This paper provides a review of the solid–liquid phase change materials (PCMs) for latent heat thermal energy storage (LHTES). The commonly used solid–liquid PCMs and their thermal properties are ...summarized here firstly. Two major drawbacks that seriously limit the application of PCMs in an LHTES system, that is, low thermal conductivity and liquid leakage, are discussed. Various methods for enhancing the thermal conductivity and heat transfer of solid–liquid PCMs are explained. Previous studies regarding form‐stable composite PCMs and microencapsulated PCMs are also presented. Furthermore, applications of the solid–liquid PCMs used in LHTES and thermal management systems are introduced and analyzed. Finally, future outlooks and research topics are proposed.
This paper provides a review of the solid–liquid phase change materials (PCMs) for latent heat thermal energy storage. The thermal properties and shortcomings of the PCMs are summed up firstly. Then, performance improvements of PCMs are discussed. And the applications used for thermal energy storage and thermal management are analyzed. Finally, the future research hotspots of PCMs are proposed.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
•Critical evaluation of state-of-the-art in heat exchanger additive manufacturing sector is conducted.•Seven major types of heat exchangers:(a). rough surfaces, (b) microchannels, (c) turbulence ...promoters, (d) cellular materials, (e) heat pipes, (f) turbomachinery cooling concepts, and (g) jet impingement are reviewed.•Surface roughness is key-consideration amongst different types of additively manufactured heat exchangers to determine the overall thermal-hydraulic performance.•Numerical optimization, surface characterization, material property specifications, process repeatability analysis, defect minimization, biomimetic technology development, heat pipes, and turbine cooling concept advancements are active areas of investigation at present.
The progress in additive manufacturing (AM) sector has transformed the ways in which heat exchangers (HXs) can be fabricated. The complex and freeform designs which could not be realized by conventional manufacturing routes can now be realized through AM technologies. The weight, volume, load bearing capabilities and manufacturing cost reductions are some of the other benefits that AM can provide over the conventional manufacturing. The relative benefits of using AM to make heat exchangers, however, are accompanied by various inherent challenges related to the process parameters, surface quality and material choice. A comprehensive understanding of the fabricated HX surface quality is imperative to explain the resulting flow and thermal characteristics. This study focusses on analyzing the thermal-hydraulic performance of additively manufactured HXs such as rough surfaces, microchannels, surface area and turbulence promoters, cellular materials, heat pipes, turbomachinery cooling designs, and jet impingement cooling concepts. The review of the existing literature suggests that the inherent surface roughness is the key consideration across different types of heat exchanger configurations manufactured by metal additive manufacturing. Significant deviation of the manufactured dimensions is observed relative to the intended design, especially when the dimensions approach the manufacturing limits. With the continuously improving AM technologies in terms of final product surface quality, dimensional accuracy, and realization of smaller length scales with accuracy, one can expect exciting times ahead in heat exchanger development and to this end, the review paper may serve as an essential reference tool.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
The present study evaluated the effect of γ (gamma) and α (alpha) Fe2O3/Kerosene nanofluids for a closed loop pulsating heat pipe under the magnetic field. The nanoparticles had a size ranged from ...10nm to 30nm. The heat transfer rate and the temperature distribution of the heat pipe were examined with and without the magnetic field. Likewise, the Fe2O3 base nanofluids were exposed to a magnetic field to measure the vapor temperature at the center of the pulsating heat pipe directly. The results showed that both heat transfer coefficient and thermal performance of the pulsating heat pipe are enhanced by the addition of Fe2O3 nanoparticles, especially when the magnetic field is present. The increased input heat flux rises the heat transfer coefficient of the condenser and the evaporator. Lower evaporator heat transfer coefficient and higher temperature difference between condenser and evaporator were seen because of α-Fe2O3 nanoparticles as compared to γ-Fe2O3 nanoparticles. Among six nanoparticles investigated in this research, the optimum type and size of Iron oxide nanoparticles under similar conditions for attaining the best heat transfer performance was 20nm γ-Fe2O3 nanoparticles.
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•Different ferro-fluids to a pulsating heat pipe under magnetic field are applied.•The increased input heat flux enhances the heat transfer coefficient of the PHP.•20nm, γ-Fe2O3 is the optimum nanoparticle for attaining the maximum heat transfer.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
•The pressure drop and heat transfer in the tube bundle during flow pulsations were investigated.•The effects of Reynolds number, frequency, amplitude and duty cycle were analyzed.•Correlations for ...heat transfer predictions were obtained.•The thermal performance factor at en equal Reynolds number and pumping power was studied.
Forced pulsating flows can be used to increase heat transfer. However, the effect of pulsating flows on heat transfer has not been sufficiently studied and requires further research. An experimental study of the effect of forced reciprocating flow pulsations on heat transfer in a in-line tube bundle was carried out. The longitudinal and transverse pitches of the tubes were 13 mm with the external tube diameter of 10 mm. The pulsation frequencies were of 0.18 Hz, 0.35 Hz and 0.45 Hz. The dimensionless pulsation amplitudes related to the tube diameter were 5, 10, and 15. The close-to-rectangular waveforms of pulsations were asymmetrical and symmetrical, with duty cycles of 0.2 and 0.5, respectively. The working medium was water with the constant Prandtl number of 4 and the Reynolds number was in the range from 1200 to 2400. The results of the experimental study show that the intensification of heat transfer increases with increasing amplitude and frequency and decreases with increasing Reynolds number. Flow pulsations increase heat transfer by 1.6 times. The pulsation duty cycle has a weak effect on heat transfer, whereas the effect of the pulsation duty cycle increases with increasing Reynolds number. The pressure drop in the tube bundle increases with the pulsation frequency and amplitude. The waveform of the pressure drop varied significantly, depending on the duty cycle of the pulsations. A thermal performance factor significantly differs for asymmetrical and symmetrical pulsations at the Reynolds number of 2400. To predict heat transfer in an in-line tube bundle with flow pulsations, empirical correlations were obtained. While the duty cycle of pulsations has a minor effect on heat transfer, the thermal performance factor of asymmetrical pulsations is higher than that of symmetrical pulsations, making asymmetrical pulsations more attractive for use in engineering applications in the studied range of regime parameters.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•PCM-cooled and PCM-heated BTMS are reviewed.•Phase change fluid (PCF), flexible phase change material (FPCM) and Hybrid cooling are analyzed.•The flammability of organic PCM needs to be solved for ...BTMS.•The stability of inorganic PCM needs to be solved for BTMS.•Various issues and challenges of BTMS based on PCM are identified.
It is known that the performance of a power battery is greatly affected by temperature. The battery pack needs an efficient thermal management system to make the power battery work in a reasonable temperature range. Battery thermal management system (BTMs) based on phase change materials (PCM), as a passive thermal management method, has the advantages of low operating cost and good temperature uniformity. This paper mainly introduces the BTMs based on PCM, including the cooling and heating system based on PCM. For the cooling system of PCM, the performance of composite phase change materials (CPCM) and its heat transfer enhancement, phase change fluid (PCF), flexible phase change materials (FPCM), and hybrid cooling systems are analyzed. For the PCM heating system, the PCM latent heat for preheating of the power battery in a cold environment has also been discussed. Finally, this paper concluded that the next research directions should focus on the improvement of thermal conductivity of PCM, flame retardancy of organic PCM, thermal stability of inorganic PCM, PCF and FPCM, and PCM-based coupled battery thermal management.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Enhancement methods of thermal conductivity for medium-high temperature PCMs.•Design and optimisation strategies for LTES heat exchangers.•LTES energy systems for heat recovery, storage and ...utilisation.•An in-depth summary of the medium-high temperature LTES materials.
Thermal energy storage (TES) technology is considered to have the greatest potential to balance the demand and supply overcoming the intermittency and fluctuation nature of real-world heat sources, making a more flexible, highly efficient and reliable thermal energy system. This article provides a comprehensive state-of-the-art review of latent thermal energy storage (LTES) technology with a particular focus on medium-high temperature phase change materials for heat recovery, storage and utilisation. This review aims to identify potential methods to design and optimise LTES heat exchangers for heat recovery and storage, bridging the knowledge gap between the present studies and future technological developments. The key focuses of current work can be described as follows: (1) Insight into moderate-high temperature phase change materials and thermal conductivity enhancement methods. (2) Various configurations of latent thermal energy storage heat exchangers and relevant heat transfer enhancement techniques (3) Applications of latent thermal energy storage heat exchangers with different thermal sources, including solar energy, industrial waste heat and engine waste heat, are discussed in detail.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•3-D simulation on microchannel heat sink with sinusoidal cavities and ribs.•Ribs and cavities reduce pressure drop, eliminate dead zone and promote flow mixing.•MCHS with sinusoidal cavities and ...rectangular improves the performance of heatsinks.
A three-dimensional numerical simulation was conducted to study the characteristics of fluid flow and heat transfer in new design of microchannel heat sink with sinusoidal cavities and rectangular ribs (MC-SCRR) for Reynolds number ranging from 100 to 800. A comparative analysis has conducted to the performance of the proposed design with related geometries such as microchannel with rectangular ribs MC-RR and microchannel with sinusoidal cavities MC-SC. The results showed that thermal performance of MC-SCRR is superior over both MC-RR and MC-SC. The new design of MC-SCRR has proved the ability to combine between two important features; large flow area which significantly reduces the pressure drop and high flow disturbances which caused by existence of ribs in the central portion of channel. The overall performance of MC-SCRR is evaluated in term of friction factor, Nusselt number and performance factor. The effect of three geometrical parameters; relative cavity amplitude (λ) relative rib width (β) and relative rib length (Γ) on the convective heat transfer and pressure drop have been investigated. The performance factor Pf for MC-SCRR with λ=0.15, β=0.13 and Γ=0.5 achieves 1.85 at Re=800.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
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•This microchannel Nusselt number has been increased by 64.5%•The coolant reduces the radiator wall temperature by 5.5 K compared to water.•Raised surface structure improves heat ...transfer in microchannels by 8%•PEC value of bionic heat sink with asymmetry concave-convex can reach 1.11.
Based on the bionic concept and fractal theory, a composite bionic microchannel radiator based on veins and honeycombs is designed in this work to address the problem of heat dissipation in electronic components. The convective heat transfer within the novel microchannel structure is numerically investigated, and the effects of the coolant (Fe3O4-water nanofluids) and the surface bump structure on the overall performance of the microchannel are explored. Compared to the traditional ordinary leaf vein-shaped fractal microchannels, the proposed microchannel heat sink in this work demonstrated a significant heat dissipation effect, with an optimal increase in the Nusselt number of 64.5%. The best microchannel heat dissipation was achieved using Fe3O4-water nanofluids with a mass fraction of 0.5%. Additionally, changing the height and arrangement of the bump structure allows for improving heat transfer by a maximum of 8% compared to microchannels without the bump structure. Furthermore, the novel bionic microchannel heat sinks are evaluated, and the resulting optimized microchannel structure has a comprehensive performance index of 1.11. Overall, the study results provide useful information and serve as a reference for designing new bionic heat sinks for the thermal management of electronic components.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
This paper presents a critical review of heat transfer applications of nanofluids. The effects of nanoparticle concentration, size, shape, and nanofluid flow rate on Nusselt number, heat transfer ...coefficient, thermal conductivity, thermal resistance, friction factor and pressure drop from numerous studies reported recently are presented. Effects of various geometric parameters on heat transfer enhancement of system using nanofluids have also been reviewed. Heat transfer devices covered in this paper include radiators, circular tube heat exchangers, plate heat exchangers, shell and tube heat exchangers and heat sinks. Various correlations used for experimental validation or developed in reviewed studies are also compiled, compared and analyzed. The pros and cons associated to the applications of nanofluids in heat transfer devices are presented in details to determine the future direction of research in this arena.
•A critical review on applications of nanofluids in heat transfer devices is presented.•Radiators, heat exchangers, heat sinks for electronic devices are thoroughly covered.•Size and shape of nanoparticles played critical role in heat transfer enhancement.•Most studies employed concentration of nanoparticles less than 1% for better enhancement.•Higher heat fluxes caused reduction in the stability of nanoparticles in base fluid.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Thermal management of metal hydride (MH) hydrogen storage systems is critically important to maintain the hydrogen absorption and release rates at desired levels. Implementing thermal management ...arrangements introduces challenges at system level mostly related to system's overall mass, volume, energy efficiency, complexity and maintenance, long-term durability, and cost. Low effective thermal conductivity (ETC) of the MH bed (~0.1–0.3 W/mK) is a well-known challenge for effective implementation of different thermal management techniques. This paper comprehensively reviews thermal management solutions for the MH hydrogen storage used in fuel cell systems by also focusing on heat transfer enhancement techniques and assessment of heat sources used for this purpose. The literature recommended that the ETC of the MH bed should be greater than 2 W/mK, and heat transfer coefficient with heating/cooling media should be in the range of 1000–1200 W/m2K to achieve desired MH's performance. Furthermore, alternative heat sources such as fuel cell heat recovery or capturing MH heat during charging and releasing it back during discharging have also been thoroughly reviewed here. Finally, this review paper highlights the gaps and suggests directions accordingly for future research on thermal management for MH systems.
•Heat transfer challenges and enhancement techniques of MH are discussed.•Thermal management arrangements of MH hydrogen storage are reviewed.•Research gaps and directions for future studies are provided.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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