What Is a Thermal Converter?

A heat exchanger (also known as a heat exchanger or heat exchange device) is a device used to transfer heat from a hot fluid to a cold fluid to meet specified process requirements. It is an industrial application of convective heat transfer and heat transfer. Heat exchangers can be classified in different ways. According to its operation process, it can be divided into three types: partition type, hybrid type, regenerative type (or regenerative type); according to its surface compactness, it can be divided into two types: compact and non-compact.

Domestic heat exchangers solve the problem of collectively heating homes and using hot water in winter. It works on the same principle as a collective heat exchanger. It's just different sizes and styles.

Can be divided into cast iron type, barrel type, steel type, water storage type, plate type.

The results are good.

The stainless steel heat exchanger is a heat exchanger made of stainless steel. It has very good anti-oxidation characteristics, safety and health. It is widely used in food, medicine, heating, domestic water, air conditioning return water and other fields. According to the data of the heat transfer equipment promotion center, the stainless steel heat exchanger has a better heat transfer effect than the traditional carbon steel heat exchanger, and has a longer life. Stainless steel heat exchangers have been widely used in many fields at present. The heat exchangers are made of food-grade stainless steel and have very prominent anti-rust and anti-scale properties. China's main regions for producing stainless steel heat exchangers are Shandong and Jiangsu. These two provinces are large provinces in the production of pressure vessels. The scale of enterprises is relatively large and their design and manufacturing capabilities are outstanding.

Hybrid heat exchangers rely on the direct contact of cold and hot fluids for heat transfer. This heat transfer method avoids the thermal resistance of dirt on the heat transfer partition and its sides. As long as the contact between the fluids is good, it will have a large Heat transfer rate. Therefore, where fluids are allowed to mix with each other, hybrid heat exchangers can be used, such as gas washing and cooling, cooling of circulating water, mixed heating between steam and water, and steam condensation. Its applications are found in chemical and metallurgical companies, power engineering, air-conditioning engineering, and many other production sectors. According to different purposes, hybrid heat exchangers can be divided into the following different types: (1) Cooling tower (or cold water tower) In this type of equipment, natural or mechanical ventilation is used to convert the The temperature-raised water is recycled after cooling and cooling to improve the economic benefits of the system. For example, the circulating water of thermal power plants or nuclear power plants, cooling water in the production of synthetic ammonia, etc., are recycled after cooling down by water cooling towers. This method has been widely used in practical engineering. (2) Gas scrubber (or scrubber) Industrially, this equipment is used for scrubbing gas for various purposes, such as absorbing certain components in a gas mixture with a liquid, removing dust from the gas, and increasing the gas Wet or dry. But its most widely used is cooling gas, and most of the liquid used for cooling is water. The spray room widely used in air-conditioning engineering can be considered a special form of it. The spraying chamber can not only cool the air like a gas washing tower, but also heat it. However, it also has disadvantages such as high water quality requirements, large floor area, and high energy consumption of pumps: therefore, in general buildings, the spray room has been used infrequently or only as a humidifying device. However, it is still widely used in textile factories, cigarette factories, etc. whose main purpose is to regulate humidity! (3) Jet heat exchanger In this type of equipment, the fluid with higher pressure is ejected from the nozzle, forming a high At low speed, the low-pressure fluid is introduced into the mixing chamber in direct contact with the jet for heat transfer, and enters the diffuser together, and is sent to the user after the outlet of the diffuser reaches the same pressure and temperature. (4) Hybrid Condenser This equipment generally condenses steam by direct contact between water and steam.

This heat exchanger is made by installing a jacket on the outer wall of the container and has a simple structure. In order to improve the heat transfer coefficient and make the liquid in the kettle heat evenly, a stirrer can be installed in the kettle. When cooling water or phase-free heating agent is passed into the jacket, a spiral partition or other measures to increase turbulence can also be provided in the jacket to increase the heat supply coefficient on the side of the jacket. Insufficient surface, can also be installed inside the kettle coil. Jacketed heat exchangers are widely used for heating and cooling in the reaction process.

Regenerative heat exchangers are equipment used for regenerative heat exchange. Built-in solid filler to store heat. Generally, fire lattices are made of refractory bricks (sometimes metal corrugated belts, etc.). The heat exchange takes place in two stages. In the first stage, the hot gas passes through the fire lattice and transfers heat to the fire lattice to be stored. In the second stage, the cold gas passes through the fire lattice and is heated by receiving the heat stored by the fire lattice. These two phases alternate. Usually two heat accumulators are used alternately, that is, when hot gas enters one device, cold gas enters the other device. Commonly used in the metallurgical industry, such as the heat storage chamber of an open steel furnace. It is also used in the chemical industry, such as air preheaters or combustion chambers in gas furnaces, and regenerative cracking furnaces in man-made petroleum plants. Regenerative heat exchangers are generally used in situations where the requirements for medium mixing are relatively low.

During the production process, due to the erosion of water by the heat exchanger tube plate, cavitation and the corrosion of trace chemical media, leaks often occur at the tube plate welds, resulting in the mixing of water and chemical materials. Other products seriously affect product quality and reduce product grade. After the weld of the condenser tube sheet leaks, the company usually repairs it with traditional repair welding methods. The internal stress of the tube sheet is prone to be generated and it is difficult to eliminate it, which causes leakage in other heat exchangers. The company checks the repair status of the equipment by pressing After repeated repair welding and experiments, 2 to 4 people need several days to complete the repair. After a few months of use, the tube sheet welds again corrode, causing waste of human, material and financial resources and increasing production costs. Through the corrosion resistance and erosion resistance of Fu Shilan polymer composites, and by protecting the new heat exchanger in advance, this not only effectively treats the weld seam and trachomat problems existing in the new heat exchanger, but also avoids chemical substances after use Corrosion of the metal surface and welding points of the heat exchanger, during regular maintenance in the future, you can also apply Fu Shilan polymer composites to protect the bare metal; even if leakage occurs after use, you can also repair in time by Fu Shilan technology, Avoid prolonged repair welding to affect production. It is because of this refined management that the probability of leakage of the heat exchanger is greatly reduced, which not only reduces the equipment purchase cost of the heat exchanger, but also guarantees product quality, production time, and improves product competitiveness.

There are many factors that affect the price of heat exchangers. The following [Heat Exchange Equipment Promotion Center] does the following analysis on the price of heat exchangers.

First, the material of the stainless steel heat exchanger is one of the factors that affects price fluctuations. The price of stainless steel fluctuates from time to time. The quotations given by general manufacturers have a cycle, which is valid during the cycle. Therefore, the price of steel affects the equipment price of the heat exchanger.
Second, the geographical distribution of stainless steel heat exchanger manufacturers affects price setting. why would you said this? Labor costs are different in different regions. Compared with a Shandong factory, the cost of a factory in Shanghai is definitely different.
Third, the size of the stainless steel heat exchanger determines the price. If the company attaches importance to quality and service, then the cost space added to the price will also increase. If the company does not attach great importance to it, the cost of joining will be very low. However, from the perspective of agency or procurement, a company without after-sale is not responsible.

1. Isolate the equipment system and drain the water from the heat exchanger.

2. Use high pressure water to clean the sludge, algae and other impurities in the pipeline, and then close the system.

3 Install between isolation valve and exchanger

Plate heat exchangers appeared in the 1920s and were used in the food industry. Heat exchangers made of plate-replacing tubes have compact structures and good heat transfer effects, so they have gradually developed into various forms. In the early 1930s, Sweden first made spiral plate heat exchangers. Next, a plate-fin heat exchanger made of copper and its alloy materials was manufactured by the UK by brazing, which was used to dissipate heat from aircraft engines. ^{[1] In} 1926, the British ^[1] Oston Chung ^[1] used indoor return air and outdoor fresh air to form a positive cross method. Due to the temperature difference and water vapor partial pressure difference between the air flow on both sides of the flat partition, Mass heat transfer occurs between the two air streams at the same time, causing a total heat exchange process. The indoor and outdoor air circulation is achieved through heat exchange. The built-in blower and exhaust fan are replaced in both directions to suppress room temperature changes and maintain sufficient fresh air in the room. ^{[1] In} the late 1930s, Sweden produced the first plate and shell heat exchanger for a pulp mill. In the meantime, in order to solve the problem of heat exchange in highly corrosive media, people began to pay attention to heat exchangers made of new materials. Around the 1960s, due to the rapid development of space technology and cutting-edge science, various high-efficiency compact heat exchangers were urgently needed, coupled with the development of stamping, brazing and sealing technologies, the heat exchanger manufacturing process was further improved. This has promoted the vigorous development and wide application of compact plate surface heat exchangers. In addition, since the 1960s, in order to meet the needs of heat exchange and energy saving under high temperature and high pressure conditions, typical shell and tube heat exchangers have also been further developed. In the mid-1970s, in order to strengthen heat transfer, a heat pipe heat exchanger was created based on research and development of heat pipes. Heat exchangers can be divided into three types according to different heat transfer methods: hybrid, thermal storage and partition wall. Hybrid heat exchangers are heat exchangers that perform heat exchange through direct contact and mixing of cold and hot fluids, also known as contact heat exchangers. Since the two fluids must be separated in time after heat exchange, this type of heat exchanger is suitable for heat exchange between gas and liquid. For example, in cooling water towers used in chemical plants and power plants, hot water is sprayed from top to bottom, and cold air is sucked in from bottom to top, on the surface of the water film or droplets and water droplets on the filling, and hot water and cold air Contact each other for heat exchange, hot water is cooled, cold air is heated, and then the density difference between the two fluids can be separated in time.

The cold and hot fluids of the partition wall heat exchanger are separated by solid partition walls, and the heat exchanger exchanges heat through the partition wall, so it is also called surface heat exchanger. This type of heat exchanger is the most widely used.

Regenerative heat exchangers are heat exchangers that use cold and hot fluids to alternately flow through the surface of the heat storage body (filler) in the heat storage chamber to perform heat exchange, such as the heat storage chamber for preheating air under the coke oven. This type of heat exchanger is mainly used to recover and utilize the heat of high temperature exhaust gas.

Partition wall heat exchangers can be divided into tube, plate and other types according to the structure of the heat transfer surface. Tube heat exchangers use tube surfaces as heat transfer surfaces, including coiled tube heat exchangers, tube-type heat exchangers, and shell-and-tube heat exchangers; plate surface heat exchangers use plate surfaces as heat transfer surfaces, including Plate heat exchanger, spiral plate heat exchanger, plate fin heat exchanger, plate shell heat exchanger and umbrella plate heat exchanger, etc .; other types of heat exchangers are heat exchangers designed to meet certain special requirements , Such as scraped surface heat exchangers, turntable heat exchangers and air coolers.

The relative flow direction of the fluid in the heat exchanger generally has two types of forward flow and reverse flow. When flowing downstream, the temperature difference between the two fluids at the inlet is the largest and gradually decreases along the heat transfer surface to the minimum at the outlet. When countercurrent, the temperature difference between the two fluids along the heat transfer surface is more uniform. Under the condition that the inlet and outlet temperatures of the cold and hot fluids are constant, when there is no phase change between the two fluids, the average temperature difference of the counter current is the largest and the downstream is the smallest.

Under the condition that the same heat transfer is completed, the average temperature difference can be increased by using counter current, and the heat transfer area of the heat exchanger can be reduced. If the heat transfer area is unchanged, the consumption of heating or cooling fluid can be reduced when using counter current. The former can save equipment costs, and the latter can save operating costs, so countercurrent heat exchange should be used as much as possible in design or production use.

When both or one of the cold and hot fluids has a phase change (boiling or condensation), since only the latent heat of vaporization is released or absorbed during the phase change, the temperature of the fluid itself does not change, so the inlet and outlet temperatures of the fluid are equal. The temperature difference between the two fluids is independent of the choice of fluid flow direction. In addition to the two flows of forward and countercurrent, there are crossflow and deflection flows.

In the process of heat transfer, it is an important issue to reduce the thermal resistance in the partition heat exchanger to improve the heat transfer coefficient. The thermal resistance mainly comes from a thin layer of fluid (called a boundary layer) that is stuck to the heat transfer surface on both sides of the partition wall, and a dirt layer formed on both sides of the wall during heat exchanger use. The thermal resistance of the metal wall is relatively small. Increasing the flow velocity and turbulence of the fluid can reduce the boundary layer, reduce the thermal resistance and increase the heat supply coefficient. However, increasing the fluid flow rate will increase energy consumption, so a reasonable coordination should be made between reducing thermal resistance and reducing energy consumption during design. In order to reduce the thermal resistance of dirt, try to delay the formation of dirt and clean the heat transfer surface regularly.

Generally, heat exchangers are made of metal materials. Among them, carbon steel and low alloy steel are mostly used for manufacturing low- and medium-pressure heat exchangers. In addition to stainless steel, which is mainly used for different corrosion-resistant conditions, austenitic stainless steel can also be used as a High and low temperature materials; copper, aluminum and their alloys are mostly used in the manufacture of low temperature heat exchangers; nickel alloys are used in high temperature conditions; in addition to the production of gasket parts, some non-metallic materials have begun to be used for the resistance of non-metallic materials. Corrosion heat exchangers, such as graphite heat exchangers, fluoroplastic heat exchangers, and glass heat exchangers.