Table of Contents
- 1 Does convective heat transfer coefficient depend on temperature?
- 2 Is convective heat transfer coefficient constant?
- 3 What is the reason for high convective heat transfer coefficient in dropwise condensation?
- 4 What is the convective heat transfer coefficient of laminar flow?
- 5 How does the thickness of the boundary layer affect heat transfer?
Does convective heat transfer coefficient depend on temperature?
The natural convection coefficient depends strongly on the temperature difference. However, the forced convection coefficient does not directly depend on surface temperature. where h is the convective heat transfer coefficient of the flow, L is the characteristic length, k is the thermal conductivity of the fluid.
Is convective heat transfer coefficient constant?
As can be seen, the constant of proportionality will be crucial in calculations and it is known as the convective heat transfer coefficient, h. This is due to turbulent flow having a thinner stagnant fluid film layer on the heat transfer surface. …
What is thermal boundary layer and why it is important?
2.05. 4.2 Thermal Conductivity. The thermal boundary layer at the bottom of the mantle is a region where heat is transported predominantly by conduction from the core into the mantle. Conductive heat is given by the product of temperature gradient and thermal conductivity of the lowermost mantle materials.
Why heat transfer coefficient for natural convection is much lesser than that for forced convection?
Why heat transfer coefficient for natural convection is much lesser than that of forced convection? (NOV-DEC 13] The convection heat transfer coefficient will usually be higher in forced convection and lower in free convection since heat transfer coefficient depends on the fluid velocity, and free convection involves …
What is the reason for high convective heat transfer coefficient in dropwise condensation?
Explanation: The convective coefficient for condensation should be high because condensation refers to a change from the vapor to a liquid phase. Explanation: It generally occurs on oily surface. It is the convective heat transfer process that is associated with a change in the phase of a fluid.
What is the convective heat transfer coefficient of laminar flow?
Typically, the convective heat transfer coefficient for laminar flow is relatively low compared to the convective heat transfer coefficient for turbulent flow. This is due to turbulent flow having a thinner stagnant fluid film layer on the heat transfer surface.
How does fluid velocity affect the heat transfer coefficient?
Both these effects will increase the heat transfer coefficient when the fluid velocity increases (better mixing in the turbulent boundary layer, thinner laminar sublayer). However, the heat transfer coefficient will still decrease along the length of the surface, but to a lesser degree than for laminar flow.
What is the relationship between temperature gradient and heat transfer coefficient?
As the position x increases, the thickness of the thermal boundary layer increases, i.e. the temperature increases over a greater distance y. Thus, the temperature gradient decreases in the x-direction and so does the local heat transfer coefficient. The local heat flux thus also decreases along the plate (see figure above)!
How does the thickness of the boundary layer affect heat transfer?
Thickness of the boundary layer and the properties of boundary layer like thermal conductivity, average temperature difference be tween wall and the bulk fluid etc., controls the overall heat transfer. Thickness of the boundary layer depends on the velocity and viscosity of fluid, heat transfer also depends on these properties.