Heat Exchangers
Heat exchangers are defined as devices that transfer heat from one liquid or gaseous substance to another in order to change the temperature of the substance for another process. Heat exchangers are constructed with thermally conducted tubes or plates. Heat exchangers are commonly used to transfer heat from air to air, water to water, or air to water to steam or a variety of other liquids.
There are numerous processes that require heat exchangers. Heat exchangers play a vital role in the operations and design of numerous machines such as air conditioning systems, heating systems, power generators, vehicles, refrigerators, oil rigs, and various engineering and chemical processing systems. The processes of waste heat recovery within industrial settings also utilize heat exchangers.
Depending on the overall function and location, heat exchangers come in a variety of configurations. Generally, they are built with a flat plate design or a shell and tube design. Air, liquids, or steam flow through a network of heat conducting tubes or cavities lined with heat conducting plates.
Plate heat exchangers come in two basic configurations—flat plate heat exchangers or plate and frame heat exchangers. Air to air and water to air heat exchangers are made with this configuration. Shell and tube heat exchangers are available in configurations such as finned tube heat exchangers, tube heat exchangers, spiral heat exchangers, or oil coolers. Marine and other water-to-water heat exchangers usually are equipped with this design. Read More…
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Plate and tubular heat exchangers vary in terms of structure, but both of these types utilize the same concepts of thermodynamics. The conductive metal plates or tube walls act are partitions, and they act as conductors between the two gases or fluids and at the same time keep the two substances separate.
Heat Exchangers – Industrial Heat Transfer, Inc.
These plates and walls are commonly made from stainless steel, due to the metal’s high durability and its ability to act as a conductor while at the same time enduring high pressures and extreme temperatures. On one side of the barrier, a heated substance transfers its heat to the cooler solution on the other side, which temporarily creates thermal stress inside the wall or tube.
In order to eliminate the thermal stress and achieve equilibrium, the thermal energy gravitates toward the cooler solution. The efficiency and speed of the process depends greatly on the size of the surface area of the partition. The larger the partition’s surface area, the more quickly and efficiently the heat will transfer.
For this reason, plate heat exchangers are used primarily to transfer heat between gases and air, since gases do not transfer heat as easily as liquids. Heat exchangers are typically constructed from materials that are corrosion resistant and durable, such as cast iron, aluminum, steel, stainless steel, bronze, copper, and titanium.
Heat exchangers are usually depended on by power generation facilities to recycle heat and to prevent processes from overheating. Industries that use heat exchangers for their processes and equipment include automotive, electronic, chemical, petrochemical, semiconductor, marine, and aerospace.
Heat exchangers are also commonly used for waste heat recovery. In this process, excess heat from one process is captured and used in another process that requires heat. This process is environmentally conscious, and in addition to heating different substances, can also be used to cool air for air conditioning and refrigeration.
Because the waste heat recovery utilizes a pre-existing heat source, the process eliminates the need for fossil fuels or electricity to generate heat, thus saving both energy and money. Processes that benefit from waste heat recovery include steel manufacturing, pulp and paper, textile manufacturing, water treatment, food processing, and pharmaceutical.
Heat exchangers have many advantages such as lower maintenance costs, improved performance, and saving time and energy. However, there are a few disadvantages. The materials used to build heat exchangers must be high quality and durable, as the process involves high levels of pressure and stress.
Corrosion is the most prominent issue in heat exchangers, and is highly difficult to avoid due to the constant high levels of humidity and constant flow of liquids. Fortunately, corrosion-related system running problems can be minimized. This can be done by using walling and tubing made that is resistant to leaching, cracking, pitting, and corrosion.
There are also liquids that can cause residue to build up over a period of time. The residue can be cleaned, and the cleaning process can be done without too much delay. Heat exchangers are common in a large number of machines, and are not always called heat exchangers. In addition to industrial process, heat exchangers can be used in energy, chemical, and mechanical systems for processes that require the transferring of heat to some degree. For example, the radiator of a car is responsible for transferring heat to the air from the vehicle’s engine.
Heat exchangers are used for other commercial purposes including include hot tub and swimming pool heaters, hot water radiators, air conditioners, and home radiators. Heat exchangers are important in making all of these applications more efficient in cost and energy, regardless of whether they are used for commercial or industrial purposes.