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A plate-fin heat exchanger is a type of
Heat is transferred from one stream through the fin interface to the separator plate and through the next set of fins into the adjacent fluid. The fins also serve to increase the structural integrity of the heat exchanger and allow it to withstand high pressures while providing an extended surface area for heat transfer.
A high degree of flexibility is present in plate-fin heat exchanger design as they can operate with any combination of gas, liquid, and two-phase fluids. Heat transfer between multiple process streams is also accommodated, with a variety of fin heights and types as different entry and exit points available for each stream.
The main four type of fins are: ''plain'', which refer to simple straight-finned triangular or rectangular designs; ''herringbone'', where the fins are placed sideways to provide a zig-zag path; and ''serrated'' and ''perforated'' which refer to cuts and perforations in the fins to augment flow distribution and improve heat transfer.
A disadvantage of plate-fin heat exchangers is that they are prone to
Heat exchanger design handbook
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heat exchanger
A heat exchanger is a system used to transfer heat between a source and a working fluid. Heat exchangers are used in both cooling and heating processes. The fluids may be separated by a solid wall to prevent mixing or they may be in direct conta ...
design that uses plates and finned chambers to transfer heat
In thermodynamics, heat is defined as the form of energy crossing the boundary of a thermodynamic system by virtue of a temperature difference across the boundary. A thermodynamic system does not ''contain'' heat. Nevertheless, the term is ...
between fluids, most commonly gases. It is often categorized as a compact heat exchanger to emphasize its relatively high heat transfer
Heat transfer is a discipline of thermal engineering that concerns the generation, use, conversion, and exchange of thermal energy (heat) between physical systems. Heat transfer is classified into various mechanisms, such as thermal conduction, ...
surface area to volume ratio.
The plate-fin heat exchanger is widely used in many industries, including the aerospace
Aerospace is a term used to collectively refer to the atmosphere and outer space. Aerospace activity is very diverse, with a multitude of commercial, industrial and military applications. Aerospace engineering consists of aeronautics and astr ...
industry for its compact size and lightweight properties, as well as in cryogenics
In physics, cryogenics is the production and behaviour of materials at very low temperatures.
The 13th IIR International Congress of Refrigeration (held in Washington DC in 1971) endorsed a universal definition of “cryogenics” and “cr ...
where its ability to facilitate heat transfer with small temperature differences is utilized.
Aluminum alloy plate fin heat exchangers, often referred to as Brazed Aluminum Heat Exchangers, have been used in the aircraft industry for more than 60 years and adopted into the cryogenic air separation industry around the time of the second world war and shortly afterwards into cryogenic processes in chemical plants such as Natural Gas Processing. They are also used in railway engines and motor cars. Stainless steel plate fins have been used in aircraft for 30 years and are now becoming established in chemical plants.
Design of plate-fin heat exchangers
Originally conceived by an Italian mechanic, Paolo Fruncillo. A plate-fin heat exchanger is made of layers of corrugated sheets separated by flat metal plates, typically aluminium, to create a series of finned chambers. Separate hot and cold fluid streams flow through alternating layers of the heat exchanger and are enclosed at the edges by side bars. Heat is transferred from one stream through the fin interface to the separator plate and through the next set of fins into the adjacent fluid. The fins also serve to increase the structural integrity of the heat exchanger and allow it to withstand high pressures while providing an extended surface area for heat transfer.
A high degree of flexibility is present in plate-fin heat exchanger design as they can operate with any combination of gas, liquid, and two-phase fluids. Heat transfer between multiple process streams is also accommodated, with a variety of fin heights and types as different entry and exit points available for each stream.
The main four type of fins are: ''plain'', which refer to simple straight-finned triangular or rectangular designs; ''herringbone'', where the fins are placed sideways to provide a zig-zag path; and ''serrated'' and ''perforated'' which refer to cuts and perforations in the fins to augment flow distribution and improve heat transfer.
A disadvantage of plate-fin heat exchangers is that they are prone to fouling
Fouling is the accumulation of unwanted material on solid surfaces. The fouling materials can consist of either living organisms ( biofouling) or a non-living substance (inorganic or organic). Fouling is usually distinguished from other sur ...
due to their small flow channels. They also cannot be mechanically cleaned and require other cleaning procedures and proper filtration for operation with potentially-fouling streams.
Flow arrangement
In a plate-fin heat exchanger, the fins are easily able to be rearranged. This allows for the two fluids to result in crossflow, counterflow, cross-counterflow or parallel flow. If the fins are designed well, the plate-fin heat exchanger can work in perfect countercurrent arrangement./ref>
Cost
The cost of plate-fin heat exchangers is generally higher than conventional heat exchangers due to a higher level of detail required during manufacture. However, these costs can often be outweighed by the cost saving produced by the added heat transfer. Plate-fin heat exchangers are generally applied in industries where the fluids have little chances of fouling. The delicate design as well as the thin channels in the plate-fin heat exchanger make cleaning difficult or impossible. Applications of plate-fin heat exchangers include: * Natural gas liquefaction * Cryogenic air separation * Ammonia production * Offshore processing * Nuclear engineering * Syngas production * Aircraft cooling of bleed air and cabin airSee also
*Plate heat exchanger A plate heat exchanger is a type of heat exchanger that uses metal plates to transfer heat between two fluids. This has a major advantage over a conventional heat exchanger in that the fluids are exposed to a much larger surface area because the fl ...
*Shell and tube heat exchanger
A shell and tube heat exchanger is a class of heat exchanger designs. It is the most common type of heat exchanger in oil refineries and other large chemical processes, and is suited for higher-pressure applications. As its name implies, this ty ...
*Heat transfer
Heat transfer is a discipline of thermal engineering that concerns the generation, use, conversion, and exchange of thermal energy (heat) between physical systems. Heat transfer is classified into various mechanisms, such as thermal conduction, ...
* LMTD
*NTU method The Number of Transfer Units (NTU) Method is used to calculate the rate of heat transfer in heat exchangers (especially counter current exchangers) when there is insufficient information to calculate the Log-Mean Temperature Difference (LMTD). In ...
References
Coulson, J. and Richardson, J (1999). Chemical Engineering- Fluid Flow. Heat Transfer and Mass Transfer- Volume 1; Reed Educational & Professional Publishing LTD {{DEFAULTSORT:Plate Fin Heat Exchanger Heat exchangers Industrial gases pt:Trocador de energia térmica#Trocador de calor de placas aletadas