A heat exchanger is a device built for efficient heat transfer from one medium to another, whether the media are separated by a solid wall so that they never mix, or the media are in direct contact. In thermal physics, heat transfer is the passage of Thermal energy from a hot to a colder body ^[1] They are widely used in space heating, refrigeration, air conditioning, power plants, chemical plants, petrochemical plants, petroleum refineries, and natural gas processing. Space heating is the Heating of a space usually enclosed such as a house or room Refrigeration is the process of removing Heat from an enclosed space or from a substance and moving it to a place where it is unobjectionable The term air conditioning refers to the cooling and dehumidification of indoor air for Thermal comfort. A power station (also referred to as generating station, power plant or powerhouse) is an industrial facility for the generation of A chemical plant is industrial process plant that manufactures (or otherwise processes Chemicals usually on a large scale Petrochemicals are chemical products made from raw materials of Petroleum or other Hydrocarbon origin An oil refinery is an industrial Process plant where Crude oil is processed and refined into more useful Petroleum products, such as Gasoline Natural gas processing plants or fractionators are used to purify the raw Natural gas extracted from underground gas fields and brought up to the surface by One common example of a heat exchanger is the radiator in a car, in which a hot engine-cooling fluid, like antifreeze, transfers heat to air flowing through the radiator. Radiators and convectors are types of Heat exchangers designed to transfer Thermal energy from one medium to another for the purpose of cooling Antifreeze is a Cryoprotectant used in Internal combustion engines and for many other heat transfer applications such as electronics cooling and Chillers

Contents 1 Flow arrangement 2 Types of heat exchangers 2.1 Shell and Tube heat exchanger 2.2 Plate heat exchanger 2.3 Regenerative heat exchanger 2.4 Adiabatic Wheel heat exchanger 2.5 Fluid heat exchangers 2.6 Dynamic Scraped surface heat exchanger 3 Phase-change heat exchangers 4 HVAC air coils 5 Spiral Heat Exchangers 5.1 Self cleaning 5.2 Applications 6 Selection 7 Monitoring and maintenance 7.1 Fouling 7.2 Maintenance 8 Heat exchangers in nature 8.1 Counter current Heat Exchangers 9 Heat Exchangers in Industry 9.1 Other Types of Heat Exchangers 10 See also 11 References 12 External links

Flow arrangement

Heat exchangers may be classified according to their flow arrangement. In parallel-flow heat exchangers, the two fluids enter the exchanger at the same end, and travel in parallel to one another to the other side. In counter-flow heat exchangers the fluids enter the exchanger from opposite ends. The counter current design is most efficient, in that it can transfer the most heat. See countercurrent exchange. Countercurrent exchange is a mechanism used to transfer some property of a Fluid from one flowing current of fluid to another across a Semipermeable membrane or thermally-conductive In a cross-flow heat exchanger, the fluids travel roughly perpendicular to one another through the exchanger.

For efficiency, heat exchangers are designed to maximize the surface area of the wall between the two fluids, while minimizing resistance to fluid flow through the exchanger. The exchanger's performance can also be affected by the addition of fins or corrugations in one or both directions, which increase surface area and may channel fluid flow or induce turbulence.

The driving temperature across the heat transfer surface varies with position, but an appropriate mean temperature can be defined. In most simple systems this is the log mean temperature difference (LMTD). The log mean temperature difference (LMTD is used to determine the temperature driving force for heat transfer in flow systems (most notably in Heat exchangers. Sometimes direct knowledge of the LMTD is not available and the NTU method is used. 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

Fig. 1: Shell and tube heat exchanger, single pass (1-1 parallel flow)

Fig. A shell and tube heat exchanger is a class of Heat exchanger designs 2: Shell and tube heat exchanger, 2-pass tube side (1-2 crossflow)

Fig. 3: Shell and tube heat exchanger, 2-pass shell side, 2-pass tube side (2-2 countercurrent)

Types of heat exchangers

Shell and Tube heat exchanger

Main article: Shell and tube heat exchanger

Shell and tube heat exchangers consist of a series of tubes. A shell and tube heat exchanger is a class of Heat exchanger designs One set of these tubes contains the fluid that must be either heated or cooled. The second fluid runs over the tubes that are being heated or cooled so that it can either provide the heat or absorb the heat required. A set of tubes is called the tube bundle and can be made up of several types of tubes: plain, longitudinally finned etc. Shell and Tube heat exchangers are typically used for high pressure applications (with pressures greater than 30 bar and temperatures greater than 260°C. ^[2] This is because the shell and tube heat exchangers are robust due to their shape.
There are several thermal design features that are to be taken into account when designing the tubes in the shell and tube heat exchangers. These include:

• Tube diameter: Using a small tube diameter makes the heat exchanger both economical and compact. However, it is more likely for the heat exchanger to foul up faster and the small size makes mechanical cleaning of the fouling difficult. To prevail over the fouling and cleaning problems, larger tube diameters can be used. Thus to determine the tube diameter, the available space, cost and the fouling nature of the fluids must be considered.
• Tube thickness: The thickness of the wall of the tubes is usually determined to ensure:
  • There is enough room for corrosion
  • That flow-induced vibration has resistance
  • Axial strength
  • Ability to easily stock spare parts cost
    Sometimes the wall thickness is determined by the maximum pressure differential across the wall.
• Tube length: heat exchangers are usually cheaper when they have a smaller shell diameter and a long tube length. Thus, typically there is an aim to make the heat exchanger as long as possible. However, there are many limitations for this, including the space available at the site where it is going to be used and the need to ensure that there are tubes available in lengths that are twice the required length (so that the tubes can be withdrawn and replaced). Also, it has to be remembered that lone, thin tubes are difficult to take out and replace.
• Tube pitch: when designing the tubes, it is practical to ensure that the tube pitch (i. e. the centre-centre distance of adjoining tubes) is not less than 1. 25 times the tubes' outside diameter

Plate heat exchanger

Main article: Plate heat exchanger

Another type of heat exchanger is the 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 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 One is composed of multiple, thin, slightly-separated plates that have very large surface areas and fluid flow passages for heat transfer. This stacked-plate arrangement can be more effective, in a given space, than the shell and tube heat exchanger. Advances in gasket and brazing technology have made the plate-type heat exchanger increasingly practical. A gasket is a mechanical seal that fills the space between two objects generally to prevent leakage between the two objects while under compression. Brazing is a joining process whereby a Filler metal or Alloy is heated to melting temperature above - or by the traditional definition in the United States In HVAC applications, large heat exchangers of this type are called plate-and-frame; when used in open loops, these heat exchangers are normally of the gasketed type to allow periodic disassembly, cleaning, and inspection. There are many types of permanently-bonded plate heat exchangers, such as dip-brazed and vacuum-brazed plate varieties, and they are often specified for closed-loop applications such as refrigeration. Refrigeration is the process of removing Heat from an enclosed space or from a substance and moving it to a place where it is unobjectionable Plate heat exchangers also differ in the types of plates that are used, and in the configurations of those plates. Some plates may be stamped with "chevron" or other patterns, where others may have machined fins and/or grooves.

Regenerative heat exchanger

A third type of heat exchanger is the regenerative heat exchanger. A regenerative heat exchanger, or more commonly a regenerator, is a type of Heat exchanger where the flow through the heat exchanger is cyclical and periodically changes In this, the heat from a process is used to warm the fluids to be used in the process, and the same type of fluid is used either side of the heat exchanger (these heat exchangers can be either plate-and-frame or shell-and-tube construction). These exchangers are used only for gases and not for liquids. The major factor for this is the heat capacity of the heat transfer matrix. Also see: Countercurrent exchange, Regenerator, Economizer

Adiabatic Wheel heat exchanger

A fourth type of heat exchanger uses an intermediate fluid or solid store to hold heat, which is then moved to the other side of the heat exchanger to be released. Countercurrent exchange is a mechanism used to transfer some property of a Fluid from one flowing current of fluid to another across a Semipermeable membrane or thermally-conductive A regenerative heat exchanger, or more commonly a regenerator, is a type of Heat exchanger where the flow through the heat exchanger is cyclical and periodically changes Economizers, or in British English economisers, are mechanical devices intended to reduce energy consumption or to perform another useful function like preheating a Fluid Two examples of this are adiabatic wheels, which consist of a large wheel with fine threads rotating through the hot and cold fluids, and fluid heat exchangers. This type is used when it is acceptable for a small amount of mixing to occur between the two streams. See also: Air preheater. An air preheater or air heater is a general term to describe any device designed to heat Air before another process (for example Combustion in a

Fluid heat exchangers

This is a heat exchanger with a gas passing upwards through a shower of fluid (often water), and the fluid is then taken elsewhere before being cooled. This is commonly used for cooling gases whilst also removing certain impurities, thus solving two problems at once. It is widely used in espresso machines as an energy-saving method of cooling super-heated water to be used in the extraction of espresso.

Dynamic Scraped surface heat exchanger

Another type of heat exchanger is called "dynamic heat exchanger" or "scraped-surface heat exchanger". This is mainly used for heating or cooling with high-viscosity products, crystallization processes, evaporation and high-fouling applications. Viscosity is a measure of the resistance of a Fluid which is being deformed by either Shear stress or Extensional stress. Crystallization is the (natural or artificial process of formation of solid Crystals precipitating from a homogeneous --> identical Solution Evaporation is the process by which Molecules in a Liquid state (e Components subject to fouling The following lists examples of components that may be subject of fouling and the direct effects of fouling heat exchanger surfaces Long running times are achieved due to the continuous scraping of the surface, thus avoiding fouling and achieving a sustainable heat transfer rate during the process. Components subject to fouling The following lists examples of components that may be subject of fouling and the direct effects of fouling heat exchanger surfaces

Phase-change heat exchangers

In addition to heating up or cooling down fluids in just a single phase, heat exchangers can be used either to heat a liquid to evaporate (or boil) it or used as condensers to cool a vapor and condense it to a liquid. In the Physical sciences a phase is a Set of states of a macroscopic physical system that have relatively uniform chemical composition and physical properties Liquid is one of the principal States of matter. A liquid is a Fluid that has the particles loose and can freely form a distinct surface at the boundaries of For other Condensers not involving heat transfer see Condenser (disambiguation A vapor or vapour (see Spelling differences) is a substance in the Gas phase at a Temperature lower than its Critical temperature Condensation is the change of the physical state of aggregation (or simply state of matter from gaseous phase into liquid phase In chemical plants and refineries, reboilers used to heat incoming feed for distillation towers are often heat exchangers. A chemical plant is industrial process plant that manufactures (or otherwise processes Chemicals usually on a large scale An oil refinery is an industrial Process plant where Crude oil is processed and refined into more useful Petroleum products, such as Gasoline Reboilers are Heat exchangers typically used to provide heat to the bottom of industrial distillation columns Distillation is a method of separating Mixtures based on differences in their volatilities in a boiling liquid mixture ^[3][4]

Distillation set-ups typically use condensers to condense distillate vapors back into liquid.

Power plants which have steam-driven turbines commonly use heat exchangers to boil water into steam. A power station (also referred to as generating station, power plant or powerhouse) is an industrial facility for the generation of Uses A Steam engine uses the expansion of steam in order to drive a Piston or Turbine to perform Mechanical work. A turbine is a rotary Engine that extracts Energy from a Fluid flow Water is a common Chemical substance that is essential for the survival of all known forms of Life. Uses A Steam engine uses the expansion of steam in order to drive a Piston or Turbine to perform Mechanical work. Heat exchangers or similar units for producing steam from water are often called boilers or steam generators. A boiler is a closed vessel in which Water or other Fluid is heated

In the nuclear power plants called pressurized water reactors, special large heat exchangers which pass heat from the primary (reactor plant) system to the secondary (steam plant) system, producing steam from water in the process, are called steam generators. Pressurized water reactor ( PWR s (also VVER if of Russian design are generation II nuclear power reactors that use ordinary Water All fossil-fueled and nuclear power plants using steam-driven turbines have surface condensers to convert the exhaust steam from the turbines into condensate (water) for re-use. Surface condenser is the commonly used term for a water cooled Shell and tube heat exchanger installed on the exhaust Steam from a Steam turbine in ^[5][6]

In order to conserve energy and cooling capacity in chemical and other plants, regenerative heat exchangers can be used to transfer heat from one stream that needs to be cooled to another stream that needs to be heated, such as distillate cooling and reboiler feed pre-heating.

This term can also refer to heat exchangers that contain a material within their structure that has a change of phase. This is usually a solid to liquid phase due to the small volume difference between these states. This change of phase effectively acts as a buffer because it occurs at a constant temperature but still allows for a the heat exchanger to accept additional heat. One example where this has been investigated is for use in high power aircraft electronics.

HVAC air coils

One of the widest uses of heat exchangers is for air conditioning of buildings and vehicles. The term air conditioning refers to the cooling and dehumidification of indoor air for Thermal comfort. This class of heat exchangers is commonly called air coils, or just coils due to their often-serpentine internal tubing. Liquid-to-air, or air-to-liquid HVAC coils are typically of modified crossflow arrangement. In vehicles, heat coils are often called heater cores. A heater core is a Radiator -like device used in heating the cabin of a Vehicle.

On the liquid side of these heat exchangers, the common fluids are water, a water-glycol solution, steam, or a refrigerant. A refrigerant is a compound used in a heat cycle that undergoes a Phase change from a Gas to a Liquid and back For heating coils, hot water and steam are the most common, and this heated fluid is supplied by boilers, for example. A boiler is a closed vessel in which Water or other Fluid is heated For cooling coils, chilled water and refrigerant are most common. Chilled water is supplied from a chiller that is potentially located very far away, but refrigerant must come from a nearby condensing unit. A chiller is a machine that removes heat from a liquid via a vapor-compression or Absorption refrigeration cycle. When a refrigerant is used, the cooling coil is the evaporator in the vapor-compression refrigeration cycle. Within a Downstream processing system several stages are used to further isolate and purify the desired product Vapor-compression refrigeration is one of the many Refrigeration cycles available for use HVAC coils that use this direct-expansion of refrigerants are commonly called DX coils.

On the air side of HVAC coils a significant difference exists between those used for heating, and those for cooling. Due to psychrometrics, air that is cooled often has moisture condensing out of it, except with extremely dry air flows. Psychrometrics or psychrometry are terms used to describe the field of engineering concerned with the determination of physical and thermodynamic properties of gas-vapor mixtures Heating some air increases that airflow's capacity to hold water. So heating coils need not consider moisture condensation on their air-side, but cooling coils must be adequately designed and selected to handle their particular latent (moisture) as well as the sensible (cooling) loads. The water that is removed is called condensate.

For many climates, water or steam HVAC coils can be exposed to freezing conditions. Because water expands upon freezing, these somewhat expensive and difficult to replace thin-walled heat exchangers can easily be damaged or destroyed by just one freeze. As such, freeze protection of coils is a major concern of HVAC designers, installers, and operators.

The introduction of indentations (1/08/1934) placed within the heat exchange fins controlled condensation, allowing water molecules to remain in the cooled air. This invention allowed for refrigeration without icing of the cooling mechanism. Inventor John C. Raisley Patent number 2,046,968 issued July 7th 1936^[7]

The heat exchangers in direct-combustion furnaces, typical in many residences, are not 'coils'. A furnace is a device used for Heating The name derives from Latin fornax, Oven. They are, instead, gas-to-air heat exchangers that are typically made of stamped steel sheet metal. The combustion products pass on one side of these heat exchangers, and air to be conditioned on the other. A cracked heat exchanger is therefore a dangerous situation requiring immediate attention because combustion products are then likely to enter the building.

Spiral Heat Exchangers

A spiral heat exchanger (SHE), may refer to a helical (coiled) tube configuration^[8], more generally, the term refers to a pair of flat surfaces that are coiled to form the two channels in a counter-flow arragement. In Mathematics, a spiral is a Curve which emanates from a central point getting progressively farther away as it revolves around the point A helix (pl helixes or helices) from the Greek word έλιξ, is a special kind of Space curve, i ^[9]. Each of the two channels has one long curved path. A pair of fluid ports are connected tangentially to the outer arms of the spiral, and axial ports are common, but optional. For the tangent function see Trigonometric functions. For other uses see Tangent (disambiguation. ^[10]

The main advantage of the SHE is its highly efficient use of space. This attribute is often leveraged and partially reallocated to gain other improvements in performance, according to well known tradeoffs in heat exchanger design. (A notable tradeoff is capital cost vs operating cost. ) A compact SHE may be used to have a smaller footprint and thus lower all-around capital costs, or an over-sized SHE may be used to have less pressure drop, less pumping energy, higher thermal efficiency, and lower energy costs. Pressure (symbol 'p' is the force per unit Area applied to an object in a direction perpendicular to the surface In Physics and other Sciences energy (from the Greek grc ἐνέργεια - Energeia, "activity operation" from grc ἐνεργός ^[11]

Self cleaning

SHE's are often used in the heating of fluids which contain solids and thus have a tendency to foul the inside of the heat exchanger. The low pressure drop gives the SHE its ability to handle fouling more easily. The SHE uses a “self cleaning” mechanism, whereby fouled surfaces cause a localized increase in fluid velocity, thus increasing the drag (or fluid friction) on the fouled surface, thus helping to dislodge the blockage and keep the heat exchanger clean. In Fluid dynamics, drag (sometimes called fluid resistance) is the force that resists the movement of a Solid object through a Fluid (a Friction is the Force resisting the relative motion of two Surfaces in contact or a surface in contact with a fluid (e "The internal walls that make up the heat transfer surface are often rather thick, which makes the SHE very robust, and able to last a long time in demanding environments. "^[12] They are also easily cleaned, opening out like an oven where any build up of foulant can be removed by pressure washing. An oven is an enclosed compartment for Heating, Baking or Drying. A pressure washer is a mechanical device that uses high-pressure water to remove mold grime dust mud and dirt from surfaces and objects such as buildings vehicles and Concrete

Applications

The SHE is ideal for applications such as pasteurization, digester heating, heat recovery, pre-heating (see: recuperator), and effluent cooling. A recuperator is a special purpose counter-flow Heat exchanger used to recover waste heat from exhaust gases For sludge treatment, SHE’s are generally smaller than other types of heat exchangers.

Selection

Due to the many variables involved, selecting optimal heat exchangers is challenging. Hand calculations are possible, but many iterations are typically needed. As such, heat exchangers are most often selected via computer programs, either by system designers, who are typically engineers, or by equipment vendors. An engineer is a person professionally engaged in a field of Engineering.

In order to select an appropriate heat exchanger, the system designers (or equipment vendors) would firstly consider the design limitations for each heat exchanger type. Although cost is often the first criterion evaluated, there other several other important selection criteria which include:

• High/ Low pressure limits
• Thermal Performance
• Temperature ranges
• Product Mix (liquid/liquid, particulates or high-solids liquid)
• Pressure Drops across the exchanger
• Fluid flow capacity
• Cleanability, maintenance and repair
• Materials required for construction
• Ability and ease of future expansion

Choosing the right heat exchanger (HX) requires some knowledge of the different heat exchanger types, as well as the environment in which the unit must operate. Typically in the manufacturing industry, several differing types of heat exchangers are used for just the one process or system to derive the final product. For example, a kettle HX for pre-heating, a double pipe HX for the ‘carrier’ fluid and a plate and frame HX for final cooling. With sufficient knowledge of heat exchanger types and operating requirements, an appropriate selection can be made to optimise the process. ^[13]

Monitoring and maintenance

Integrity inspection of plate and tubular heat exchanger can be tested in-situ by the conductivity or helium gas methods. These methods confirm the integrity of the plates or tubes to prevent any cross contamination and the condition of the gaskets.

Condition monitoring of heat exchanger tubes may be conducted through Nondestructive methods such as eddy current testing. Tubular NDT ( Nondestructive testing) is the application of various technologies to detect anomalies such as Corrosion and manufacturing defects in Metallic An eddy current (also known as Foucault current) is an electrical phenomenon discovered by French physicist Léon Foucault in

The mechanics of water flow and deposits are often simulated by computational fluid dynamics or CFD. Computational fluid dynamics (CFD is one of the branches of Fluid mechanics that uses Numerical methods and algorithms to solve and analyze problems that involve Fouling is a serious problem in some heat exchangers. Components subject to fouling The following lists examples of components that may be subject of fouling and the direct effects of fouling heat exchanger surfaces River water is often used as cooling water, which results in biological debris entering the heat exchanger and building layers, decreasing the heat transfer coefficient. The heat transfer coefficient, in Thermodynamics and in mechanical and Chemical engineering, is used in calculating the Heat transfer, typically Another common problem is scale, which is made up of deposited layers of chemicals such as calcium carbonate or magnesium carbonate. Calcium carbonate is a Chemical compound with the Chemical formula Ca[[Carbon C]] O 3 Magnesium carbonate, MgCO3 is a white Solid that occurs in nature as a Mineral.

Fouling

Fouling occurs when a fluid goes through the heat exchanger, and the impurities in the fluid precipitate onto the surface of the tubes. Precipitation of these impurities can be caused by:

• Frequent use of the Heat Exchanger
• Not cleaning the Heat Exchanger regularly
• Reducing the velocity of the fluids moving through the heat exchanger
• Over-sizing of the heat exchanger

Effects of fouling are more abundant in the cold tubes of the heat exchanger, than in the hot tubes. Impurities are Substances inside a confined amount of Liquid, Gas, or Solid, which differ from the Chemical composition of the material This is because impurities are less likely to be dissolved in a cold fluid. This is because solubility increases as temperature increases.

Fouling reduces the cross sectional area for heat to be transferred and causes an increase in the resistance to heat transfer across the heat exchanger. This is because the thermal conductivity of the fouling layer is low. This reduces the overall heat transfer coefficient and efficiency of the heat exchanger. The heat transfer coefficient, in Thermodynamics and in mechanical and Chemical engineering, is used in calculating the Heat transfer, typically This in turn, can lead to an increase in pumping and maintenance costs.

Maintenance

Plate heat exchangers need to be dissembled and cleaned periodically. Tubular heat exchangers can be cleaned by such methods as acid cleaning, sandblasting, high-pressure water jet, bullet cleaning, or drill rods. Sandblasting or Bead blasting is a generic term for the process of smoothing shaping and cleaning a hard surface by forcing solid particles across that surface at high speeds A water jet cutter is a tool capable of slicing into Metal or other materials using a jet of Water at high velocity and pressure or a mixture of water and an

In large-scale cooling water systems for heat exchangers, water treatment such as purification, addition of chemicals, and testing, is used to minimize fouling of the heat exchange equipment. Water treatment describes those processes used to make water more acceptable for a desired end-use A chemical substance is a Material with a definite chemical composition. Other water treatment is also used in steam systems for power plants, etc. to minimize fouling and corrosion of the heat exchange and other equipment.

A variety of companies have started using waterborne oscillations technology to prevent biofouling. Biofouling or biological fouling is the undesirable accumulation of Microorganisms Plants Algae and Animals on submerged structures Without the use of chemicals, this type of technology has helped in providing a low-pressure drop in heat exchangers.

Heat exchangers in nature

Counter current Heat Exchangers

Heat exchangers occur naturally in the circulation system of fish and whales. Fish are aquatic Vertebrate animals that are typically ectothermic (previously Cold-blooded) covered with scales, and equipped with two Whales are marine mammals which are neither Dolphins (ie members of the families Delphinidae or Platanistoidae) nor Porpoises Orcas Arteries to the skin carrying warm blood are intertwined with veins from the skin carrying cold blood, causing the warm arterial blood to exchange heat with the cold venous blood. This reduces the overall heat loss in cold waters. Heat exchangers are also present in the tongue of baleen whales as large volumes of water flow through their mouths[1] [2]. The baleen whales, also called whalebone whales or great whales, form the Mysticeti, one of two suborders of the Cetacea (whales dolphins and Wading birds use a similar system to limit heat losses from their body through their legs into the water.

In species that have external testes (such as humans), the artery to the testis is surrounded by a mesh of veins called the pampiniform plexus. The Spermatic veins emerge from the back of the Testis, and receive tributaries from the Epididymis: they unite and form a convoluted plexus the plexus pampiniformis This cools the blood heading to the testis, while reheating the returning blood.

Heat Exchangers in Industry

Heat exchangers are widely used in industry both for cooling and heating large scale industrial processes. The type and size of heat exchanger used can be tailored to suit a process depending on the type of fluid, its phase, temperature, density, viscosity, pressures, chemical composition and various other thermodynamic properties.

In many industrial processes there is waste of energy or a heat stream that is being exhausted, heat exchangers can be used to recover this heat and put it to use by heating a different stream in the process. This practice saves a lot of money in industry as the heat supplied to other streams from the heat exchangers would otherwise come from an external source which is more expensive and more harmful to the environment.

Heat exchangers are used in many industries, some of which include:

• Waste water treatment
• Refrigeration systems
• Wine-brewery industry
• Petroleum industry

In the waste water treatment industry, heat exchangers play a vital role in maintaining optimal temperatures within anaerobic digesters so as to promote the growth of microbes which remove pollutants from the waste water. The common types of heat exchangers used in this application are the double pipe heat exchanger as well as the plate and frame heat exchanger.

Other Types of Heat Exchangers

The human lungs also serve as an extremely efficient heat exchanger due to their large surface area to volume ratio[3].

See also

• Reboiler
• Steam generator (nuclear power)
• Heat pump
• Architectural engineering
• Mechanical engineering
• Heat recovery ventilation
• Log mean temperature difference (LMTD)
• Micro heat exchanger
• Thermosiphon

References

Coulson, J. and Richardson, J (1999). Chemical Engineering- Fluid Flow. Heat Transfer and Mass Transfer- Volume 1; Reed Educational & Professional Publishing LTD

External links

• Heat Exchanger Tutorials
• Specifying Heat Exchangers
• Heat Exchanger Technology Overview
• Shell and Tube Heat Exchanger Design Software for Educational Applications (PDF)
• EU Pressure Equipment Guideline
• A Thermal Management Concept For More Electric Aircraft Power System Application (PDF)
• Mechanical design fundamentals for heat exchangers
• Heat transfer fundamentals
• Forum about heat exchangers
• Stainless Steel Heat Exchanger
• Process Screw Heat Exchanger
• Open Cell Foam Heat Pump

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