15 results
Search Results
2. Targeted alignment of fillers in plastic pipes for increased heat transfer in heat exchanger systems.
- Author
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Buchalik, Kevin, Schiffers, Reinhard, Grundler, Marco, and Kayser, André
- Subjects
- *
HEAT exchangers , *HEAT pipes , *PLASTIC pipe , *HEAT transfer , *HEATING , *PIPE - Abstract
Pipes in heat exchanger systems are usually made of metallic materials to achieve a high level of thermal conductivity and thus high efficiency. However, substitution with polymer materials has a great potential. Plastics save weight, can be produced at lower cost and emissions, and are ideal for use in corrosive or chemically aggressive environments, where most metals fail. The challenge, however, is their much lower thermal conductivity in comparison. To reduce this disadvantage, fillers are used to transport thermal energy through the less conductive polymer matrix. In fact, high filler ratios are required to achieve an acceptable level of thermal conductivity for heat exchanger systems. However, these high filler ratios have a significant impact on the material properties of the polymer, such as the flexibility, which is drastically reduced. The result is a brittle material with limited suitability for use in heat exchanger systems. This paper describes a novel approach to effectively increase the thermal conductivity of polymer materials by optimizing the orientation of anisotropic filler particles by die design. Standard pipe extrusion dies result in continuous shear forces in the direction of extrusion. Accordingly, the resulting filler network has a higher thermal conductivity in the axial direction of the pipe than radially through the pipe wall. However, radial heat transfer is essential in pipe heat exchanger systems. To improve this, various die designs for targeted radial alignment of filler particles are discussed in this paper. Furthermore, the potential for improvement of the die designs is investigated. So far, the most efficient die design achieves an increase in thermal conductivity of up to 74 % compared to a standard pipe extrusion die. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
3. Performance analysis of closed loop pulsating heat pipe using nanofluid fused with refrigerant.
- Author
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Veerasamy, Aruna, Balakrishnan, Kanimozhi, and Antony, Godwin
- Subjects
- *
HEAT pipes , *NANOFLUIDS , *REFRIGERANTS , *HEAT transfer - Abstract
This paper aims to improve the thermal performance of Closed loop pulsating heat pipe (CLPHP) with nanofluid fused with refrigerants. In this paper, the thermal studies were carried out by SWCNT and MWCNT nanofluids fused with R-134a. Experimentation was conducted at 10W heating power and 90° inclination angle, temperature difference from evaporator and condenser were validated. Results indicate that using nanofluid fused with R-134a, could improve the thermal performance of heat pipes. And the readings were taken every two minutes. And the obtained result was plotted to and the result shows the addition of CNT nanofluid to the refrigerant improves the Thermal performance of the closed-loop heat pipe (CLPHP). Compare to SWCNT, MWCNT with R-134a shows better heat transfer and improve the cooling capacity. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
4. Numerical investigation of the effect of fin helical pitch on the hydrothermal performance of heat exchanger.
- Author
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Khudhair, Zahraa. and Freegah, Basim
- Subjects
- *
HEAT exchangers , *NUSSELT number , *HEAT pipes , *FINS (Engineering) , *HEAT transfer , *SCREWS , *HEAT sinks , *ADHESIVE tape - Abstract
Heat exchangers are a common heat transfer mechanism used in a variety of applications ranging from home to industrial, aircraft, and vehicles. The aim of this research is to study the hydrothermal efficiency of a double pipe heat exchanger with helical fins on annular side of counter flow heat exchanger numerically and compare the results of a double tube with and without screw tape. The investigation begins by employing numerical modeling of helical tapes under different configurations, with different pitches (10, 15, and 20) mm and one height of 10 mm as passive heat transfer augmentation strategies, which are simulated using ANSYS 2022 R1 software. The findings reveal that the current work's numerical results and earlier research's experimental findings are in good accord. Furthermore, while using (Helical Tap Insert) (HTI), the thermal performance of the new typical is found to be better than the typical model. Furthermore, it was found that the Nusselt number achieves the highest growth when the pitch (p) is (20) mm and increases the pressure drop. Furthermore, it was discovered that when the pitch (p) is (20) mm and pressure drop is increased, the Nusselt number grows the most. Furthermore, as associated to the typical model, the total thermal effectiveness of heat exchanger for the new model has greater by 9.9%. This difference is due to the fact that in the theoretical study, ideal conditions are assumed. The experimental design, the assumptions, operating circumstances, and accuracy of the devices are taken into account. It was noted that the value of the specified percentage of hydrothermal improvement achieved the highest value in performance for the same case that was with spiral fin and pitch length (20) mm, which is 1.6% compared to the traditional model. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
5. A preliminary study on heat pipe solar evacuated tube collector using nano fluid as a performance parameter for heat transfer enhancement.
- Author
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Desai, Shivani and Subhedar, Dattatraya
- Subjects
- *
SOLAR concentrators , *NANOFLUIDS , *SOLAR thermal energy , *SOLAR heating , *HEAT pipes , *SOLAR water heaters , *HEAT transfer , *HEAT transfer fluids - Abstract
Extracting clean Energy through different technologies and producing electricity has played a major role nowadays due to constant growing energy consumption because of increase in population as well as deteriorating effect on atmosphere due usage of fossil fuels. To have an efficient clean energy technology has become the necessity of time. Application of solar thermal energy as Solar cooker, Solar dryer, Solar Water Heater, Solar desalination etc, are widely used in industry and domestic applications. Among these different application of Solar Thermal Energy, Evacuated Tube Collectors are used extensively so far as it proposes less convection losses which arise in solar concentrators from the movement of air over hot receiver surfaces. It is found that use of nanofluid for the thermal performance enhancement of Evacuated tube collector using heat pipe significantly changed scenario of using ETC. With this paper various characteristics of using nano fluid with Evacuated tube collector has been critically reviewed for the thermal performance enhancement of ETC with effect of parameters like weight fraction, filling ratio, type of nano particle. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
6. Heat transfer and friction factor augmentation using twisted tape in a double pipe heat exchanger: A critical review.
- Author
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Heeraman, Jatoth, Kumar, R., and Chausariya, Prem
- Subjects
- *
HEAT pipes , *HEAT exchangers , *HEAT transfer , *CONDOMINIUMS , *LITERATURE reviews , *ADHESIVE tape , *PIPE - Abstract
In order to transfer heat with minimal leakage to surroundings and to increase efficiency energy exchanger systems are used through various methods. the output from the twin-pipe energy exchanger system is essential in terms of both system economics and efficiency. as a result, boosting the rate of thermal gradient rate is important for long-term energy growth. the goal of this study was to review heat transmission and friction properties in the horizontal double pipe heat exchanger. after thorough literature review, it has been concluded that various author has investigated different types of twisted tape insert their experimental and modeling studies and a little work is observed using twisted tape inserts with dimple configurations in a double pipe heat exchanger. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
7. Using magnesium oxide MgO nanoparticles to enhance heat transfer in a double pipe heat exchanger: A CFD study.
- Author
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Gabir, Mustafa M. and Alkhafaji, Dhirgham
- Subjects
- *
HEAT pipes , *HEAT exchangers , *NANOFLUIDS , *HEAT transfer , *MAGNESIUM oxide , *HEAT equation - Abstract
Recently heat transfer enhancement utilizing double pipe heat exchangers had been a key of engineering research topic in different field. The present work illustrates how magnesium oxide nanofluid (MgO) affects the enhancement of heat energy exchange in a double pipe heat exchanger at different concentrations of nanoparticles. The governing equations of heat and fluid flow had been solved using ANSYS FLUENT based upon finite volume scheme. The temperatures for hot and cold streams at the inlet are 50 oC & 25 oC respectively. The volumetric flowrates for hot fluid (8-20) LPM and for cold fluid 8 LPM. The magnesium oxide nanoparticles MgO have concentrations range (0.125 % - 2%) by volume were implemented. According to the findings of the study implemented in sustainable applications and different industries fields, heat energy exchange rises when the volume concentration of nanoparticles increases also. Currently, there are several studies have been conducted to assess the consequence of nanofluid that enhancement heat energy exchange in the double pipe heat exchanger. The type and concentration of nanoparticles in the base fluid play important role in the enhancement of heat energy exchange. This paper illustrated the effect of increased magnesium oxide nanofluid MgO nanoparticles concentration on the heat energy exchange of a double pipe heat exchanger. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
8. Experimental study of heat transfer and pressure drop in a channel with different type of inserts.
- Author
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Khudhur, Dhamyaa S., Kassim, Muna S., and Hussein, Haider Ali
- Subjects
- *
HEAT transfer coefficient , *PRESSURE drop (Fluid dynamics) , *HEAT transfer , *HEAT convection , *HEAT flux , *HEAT pipes , *FORCED convection , *SUPERCONDUCTING magnets , *ADHESIVE tape - Abstract
This study investigates heat transmission and thermal performance factor characteristics in a tube with coil wire and twisted tape inserts using air as the working fluid. This study investigates heat transmission and thermal performance factor characteristics in a tube with coil wire and twisted tape inserts using air as the working fluid. The goal of this research is to improve forced convection heat transfer in tubes with and without swirl inserts and coil wire inserts for air Reynolds numbers ranging from 10.328×103 to 11.769×103. The impacts of different parameters of heat transfer are considered in this work with heat flux are constant conditions of 600 W/m2 and 800 W/m2 with using the coil wire and twisted tapes with three ratios (y/w = 3, 4 and 5). The test section is a horizontal annular passage with outer diameter 10 cm. The results showed that using coil wire inserts to improve heat transfer coefficient factors in tubes resulted in local heat transfer coefficient percentages of (5.1%) to (7.8%) with heat flux are constant conditions of 600 W/m2 and 800 W/m2, respectively. While tube with swirl inserts provide local heat transfer coefficient percentages of (3.6% to 6.1%) for heat fluxes (600) W/m2 and (800) W/m2, respectively. The obtained results demonstrate that as the twisted ratio (y/w) decreases, the mean Nusselt number and heat transfer coefficient in the tube with twisted tape and coil wire rise. Experimental results is shown, heat transfer coefficient for the coil wire when compared with that of swirl inserts tube were ranged between (10.6%) to (16.5%) and (11.5%) to (17.3%) for the heat flux (600) W/m2. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
9. Numerical investigation of thermal and hydraulic development for a double pipe heat exchanger.
- Author
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Hamdan, O. A., Naser, M. A., Allawe, A. S., Anead, Hosham Salim, Jalil, Jalal M., Hussein, Hashim Abed, Mahel, Farag, Ibrahim, Raheek I., and Mohammed, Jamal A.
- Subjects
- *
HEAT exchangers , *HEAT pipes , *HEAT transfer , *ADHESIVE tape , *NUMERICAL analysis - Abstract
Investigation still on board for finding the best techniques to develop the thermal and hydraulic performance of the heat exchanger. One of the useful, practical methods for finding the modification is the numerical analysis. This numerical analysis was obtained by modelling and simulation using ANSYS FLUENT software. In this present work five elements were modelled and simulated of three different configuration models, helical tape, rectangular and triangular straight strip inserts were inserted inside the inner pipe. This simulation was employed according to the working operation conditions of the real practical double pipe heat exchanger. The results show that, the helical tape configuration demonstrated the effective enhancing technique of the heat transfer, which is improving the thermo-hydraulic performance of this type of heat exchanger in this study. According to this work, the technique of studying numerically the design enhancement of the heat exchanger can produce an excellent result and gives a good recommendation to transfer it into practical work. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
10. Thermoelectric power generation from micro power supplies to kilowatt systems.
- Author
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Luo, Ding, Li, Ying, Huang, Kuo, and Yan, Yuying
- Subjects
- *
THERMOELECTRIC generators , *POWER resources , *THERMOELECTRIC power , *WASTE heat , *THERMOELECTRIC apparatus & appliances , *THERMOELECTRIC materials , *HEAT pipes , *HEAT transfer - Abstract
Energy crisis and carbon emission are increasingly prominent issues in our society. As one of the clean energy sources, thermoelectric power generation is a promising alternative energy technology to convert heat into electricity. If there is a heat source, thermoelectric generators can provide electricity for watches, sensors, electronics, spacecraft, etc., and can also be used to recover waste heat, such as automobile exhaust heat, industrial waste heat, ship waste heat, etc. This paper begins with the basic principles of thermoelectric generators and an outlook of thermoelectric materials in different application scenarios. Then, the thermoelectric generator systems, which can be classified into different groups according to their different power generation levels, also the corresponding progress, challenges, and future development are presented. In addition to exploring high-performance thermoelectric materials, the system efficiency of thermoelectric generators is much dependent upon advanced structural design and thermodynamic optimizations. In the previous and present works, some new optimization methods are applied to improve the performance of thermoelectric devices and systems, these include such as the asymmetric design, phase change heat transfer, optimization for thermoelectric devices based on temperature distributions, also heat pipe and converging design for thermoelectric generator systems. These works help breakthrough in thermoelectric power generation from low-level power generation to relatively higher-level power generation. The current progress helps provide a comprehensive insight into thermoelectric power generation technology from micro power supplies to kilowatt systems. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
11. Characterization of liquid behavior in distributor of falling-film evaporator.
- Author
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Kim, Jungchul, Kim, Chan Geun, Kim, Hak Soo, Kim, Wookyoung, and Kim, Dong Ho
- Subjects
FALLING films ,LIQUID films ,EVAPORATORS ,HEAT pipes ,HEAT transfer ,REFRIGERANTS ,LIQUIDS - Abstract
Recently, the development of environmentally friendly refrigerants has emerged as a major issue in industry. Owing to the high cost of developing new refrigerants, falling-film evaporators are attracting increasing interest, given their reduced refrigerant usage compared with flooded evaporators. In falling–film evaporators, the distributor at the top of the evaporator uniformly delivers refrigerant through multiple holes over heat transfer tubes. We focus on the liquid (refrigerant) behavior in the distributor of a falling-film evaporator. To understand the underlying mechanism, we perform experiments on single hole as well as multiple holes in the distributor. For both cases, we have derived theories that predict the refrigerant height in the distributor, according to the flow rate. They show good agreement with the experimental measurements. By changing the hole diameter, number of holes, and flow rate, we quantitatively characterize parametric dependencies that determine the liquid behavior. In addition, we unveil a negative effect of the supply stream from the upper distributor that locally mitigates the outflow rate from the distributor. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
12. Overview of heat pipe and applications in renewable energy based systems.
- Author
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Tripati, Sushil
- Subjects
HEAT pipes ,GREENHOUSE gases ,RENEWABLE energy sources ,PHASE transitions ,HEAT transfer - Abstract
The heat pipe is among thermal physics' greatest accomplishments and the thermal transmission technology of this century owing to its different capacity for transporting heat from broad distance eliminating any loss. The core uses of heat pipes tackle environmental problems, energy management and fuel performance. High heat flux applications plus the circumstances in which non-uniform heat charge combination, reduced airflow through the components that generate heat and weight or space constraints have been created, as an efficient and proven thermal solution. This segment discusses technology for heat pipe briefly and illustrates its simple applications as passive thermal control system. Heat pipes have a passive function and high performance for certain applications with a two-stage efficient heat transfer device. Energy saving schemes is introduced by way of wickless assisted with wickless heat pipes or capillary pumped loop for agricultural cold storage, data center cooling, bakery waste heat collection and vehicle dashboard cooling. Thermosyphons are used to collect accumulated heat (solar pool, geothermal water), to dissipate excess heat to the atmosphere and to retain surplus heat in materials of phase transition. The method built for green energy is focused on electricity storage. In such uses, heat pipes have an inexpensive alternative to zero greenhouse gas emissions. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
13. Heat transfer of thin flat heat pipes with gradually varied vapor–liquid channels.
- Author
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Peng, Guohong, Zhang, Zhikun, Wang, Yaxin, Zhang, Yanhui, and Zhao, Zhengang
- Subjects
HEAT transfer ,THERMAL resistance ,CHANNEL flow ,HEAT pipes ,HEAT flux ,ELECTRONIC circuits ,TEMPERATURE distribution - Abstract
The heat flow density is constantly increasing due to the growing demand for the integration and compaction of electronic devices. A sintered thin flat heat pipe (TFHP) is a typical device for managing the heat flux of highly integrated electronic circuits. Four different structures of the vapor–liquid flow channel architecture are designed in this work. Heat transfer performance tests of different TFHPs are carried out for different thermal powers. The surface temperature distribution and thermal resistance of the TFHP under different operating conditions are investigated. The experimental results show that the design of the vapor–liquid flow channel significantly impacts the TFHP's heat transfer performance and that the wedge-shaped wick is better suited to the flow channel. The wedge-shaped wick has the lowest thermal resistance of 0.28 °C/W and the most elevated maximum thermal power of 22 W. The heat dispatch performance of the sintered wick TFHP is improved. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
14. Heat transfer of copper mesh–powder composite-based sintered-wick vapor chamber.
- Author
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Zhao, Zhengang, Li, Lei, Wang, Yuyuan, Wang, Yaxin, and Hui, Yueyao
- Subjects
HEAT transfer ,COPPER ,GASES ,THERMAL resistance ,HEAT pipes ,COPPER powder ,LIQUID films - Abstract
With the rapid spread of high-power density equipment, the vapor chamber must adapt to more applicable environments and exhibit a better heat transfer performance. The copper mesh and powder are sintered in this work to make a composite wick vapor chamber (CW-VC). Six sections of copper wire are cut and sintered together with the wick as the inner support column of the CW-VC. The effects of filling ratio and inclination on the heat transfer performance of the vapor chamber are investigated. The experimental results showed that the maximum thermal power of the CW-VC is 23.29 W at the optimal liquid filling ratio of 80% and the lowest thermal resistance is 0.33 °C/W. Below the liquid filling ratio of 60%, when the inclination angle of the CW-VC increases, its thermal resistance increases. At filling ratios of 70%, 80%, and 90%, the inclination angle of 30° can reduce the thermal resistance of the CW-VC. It implies that the inclination angle of the CW-VC can be increased appropriately to reduce the thermal resistance when the filling ratio is high. However, when the liquid filling ratio is low, increasing the inclination angle of the CW-VC will make the liquid film of the evaporator thinner and dry out earlier and its thermal resistance will increase. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
15. Study on the heat transfer enhancement of self-excited oscillating pulsating flow by the boundary vortex group.
- Author
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Sun, Xiao, Wang, Zhaohui, Cheng, Ziqiang, Wang, Dongdong, and Gao, Quanjie
- Subjects
HEAT transfer ,HEAT transfer coefficient ,SELF-induced vibration ,BOUNDARY layer (Aerodynamics) ,HEAT pipes - Abstract
In this work, the self-excited oscillating pulsating circular pipe is the object of study. Based on the flow evolution characteristics of the boundary layer and vortex, the mechanism of enhanced heat transfer by self-excited oscillating pulsating flow is investigated. Moreover, a vital flow structure, the boundary vortex ring (BVR for short), is proposed. The study results show that the vortex evolution within the shear layer inside the self-excited oscillating pulsating chamber has an important influence on the formation of the downstream boundary vortex ring. Both have the same period but different phases. The boundary vortex group formed by the BVR is distributed at intervals in the pipe, and its role in promoting fluid flow increases first and then decreases. At the same time, the strength of the central mainstream area is gradually strengthened. The boundary vortex group's flow state determines the downstream pipe's heat transfer characteristics. The low-velocity zone on both sides determines the position of the heat transfer coefficient enhancement, and the central vorticity determines the amplitude of the enhancement. The boundary vortex group with a complete structure can effectively promote heat transfer, while the boundary vortex group with an incomplete structure can suppress heat transfer. The time-averaged boundary layer thickness increase ratio δ′ and the time-averaged equal diameter circular tube performance evaluation index η
T provide the fundamental indexes for designing and optimizing variable cross section heat transfer circular tubes. Furthermore, the heat transfer coefficient of the tube wall varies synchronously with the thickness of the boundary layer. [ABSTRACT FROM AUTHOR]- Published
- 2022
- Full Text
- View/download PDF
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