共查询到20条相似文献,搜索用时 10 毫秒
1.
D. Arunachalam Anuj Kumar Shukla Anupam Dewan Rahul Salhotra Deepak Kumar Singh 《亚洲传热研究》2023,52(6):4401-4421
This paper investigates the flow and thermal properties of a combined multiple shell pass (CMSP)-shell and tube heat exchanger (STHE) with the provision of unilateral ladder-type helical baffle (ULHB) and continuous helical baffle (HB) in the outer shell pass of the heat exchanger. Two CMSP-STHEs with ULHB and HB, respectively, are compared with the traditional STHE having segmental baffles (SG-STHE) using the computational fluid dynamics method. The computational outcomes are validated with the empirical correlations of the Kern and Esso method. The Reynolds-averaged Navier–Stokes-based standard k–ω turbulence model accurately predicts the heat transfer (HT) rate and pressure drop. The computed results of HT rate, pressure drop, and logarithmic mean temperature difference corresponding to various mass flow rates (m) for three STHEs are presented. The results show that the overall HT rate of CMSP (ULHB)-STHE and the CMSP (HB)-STHE at the same mass flow rate are nearly 28.3% and 14.8% larger than that of traditional SG-STHE, respectively. Furthermore, the overall area-weighted average pressure drop (ΔP) of CMSP (HB)-STHE is smaller than that of SG-STHE by 26.5% at the same mass flow rate (m) and for CMSP (ULHB)-STHE it is larger by 2% than that of traditional STHE. Based on the above results, it is concluded that the CMSP (ULHB)-STHE is a suitable replacement for the conventional SG-STHEs. 相似文献
2.
3.
Among the heat exchangers (HE), the shell and tube type is being widely used in different applications like oil, chemical, and power plant Industries. The incorporation of segmental baffles (SB) improves the HE capacity from higher temperature fluid to lower temperature fluid. Nanofluids can be effectively used to enhance the heat transfer rate. In this study, numerical simulations have been carried out in a shell and tube heat exchanger (STHX). Among HE design methods, Tubular Exchanger Manufacturers Association (TEMA) standard is being used for better design by many researchers. In this paper, the computational fluid dynamics analysis was carried out with Al2O3, CuO, and SiO2 nanofluids amid 1, 3, and 5 vol. % with water emulsion to enhance the heat transfer coefficient of STHX. The nanofluid has been used in the cold fluid of the HE and on the other side hot water is used. From the results, it is noticed that with the increase of Nanofluids, the value of heat transfer coefficients is found to be increasing. The overall heat transfer coefficient has been enhanced for Al2O3, CuO, and SiO2 about 10.41%, 12.27%, and 9.56%, respectively, at 0.22 kg/s for the 5 vol. % addition. It is also depicted that the pressure drop is increasing with the incorporation of nanofluids. 相似文献
4.
5.
对国内现有内燃机车用热交换器的传热机理和结构进行了分析、比较和研究,指出热交换器传热强化应采取的措施,并针对光管热交换器、螺旋扁管热交换器、螺旋隔板热交换器作了性能对比研究,指出螺旋隔板热交换器具有较高的冷却能力。 相似文献
6.
Mohammadreza Hasandust Rostami Gholamhassan Najafi Barat Ghobadin Ali Motevali 《亚洲传热研究》2020,49(8):4783-4800
The experimental study, thermal performance, and pressure drop of single-walled carbon nanotube (SWCNT) and graphene quantum dot (GQD) nanofluids in shell and tube heat exchanger with fin blade tubes are evaluated. The effects of the working fluid (water) volume flow rates ( 2.5–10 L/min), volume concentration of nanoparticles ( 0.0%, 1%, 3%, and 5%), Reynolds number of working fluid (Re = 850–3300), and tube building (heat exchanger with fin blade tubes and without fin blade tube) have been analyzed. Results represent that with augmentation of volume concentration of SWCNT nanoparticle up to 1%, heat transfer rate increases by ∼5% and then up to 5% volume concentration of SWCNT nanoparticle decreased about 17%, also this calculation for GQD nanoparticle conducted and results represented decreasing 6% and approximately unchanged heat transfer rate, respectively. With regard to obtained results, heat transfer rate of heat exchanger can be improved by using the fin blades by 188%, compered without fin blade heat exchanger also most related increase for pressure drop of heat exchanger was recorded about 80% for 5% SWCNT of nanofluid. At the end, the mean enhancement in effectiveness of heat exchanger with various concentrations of SWCNT and GQD nanofluids and using the fin blades is about over 100% and 85%, respectively. In fact, the present study shows that applying the new finned tubes in the heat exchanger has more impact, related to the mentioned nanoparticles on the thermal properties of heat exchanger. 相似文献
7.
8.
Extended surfaces mostly aim to improve the heat transfer upon increasing the area of heat transfer. In this paper, the influence of using fins on flow behaviors and the heat transfer of the shell and tube heat exchanger has been investigated. In this regard, the present results are verified with available experimental data in the literature for a helical tube without fins. The effects of fin density (fin per inch), its height, and material have been studied on the heat transfer rate. In addition, the effects of radial pitch and the number of coil loops are studied. The results indicate that implementing extended surfaces significantly increases the heat transfer rate. The increase of fin density from 8 to 12 and the height from 11.5 to 13.5 mm enhances heat transfer up to 48% and 43% depending on Dean number, respectively. The rise of coil pitch augments the overall heat transfer, and it is more efficient at lower Dean numbers. The predicted results also show that the fin material does not have any significant effect on heat transfer. 相似文献
9.
连续螺旋折流板换热器动态特性研究 总被引:1,自引:1,他引:0
建立了可进行壳管式换热器动态特性试验研究系统,通过试验研究的方法对水-油为换热工质的连续螺旋折流板换热器动态特性进行了试验研究,进口流量扰动为等百分比流量特性,研究了四种流量扰动方式下水和油出口温度的动态响应。同时研究了在一定R e下,不同的流体扰动量对换热器进出口温升的影响,得到了换热器进出口温升与流体扰动量之间的关联式。实验表明,较于气体而言,液-液换热系统温度的动态响应时间比较长,研究发现在正负的流量扰动下,螺旋折流板换热器进出口温度变化呈现线性变化,进出口温升在正负流量扰动下其变化曲线具有对称特征。 相似文献
10.
Mehdi Noorbakhsh Mohsen Pourfallah Seyed S. M. Ajarostaghi Mohammad Zaboli 《亚洲传热研究》2020,49(8):4678-4703
Heat exchangers are extensively used in various industries. In this study, the impact of geometric and flow parameters on the performance of a shell and double helical coil heat exchanger is studied numerically. The investigated geometric parameters include external coil pitch, internal coil pitch, internal coil diameter, and coil diameter. The influences of considered geometrical parameters are analyzed on the output temperature of the hot and cold fluid, convective heat transfer coefficient, pressure drop, and average Nusselt number. Water is considered as working fluid in both shell and tube. As an innovation, double helical coils are used instead of one in the heat exchanger. To compare the obtained results accurately, in each section, the heat transfer area (coil outer surface) is kept constant in all models. The results show that the geometrical parameters of double helical coils significantly affect the heat transfer rate. 相似文献
11.
Wu Shuangying Li Yourong Thermal Engineering College of Chongqing University Chongqing China 《热科学学报(英文版)》2001,10(3):218-222
honductiOnHeat exchangee as one of the thennal equlpment,is widely used in energy systems, the imPrvement ofheat exchangers perfonnance is imPOrtan for savingenergy and twving tbe efficiency, so it is necessaryto emPloy a general driterion to evaluate heatexchanger perfrmance. In the design of heatexchangers, numrous perfrmance evaluation criteriaealst tO heIP to detennine their fhatUfs11]. Thesecriteria lead towards the goal of oPtindzationprocedurs. They dePend on the asPeCt of o~zation… 相似文献
12.
This paper evaluates the optimum coolant temperature considering the exergy loss in a shell and tube condenser in which vapor is at its saturated temperature. First, exergy loss was formulated mathematically and then presented as a function of operating temperatures and optimum coolant and steam mass flow rates. The optimization problem was defined by full condensation of vapor in a condenser and solved by a sequential quadratic programming method. The optimization results were obtained for an industrial condenser for two condensate temperatures of 46°C and 54°C. When the upstream steam mass flow rate increased, the optimum coolant temperature and the exergy efficiency decreased, and the exergy loss also increased simultaneously. The results showed higher values for the higher condensate temperature of 54°C compared with that for 46°C. For instance, if the condensate temperature increases from 46°C to 54°C, the coolant temperature will be increased from 16.76°C to 25.17°C. In addition, by assuming the ambient temperature of 15°C, the exergy loss will be decreased from 172.5 to 164.6 kW. A linear relationship was also shown between the exergy efficiency and the dimensionless temperature, which is presented as a ratio of the temperature difference rate between inlet cooling water and ambient temperatures to the temperature difference rate of condensate and ambient temperatures. 相似文献
13.
Investigation of thermohydraulic performance of triple concentric-tube heat exchanger with CuO/water nanofluid: Numerical approach 下载免费PDF全文
In this study, numerical investigation of CuO/water nanofluids in a triple concentric-tube heat exchanger has been carried out using a commercial CFD software. The primary objective of this study is to conduct a heat transfer and pressure drop characteristics of water-based CuO nanofluids under turbulent flow regime. Reynolds number for the nanofluid has also been considered in the range of 2500 to 10,000 with a nanoparticle volume concentration of 0% to 3%. The effects of flow rate, volume concentration of nanoparticles, and flow arrangement on heat transfer performance of nanofluid have been studied for four flow arrangements. The comparison of the performance with and without nanofluid has been done. It was found that thermal performance and overall effectiveness increased with the increase in Reynolds number and volume concentration of nanoparticles in all the four flow arrangements for the considered range of operating parameters. 相似文献
14.
选取矩形截面平直翅片板翅式换热器的矩形单通道运用fluent软件进行数值模拟。首先对不同波高和波距的三组九种几何尺寸的翅片在同一工况下进行数值模拟,选出每组中传热和阻力综合性能最优者。然后对选出的三种翅片在不同工况下进行数值模拟,最终选出一种传热和阻力综合性能最优的。并对实物换热器进行试验研究,同时将试验结果和数值模拟结果进行对比分析,验证了数值模拟的正确性。 相似文献
15.
Roghayeh Lotfi Ali Morad RashidiAzadeh Amrollahi 《International Communications in Heat and Mass Transfer》2012
Heat transfer enhancement of multi-walled carbon natube(MWNT)/water nanofluid in a horizontal shell and tube heat exchanger has been studied experimentally. Carbon nanotubes were synthesized by the use of catalytic chemical vapor deposition (CCVD) method over Co–Mo/MgO nanocatalyst. Obtained MWNTs were purified using a three stage method. COOH functional groups were inserted for making the nanotubes hydrophilic and increasing the stability of the nanofluid. The results indicate that heat transfer enhances in the presence of multi-walled nanotubes in comparison with the base fluid. 相似文献
16.
17.
Heat exchangers operating in process industries are fouled during operations and results in decrease in the thermal efficiency of a heat exchanger. Once the thermal efficiency decreases to a minimum acceptable level, cleaning of the equipment becomes necessary to restore the performance. This paper uses C-factor as a tool for investigation of the performance of a heat exchanger due to fouling which consequently gives information regarding the extent of fouling developed on the heat transfer surfaces. The fouling parameters are predicted by measurements of flow rate and pressure drop. In contrast to most conventional methods, the extent of fouling can be detected considering the flow rate and pressure drop when the heat exchanger operates in transient states. The C-Factor is first calculated through out cleaning period and then compared with the clean and the design value. The results show that the proposed tool is very effective in detecting the fouling developed and the corresponding degradation in heat transfer efficiency of a heat exchanger. Hence the results of this work can find applications in predicting the reduction in heat transfer efficiency due to fouling in heat exchangers that are in operation and assist the exchanger operators to plan cleaning schedules. 相似文献
18.
19.
20.
Mohammad Zaboli Seyfolah Saedodin Seyed Soheil Mousavi Ajarostaghi Mehdi Nourbakhsh 《亚洲传热研究》2021,50(6):6043-6067
In this paper, turbulence heat transfer and nanofluid flow in a shell and corrugated coil tube heat exchanger are evaluated numerically. The three-dimensional numerical simulations have been done by finite volume method using a commercial computational fluid dynamics code. The spatial discretization of mass, momentum, turbulence dissipation rate, and turbulence kinetic energy equations has been achieved by a second-order upwind scheme. A SIMPLE algorithm has been used for velocity–pressure coupling. To calculate gradients, Green-Gauss cell-based method has been utilized. The cross-section of the coil tube is lobe shaped. First, the impact of corrugated tube cross-section type and then, the impact of utilizing different types of nanofluid on thermal performance are investigated. The outcomes indicate that at high Reynolds number, utilizing a five-lobe cross-section causes augmentation in Nusselt number and pressure drop by about 4.8% and 3.7%, respectively. However, the three-lobe type shows the highest thermal performance. Moreover, water/CuO has the most thermal performance. As the volume concentration of the nanofluid increases, the thermal performance declines. 相似文献