Which of the following is a case of steady state heat transfer?
Solution(By Examveda Team) Heating of building in winter-Conduction is heat traveling through a solid material. On hot days, heat is conducted into your home through the roof, walls, and windows.
Which of the following is a case of heat transfer by radiation?
Solution(By Examveda Team) Radiation refers to the emission of energy in rays or waves. Heat moves through space as energy waves. It is the type of heat one feels when sitting in front of a fireplace or around a campfire.
What is the purpose of using fins in heat transfer?
In the study of heat transfer, fins are surfaces that extend from an object to increase the rate of heat transfer to or from the environment by increasing convection. The amount of conduction, convection, or radiation of an object determines the amount of heat it transfers.
What is M in heat transfer?
Unsteady state heat transfer we arrive at a general expression for the temperature change: The last term m is the relationship between the thermal conductivity (k) and the overall heat transfer coefficient (h).
What are the types of fins in heat transfer?
1) Constant Area Straight Fin 2) Variable Area Straight Fin 3) Pin Fin 4) Annular Fin
- Constant Area Straight Fin.
- Variable Area Straight Fin.
- Pin Fin.
- Annular Fin.
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.
Where are fins used in heat transfer?
Fins are thus used whenever the available surface area is found insufficient to transfer required quantity of heat with available temperature gradient and heat transfer coefficient. In the case of fins the direction of heat transfer by convection is perpendicular to the direction of conduction heat flow.
What is overall heat transfer coefficient?
The overall heat transfer coefficient, or U-value, refers to how well heat is conducted through over a series of resistant mediums. Its units are the W/(m2°C) [Btu/(hr-ft2°F)].
What does negative heat transfer coefficient mean?
In case of constant wall temperature, using adiabatic wall temperature as reference temperature can result in negative heat transfer coefficient, which means the heat flux has a different direction with the defined driving temperature difference.
How do you increase overall heat transfer coefficient?
To increase heat-transfer rates, the velocity through a jacket can be increased by recirculating the cooling or heating liquid. For simple jackets without baffles, heat-transfer will be mainly by natural convection and the heat-transfer coefficient will range from 200 to 400 W/m2 °C.
Is higher overall heat transfer coefficient better?
Assuming the heat transfer surface and temperature difference remain unchanged, the greater the U value, the greater the heat transfer rate. In other words, this means that for a certain heat exchanger and product, a higher U value could lead to shorter batch times and increased production/revenue.
What affects overall heat transfer coefficient?
The factors affecting overall heat transfer coefficient are : Physiochemical properties of fluids ( both cold and hot ) such a viscosity , density, specific heat, thermal conductivity. Geometry of the exchanger ( equivalent length and heat exchanging area ) Velocity of flowing fluids.
What is the heat transfer coefficient dependent on?
Heat transfer coefficient depends on both the thermal properties of a medium, the hydrodynamic characteristics of its flow, and the hydrodynamic and thermal boundary conditions.
Which flow is the heat transfer coefficient higher?
liquid flows
What is the convective heat transfer coefficient a function of?
The convective heat transfer coefficient (h), defines, in part, the heat transfer due to convection. The convective heat transfer coefficient is sometimes referred to as a film coefficient and represents the thermal resistance of a relatively stagnant layer of fluid between a heat transfer surface and the fluid medium.
What is the average convective heat transfer coefficient?
14.3. 1.2 Thermal convection
| Type of Convection | Convective Heat Transfer Coefficient, h | |
|---|---|---|
| Btu / ( h×ft 2 ×R ) | W / ( m 2 ×K ) | |
| Air, forced convection | 2–100 | 10–500 |
| Liquids, forced convection | 20–3000 | 100–15,000 |
| Boiling water | 500–5000 | 2500–25,000 |
How do you calculate convective heat transfer?
Common units used to measure the convective heat transfer coefficient are:
- 1 W/(m2 K) = 0.85984 kcal/(h m2 ° C) = 0.1761 Btu/(ft2 h ° F)
- 1 kcal/(h m2 ° C) = 1.163 W/(m2 K) = 0