Heat exchanger manufacturers will give you a detailed introduction to the 5 types of heat exchangers:
In recent years, domestic improvements in the performance of heat exchangers in terms of energy saving and efficiency enhancement have achieved remarkable results in improving heat transfer efficiency, reducing heat transfer area, reducing pressure drop, and increasing the thermal strength of the device. Large-scale and high-efficiency heat exchangers also tend to be large-scale, and they are developing in the direction of low temperature difference design and low pressure loss design.
1. Pneumatic spraying finned tube heat exchanger
Russia has proposed an advanced method, namely pneumatic spraying, to improve the performance of the finned surface. The essence is to spray powder particles on the surface of the fin with a high-speed cold or slightly warmed fluid containing particles. This method can not only spray metal but also cermet mixture, so as to obtain a variety of surfaces with different properties.
Usually in practice, the contact resistance of the bottom surface of the fin is one of the factors that restrict the addition of fins to the tube. In order to evaluate the finned tube heat exchanger components, an experimental study was carried out. The test is to spray AC-aluminum on the surface of the fin, and add 24A white electric furnace alumina. After sorting out the data obtained from the test, the contact resistance of the bottom surface of the fin can be evaluated.
Comparing the efficiency of the studied fin with the calculated data, it is concluded that the contact resistance of the bottom surface of the pneumatic spraying fin has no substantial effect on the efficiency.
In order to verify this, the metallographic structure analysis was carried out on the transition zone between the tube and the fin. The analysis of the test piece in the transition zone shows that there are no imperceptible micro-cracks along the entire length of the connecting boundary.
Therefore, the pneumatic spraying method promotes the formation of the branch boundary between the surface and the basic interaction, and can promote the penetration of the powder particles into the matrix, which shows that the adhesion strength is high, there is physical contact and the formation of metal chains.
2. Welded plate heat exchanger
The use of welded structures instead of rubber gasket seals, and the emergence of fully welded and semi-welded plate heat exchangers eliminates the limitations of gasket materials in terms of temperature, corrosion, and pressure resistance. The use of plate heat exchangers for corrosive media has been greatly developed in recent years. The Chiyoda hybrid welded plate heat exchanger cooperated with Germany and Japan, the operating pressure can be
From vacuum to 6, the operating temperature is 200℃～900℃, and the heat exchange area F of a single unit is 3m2～2 000m2. It can be used for gas-gas, gas-liquid, liquid-liquid heat exchange and vapor condensation.
The US VICARB company developed the COMPBLOC welded plate heat exchanger in 1989, which is a compact, efficient and patented heat exchanger.
3. Spiral baffle heat exchanger
Spiral baffle heat exchanger is a newly developed shell-and-tube heat exchanger, which was proposed by ABB in the United States. In tube and tube heat exchangers, the shell side is usually a weak link. The American ABB company has proposed a brand-new plan, using spiral baffles.
The basic principle is: install a special plate with a circular cross section in the "quasi-spiral baffle system", each baffle plate occupies 1/4 of the cross section in the shell side of the heat exchanger, and its inclination angle is towards the axis of the heat exchanger, That is to maintain a certain inclination with the axis of the heat exchanger. The peripheries of adjacent baffles are connected to form a continuous spiral with the outer circle.
Each baffle forms a certain angle with the flow direction of the shell-side fluid, so that the shell-side fluid makes a spiral motion, which can reduce the dead angle between the tube sheet and the shell that is easy to foul, thereby improving the heat exchange efficiency. Because the medium flows in a spiral pattern, a velocity gradient is generated in the radial direction and radial turbulence is formed, which completely changes the fluid flow mode and flow field distribution of the arcuate baffle heat exchanger, and reduces the thickness of the stagnant bottom layer on the surface of the heat transfer tube. , The heat transfer film coefficient is improved, the heat transfer dead zone of the arcuate plate is eliminated, and the heat transfer state of the shell side is greatly improved. In addition, the spiral baffle structure can meet a wide range of process conditions, and has great flexibility in design. The spiral angle can be selected for various special process conditions.
4. New twist tube heat exchanger
The Swedish company Alares has developed a flat tube heat exchanger, usually called a twist tube heat exchanger. The manufacturing process of the spiral flat tube includes two processes: "flattening" and "hot twisting". The improved twist tube heat exchanger is as simple as the traditional shell-and-tube heat exchanger, but has improved heat transfer, reduced fouling, true reverse flow, reduced costs, no vibration, saved space, and no baffle elements . Due to the unique structure of the tube, the tube side and the shell side are in spiral motion at the same time, which promotes the degree of turbulence. The total heat transfer coefficient of this heat exchanger is 40% higher than that of conventional heat exchangers, and the pressure drop is almost equal. When assembling the heat exchanger, the spiral flat tube and the smooth tube can also be mixed. The heat exchanger is manufactured in strict accordance with the ASME standard. It can be replaced by this type of heat exchanger wherever shell-and-tube heat exchangers and traditional devices are used. It can obtain common shell-and-tube heat exchangers and plate and frame heat transfer equipment. The best value obtained is estimated to have broad application prospects in the chemical and petrochemical industries.
5. Hitan wire-wound wreath heat exchanger
This type of heat exchanger is a new product developed by the British company Cal Gavin Ltd. It uses a filiform flower insert called Hitan mat rix element s, which can make the fluid produce radial displacement and spiral flow at low speeds. The superimposed three-dimensional complex flow can increase the induced turbulence and enhance the fluid disturbance along the temperature gradient direction, and can greatly increase the heat transfer coefficient without increasing the resistance.