The rumored laminated cooler is the first choice for the air compressor interstage cooler for air separation equipment. However, the heat exchanger element* fin of the laminated cooler has been used in the form of a plane, which has low efficiency, small heat transfer coefficient and large product structure size.
In order to improve the heat transfer efficiency of the compressor interstage cooler, reduce the overall size of the equipment, reduce the manufacturing cost, reduce the power consumption of the pump during operation, save energy and reduce consumption, and carry out research on high efficiency and low resistance gas side enhanced heat transfer technology, Developed a "front and rear dense" slotted fin. Replacing conventional planar fins with slotted fins greatly improves the heat transfer efficiency of the interstage cooler.
1 Test results and analysis In order to obtain the heat transfer characteristic curve of the slotted fins, the superiority of the slotted fins was verified, and the tube fins and the tube bundles of the "pre-sparing and dense" slotted fins were respectively fabricated and commissioned by the university. Wind tunnel test. The structure of the plane fin and the "front and rear dense" slotted fin is as shown in the figure. The relationship between the Nusselt number Nu of the outer air side of the tube and the Reynolds number Re is as shown, and the relationship between the resistance factor f and Re is as shown. Show.
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The relationship between the Reynolds number Re and the Nusselt number Nu of the air side of the two kinds of finned tubes â–¡The planar finned Reynolds number is the relationship between the resistance factor f of the air side of the two finned tubes and the Reynolds number Re. The finned tube bundle prototype was tested and tested, and the relationship between heat transfer and pressure drop was obtained, and analyzed and compared.
a) Compared with the planar fins, the proportion of the enhanced heat transfer of the slotted fins remains basically the same, and the heat transfer coefficient is about 26% higher than that of the planar fins.
(2) The resistance ratio of the slotted fin to the resistance of the planar fin changes little, and the flow rate decreases slightly. The resistance of the slotted fin is about 22% higher than that of the plane fin.
(3) For the cooler, whether the planar fin or the slotted fin is used, the mass flow rate of the treated gas is constant, and thus the same pumping force is the same pressure drop. If the length of the gas flow direction of the cooler is shortened by 25%, the slit fins can maintain the pressure drop within the range of the planar fins and achieve the specified heat exchange amount.
(4) According to the test results and the comprehensive analysis and comparison of flow and heat transfer performance, it is concluded that the new ''front and rear dense' slotted fins have excellent heat transfer and resistance characteristics compared with the planar fins. .
2 The structure and process characteristics of the laminated cooler using the “front and rear dense†slotted fins (1) Structural form: The cooler is generally horizontal, and the tube bundle is in a floating form.
(2) The tube bundle is composed of a plurality of fin units, each fin unit is staggered by 6 *19 mm heat exchange tubes, and the fins are jacketed, and the tubes and fins are expanded by hydraulic method to ensure the tubes and fins. Firmly combined to ensure heat transfer.
(3) Process flow: the inside of the heat exchange tube is cooling water, and the outside of the tube is cooled gas. When the gas flows between the tubes, the heat is transferred to the heat exchange tubes through the fins, and finally the heat is exchanged with the cooling water in the tubes to achieve the purpose of heat exchange. The heat transfer effect of the gas is enhanced by the action of the slit of the fin.
The calculation results and analysis of 3 "front and rear dense" slotted fins and plane fins are now based on a set of 30000m3/h air separation equipment, with a laminated interstage cooler of the air compressor. The ''front and rear dense' slotted fins and plane fins are used as heat exchange elements respectively. The main performance parameters are compared in Table 1. Table 1" Front and rear dense "Slotted fins and plane fins laminated The main performance parameters of the interstage cooler are compared with the sheet type air intake heat load tube bundle unit number tube bundle length heat exchange area pressure drop slotted fin plane fins. It can be seen from Table 1 that in the same level of air separation equipment, air compressor level The intercooler should achieve the same performance and technical specifications. Compared with the traditional planar fins, the 'front front and rear dense†slotted fins reduce the heat exchange area by about 16%, saving heat exchange tubes and fin materials. It reduces the weight of the equipment and reduces the manufacturing cost.
4 Engineering application As the core part of the new generation of high-efficiency and low-resistance gas-side heat transfer enhancement technology, the successful development of the “front and rear dense†slotted fins has greatly improved the heat transfer efficiency of the cooler, reducing power consumption and manufacturing cost.
At present, the laminated cooler with ''front and rear dense' slotted fins has been mass-produced industrially, and it has been equipped for large, medium and small air separation equipment, and successfully applied to the air separation equipment of 60000m3/h class. Supported air compressor.
5 Conclusion Air separation equipment is an indispensable major supporting equipment for many important industrial equipments in the country. The air compressor interstage coolers for air separation equipment can improve the technical content and market competitiveness of China. Improvement in design, manufacturing level and comprehensive development capabilities. The laminated cooler with ''front and rear dense' slotted fins) has outstanding innovation and obvious technical advantages. It can completely replace the foreign similar technology and can be used as a new generation of replacement products with a very broad market. prospect.
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