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螺旋隔板换热器的研究及工业应用 总被引:2,自引:0,他引:2
螺旋隔板换热器主要包括两种不同类型的结构形式,即没有中心管的非整体连续的螺旋隔板换热器和有中心管的整体连续的螺旋隔板换热器.本文总结了国内外学者对螺旋隔板换热器所做的主要研究工作,这包括壳程流体的动力学研究、传热与压降性能研究和数值模拟,并介绍了整体连续型螺旋隔板强化管换热器在工业中的应用.最后,对螺旋隔板换热器的下一步研究工作进行了展望. 相似文献
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均热炉应用金属换热器代替传统的非金属陶土换热器,可以提高换热效率,降低均热炉燃气消耗。文章通过数值模拟试验,研究了换热器改造后的流场和温度场,进一步验证了节能改造的可行性。 相似文献
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针对弓形折流板管壳式换热器流动死区大,压降高的不足,提出外螺旋折流板内斜百叶折流板的双壳程管壳式换热器结构,外螺旋角为15°~40°,内斜百叶折流板倾角为45°。通过三维数值模拟,研究其传热和阻力特性,获得其局部流场,并与传统弓形折流板换热器进行了对比,同时分析了外壳程螺旋折流板不同倾角对其性能的影响。结果表明:双壳程管壳式换热器的壳侧流场分布均匀,流动死区减小,综合性能高于相同壳径和管束布置的弓形折流板管壳式换热器,外螺旋角为30°时,单位压降下的传热系数平均提高了24. 4%。当外螺旋角为20°时,该换热器具有最好的综合性能。 相似文献
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对倾斜角20°有34根管子的周向重叠三分螺旋折流板换热器进行了数值模拟研究,通过在三分螺旋折流板换热器壳侧通道内偏心纵向切面和横切面以及六边形纵向切面上速度矢量流场和压力云图的叠加展示,不仅呈现了壳侧总体螺旋速度的周向分量的轨迹,而且从所呈现的轴向和径向速度分量揭示了二次流和相邻折流板V型缺口处逆向泄漏的踪迹.研究结果表明:流体在螺旋通道内在离心力作用下呈现向外扩张的流动趋势,然后在外围高、中心低的压力分布作用下沿着靠近折流板附近的流速较低的区域向心流动返回轴中心,形成单涡型迪恩二次流;二次流增强了流体的掺混,从而有利于强化传热. 相似文献
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Jian-Fei Zhang Ya-Ling He Wen-Quan Tao 《International Journal of Heat and Mass Transfer》2009,52(23-24):5381-5389
In this paper, based on the simplified periodic model the performance predictions for heat exchanger with middle-overlapped helical baffles are carried out by 3D simulation for three different helix angles (30°, 40° and 50°), and the commercial codes of GAMBIT 2.3 and FLEUNT 6.3 are adopted in the simulation. It is found that the model average heat transfer coefficient per unit pressure drop of the 40° angle case is the largest, which is in qualitative agreement with the existing literature. The predicted average intersection angle of this case is the smallest, being consistent with the field synergy principle. The performance of periodic model with continuous helical baffle is also compared with that of the noncontinuous middle-overlapped helical baffles. It is found that the heat transfer coefficient per unit pressure drop of the noncontinuous middle-overlapped helical baffles is appreciably larger than that of the continuous helical baffle, indicating that the heat exchanger with noncontinuous middle-overlapped helical baffles has its advantage over the one with continuous helical baffle. 相似文献
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连续型螺旋折流板换热器结构及性能研究 总被引:2,自引:0,他引:2
连续型螺旋折流板换热器一直受限于加工工艺而未能得到广泛应用,本文提出采用加装中芯管的方法,实现了连续型折流板的加工,并给出了连续型折流板螺旋升角和螺旋包络面的计算方法。利用Fluent软件,与现今应用较广泛的1/4椭圆形折流板换热器的流动和换热特性进行模拟比较。结果表明,连续型折流板换热器换热能力提高了近一倍,综合性能系数也提高了近30%,虽然1/4椭圆折流板压力降较小,但其折流板的漏流,也严重降低了传热能力。为在工程中推广应用连续型螺旋折流板换热器,本文提供了理论依据和技术支撑。 相似文献
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Heat exchangers contribute significantly to many energy conversion processes. Applications range from power production, petroleum refining and chemicals, paper and pharmaceutical production, to aviation and transportation industries. A large percentage of world market for heat exchangers is served by the industry workhorse, the shell-and-tube heat exchanger. Recent developments in other exchanger geometries have penetrated in various industry applications; however, the shell-and-tube exchanger by far remains the industry choice where reliability and maintainability are vital. Over the years, significant research and development efforts are devoted to better understand the shell-side geometry. New geometries are introduced for performance enhancement and to improve reliability. The pioneering work published by J. Nemcansky et al. in the Trans. Institute of Chemical Engineers in May, 1990, on helical baffles paved the way to a major shift from a conventional understanding of baffles in a shell-and-tube heat exchanger. Helical baffles serve as guide vanes for shell-side flow as compared to creating flow channels with conventional segmented baffles. In the past decade, ABB Lummus Heat Transfer has extended the understanding of the helical baffle geometry through extensive testing and development. CFD flow simulation studies have further confirmed the helical baffle advantage. Industry feedback on operating Helixchanger® heat exchangers—the shell-and-tube heat exchangers with helical baffles—has demonstrated low fouling characteristics as well as a higher conversion of shell-side pressure drop to heat transfer. In this paper, the characteristics of this novel Helixchanger heat exchanger are discussed. Examples from early installations in the power industry to the major applications in the petro-chemical and refining industries are presented, illustrating the advantages in reducing fouling and increasing reliability while achieving lower total life cycle costs. 相似文献
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Using the three-dimensional (3D) modeling software Gambit, a mathematical model of a circumferential overlap trisection helical baffle shell-and-tube heat exchanger (cothSTHX) was developed with 34 tubes and three pulling rods with an equilateral triangle tube layout and a baffle incline angle of 20°. The numerical simulation of flow and thermal performances was performed with the analysis software Fluent. The temperature, pressure, and velocity nephograms are shown for different slices, including spiral, concentric hexagon longitudinal, meridian, eccentric longitudinal, and transverse slices. The nephograms of temperature, pressure, and velocity with superimposed velocity vectors vividly display the important parameters of the cothSTHX. The “Dean vortex secondary flow” is a key mechanism to enhance the heat transfer in heat exchangers, which is clearly depicted to show that the spiral fluid flows outward under the centrifugal force, then flows back to the axis under the radial differential pressure, forming a single vortex in each helix cycle. The structure of circumferential overlap baffles restricts the shortcut leakage flow, and the flow pattern in the cothSTHX is very close to “plug flow” on the unfolded hexagon slices. 相似文献
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Mario Antonio Cucumo Vittorio Ferraro Dimitrios Kaliakatsos Marilena Mele Antonio Galloro Rosario Schimio 《传热工程》2020,41(12):1026-1039
AbstractIn the article, a three-dimensional numerical solution of two real shell-and-tube heat exchangers, with different types of baffles, segmental, and pseudohelical, is presented, through the use of commercial codes, in order to evaluate the influence of the baffles type on heat exchanger performance. The parameters to be evaluated, which influence the efficiency of the thermal exchange and the maintenance and pumping costs, are the pressure drops, the heat transfer coefficient, and the fouling resistance. The fluid dynamic study of the shell-and-tube heat exchanger is conducted under stationary flow conditions. In the article, furthermore, the results of the thermohydraulic analysis, performed under stationary flow conditions, more "helical baffles" exchangers, with different baffles helix angle, are presented. Exchangers with pseudohelical baffles inclined by 7°, 20°, 30°, 40°, 45°, and 50° are analyzed. The simulations are carried out considering a real fluid, approximately incompressible, under laminar flow conditions. Finally, to verify the correctness of the results, they are compared with correlations in the literature. 相似文献
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Arasy Fahruddin Djatmiko Ichsani Fadlilatul Taufany Budi U.K. Widodo Wawan A. Widodo 《International Journal of Hydrogen Energy》2021,46(8):6028-6036
Flow field design on the cathode side, inspired by leaf shapes, leads to a high performance, as it achieves a good distribution of reactants. Furthermore, the addition of baffles to the cathode channel also increases the supply of reactants in the cathode catalyst. However, research on the addition of baffles to the cathode channel has still been limited to straight channels and conventional flow fields. Therefore, in this work, a numerical study was conducted to investigate the effect of baffles on the leaf flow field on the performance of a polymer electrolyte membrane fuel cell. The generated 3D model is composed of nine layers with a 25-cm2 active area. The beam and chevron shapes of the baffles, which were inserted into the mother channel, were compared. The simulation results revealed that the addition of beam-shaped baffles that are close to each other can increase the current and power densities by up to 18% due to the more uniform distribution of the oxygen mass fraction. 相似文献
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In the present work, the shell and tube heat exchanger (STHX) is designed based on The Tubular Exchanger Manufacturers Association standards with hot fluid (water) flowing on the shell side and cold fluid on the tube side. A comparison is made between the Nusselt number and friction factor obtained from numerical and experimental results of segmental baffles (SBs) and helical baffles (HB) with different baffle inclinations. The results show that SB provided a higher Colburn factor (js) when compared with HBs STHXs (20°, 30°, 40°, and 50°), but shell side pressure drop is lower for 40° HBs STHXs for the same shell side fluid flow rates. 相似文献