity = absorptivity coefficient according to Kirchhoff. …

How is material emissivity calculated?

The calculation of “effective emissivity” = total actual emitted radiation / total blackbody emitted radiation (note 1).

What factors affect emissivity?

Factors affecting emissivity

• Material. Non-metals, usually have a high emissivity, and are usually fairly constant over time.
• Surface. Polished and shiny surfaces tend to have lower emissivity.
• Viewing angle.
• Wavelength.
• Geometry.
• Temperature.

What does emissivity depend on?

The emissivity also depends on the temperature of the surface as well as wavelength and angle. Knowledge of surface emissivity is important both for accurate non-contact temperature measurement and for heat transfer calculations. Radiation thermometers detect the thermal radiation emitted by a surface.

Is emissivity less than 1?

Emissivity values can range from 0 to 1. A blackbody has an emissivity of 1, while a perfect reflector or whitebody has an emissivity of 0. Many minerals and metals have emissivities significantly less than 1. Depending on the material, emissivity can also vary depending on its temperature.