Fundamental Heat Transfer Processes Of Heat Exchangers
Posted in Uncategorised, on May 10, 2022 By Admin
For myriad engineering applications, there is a requirement for efficient heat transfer between two or more fluids. For this purpose, heat exchangers are used. With several individual components and a complex mechanism, these parts of the heat exchanger can also be repaired or replaced as required. Now, coming to the fundamental classification of this device, there are several ways to classify it, including the different methods of heat transfer. 3 such types of energy flow mechanisms will be discussed below.
What are the basic modes of heat transfer in a heat exchanger?
This is a process wherein there is a direct transfer of heat energy between two surfaces that are in contact with one another. The hotter surface will release and transfer heat to the colder surface until thermal equilibrium is achieved. On a molecular scale, the heat can be picturized as kinetic energy, wherein the heated molecules collide with one another and transfer the energy across the surface of the material. For conduction purposes, it’s vital for a material to have excellent thermal conductivity, which is mostly found in metals.
This is a more indirect method of heat transfer as heat is exchanged by the motion of fluids. When a fluid is heated, its temperature increases and it also becomes lighter, thereby rising to the surface. The molecules of this heated fluid then come in contact with the denser, colder sections of the fluid, which absorb this heat. The formerly heated molecules are then cooled once again and sink down, while the molecules that absorbed the energy now rise up, thereby creating a circular convection current.
Radiation can be defined as the transfer of heat through electromagnetic waves. Radiation is transferred through a vacuum by the constant movement of electrons, thus it doesn’t require a solid or fluid medium to transfer energy. Hence, it can also be considered a direct method of heat transfer.
Thus, these are 3 main mechanisms used in most heat exchangers in some capacity, either individually, or in combination with one another.
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