How do you calculate heat transfer from fins?
The rate of heat transfer from a solid surface to atmosphere is given by Q = hA ∆ T where, h and ∆T are not controllable. So, to increase the value of Q surface area should be increased. The extended surface which increases the rate of heat transfer is known as fin.
What is the convective heat transfer coefficient?
The convective heat transfer coefficient, h, can be defined as: The rate of heat transfer between a solid surface and a fluid per unit surface area per unit temperature difference.
What is correct formula of Biot number?
The Biot number equals the product of the heat transfer coefficient and the characteristic length divided by thermal conductivity.
How do you find the surface area of a fin?
where Af is the fin surface area, Ap is the primary surface area and A = Af + Ap. In Eq. (1), the heat transfer coefficients of finned and unfinned surfaces are idealized to be equal.
What is finned evaporator?
The finned evaporators are the bare tube type of evaporators covered with the fins. When the fluid (air or water) to be chilled flows over the bare tube evaporator lots of cooling effect from the refrigerant goes wasted since there is less surface for the transfer of heat from the fluid to the refrigerant.
What is microchannel heat exchanger?
Introducing Microchannel Heat Exchangers (MCHEs) MCHEs are a variation of fin and tube heat exchangers. At least one fluid, usually refrigerant or water, flows through tubes or enclosed channels while air flows cross-current through the connected fins. The hydraulic diameter of the channels is less than 1 mm.
Do heat transfer and pressure drop correlations exist for plain finned tubes?
Ward and Young developed heat transfer and pressure drop correlations for plain finned tubes with triangular pitch. They compared their pressure drop data with a correlation from literature [29]. Breber [31] presents a review and evaluation of heat transfer and pressure drop predictive method for tube bundles with stud fins.
What is the heat transfer coefficient of a fin?
We assume (using the Reynolds analogy or other approach) that the heat transfer coefficient for the fin is known and has the value . The end of the fin can have a different heat transfer coefficient, which we can call . The approach taken will be quasi-one-dimensional, in that the temperature in the fin will be assumed to be a function of only.
Why are finned tubes used in tube heat exchangers?
Whenever gas/water heat exchangers are used, the heat transfer coefficient α0on the air side of air/water tube heat exchangers, e.g. steam boilers or heat recovery boilers, is inherently lower than the heat transfer coefficient on the inside of the water tubes. Finned tubes are applied to enhance heat transfer.
How to increase the surface area of a heat transfer tube?
On the one hand, the heat-transferring surface can be enlarged by an arrangement of annular fins or other elements. This increase of total tube surface allows transfer of a greater amount of heat from hot gas, but the demand for smaller installation sizes requires smaller fin pitch with larger fin height.