Stelrad - Fit for the Future - Catalog - Page 13
Important
heat
exchanger
principles
The ability of any heat exchanger to transfer energy (heat) from
one material to another (or a different body of the same material)
depends upon:
> T he temperature difference between the two materials or bodies.
Meaning, the greater the difference then the greater the heat flux (rate of energy
transfer through a given surface).
> T he amount of surface area of the two materials or bodies that are in contact with
each other (albeit through the medium of the heat exchanger material).
That is the effective surface area of the heat exchanger itself.
Meaning, the greater the area then the greater the rate of energy transferred.
>
he thermal conductivity of the heat exchanger material.
T
Meaning, the higher the thermal conductivity then the higher the heat flux.
As one material or body is heated by the other then they approach the same (equilibrium)
temperature. Introducing a flow of the two materials (in this case hot water and cooler
air) or bodies through the heat exchanger ensures that a higher temperature differential
as possible is achieved.
Increasing the flow rates of materials (water / air) that are to have heat exchanged
between them, without increasing their contact surface areas (heat exchanger surface
area) cannot produce significant performance gains.
Increasing the flow rates of the materials (water / air) that are to have heat exchanged
between them, without increasing the thermal conductivity of any separating medium
(heat exchanger material) between them cannot produce significant performance gains.
Therefore, the capacity of the heat exchanger to transfer energy and deliver a heat flux
(from one medium or body of material) to another will depend upon both the effective
surface area and the thermal conductivity of the material used in the heat exchanger.
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