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Showing papers on "Heat sink published in 2017"


Journal ArticleDOI
15 Sep 2017-Science
TL;DR: A cooling device with a high intrinsic thermodynamic efficiency using a flexible electrocaloric polymer film and an electrostatic actuation mechanism is developed, which is more efficient and compact than existing surface-conformable solid-state cooling technologies.
Abstract: Solid-state refrigeration offers potential advantages over traditional cooling systems, but few devices offer high specific cooling power with a high coefficient of performance (COP) and the ability to be applied directly to surfaces. We developed a cooling device with a high intrinsic thermodynamic efficiency using a flexible electrocaloric (EC) polymer film and an electrostatic actuation mechanism. Reversible electrostatic forces reduce parasitic power consumption and allow efficient heat transfer through good thermal contacts with the heat source or heat sink. The EC device produced a specific cooling power of 2.8 watts per gram and a COP of 13. The new cooling device is more efficient and compact than existing surface-conformable solid-state cooling technologies, opening a path to using the technology for a variety of practical applications.

292 citations


Journal ArticleDOI
TL;DR: In this paper, a review of various methods that can be used to minimize the negative impacts of the increased temperature while making an attempt to enhance the efficiency of photovoltaic solar panels operating beyond the recommended temperature of the Standard Test Conditions (STC).
Abstract: Cooling the operating surface is a key operational factor to take into consideration to achieve higher efficiency when operating solar photovoltaic systems. Proper cooling can improve the electrical efficiency, and decrease the rate of cell degradation with time, resulting in maximisation of the life span of photovoltaic modules. The excessive heat removed by the cooling system can be used in domestic, commercial or industrial applications. This paper presents a review of various methods that can be used to minimize the negative impacts of the increased temperature while making an attempt to enhance the efficiency of photovoltaic solar panels operating beyond the recommended temperature of the Standard Test Conditions (STC). Different cooling technologies are reviewed, namely Floating tracking concentrating cooling system (FTCC); Hybrid solar Photovoltaic/Thermal system cooled by water spraying; Hybrid solar Photovoltaic/ Thermoelectric PV/TE system cooled by heat sink; Hybrid solar Photovoltaic/Thermal (PV/T) cooled by forced water circulation; Improving the performance of solar panels through the use of phase-change materials; Solar panel with water immersion cooling technique; Solar PV panel cooled by transparent coating (photonic crystal cooling); Hybrid solar Photovoltaic/Thermal system cooled by forced air circulation, and Solar panel with Thermoelectric cooling. Several research papers are reviewed and classified based on their focus, contribution and the type of technology used to achieve the cooling of photovoltaic panels. The discussion of the results has been done based on the advantages, disadvantages, area of application as well as techno-economic character of each technology reviewed. The purpose of this review is to provide an understanding for each of the above-mentioned technologies to reduce the surface temperature of the PV module. The study will focus on the surface temperature reduction array bound by each of the cooling technologies. The performance of each cooling technology will also be highlighted. In addition to this study, this review will include a discussion comparing the performance of each cooling technology. The outcomes of this study are detailed in the conclusion section. This paper has revealed that any adequate technology selected to cool photovoltaic panels should be used to keep the operating surface temperature low and stable, be simple and reliable and, if possible, enable the use of extracted thermal heat to enhance the overall conversion efficiency. The presented detailed review can be used by engineers working on theory, design and/or application of photovoltaic systems.

288 citations


Journal ArticleDOI
TL;DR: In this article, phase change material (PCM) based pin-fin heat sinks are used to increase reliability, to ensure sufficiently lower temperature, to stretch the operating duration and to improve the functionality of installed features.

237 citations


Journal ArticleDOI
TL;DR: In this article, an improved design of wavy microchannel heat sink with changing wavelength or/and amplitude along the flow direction is proposed, and the thermal resistance R and the maximum bottom wall temperature difference Δ T b,max for the new design are compared with those for the straight and the original wavy design under a constant pumping power.

207 citations


Journal ArticleDOI
TL;DR: In this article, heat transfer and pressure drop characteristic associated with minichannel heat sink is investigated experimentally and the results indicate that TiO2 nanofluid thermal performance is strongly dependent on heating power and its usefulness heat transfer characteristic could be achieved more effectively at lower heating power.

176 citations


Journal ArticleDOI
TL;DR: In this paper, the feasibility of a new challenging use of Aluminum Oxide (Al 2 O 3 ) and Carbon Black (CB) nanoparticles to enhance the thermal properties: thermal conductivity, specific heat, and latent heat of pure paraffin waxes.

163 citations


Journal ArticleDOI
TL;DR: Regulating landscape composition and configuration would help mitigate the UHI in megacities by showing that landscape composition has more significant effects on thermal environment than configuration.

156 citations


Journal ArticleDOI
TL;DR: In this paper, the authors reviewed various kinds of heat storage materials, their composites and applications investigated over the last two decades and found that sensible heat storage systems are bulkier in size as compared to the latent heat storage system.
Abstract: This paper reviews various kinds of heat storage materials, their composites and applications investigated over the last two decades. It was found that sensible heat storage systems are bulkier in size as compared to the latent heat storage systems. Latent heat storage system using phase change materials (PCMs) stores energy at high density in isothermal way. Various geometries of PCM containers used for enhancement of heat transfer area, materials used for the construction of PCM containers and their interaction with heat storage materials are studied. The choice of storage material depends on the desired temperature range, application of thermal storage unit and size of thermal storage system. Low temperature heat storage system uses organic phase change materials while inorganic phase change materials are best suited for high temperature heat storage. Heat transfer within the PCM can be enhanced by preparing composite of high thermal conductivity as well as by altering the geometrical design like addition of fins, use of straight and helical tubes etc. Shell and tube configurations were mostly used for thermal storage systems. Heat transfer enhancement using PCM composite is a promising approach as it reduces cost and bulkiness to the system.

152 citations


Journal ArticleDOI
TL;DR: In this paper, the authors proposed a hybrid liquid air energy storage (LAES) configuration, whereby the excess heat of compression is used as a heat source to power an organic Rankine Cycle (ORC), whereas a Vapor Compression Refrigeration Cycle (VCRC) acts as aheat sink, leading to the production of additional electricity.

150 citations


Journal ArticleDOI
TL;DR: In this paper, the authors examined the angle effect of pin fin heat sink channel in terms of convective heat transfer coefficient, log mean temperature difference and thermal resistance using water-based graphene nanoplatelets (GNPs) nanofluids in a flow rate range of 0.25-0.75 LPM.

150 citations


Journal ArticleDOI
TL;DR: In this paper, the effects of the presence of a heat sink and a heat source and their lengths and locations and the entropy generation on MHD mixed convection flow and heat transfer in a porous enclosure filled with a Cu-water nanofluid was investigated numerically.
Abstract: In this work, the effects of the presence of a heat sink and a heat source and their lengths and locations and the entropy generation on MHD mixed convection flow and heat transfer in a porous enclosure filled with a Cu-water nanofluid in the presence of partial slip effect are investigated numerically. Both the lid driven vertical walls of the cavity are thermally insulated and are moving with constant and equal speeds in their own plane and the effect of partial slip is imposed on these walls. A segment of the bottom wall is considered as a heat source meanwhile a heat sink is placed on the upper wall of cavity. There are heated and cold parts placed on the bottom and upper walls, respectively, while the remaining parts are thermally insulated. Entropy generation and local heat transfer according to different values of the governing parameters are presented in detail. It is found that the addition of nanoparticles decreases the convective heat transfer inside the porous cavity at all ranges of the heat ...

Journal ArticleDOI
TL;DR: In this article, phase change material (PCM) is employed to absorb thermal energy released by such electronics, and the effect of fin configuration, PCM volume, latent heat phase, power densities, thermal capacity and thermal conductance are reported.

Journal ArticleDOI
TL;DR: In this article, a thermally coupled model of concentrated photovoltaic-thermo-elctric (CPV/TEG) system is established to investigate feasibility of the hybrid system over wide range of solar concentrations and different types of heat sinks.

Journal ArticleDOI
TL;DR: In this article, the authors classified radiative cooling research into three categories: radiative background, selective radiative heating, theoretical approach and numerical simulations, and prototype radiotiative cooling prototypes.
Abstract: Radiative cooling is a technology intended to provide cooling using the sky as a heat sink. This technology has been widely studied since 20th century but its research is scattered all over the literature, requiring of a review to gather all information and a state-of-the-art. In the present article, the research has been classified in: (1) radiative cooling background, (2) selective radiative cooling, (3) theoretical approach and numerical simulations, and (4) radiative cooling prototypes. Even though this is a low-grade technology it can dramatically reduce the energy consumption, since it is renewable and requires low energy for its operation. However, new functionalities of the device, apart from radiative cooling, are required for profitable reasons. Some recommendations extracted from the literature to improve the efficiency of radiative cooling are: to use a cover to achieve low temperatures, to use water instead of air as heat-carrier fluid, and to couple the device with heat storage. Finally, further research should be focused in the development of new materials with improved radiative properties, the measurement of incoming infrared atmospheric radiation and/or new technics to predict it, and the evaluation of new device concepts.

Journal ArticleDOI
TL;DR: In this article, the performance of GNPs nanofluids with 10% weight concentration was compared with distilled water on integral fin heat sink in laminar range at heat flux of 47.96°C and 23.91°C.

Journal ArticleDOI
TL;DR: In this paper, the principles of thermo-electric power production, as well as the materials use, performance achieved, and application areas are reviewed, while taking a particular deliberation on TEG heat sinks geometries and categories.

Journal ArticleDOI
TL;DR: In this paper, a horizontal phase change material (PCM)-assisted heat pipe system for electronic cooling was introduced as a potential solution to this problem and a computational fluid dynamic model was developed and validated to assist the investigation.

Journal ArticleDOI
TL;DR: In this article, phase change materials (PCMs) were used as thermal conductivity enhancers (TCEs) for passive cooling systems. But, the authors focused on the optimization of passive cooling system using extruded finned surfaces.

Journal ArticleDOI
Yunchao Jia1, He Hui1, Yi Geng1, Bai Huang1, Xiaodong Peng1 
TL;DR: In this paper, a high thermally conductive property was achieved by using fused deposition modeling (FDM) for 3D printing with graphite flakes vertically aligned in the in-plane direction.

Journal ArticleDOI
TL;DR: In this paper, the use of passive cooling methods in microchannel heat sink is comprehensively discussed and the effects of some important parameters such as the type of channel types, surface roughness, fluid additives, and Reynolds number on the rate of heat transfer in micro channel heat sink are presented.

Journal ArticleDOI
TL;DR: The presented methodology to form a nanometric gap with functional heat flux paves the way to the smart thermal management in various scenes ranging from highly integrated systems to macroscopic apparatus.
Abstract: Dynamic control of electromagnetic heat transfer without changing mechanical configuration opens possibilities in intelligent thermal management in nanoscale systems. We confirmed by experiment that the radiative heat transfer is dynamically modulated beyond the blackbody limit. The near-field electromagnetic heat exchange mediated by phonon–polariton is controlled by the metal–insulator transition of tungsten-doped vanadium dioxide. The functionalized heat flux is transferred over an area of 1.6 cm2 across a 370 nm gap, which is maintained by the microfabricated spacers and applied pressure. The uniformity of the gap is validated by optical interferometry, and the measured heat transfer is well modeled as the sum of the radiative and the parasitic conductive components. The presented methodology to form a nanometric gap with functional heat flux paves the way to the smart thermal management in various scenes ranging from highly integrated systems to macroscopic apparatus.

Journal ArticleDOI
TL;DR: In this article, the heat transfer performance of the micro-channel heat sinks with five different pin-fin configurations were investigated numerically and experimentally, and the computational fluid dynamics simulations showed that the pin fin shape changes the thermo-fluid characteristics of a microchannel heat sink inducing the lowest thermal resistance and uniformity of the chip's top surface (UCTS).

Journal ArticleDOI
TL;DR: In this paper, the authors evaluated the performance of a biological nanofluid containing silver nanoparticles in a liquid block heat sink for cooling of an electronic processor, and the results showed that the nanoparticles synthesized through plant extract technique from green tea leaves are employed.

Journal ArticleDOI
Daxiang Deng1, Wei Wan1, Yu Qin1, Jingrui Zhang1, Xuyang Chu1 
TL;DR: In this paper, a structured microchannel with micro cone pin fin was developed for the utilizations in advanced microchannel heat sinks to cool high heat-flux devices, which provided lots of stable nucleation sites by producing lots of tiny reentrant cavities and introduced significant wicking effects to maintain the liquid rewetting and hinder the local dry-out.

Journal ArticleDOI
TL;DR: In this article, four types of staggered micro pin fin with different cross-section shapes, i.e., square, circular, diamond and streamline, were fabricated by a laser micromilling method, and constructed for heat sinks cooling systems.

Journal ArticleDOI
TL;DR: In this paper, a new design of wavy microchannel heat sink with porous fins is proposed to reduce simultaneously pressure drop and thermal resistance, which is attributed to the combination of the enhanced coolant mixing by Dean vortices, the prolonged flow route by increasing equivalent channel length, and the forced permeation by jet-like impingement.

Journal ArticleDOI
TL;DR: A detailed review of the experimental and numerical works carried out on heat transfer enhancement techniques which focus on minimization of heat loss, use of turbulators, addition of nanofluid and selective coatings in the receiver tube of a solar PTC is presented in this paper.
Abstract: A solar collector is a device which helps to harnesses solar radiation into useful form of energy. Among various solar collectors, the parabolic trough collector (PTC) is considered to be the best option for medium temperature (150–400 °C) heat requirements. The popularity of solar parabolic trough technology has generated interest in higher efficiency energy recovery potential. The absorber tube, also called the receiver tube or heat collection element, is one of the main functional units of a solar PTC in addition to other elements like parabolic mirrors, metal support structure and tracking unit assembly. Parabolic mirrors reflect to a focal point and concentrate falling sun rays onto an absorber tube, which is made up of a long metallic structure covered by an evacuated glass envelope to reduce convective heat transfer losses. Many techniques were attempted to enhance the heat transfer potential in the receiver tube portion of a solar PTC which includes techniques such as half insulation receiver, cavity receivers, vacuum outer shell, inclusion of inserts, baffles, artificially roughened sinks, selective coatings etc. In some of the research works, nanoparticles were also used to enhance heat transfer properties of the heat transfer fluid. In this paper, detailed review of the experimental and numerical works carried out on heat transfer enhancement techniques which focus on minimization of heat loss, use of turbulators, addition of nanofluid and selective coatings in the receiver tube of a solar PTC are presented. Further the major reasons for heat loss in the receiver tube and comparative study of various heat transfer enhancement techniques are summarised.

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the thermal performance of a copper-made heat sink with rectangular microchannel and found that carbon nano tube aqueous nanofluid is used as a coolant inside the microchannel at mass concentrations of 0.05-0.1%.

Journal ArticleDOI
TL;DR: In this paper, the authors developed thin-film microwave power attenuators operating from 1 to 10 GHz, which are built on a quartz substrate and use 75nm thick films of nichrome for dissipative components and 1 μm thick silver films as hot electron heat sinks.
Abstract: To reduce the level of thermally generated electrical noise transmitted to superconducting quantum devices operating at 20 mK, we have developed thin-film microwave power attenuators operating from 1 to 10 GHz. The 20 and 30 dB attenuators are built on a quartz substrate and use 75 nm thick films of nichrome for dissipative components and 1 μm thick silver films as hot electron heat sinks. The noise temperature of the attenuators was quantified by connecting the output to a 3D cavity containing a transmon qubit and extracting the dephasing rate of the qubit as a function of temperature and dissipated power P d in the attenuator. The minimum noise temperature T n of the output from the 20 dB attenuator was T n ≤ 53 mK for no additional applied power and T n ≈ 120 mK when dissipating 30 nW. In the limit of large dissipated power ( P d > 1 nW), we find T n ∝ P d 1 / 5.4, consistent with detailed thermal modeling of heat flow in the attenuators.

Journal ArticleDOI
TL;DR: In this article, the authors investigated the importance of wrapping cylindrical battery cells (18650 type) in thermally and electrically insulating mica sleeve, to fix the cells in a thermally conductive aluminum heat sink.