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1
Sun, Lin, Biwei Fu, Menghui Wei e Si Zhang. "Analysis of Enhanced Heat Transfer Characteristics of Coaxial Borehole Heat Exchanger". Processes 10, n. 10 (12 ottobre 2022): 2057. http://dx.doi.org/10.3390/pr10102057.
Testo completoAbstract (sommario):
Coaxial borehole heat exchangers provide a practical method for geothermal energy extraction, but heat transfer efficiency is low. In order to address this problem, three coaxial borehole heat exchangers with vortex generators, based on the enhanced heat transfer theory, are proposed in this paper. The author compared and analyzed the heat transfer performance of three coaxial borehole heat exchangers with vortex generators and those of traditional structures, which explains why the new heat exchanger’s heat transfer mechanism is enhanced. The results demonstrated that the vortex generator can enhance the fluid flow’s turbulent kinetic energy in the coaxial heat exchanger. This generator can also improve the mixing characteristics of the fluid flow and heat transfer. The resultant increase in the inlet flow velocity can decrease the friction coefficient f, increase the Nusselt number and strengthen the coaxial sleeve. As a result, the heat exchange performance of the tubular heat exchanger will also be improved. The thread vortex generator (TVG) heat exchanger outperforms the other three heat exchangers in terms of heat exchange performance, extraction temperature and heat extraction power. The results evidenced that the TVG heat exchanger is better than the smooth tube heat exchanger. The thermal performance coefficient PEC was improved by 1.1 times, and the extraction temperature and heating power were increased by 24.06% and 11.93%, respectively. A solid theoretical foundation is provided by the extracted outcomes for designing and selecting high-efficiency coaxial borehole heat exchangers suitable for geothermal energy extraction.
2
Shaimerdenova, К. М., E. R. Schrager, A. S. Tussypbaeva e Zh K. Nausharban. "Investigation of heat exchange processes in vertically arranged heat exchangers". Bulletin of the Karaganda University. "Physics" Series 94, n. 2 (28 giugno 2019): 66–72. http://dx.doi.org/10.31489/2019ph2/66-72.
Testo completo
3
Ge, Yu Lin, Ping Wang, Sheng Qiang Shen e Jun Liang Xu. "Synthesis Method of Heat Exchanger Network for Distillation Device". Advanced Materials Research 199-200 (febbraio 2011): 1509–12. http://dx.doi.org/10.4028/www.scientific.net/amr.199-200.1509.
Testo completoAbstract (sommario):
Mathematical programming model for synthesis of heat exchanger network for distillation unit is established. MINLP problem for heat exchanger network is solved by branch-bound method. Two kinds of heat exchanger network with splitting stream and without splitting stream are obtained. 142 heat exchangers, 8 coolers and 4 heaters are needed in the heat exchanger network without splitting stream. 34 heat exchangers, 8 coolers, 4 heaters, 11 splitters and 11 mixers are needed in the heat exchanger network with splitting stream. The matching situation including heat load, heat exchange area, duty of utilities, flow fraction of splitting, temperature of inlet and outlet, etc. for cold and hot streams in the heat exchanger network with splitting stream is presented in detail, Analysis the relationship between total heat exchange area, total heat load, total capital cost and annual operation cost of the heat exchanger network. Taking the number of heat exchangers and operational flexibility of heat exchange network into consideration, the heat exchanger network with splitting stream is suggested to be selected.
4
Rydalina, Natalia, Oleg Stepanov e Elena Antonova. "The use of porous metals in the design of heat exchangers to increase the intensity of heat exchange". E3S Web of Conferences 178 (2020): 01026. http://dx.doi.org/10.1051/e3sconf/202017801026.
Testo completoAbstract (sommario):
Heat exchangers are widely used in heat supply systems. To increase the efficiency of heat supply systems, heat exchangers with porous metals are proposed to design. There was a test facility set up to study new types of heat exchangers. The countercurrent flow of heat carriers was activated in those heat exchangers. Freon moved through the heat exchanger pores, and water moved through the inner tubes. It should be noted that the porous materials in the heat exchangers differed in the coefficient of porosity. To be compared, one of the heat exchangers did not contain any porous material. The first test cycle proved the feasibility of using porous metals in heat exchange equipment. Afterwards, a simplified mathematical model of the heat exchanger was compiled. Such an analytical form makes a solution convenient for engineering calculations. Numerical calculations based on this model were compared with the experimental data. Heat transfer intensity of materials with different porosity was compared.
5
Lee, Seung-Rae. "Evaluation of Heat Exchange Rate of Different Types of Ground Heat Exchangers". Journal of the Korean Society of Civil Engineers 33, n. 6 (2013): 2393. http://dx.doi.org/10.12652/ksce.2013.33.6.2393.
Testo completo
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Rostami, Mohammadreza Hasandust, Gholamhassan Najafi, Ali Motevalli, Nor Azwadi Che Sidik e Muhammad Arif Harun. "Evaluation and Improvement of Thermal Energy of Heat Exchangers with SWCNT, GQD Nanoparticles and PCM (RT82)". Journal of Advanced Research in Fluid Mechanics and Thermal Sciences 79, n. 1 (31 dicembre 2020): 153–68. http://dx.doi.org/10.37934/arfmts.79.1.153168.
Testo completoAbstract (sommario):
Today, due to the reduction of energy resources in the world and its pollutants, energy storage methods and increase the thermal efficiency of various systems are very important. In this research, the thermal efficiency and energy storage of two heat exchangers have been investigated in series using phase change materials (RT82) and single wall carbon nanotubes (SWCNT) and graphene quantum dot nanoparticles (GQD) In this research, two heat exchangers have been used in combination. The first heat exchanger was in charge of storing thermal energy and the second heat exchanger was in charge of heat exchange. The reason for this is to improve the heat exchange of the main exchanger (shell and tube) by using heat storage in the secondary exchanger, which has not been addressed in previous research. The results of this study showed that using two heat exchangers in series, the thermal efficiency of the system has increased. Also, the heat energy storage of the double tube heat exchanger was obtained using phase change materials in the single-walled carbon nanotube composition of about 3000 W. The average thermal efficiency of the two heat exchangers as the series has increased by 52%. In general, the effect of the two heat exchangers on each other was investigated in series with two approaches (energy storage and energy conversion) using fin and nanoparticles, which obtained convincing results.
7
Zhang, Zhou Wei, Ya Hong Wang e Jia Xing Xue. "Research and Develop on Series of Cryogenic Liquid Nitrogen Coil-Wound Heat Exchanger". Advanced Materials Research 1070-1072 (dicembre 2014): 1817–22. http://dx.doi.org/10.4028/www.scientific.net/amr.1070-1072.1817.
Testo completoAbstract (sommario):
The research and development situation of liquid nitrogen coil-wound heat exchanger were discussed in view of heat exchange in gas purification field in petrol-chemical industry. The basic designing methods and the multi-stream heat exchange process were illustrated by the cryogenic and high pressure crossing heat exchange equipments of liquid nitrogen coil-wound heat exchanger with multi-stream and multiphase flow, including Three-stream back-cooling heat exchangerin first stage, Four-stream back-cooling heat exchangerin second stage, Five-stream back-cooling heat exchangerin third stage, Multi-stream main back-coolingcoil-wound heat exchanger etc. A series of coil-wound heat exchangers with different mixed fluids and different applications were described. The winding structure characteristics and the work principles of the spiral pipe bundles were elaborated to give references for the scientific design and calculation of coil-wound heat exchanger in cryogenic field. The important research directions and the critical scientific problems were forecasted.
8
Rydalina, N. V., B. G. Aksenov, O. A. Stepanov e E. O. Antonova. "Application of porous materials in heat exchangers of heat supply system". Power engineering: research, equipment, technology 22, n. 3 (8 settembre 2020): 3–13. http://dx.doi.org/10.30724/1998-9903-2020-22-3-3-13.
Testo completoAbstract (sommario):
Heat exchange capacity increase is one of the main concerns in the process of manufacturing modern heat exchange equipment. Constructing heat exchangers with porous metals is an advanced technique of heat exchange increase. A construction of heat exchangers with porous aluminum is described in this paper. The first heat transfer agent (hot water) flows through thin copper tubes installed within the porous aluminum. The second heat transfer agent (freon) flows through the pores of aluminum. Laboratory facility was created to study such a heat exchanger. Series of experiments were carried out. The purpose of the research presented here is to create a mathematical model of heat exchangers with porous metals, to perform analytical calculation of the heat exchangers and to confirm the results with the experimental data. In this case, one can`t use the standard methods of heat exchangers calculation because the pores inner surface area is indeterminate. The developed mathematical model is based on the equation describing the process of cooling the porous plate. A special mathematical technique is used to take into account the effect of tubes with water. The model is approximate but its solution is analytic. It is convenient. One can differentiate it or integrate it, which is very important. Comparison of calculated and experimental data is performed. Divergence of results is within the limits of experimental error. If freon volatilizes inside the heat exchanger, the heat of phase transition has to be taken into account alongside with heat capacity. The structure of the mathematical model makes it possible. The results presented in this paper prove the practicability of using porous materials in heat exchange equipment.
9
Fakheri, Ahmad. "Heat Exchanger Efficiency". Journal of Heat Transfer 129, n. 9 (16 novembre 2006): 1268–76. http://dx.doi.org/10.1115/1.2739620.
Testo completoAbstract (sommario):
This paper provides the solution to the problem of defining thermal efficiency for heat exchangers based on the second law of thermodynamics. It is shown that corresponding to each actual heat exchanger, there is an ideal heat exchanger that is a balanced counter-flow heat exchanger. The ideal heat exchanger has the same UA, the same arithmetic mean temperature difference, and the same cold to hot fluid inlet temperature ratio. The ideal heat exchanger’s heat capacity rates are equal to the minimum heat capacity rate of the actual heat exchanger. The ideal heat exchanger transfers the maximum amount of heat, equal to the product of UA and arithmetic mean temperature difference, and generates the minimum amount of entropy, making it the most efficient and least irreversible heat exchanger. The heat exchanger efficiency is defined as the ratio of the heat transferred in the actual heat exchanger to the heat that would be transferred in the ideal heat exchanger. The concept of heat exchanger efficiency provides a new way for the design and analysis of heat exchangers and heat exchanger networks.
10
Osipov, S. N., e A. V. Zakharenko. "Energy-Efficient Compact Heat Exchangers Made of Porous Heat-Conducting Materials". ENERGETIKA. Proceedings of CIS higher education institutions and power engineering associations 61, n. 4 (20 luglio 2018): 346–58. http://dx.doi.org/10.21122/1029-7448-2018-61-4-346-358.
Testo completoAbstract (sommario):
After successful increase of levels of thermal resistances of building enclosing structures, expenses of heat on ventilation of rooms in many cases reached similar magnitudes of indicators of heating in a cold season. Therefore, the development of new efficient heat exchangersheat exchangers of small size is of particular importance. It is possible now to create highperformance thin (of a few centimeters) heat exchangers of such high-porous heat-conducting materials as copper, aluminum, etc. Highly porous materials include porous-permeable structures having an open porosity (with a total pore surface area of more than 50 % in relation to a smooth surface). One of the main conditions for the qualitative use of such high-porous thermal conductive materials is the rapid removal of condensate outside the heat exchange zone without a significant increase in filtration resistance. Thermal calculation of such heat exchangers is based on the criteria of Fourier (Fu) and Predvoditelev (Рd). Various ways of using high-porous heat-conducting materials in the design of heat exchangers are considered. The method of production of the heat exchanger based on the application of porous-permeable material in the channels of the heat exchange part of recuperative devices is presented; the difference of the method is that the heat exchange part is performed of two or more parallel heat exchange plates with spacing between them. It has been found that a significant increase in the energy efficiency of heat exchangers of this type is possible due to the application of even small discontinuities of the heat-conducting layers of high-porous materials so to use the specific features of increased heat exchange of the initial sections with the flowing fluid. One of the main advantages of using air-to-air heat exchangers made of foamed high-heat-conducting material in the climatic conditions of Belarus is freezing resistance.
11
Mikulionok, Іgor, Аnton Karvatskii, Olena Ivanenko e Serhii Leleka. "Heat exchangers with fluidization of bulk material (Design review)". Proceedings of the NTUU “Igor Sikorsky KPI”. Series: Chemical engineering, ecology and resource saving, n. 3 (30 settembre 2022): 23–38. http://dx.doi.org/10.20535/2617-9741.3.2022.265359.
Testo completoAbstract (sommario):
A classification of heat exchangers with fluidization of bulk material for use in enterprises of the chemical, mining, construction, food, metallurgical and processing industries has been developed. A critical review of the most characteristic designs of heat exchangers with a fluidized bed, proposed by scientists, designers and inventors of the leading countries of the world, has been carried out. The designs of heat exchangers are analyzed depending on the method of fluidization, the role of bulk material in the heat exchange process, the nature of the heat exchange process over time, the nature of fluidization (in continuous heat exchangers), the mechanism of heat exchange of bulk material, the number of fluidized beds, the presence of additional heat exchange devices in the heat exchanger, the presence of movable structural elements, as well as the type of bulk material of the fluidized bed.
An analysis of the designs of heat exchangers with a fluidized bed indicates their considerable diversity, however, the most simple to manufacture and operate reliable devices with fixed structural elements and one fluidized bed remain in demand by the industry. The most promising direction for improving fluidized bed heat exchangers is the development of specialized (for processing bulk material or fluid coolant) designs of apparatuses.
In the future, it is planned to analyze the designs of other types of heat exchangers, as well as ways to improve their efficiency.
12
Zheng, Can, Fei Wang e Yong Gang Lei. "Numerical Simulation of a Shell-and-Tube Heat Exchanger with Special Form Helical Baffles". Advanced Materials Research 860-863 (dicembre 2013): 754–57. http://dx.doi.org/10.4028/www.scientific.net/amr.860-863.754.
Testo completoAbstract (sommario):
A new type of helical baffles heat exchanger is presented in this paper. Comparative study, through numerical simulation, was undertook between the new helical baffles heat exchanger and segmental baffle board heat exchanger in shell side flow and heat exchange characteristics. Fluid medium in the shell side is air. At the same velocity in the same flow conditions, pressure drop of helical baffles heat exchangers fell by an average of 26.8% compared with segmental baffle board heat exchangers, and the unit pressure drop of the heat transfer ratio of helical baffles heat exchanger increased by an average of 40.6%.
13
Chen, T. Y., H. P. Cho, C. S. Jwo, M. H. Hung e W. S. Lee. "Analyzing How the ZrO2Far Infrared Material Affects the Performance of Smooth Tube Heat Exchangers". Journal of Nanomaterials 2015 (2015): 1–6. http://dx.doi.org/10.1155/2015/124632.
Testo completoAbstract (sommario):
The aim of this study was to investigate the effect of the 100 nm ZrO2far infrared material on the heat exchange efficiency of smooth tube heat exchangers. In the experiments designed for this purpose, the ZrO2powder and water based acrylic paint were mixed separately using a two-step mixing method and the mixture samples were sprayed, respectively, onto heat exchangers for testing their heat exchange efficiency under stable ambient conditions. Results from the experiments showed 31.8% and 21.5% increases in heat transfer in the heat exchanger sprayed with 7.5 wt.% ZrO2powder and with inlet water temperatures at 45°C and 55°C relative to the heat exchanger sprayed with 0 wt.% acrylic paint and 26.4% and 18.9% increases in heat transfer relative to the heat exchanger not sprayed with acrylic paint. The experiments also verified that heat could be transferred through radiation. The additive ZrO2nanopowder in these experiments is proven to be able to improve the efficiency of heat exchangers through radiation, thereby increasing the feasibility of its application in practice.
14
Haghshenas, Fard, Mohammad Talaie e Somaye Nasr. "Numerical and experimental investigation of heat transfer of ZnO/Water nanofluid in the concentric tube and plate heat exchangers". Thermal Science 15, n. 1 (2011): 183–94. http://dx.doi.org/10.2298/tsci091103048h.
Testo completoAbstract (sommario):
The plate and concentric tube heat exchangers are tested by using the water-water and nanofluid-water streams. The ZnO/Water (0.5%v/v) nanofluid has been used as the hot stream. The heat transfer rate omitted of hot stream and overall heat transfer coefficients in both heat exchangers are measured as a function of hot and cold streams mass flow rates. The experimental results show that the heat transfer rate and heat transfer coefficients of the nanofluid in both of the heat exchangers is higher than that of the base liquid (i.e., water) and the efficiency of plate heat exchange is higher than concentric tube heat exchanger. In the plate heat exchanger the heat transfer coefficient of nanofluid at mcold = mhot = 10 gr/sec is about 20% higher than base fluid and under the same conditions in the concentric heat exchanger is 14% higher than base fluid. The heat transfer rate and heat transfer coefficients increases with increase in mass flow rates of hot and cold streams. Also the CFD1 code is used to simulate the performance of the mentioned heat exchangers. The CFD results are compared to the experimental data and showed good agreement. It is shown that the CFD is a reliable tool for investigation of heat transfer of nanofluids in the various heat exchangers.
15
Cui, W. H., L. H. Gong, Q. M. Jia, Z. Y. Li, M. He, W. P. Zhu e M. M. Zhang. "Numerical study of heat transfer characteristics of intermittent flow cold storage surface heat exchanger". IOP Conference Series: Materials Science and Engineering 1301, n. 1 (1 maggio 2024): 012036. http://dx.doi.org/10.1088/1757-899x/1301/1/012036.
Testo completoAbstract (sommario):
Abstract The intermittent flow cold storage surface heat exchanger is a key component of the new pulse tube expansion cryogenic refrigerator, which is responsible for the periodic heat transfer of cold and hot helium, and its heat exchange efficiency directly affects the thermodynamic efficiency of the whole machine. In this study, a three-dimensional model of the heat exchanger unit is established, and numerical simulation is employed to investigate its heat exchange characteristics. The analysis focuses on understanding the internal temperature distribution patterns within the heat exchanger and explores the influence of wall materials on its heat transfer characteristics. Results show that the existence of the temperature lag loop minimizes the effective heat transfer temperature difference, consequently decreasing the heat exchanger’s efficiency. Moreover, the choice of wall material significantly affects the performance of the heat exchanger, with optimal thermal conductivity and volumetric specific heat enhancing its efficiency. This research provides valuable insights for future design and improvement of similar heat exchangers.
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Ghorbani, M., e S. F. Ranjbar. "Optimization of Compressed Heat Exchanger Efficiency by Using Genetic Algorithm". International Journal of Applied Mechanics and Engineering 24, n. 2 (1 maggio 2019): 461–72. http://dx.doi.org/10.2478/ijame-2019-0029.
Testo completoAbstract (sommario):
Abstract Due to the application of coil-shaped coils in a compressed gas flow exchanger and water pipe flow in airconditioner devices, air conditioning and refrigeration systems, both industrial and domestic, need to be optimized to improve exchange capacity of heat exchangers by reducing the pressure drop. Today, due to the reduction of fossil fuel resources and the importance of optimal use of resources, optimization of thermal, mechanical and electrical devices has gained particular importance. Compressed heat exchangers are the devices used in industries, especially oil and petrochemical ones, as well as in power plants. So, in this paper we try to optimize compressed heat exchangers. Variables of the functions or state-of-the-machine parameters are optimized in compressed heat exchangers to achieve maximum thermal efficiency. To do this, it is necessary to provide equations and functions of the compressed heat exchanger relative to the functional variables and then to formulate the parameter for the gas pressure drop of the gas flow through the blades and the heat exchange surface in relation to the heat duty. The heat transfer rate to the gas-side pressure drop is maximized by solving the binary equation system in the genetic algorithm. The results show that using optimization, the heat capacity and the efficiency of the heat exchanger improved by 15% and the pressure drop along the path significantly decreases.
17
Sliwa, Tomasz, Aneta Sapińska-Śliwa, Andrzej Gonet, Tomasz Kowalski e Anna Sojczyńska. "Geothermal Boreholes in Poland—Overview of the Current State of Knowledge". Energies 14, n. 11 (2 giugno 2021): 3251. http://dx.doi.org/10.3390/en14113251.
Testo completoAbstract (sommario):
Geothermal energy can be useful after extraction from geothermal wells, borehole heat exchangers and/or natural sources. Types of geothermal boreholes are geothermal wells (for geothermal water production and injection) and borehole heat exchangers (for heat exchange with the ground without mass transfer). The purpose of geothermal production wells is to harvest the geothermal water present in the aquifer. They often involve a pumping chamber. Geothermal injection wells are used for injecting back the produced geothermal water into the aquifer, having harvested the energy contained within. The paper presents the parameters of geothermal boreholes in Poland (geothermal wells and borehole heat exchangers). The definitions of geothermal boreholes, geothermal wells and borehole heat exchangers were ordered. The dates of construction, depth, purposes, spatial orientation, materials used in the construction of geothermal boreholes for casing pipes, method of water production and type of closure for the boreholes are presented. Additionally, production boreholes are presented along with their efficiency and the temperature of produced water measured at the head. Borehole heat exchangers of different designs are presented in the paper. Only 19 boreholes were created at the Laboratory of Geoenergetics at the Faculty of Drilling, Oil and Gas, AGH University of Science and Technology in Krakow; however, it is a globally unique collection of borehole heat exchangers, each of which has a different design for identical geological conditions: heat exchanger pipe configuration, seal/filling and shank spacing are variable. Using these boreholes, the operating parameters for different designs are tested. The laboratory system is also used to provide heat and cold for two university buildings. Two coefficients, which separately characterize geothermal boreholes (wells and borehole heat exchangers) are described in the paper.
18
Yu, Chao, Mingzhen Shao, Wenbao Zhang, Guangyi Wang e Mian Huang. "Study on Heat Transfer Synergy and Optimization of Capsule-Type Plate Heat Exchangers". Processes 12, n. 3 (18 marzo 2024): 604. http://dx.doi.org/10.3390/pr12030604.
Testo completoAbstract (sommario):
An efficient and accurate method for optimizing capsule-type plate heat exchangers is proposed in this paper. This method combines computational fluid dynamics simulation, a backpropagation algorithm and multi-objective optimization to obtain better heat transfer performance of heat exchanger structures. For plate heat exchangers, the heat transfer coefficient j and friction coefficient f are a pair of contradictory objectives. The optimization of capsule-type plate heat exchangers is a multi-objective optimization problem. In this paper, a backpropagation neural network was used to construct an approximate model. The plate shape was optimized by a multi-objective genetic algorithm. The optimized capsule-type plate heat exchanger has lower flow resistance and higher heat exchange efficiency. After optimization, the heat transfer coefficient is increased by 8.3% and the friction coefficient is decreased by 14.3%, and the heat transfer effect is obviously improved. Further, analysis of flow field characteristics through field co-ordination theory provides guidance for the further optimization of plates.
19
Zhang, Yin, Yinping Zhang e Xin Wang. "Inverse Problem Method to Optimize Cascade Heat Exchange Network in Central Heating System". International Journal of Energy Optimization and Engineering 9, n. 3 (luglio 2020): 62–82. http://dx.doi.org/10.4018/ijeoe.2020070105.
Testo completoAbstract (sommario):
In central heating systems, heat is often transferred from heat source to users by the heat network where several heat exchangers are installed at the heat source, substations, and terminals. In this article, the mathematical optimization model of the cascade heat exchange network with three-stage heat exchangers in a series is established. The aim is to maximize the cold fluid temperature for a given hot fluid temperature and overall heating capacity, the optimal heat exchange area distribution, and the medium fluid flow rates are determined through an inverse problem and variation method. The results show that the heat exchange areas should be distributed equally for each heat exchanger. It also indicates that in order to improve the thermal performance of the whole system, more heat exchange areas should be allocated to the heat exchanger where flow rate difference between two fluids is relatively small.
20
Azwinur, Azwinur, e Zulkifli Zulkifli. "KAJI EKSPERIMENTAL PENGARUH BAFFLE PADA ALAT PENUKAR PANAS ALIRAN SEARAH DALAM UPAYA OPTIMASI SISTEM PENGERING". SINTEK JURNAL: Jurnal Ilmiah Teknik Mesin 13, n. 1 (1 giugno 2019): 8. http://dx.doi.org/10.24853/sintek.13.1.8-14.
Testo completoAbstract (sommario):
Heat exchangers or heat exchangers are tools used to change the temperature of the fluid or change the fluid phase by exchanging heat with another fluid. In a heat exchanger, the ability to exchange heat is largely determined by the type of fluid flow and fluid passing through the heat exchanger. The use of heat exchangers in the field of drying is now a necessity to overcome the problems of drying productivity. The purpose of this study was carried out to determine the effectiveness of the heat exchanger experimentally based on directional flow by comparing construction using baffle and without using baffle in an effort to optimize the drying system. The research method was carried out by fabricating 2 units of heat exchangers and by field testing. The test data obtained are the input and output temperatures of the heating fluid flow and cooling fluid flow and flow velocity. Based on preliminary research data shows that the use of baffle affects the increase in temperature on the heat exchanger, where at the fresh air outlet that does not use baffle produces a temperature of 72oC while the baffle produces 88oC with the Log Mean Temperature Difference heat exchanger without using a baffle higher than heat exchanger that uses a baffle guide blade. This can illustrate that the smaller heat losses are wasted so that the absorption of heat by the reverse system will be higher.
21
Liu, Qing Yun, Fu Bing Tu e Sheng Yang Gao. "Numerical Simulation and Optimization of Radial Heat Pipe Heat Exchanger Based on Field Synergy Principle". Advanced Materials Research 834-836 (ottobre 2013): 1418–22. http://dx.doi.org/10.4028/www.scientific.net/amr.834-836.1418.
Testo completoAbstract (sommario):
This paper mainly explores the numerical simulation of flow and temperature fields in the shell-side of the radial heat pipe heat exchangers (HPHE), using CFD software-FLUENT. Field synergy principle is applied to analyze heat and mass transfer mechanism of heat exchangers; also, the influence of the variation of principle constructor parameters of heat exchangers on the field synergy effect and heat exchange performance has been studied. It has been found that better performance of heat exchangers is achieved with better field synergy effect; in the context of increasing transverse and longitudinal tube pitches within certain values of data, the heat transfer coefficient decreases as synergy angle increases. Variation of fin height has little effect on synergy angle, but it would decrease the heat transfer coefficient at unit pressure drop (k/Δp) as it increases; as fin pitch increases, the synergy angle first decreases and then grows, while k/Δp first increases and then decreases. The optimal ranges of heat exchanger structure parameters values were found.
22
Zhou, Tao, Bingchao Chen e Huanling Liu. "Study of the Performance of a Novel Radiator with Three Inlets and One Outlet Based on Topology Optimization". Micromachines 12, n. 6 (21 maggio 2021): 594. http://dx.doi.org/10.3390/mi12060594.
Testo completoAbstract (sommario):
In recent years, in order to obtain a radiator with strong heat exchange capacity, researchers have proposed a lot of heat exchangers to improve heat exchange capacity significantly. However, the cooling abilities of heat exchangers designed by traditional design methods is limited even if the geometric parameters are optimized at the same time. However, using topology optimization to design heat exchangers can overcome this design limitation. Furthermore, researchers have used topology optimization theory to designed one-to-one and many-to-many inlet and outlet heat exchangers because it can effectively increase the heat dissipation rate. In particular, it can further decrease the hot-spot temperature for many-to-many inlet and outlet heat exchangers. Therefore, this article proposes novel heat exchangers with three inlets and one outlet designed by topology optimization to decrease the fluid temperature at the outlet. Subsequently, the effect of the channel depth on the heat exchanger design is also studied. The results show that the type of exchanger varies with the channel depth, and there exists a critical depth value for obtaining the minimum substrate temperature difference. Then, the flow and heat transfer performance of the heat exchangers are numerically investigated. The numerical results show that the heat exchanger derived by topology optimization with the minimum temperature difference as the goal (Model-2) is the best design for flow and heat transfer performance compared to other heat sink designs, including the heat exchanger derived by topology optimization having the average temperature as the goal (Model-1) and conventional straight channels (Model-3). The temperature difference of Model-1 can be reduced by 37.5%, and that of Model-2 can be decreased by 62.5% compared to Model-3. Compared with Model-3, the thermal resistance of Model-1 can be reduced by 21.86%, while that of Model-2 can be decreased by 47.99%. At room temperature, we carried out the forced convention experimental test for Model-2 to measure its physical parameters (temperature, pressure drop) to verify the numerical results. The error of the average wall temperature between experimental results and simulation results is within 2.6 K, while that of the fluid temperature between the experimental and simulation results is within 1.4 K, and the maximum deviation of the measured Nu and simulated Nu was less than 5%. This indicated that the numerical results agreed well with the experimental results.
23
Wang, Fang, Yunding Li, Mengwei Liu, Dongqing Pang, Weifeng Du, Yichi Zhang, Xiaoqian Cheng, Tangtang Gu e Wenliang Guo. "Comprehensive Evaluation of the Performances of Heat Exchangers with Aluminum and Copper Finned Tubes". International Journal of Chemical Engineering 2023 (20 dicembre 2023): 1–11. http://dx.doi.org/10.1155/2023/6666947.
Testo completoAbstract (sommario):
The finned-tube heat exchanger is the core part of an air conditioning system. Its heat exchange performance directly affects the energy consumption and efficiency of the air conditioner. The shortage and rising price of copper have led to increasing replacement of copper tubes with aluminum tubes in finned-tube heat exchangers. This paper studies two kinds of such heat exchangers, one consisting of copper tubes and aluminum fins and the other consisting of aluminum tubes and aluminum fins. The influences of the different base tube materials on heat transfer are compared and analyzed in terms of heat transfer strength and cost per unit heat transfer. The results show that the heat transfer and heat transfer coefficient increase with increasing inlet wind speed. Under different inlet wind speeds, the heat transfer and heat transfer coefficient of the finned-tube heat exchanger with aluminum tubes are 4%–12% and 7%%–9% lower than those of an identically structured heat exchanger with copper tubes, respectively. The aluminum-aluminum exchanger achieves 67% higher heat transfer than that of the copper-aluminum exchanger at only 8% of the cost. These results are significant for guiding the development and application of finned-tube heat exchangers.
24
Kovarik, M. "Optimal Heat Exchangers". Journal of Heat Transfer 111, n. 2 (1 maggio 1989): 287–93. http://dx.doi.org/10.1115/1.3250676.
Testo completoAbstract (sommario):
The design of optimal heat exchangers is formulated as the solution of five simultaneous equations. The analysis of these equations yields general properties of optimal crossflow heat exchangers; in particular, an upper bound of 1/3 is given for the fractional cost of maintaining the flow through the heat exchanger. Some of these general properties also apply in the presence of a simple constraint. It is shown that some technically feasible designs cannot be optimal under realistic costs and others under any costs.
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Mikielewicz, Dariusz, e Jan Wajs. "Possibilities of Heat Transfer Augmentation in Heat Exchangers with Minichannels for Marine Applications". Polish Maritime Research 24, s1 (25 aprile 2017): 133–40. http://dx.doi.org/10.1515/pomr-2017-0031.
Testo completoAbstract (sommario):
Abstract In the paper, new trends in the development of microchannel heat exchangers are presented. The exchangers developed in this way can be applied in marine industry. Main attention is focused on heat exchanger design with reduced size of passages, namely based on microchannels. In authors′ opinion, future development of high power heat exchangers will be based on networks of micro heat exchangers.
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Ghosh, I., S. K. Sarangi e P. K. Das. "Simulation Algorithm for Multistream Plate Fin Heat Exchangers Including Axial Conduction, Heat Leakage, and Variable Fluid Property". Journal of Heat Transfer 129, n. 7 (27 dicembre 2006): 884–93. http://dx.doi.org/10.1115/1.2717938.
Testo completoAbstract (sommario):
The effect of axial conduction through heat exchanger matrix, heat exchange with the surroundings, and variable fluid properties are included in the simulation algorithm of multistream plate fin heat exchangers. The procedure involves partitioning of the exchanger in both axial and normal directions, writing conservation equations for each segment, and solving them using an iterative procedure. In the normal direction, the exchanger is divided into a stack of overlapping two-stream exchangers interacting through their common streams. In the axial direction, the exchanger is successively partitioned to 2k segments, the final value of k being determined by the point where further partitioning has only marginal effect. The effects of axial conduction, heat leakage, and variable fluid properties are illustrated with the help of multistream heat exchanger examples solved by the above-mentioned technique.
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Ding, Yi, Qiang Guo, Wenyuan Guo, Wenxiao Chu e Qiuwang Wang. "Review of Recent Applications of Heat Pipe Heat Exchanger Use for Waste Heat Recovery". Energies 17, n. 11 (23 maggio 2024): 2504. http://dx.doi.org/10.3390/en17112504.
Testo completoAbstract (sommario):
With the reduction in fossil fuels and growing concerns about global warming, energy has become one of the most important issues facing humanity. It is crucial to improve energy utilization efficiency and promote a low-carbon transition. In comparison with traditional heat exchangers, heat pipe heat exchangers indicate high compactness, a flexible arrangement, complete separation of hot and cold fluids, good isothermal operations, etc. As a result, heat pipe heat exchangers have attracted wide attention and application in various fields in recent years. This paper provides an overview of the application of heat pipe heat exchangers, with a focus on the application in waste heat recovery, and analyzes the opportunities and challenges of heat pipe heat exchanger applications based on existing publications.
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Dawood Jumaah, Itimad, Senaa Kh. Ali e Anees A. Khadom. "Evaluation Analysis of Double Coil Heat Exchanger for Heat Transfer Enhancement". Diyala Journal of Engineering Sciences 14, n. 1 (15 marzo 2021): 96–107. http://dx.doi.org/10.24237/djes.2021.14109.
Testo completoAbstract (sommario):
In order to maximize the thermal efficiency of shell and coil heat exchangers, substantial research has been done and geometrical modification is one way to improve the exchange of thermal energy between two or more fluids. One of the peculiar features of coiled geometry is that the temperature distribution is highly variable along the circumferential section due to the centrifugal force induced in the fluid. Moreover, most researchers are concentrated on using a shell and single helical coil heat exchanger to enhance the heat transfer rate and thermal efficiency at different operating parameters. Therefore, the aim of this study is to investigate temperature variation ((T-1, T-2, T-3 and T-4) across a shell and single/double coil heat exchanger at different coil pitches, hot water flow rate, and cold-water flow rate along the outer surface of the coil using experimental and numerical analysis. For single and double coil heat exchangers, Computational Fluid Dynamics (CFD) is carried out using pure water with a hot water flow rate ranging between 1-2 l/min for the coil side heat exchanger. For single coil heat exchangers, the numerical analysis findings showed a good agreement with experimental four-temperature measurement results (T-1, T-2, T-3 and T-4) with an error rate of 1.80%, 3.05%, 5.34% and 2.17% respectively. Moreover, in the current double coil analysis, the hot outlet temperature decreased by 3.07% compared to a single coil (baseline case) at a 2.5L/min hot water flow rate. In addition, increasing the coil pitch will increase the contact between the hot fluid and the coil at a constant hot water flow rate and thereby decrease the hot fluid outlet temperature. Finally, a computational analysis was carried out to examine the flow structure inside single and double coil heat exchangers, and the findings indicated that the effect of centrifugal forces in double coil heat exchangers at various coil pitches caused the secondary flow to be substantially reduced.
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Dzianik, František, Štefan Gužela e Eva Puškášová. "Suitability Assessment of Two Types of Heat Exchangers for High Temperature, Naturally Circulating Helium Cooling Loop". Strojnícky casopis – Journal of Mechanical Engineering 69, n. 1 (1 maggio 2019): 39–50. http://dx.doi.org/10.2478/scjme-2019-0003.
Testo completoAbstract (sommario):
AbstractThe paper presents a comparison of the process properties of two types of the heat exchangers designed for the heat removal from a high temperature helium cooling loop with steady natural circulation of helium. The first considered heat exchanger is a shell and tube heat exchanger with U-tubes and the other one is a helical coil heat exchanger. Using the thermal and hydrodynamic process calculations, the thermal performance of the two alternative heat exchangers are determined, as well as the pressure drops of flowing fluids in their workspaces. The calculations have been done for several defined operating conditions of two considered types of heat exchangers. The operating conditions of heat exchangers correspond to the certain helium flow rates.
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Zhelykh, Vasyl, Olena Savchenko e Vadym Matusevych. "Horizontal earth-air heat exchanger for preheating external air in the mechanical ventilation system". Selected Scientific Papers - Journal of Civil Engineering 13, n. 1 (1 dicembre 2018): 71–76. http://dx.doi.org/10.1515/sspjce-2018-0021.
Testo completoAbstract (sommario):
Abstract To save traditional energy sources in mechanical ventilation systems, it is advisable to use low-energy ground energy for preheating or cooling the outside air. Heat exchange between ground and outside air occurs in ground heat exchangers. Many factors influence the process of heat transfer between air in the heat exchanger and the ground, in particular geological and climatic parameters of the construction site, parameters of the ventilation air in the projected house, physical and geometric parameters of the heat exchanger tube. Part of the parameters when designing a ventilation system with earth-air heat exchangers couldn’t be changed. The one of the factors, the change which directly affects the process of heat transfer between ground and air, is convective heat transfer coefficient from the internal surface of the heat exchanger tube. In this article the designs of a horizontal earthair heat exchanger with heat pipes was proposed. The use of heat pipes in designs of a horizontal heat exchanger allows intensification of the process of heat exchange by turbulence of air flow inside the heat exchanger. Besides this, additionally heat transfer from the ground to the air is carried out at the expense of heat transfer in the heat pipe itself.
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Kumar, Sunil, e Ravindra Mohan. "A Review on The CFD Analysis of Nano Water Fluid On Helically Coiled Double Tube Heat Exchanger". SMART MOVES JOURNAL IJOSCIENCE 5, n. 10 (16 ottobre 2019): 3. http://dx.doi.org/10.24113/ijoscience.v5i10.232.
Testo completoAbstract (sommario):
Heat exchanger is an important device which is used in thermal systems in many industrial fields. Nano fluids are recently employed as coolants to improve the efficacy of heat exchangers. Regarding unique characteristics of Nano fluids, research studies in this area have witnessed a remarkable growth. Latest investigations conducted on use of Nano fluids in heat exchangers including those carried out on plate heat exchangers, double pipe heat exchangers, shell and tube heat exchangers, and compact heat exchangers are reviews and summarized. Meanwhile, some very interesting aspects of Nano fluids in combination with heat exchangers are presented. The challenges and prospects for future research are presented in this paper.
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Pulin, Anton, Mikhail Laptev, Nikolay Kortikov, Viktor Barskov, Gleb Roschenko, Kirill Alisov, Ivan Talabira et al. "Numerical Investigation of Heat Transfer Intensification Using Lattice Structures in Heat Exchangers". Energies 17, n. 13 (7 luglio 2024): 3333. http://dx.doi.org/10.3390/en17133333.
Testo completoAbstract (sommario):
Heat exchangers make it possible to utilize energy efficiently, reducing the cost of energy production or consumption. For example, they can be used to improve the efficiency of gas turbines. Improving the efficiency of a heat exchanger directly affects the efficiency of the device for which it is used. One of the most effective ways to intensify heat exchange in a heat exchanger without a significant increase in mass-dimensional characteristics and changes in the input parameters of the flows is the introduction of turbulators into the heat exchangers. This article investigates the increase in efficiency of heat exchanger apparatuses by introducing turbulent lattice structures manufactured with the use of additive technologies into their design. The study is carried out by numerical modeling of the heat transfer process for two sections of the heat exchanger: with and without the lattice structure inside. It was found that lattice structures intensify the heat exchange by creating vortex flow structures, as well as by increasing the heat exchange area. Thus, the ratio of convection in thermal conductivity increases to 3.03 times. Also in the article, a comparative analysis of the results obtained with the results of heat transfer intensification using classical flow turbulators is carried out. According to the results of the analysis, it was determined that the investigated turbulators are more effective than classical ones, however, the pressure losses in the investigated turbulators are much higher.
33
Fyk, Mykhailo, Volodymyr Biletskyi, Ihor Ryshchenko e Mohammed Abbood. "Improving the geometric topology of geothermal heat exchangers in oil bore-holes". E3S Web of Conferences 123 (2019): 01023. http://dx.doi.org/10.1051/e3sconf/201912301023.
Testo completoAbstract (sommario):
A review has been conducted of key trends in the development of geometric topology of geothermal heat exchangers. Authors proposed approaches to improving the designs and network structures for heat-transfer media circulation in the bottom-hole space of oil-and-gas reservoirs. Four geometric topologies of geothermal heat exchangers have been analysed: І – ІІ – rectilinear vertical smooth and finned pipelines; ІІІ – IV – a cluster in the form of a set of smooth and finned single-pipe elements, representing a figure of “squirrel wheel” or “meridian sphere” type. It is shown that the most effective technical solution, which ensures the increase in the coefficient of performance (COP) of bore-hole geothermal systems is finning the heat exchanging pipes. For the heat exchangers of І – ІІ type, the calculated increase in COP in comparison with smooth pipes is 40%, and for ІІІ – IV type – 95%. The key parameters influencing the COP of a geothermal heat exchanger are: the radius of fluids draining out during the heat exchange process, the radius of pipelines with circulating heat-transfer medium, the diameter of a cluster heat exchanger, the heat exchange area, the parameters of rocks thermal resistance in the bottom-hole zone of heat-receiving.
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Veerabhadrappa, Kavadiki, Dhanush Dayanand, Darshan Dayanand, Vinayakaraddy, K. N. Seetharamu e Preadeep Hegde. "Analysis of Two Fluid Four-Channel Heat Exchanger Using Finite Element Method". Applied Mechanics and Materials 813-814 (novembre 2015): 658–62. http://dx.doi.org/10.4028/www.scientific.net/amm.813-814.658.
Testo completoAbstract (sommario):
The development of heat exchangers from two streams to multi-stream passage arrangement becomes a key problem for heat exchanger design. In this paper, a new design is developed for multi-stream (four-channel) heat exchanger. Multi-channel heat exchangers are extensively used in refrigeration and air conditioning, chemical industries, milk pasteurization, cryogenics industries and energy-recovery applications due to their higher heat transfer rates. The focus of this study is to determine the performance of four-channel counter flow heat exchanger. The hot and cold fluids are assumed to recirculate and exchange heat between them. Finite element model of the heat exchanger is developed based on the detailed geometry and the specific working conditions with the help of which effectiveness of the four-channel heat exchanger is computed. Non-Dimensional parameters are introduced which makes the analysis more versatile. The effectiveness is computed for different values of NTU and heat capacity ratio.
35
McNaught, J. M. "Heat exchangers". Chemical Engineering Science 48, n. 22 (1993): 3877. http://dx.doi.org/10.1016/0009-2509(93)80232-f.
Testo completo
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Vago, G. J. "Heat exchangers". International Journal of Heat and Fluid Flow 13, n. 4 (dicembre 1992): 412. http://dx.doi.org/10.1016/0142-727x(92)90012-x.
Testo completo
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Dahl, S. D., e J. H. Davidson. "Performance and Modeling of Thermosyphon Heat Exchangers for Solar Water Heaters". Journal of Solar Energy Engineering 119, n. 3 (1 agosto 1997): 193–200. http://dx.doi.org/10.1115/1.2888018.
Testo completoAbstract (sommario):
Determining the performance of indirect solar heating systems that use thermosyphon heat exchangers requires knowledge of how thermosyphon flow rate and heat exchanger performance vary with operating conditions. In this paper, measured performance of a two-pass, tube-in-shell, double-wall heat exchanger is discussed in terms of modeling issues. Thermosyphon heat exchangers may operate in the developing, mixed convection regime where natural convection effects can significantly influence overall heat transfer and friction coefficients. Existing models which assume the thermal and hydraulic behaviors of thermosyphon heat exchangers are only functions of the thermosyphon and collector flow rates may not be suitable for all heat exchanger types. For example, the overall heat-transfer coefficient-area product for the two-pass, tube-in-shell heat exchanger is best expressed as a function of Reynolds, Grashof, and Prandtl numbers on the thermosyphon side of the heat exchanger. It is proposed that annual simulations of solar water heaters with thermosyphon heat exchangers use this type of relationship to characterize heat transfer in the heat exchanger.
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Liu, Yadan, Shaohua Chen, Caiyu Zhang, Hui Ma, Na Li e Juan Bai. "Power disassembly equipment for high efficiency heat transfer plate heat exchangers". Thermal Science 28, n. 2 Part B (2024): 1431–39. http://dx.doi.org/10.2298/tsci2402431l.
Testo completoAbstract (sommario):
Plate heat exchangers are realized by means of a heat transfer mechanism, in which heat is naturally transferred from the hot substance to the object with a lower temperature according to the laws of thermodynamics. Two liquids of different temperatures flow on the wall, heat transfer on the wall and convection of the liquid on the wall, thus promoting heat transfer between the two liquids. Under the same flow rate and power consumption conditions, its heat transfer coefficient is three times that of shell and tube heat exchangers, which is a key and efficient new equipment for effectively using effective resources and saving and developing new energy. However the heat supply plate heat exchanger has a tiny circulation surface and is easily obstructed. Regular maintenance and cleaning, troubleshooting, and plate replacement all necessitate frequent heat exchanger disassembly and installation. The requirements and challenges in dismantling and assembling the heat exchanger are very high, and manual disassembly is wasteful, making consistent force difficult to achieve. The current methods of disassembly and assembly are inefficient and incorrect. The intelligent mechanization of disassembly and assembly equipment is realized in this paper by driving, clamping, automatic control, distance measurement, sensing, and other systems. The problems of uneven force, low efficiency, and precision in plate heat exchanger disassembly and assembly are solved. Our power disassembly equipment for high efficiency heat transfer plate heat exchangers not only enhances disassembly efficiency and precision, but it also ensures the safe operation of the plate heat exchanger heating system, and the heat transfer efficiency and heat exchange efficiency are improved. Furthermore, it has a wide range of applications in the petroleum, chemical, and other industries.
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Luo, Xinmei, e Shengming Liao. "Numerical Study on Melting Heat Transfer in Dendritic Heat Exchangers". Energies 11, n. 10 (20 settembre 2018): 2504. http://dx.doi.org/10.3390/en11102504.
Testo completoAbstract (sommario):
The dendritic fin was introduced to improve the solid-liquid phase change in heat exchangers. A theoretical model of melting phase change in dendritic heat exchangers was developed and numerically simulated. The solid-liquid phase interface, liquid phase rate and dynamic temperature change in dendritic heat exchanger during melting process are investigated and compared with radial-fin heat exchanger. The results indicate that the dendritic fin is able to enhance the solid-liquid phase change in heat exchanger for latent thermal storage. The presence of dendritic fin leads to the formation of multiple independent PCM zones, so the heat can be quickly diffused from one point to across the surface along the metal fins, thereby making the PCM far away from heat sources melt earlier and faster. In addition, the dendritic structure makes the PCM temperature distribution more uniform over the entire zone inside heat exchangers due to high-efficient heat flow distribution of dendritic fins. As a result, the time required for the complete melting of the PCM in dendritic heat exchanger is shorter than that of the radial-fin heat exchanger.
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Abdel-Kawi, Osama, H. F. Elbakhshawangy e Abdelfatah Abdelmaksoud. "Numerical and Experimental Performance Analysis for Different Types of Heat Exchangers". Journal of Mechanical, Civil and Industrial Engineering 3, n. 1 (24 febbraio 2022): 13–27. http://dx.doi.org/10.32996/jmcie.2022.3.1.3.
Testo completoAbstract (sommario):
Heat exchangers are devices whose primary responsibility is to transfer heat, typically from one fluid to another. In such applications, the heat exchangers can be parallel flow, crossflow, or counter flow. An essential part of any heat exchanger analysis is the determination of the effectiveness of the heat exchanger. In the present work, three different types of heat exchangers are investigated. Numerical and experimental performance analyses are applied. The main objective of the present work is to compare the effectiveness of each heat exchanger at different conditions. Six experimental investigations for Plate, shell & tube, and fluidized bed heat exchangers are executed. All experimental tests are reached to steady-state conditions. The results show that the counter flow plate heat exchanger has an effectiveness of 90% compared with the parallel flow of 60% effectiveness for working experimental conditions. Also, the fouling effect in decreasing heat transfer is cleared. In the present work, fouling decreases effectiveness from about 18% to about 4%. In addition, the effectiveness of the fluidized bed heat exchanger depends on the material used for the bed. Finally, the overall heat transfer coefficient is obtained and compared for all experimental tests, and it is directly proportional to the effectiveness of the heat exchanger. The FEHT program is used to get the temperature distribution in all types of present work heat exchangers.
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Wu, Zhiwei, e Caifu Qian. "Study on Behavior of the Heat Exchanger with Conically-Corrugated Tubes and HDD Baffles". ChemEngineering 6, n. 1 (2 gennaio 2022): 1. http://dx.doi.org/10.3390/chemengineering6010001.
Testo completoAbstract (sommario):
Baffles with holes in different diameters (or HDD baffles) and conically-corrugated tubes are respectively longitudinal flow baffle and high-efficiency heat exchange tubes proposed by the author. In this paper, vibrations of tube bundles with HDD baffles and fluid flow as well as heat transfer inside conically-corrugated tubes were numerically simulated, and the heat exchanger with conically-corrugated tubes and HDD baffles was tested for the heat transfer efficiency. It is found that compared with the traditional segmental baffles, tube bundle vibrations in heat exchangers, if using the HDD baffles, can be significantly reduced. Regarding heat transfer efficiency, conically-corrugated tubes are much better than smooth tubes and even better than other high-efficiency heat transfer tubes. Compared with the traditional heat exchangers, heat exchangers constructed with conically-corrugated tubes and the HDD baffles can provide better heat transfer efficiency and less tube bundle vibration.
42
Badawy, Faris Ali, e Kadhum Audaa Jehhef. "NANOFLUIDS HEAT TRANSFER INTENSIFICATION IN DOUBLE PIPE HEAT EXCHANGERS: REVIEW ARTICLE". Acta Mechanica Malaysia 5, n. 2 (2022): 16–23. http://dx.doi.org/10.26480/amm.01.2022.16.23.
Testo completoAbstract (sommario):
In current years, the warmth switch enhancement developed with the aid of the usage of nanofluid. A nanofluid is a kind of fluid that organized by means of dispraised of nanoparticles of metal, oxides or carbides with 100 nm size that depressed in water, ethylene glycol or oil. The enhancement of warmness transfer overall performance through expending nanofluid primarily relies upon on the type of nanoparticles, kind of base fluid, form of nanoparticles, size of nanoparticles and nanoparticles attention in the base fluid. In this paper, several newly massive numbers of studied have been being provided to discover the nanofluid enhancement the warmth switch charge in several heat exchangers kinds such as double-pipe warmth exchangers, plate heat exchangers, cross-flow warmth exchangers and shell and tube warmth exchangers. In existing review article, it presents quite a few experimental and numerical research studies that investigated the impact of using nanoparticles in the single and hybrid nanofluids to acquire greater overall performance of enhancement of warmness switch in the double pipe warmness exchangers conferring to relative route of movement of fluids (Parallel flow and Counter flow) and the nature of warmth trade process. The current study showed that there is a wide use of nanofluids in double pipe heat exchangers in all dimensions. Where the comparison showed that the use of nanofluids, whether inside the inner tube or in the annular tube of the heat exchanger, will effectively lead to heat transfer, reduce the size of the heat exchanger and reduce the cost of manufacturing and materials
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Anantha, Sobhanadri, Senthilkumar Gnanamani, Vivekanandan Mahendran, Venkatesh Rathinavelu, Ramkumar Rajagopal, Dawit Tafesse e Parthipan Nadarajan. "A CFD investigation and heat transfer augmentation of double pipe heat exchanger by employing helical baffles on shell and tube side". Thermal Science 26, n. 2 Part A (2022): 991–98. http://dx.doi.org/10.2298/tsci201120300a.
Testo completoAbstract (sommario):
The inclusion of baffles in a double pipe heat exchanger is becoming increasingly important as it improves the heat exchanger's performance. The CFD analysis is used in this paper to investigate the performance of double pipe heat exchangers with and without helical baffles on both shell tube sides. The 3-D CFD model was created in Solid Works, and the FloEFD software was used to analyze the conjugate heat transfer between the heat exchanger's tube and shell sides. Heat transfer characteristic like outlet temperature of shell and tube are investigated along with pressure drop on shell and tube side. Based on CFD results of double pipe heat exchanger with helical baffle on both shell side and tube side (Type 4) gives the better results than the other type of heat exchangers with an increased pressure drop than the others, results reveals that Type 4 outlet temperature of shell side is 8% higher and on tube side it is 5.5% higher, also pressure drop on shell side is 12% higher and on tube side it is 42% higher than the other types.
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Wang, Bohong, Jiří Jaromír Klemeš, Petar Sabev Varbanov e Min Zeng. "An Extended Grid Diagram for Heat Exchanger Network Retrofit Considering Heat Exchanger Types". Energies 13, n. 10 (24 maggio 2020): 2656. http://dx.doi.org/10.3390/en13102656.
Testo completoAbstract (sommario):
Heat exchanger network (HEN) retrofit is a vital task in the process design to improve energy savings. Various types of heat exchangers such as shell and tube, double-pipe, compact plate, and spiral tube have their working temperature ranges and costs. Selecting suitable types of heat exchangers according to their temperature ranges and costs is a crucial aspect of industrial implementation. However, considering the type of heat exchangers in the HEN retrofit process is rarely seen in previous publications. This issue can be solved by the proposed Shifted Retrofit Thermodynamic Grid Diagram with the Shifted Temperature Range of Heat Exchangers (SRTGD-STR). The temperature ranges of six widely used heat exchanger types are coupled in the grid diagram. This diagram enables the visualisation of identifying the potential retrofit plan of HEN with heat-exchanger type selection. The retrofit design aims to minimise utility cost and capital cost. An illustrative example and a case study are presented to show the effectiveness of the method.
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Singh, Nitesh Kumar, e N. V. Saxena. "Study on Thermal Behavior of Flat Plate Heat Exchanger". SMART MOVES JOURNAL IJOSCIENCE 6, n. 7 (24 luglio 2020): 3235. http://dx.doi.org/10.24113/ijoscience.v6i7.315.
Testo completoAbstract (sommario):
The plate Fin-and-tube heat exchangers are one of the most common types of heat exchangers used in various industrial applications such as heating, cooling, air conditioning, power plants, chemical plants, petrochemical plants, oil refineries, natural gas processing, industry aerospace, and wastewater treatment. It is very important to reduce the size and weight and improve the heat transfer rate of the heat exchanger. Finned and tubular heat exchangers with different geometries and orientations are used to improve thermal performance. This paper presents the Plate fin heat exchanger and types of Plate Fin Heat Exchanger Surfaces.
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Abdul Razzaq, Ali k., e Khudheyer S. Mushatet. "A Review Study for a Twisted Tube Heat Exchanger". Journal of Nanofluids 12, n. 2 (1 marzo 2023): 299–317. http://dx.doi.org/10.1166/jon.2023.1926.
Testo completoAbstract (sommario):
They are considering the increasing demand and urgent need in different industries and the importance of heat exchangers imposed the development of heat exchangers to increase heat transfer and increase general performance, reducing volume and cost. The essential heat exchanger used in many industries is the double tube heat exchanger. This type has been distinguished by its simplicity and wide use in recent years. Several improvement methods have been applied, including passive, active, and compound techniques. Passive technologies change the geometry of heat exchangers and are one of the most effective processes to increase overall heat performance. Besides, the hybridization of flow liquids is one of the most critical approaches to increase heat transfer as nanofluids. This review discusses and analyzes the evolution of heat exchangers and methods for improving passive heat transmission. In addition, experimental and numerical research that used nanofluids in heat exchangers was discussed. Moreover, different twisted shapes of the heat exchanger tubes (elliptical and oval, square, and triangle) were studied, which generated secondary eddy flow that increases the intensity of turbulence and mixing, thus improving heat transfer. Also, additives inside heat exchanger tubes include twisted tapes, ribs, and conical rings. The engagement between the Nusselt number and the coefficient of friction was also offered.
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Sokolnikas, Ignas, Kęstutis Čiuprinskas e Jolanta Čiuprinskienė. "Minimization of the Lifecycle Cost of a Rotary Heat Exchanger Used in Building Ventilation Systems in Cold Climates". Strojniški vestnik – Journal of Mechanical Engineering 67, n. 6 (15 giugno 2021): 302–10. http://dx.doi.org/10.5545/sv-jme.2021.7168.
Testo completoAbstract (sommario):
This article presents an analysis of rotary heat exchangers (RHE) used as heat recovery units in building ventilation systems in cold climates. Usually, heat exchangers with the highest heat transfer efficiency are the preferable option for this purpose. However, such exchangers usually have the highest media pressure drop, thus requiring the highest amount of energy for media transportation. In this study, the problem is solved by analysing the lifecycle cost (LCC) of the RHE including both the recovered heat and the electricity consumed in the fans of the air handling unit (AHU). The purpose of the investigation was to determine the optimal set of geometrical characteristics such as the exchanger’s length, foil thickness, the height and width of the air channel. Two hundred and seventy different combinations were examined using analytical dependencies and ANSYS simulations. The results are compared with experimental data obtained earlier at the KOMFOVENT laboratory. The results show that the best overall energy efficiency is obtained in heat exchangers that do not offer the best heat recovery efficiency, and LCC differences in the same climatic and economic conditions can go as high as 31 %, mainly due to the geometrical parameters of the heat exchanger.
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Rafalskaya, Tatyana A., e Valery Ya Rudyak. "Influence of coolant flow rates on the heat exchanger parameter at variable operation modes". Vestnik MGSU, n. 5 (maggio 2019): 621–33. http://dx.doi.org/10.22227/1997-0935.2019.5.621-633.
Testo completoAbstract (sommario):
Introduction. Being used in various industries, heat exchangers most often work under conditions of variable coolant flows and temperatures. At the same time, the existing theories of calculating the heat exchanger operation modes are based on the use of constant unitless parameters at any operation mode. Taking into account the effect of coolant rates on the heat transfer coefficient of the heat exchangers, the given relations are bound to specific types of heat exchangers and can only be used at constant coolant temperatures. The purpose of this study is to obtain expressions for determining the effect of coolant flow rates on the variable heat exchanger parameter.
Materials and methods. The main variable operation modes for water-to-water heat exchangers used in heat supply systems are determined. Using simulation in the PTC Mathcad software, dependencies describing the change in the heat exchanger parameter for all the considered variable operation modes are defined. This made it possible to obtain a general formula for the change in the heat exchanger parameter for varying coolant flow rates. Coefficients in this formula take into consideration the effect of coolant temperatures, which cannot be known when calculating variable conditions, especially when the interconnected heat exchangers are operating.
Results. To test applicability of the existing relations describing the change in the heat exchanger parameter and of obtained formula, a large number of heat exchangers is calculated at variable operation modes. Comparison with the simulation results shows that the correlations of heat exchanger theories work well at the mode with constant coolant temperatures only, while their use at other operation modes can lead to large calculation errors.
Conclusions. The obtained formula allows finding the effect of coolant flow rates on the variable heat exchanger parameter. The formula can be used to predict the operation modes of large systems including a large number of various-type heat exchangers.
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Ahmad, Mateen, Waseem Saeed e Khaqan Javed. "Temperature Distribution Analysis along the Length of Floating Head Multi Stream Heat Exchanger". International Journal of Chemical Engineering and Applications 12, n. 3 (settembre 2021): 17–21. http://dx.doi.org/10.18178/ijcea.2021.12.3.790.
Testo completoAbstract (sommario):
Heat transfer between two streams is common and simple and well established and perfectly commercialized. Normally, the exchanger that is used for this purpose is shell and tube heat exchanger but in some industrial production unit where more than one reactant is to be preheated or pre-cooled for chemical reaction and same as post heating and post cooling required of multiple streams at same or different temperatures, Problem that is associated with such type shell and tube heat exchanger is that it can’t handle the multiple stream and for handling multiple streams we required more number of exchangers due to which capital cost increases and required more care of handling because the number of units increases. To overcome this problem, we need more than one heat sinks with one or more than one heat source that will minimize the covered volume per unit heat transfer area, the number of unit operation, operation time, man power and the capital cost with increasing thermal efficiency and heat utilization so to overcome this problem we need to move towards multi stream heat exchanger for handling multiple streams at once for heat exchange. Multi stream heat exchanger is opening of a new class of heat transfer equipment which deals more than two different streams for heat exchange. Such a way number of units can be reduced, which minimize time and space. With a little bit increase in complexity the operational cost will decrease and improve the thermal efficiency of heat transfer equipment, which minimize thermal losses and maximize the heat utilization which directly decrease the equipment size and capital cost. In the previous study we have discuss our research on the fabrication and Comparative Study of Floating Head (Triple pipe) Multi Stream Heat Exchanger with Shell & Tube This work is about the investigation involves the tentative examination of the heat exchange through the Floating Head Multi-Stream Heat Exchanger to evaluate the temperature distribution along the length, in which cool liquids are flowing through the inner and external pipe and hot liquid is moving through the central pipe of the exchanger.
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Fakheri, Ahmad. "Efficiency analysis of heat exchangers and heat exchanger networks". International Journal of Heat and Mass Transfer 76 (settembre 2014): 99–104. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2014.04.027.
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