Design and modeling of a fluid-based micro-scale electrocaloric refrigeration system

Guo, Dongzhi; Gao, Jinsheng; Yu, Ying-Ju; Santhanam, Suresh; Slippey, Andrew; Fedder, Gary K.; McGaughey, Alan J. H.; Yao, Shi‐Chune

doi:10.1016/j.ijheatmasstransfer.2014.01.043

Cited by 71 publications

(43 citation statements)

References 20 publications

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“…[5][6][7][8][9][10][11] These works have put forward electrocaloric materials as cost-effective, efficient, and environmentally friendly media for cooling applications such as residential and commercial chillers, air-condition systems, and a wide range of on-chip and sensors coolers. 12,13 Higher electric field renders larger electrocaloric effect, and therefore, thin films, characterized by high breakdown fields, disclose larger electrocaloric effect (up to 45 K 10 ) than bulk (typically up to 2 to 3 K). However, thin films have small thermal mass which brings about small transient electrocaloric heat.…”

Section: Introductionmentioning

confidence: 99%

Experimentally validated finite element model of electrocaloric multilayer ceramic structures

Smith

Rokosz

Correia

2014

Journal of Applied Physics

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A chip scale electrocaloric effect based cooling deviceA novel finite element model to simulate the electrocaloric response of a multilayer ceramic capacitor (MLCC) under real environment and operational conditions has been developed. The two-dimensional transient conductive heat transfer model presented includes the electrocaloric effect as a source term, as well as accounting for radiative and convective effects. The model has been validated with experimental data obtained from the direct imaging of MLCC transient temperature variation under application of an electric field. The good agreement between simulated and experimental data, suggests that the novel experimental direct measurement methodology and the finite element model could be used to support the design of optimised electrocaloric units and operating conditions. [http://dx.

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Section: Introductionmentioning

confidence: 99%

Experimentally validated finite element model of electrocaloric multilayer ceramic structures

Smith

Rokosz

Correia

2014

Journal of Applied Physics

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“…EC cooling, which operates on a refrigeration cycle analogous to magnetocaloric cooling, is an emerging technology. 8 The highest reported adiabatic temperature change in a bulk EC material is 2.5 K at an electric field of 3 V/lm and a temperature of 434 K 11 The P(VDF-TrFE-CFE) terpolymer demonstrates an adiabatic temperature change of 16 K at an electric field of 150 V/lm near room temperature 12 and is easily and economically fabricated, making it favorable for mass production.13 These findings point to the potential of applying EC cooling in micro-devices using polymer thin films.Direct and indirect techniques can be applied to measure the EC effect. In the indirect measurement, a differential scanning calorimeter is used to measure the heat flow under a high electric field and isothermal conditions.…”

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confidence: 99%

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confidence: 99%

Electrocaloric characterization of a poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) terpolymer by infrared imaging

Guo

Gao

et al. 2014

Applied Physics Letters

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The electrocaloric effect in thin films of a poly(vinylidene fluoride-trifluoroethylene chlorofluoroethylene) terpolymer (62.6/29.4/8 mol. %, 11-12 lm thick) is directly measured by infrared imaging at ambient conditions. The adiabatic temperature change is estimated to be 5.2 K for an applied electric field of 90 V/lm. The temperature change is independent of the operating frequency in the range of 0.03-0.3 Hz and is stable over a testing period of 30 min. Application of this terpolymer is promising for micro-scale refrigeration. V C 2014 AIP Publishing LLC.[http://dx.doi.org/10.1063/1.4890676] Micro-scale refrigeration systems are widely used for the cooling of integrated circuits, microelectromechanical sensors, and biomedical devices.1 Environment-friendly cooling technologies with a high efficiency are attractive due to growing energy demands and stringent environmental requirements. 2Although thermoelectric cooling is commonly applied and has been scaled to the micro-domain, 3-6 the low efficiency and challenges in material fabrication suggest that alternatives are needed. 6 While refrigeration based on the magnetocaloric effect 7 can be employed to achieve extremely low temperatures, miniaturization of devices is challenging while maintaining a high cooling performance due to the difficulty of realizing the large magnetic fields required. 2The electrocaloric (EC) effect is a phenomenon in which reversible, polarization-related temperature and entropy changes occur when an electric field is applied to certain materials. EC cooling, which operates on a refrigeration cycle analogous to magnetocaloric cooling, is an emerging technology. 8 The highest reported adiabatic temperature change in a bulk EC material is 2.5 K at an electric field of 3 V/lm and a temperature of 434 K 11 The P(VDF-TrFE-CFE) terpolymer demonstrates an adiabatic temperature change of 16 K at an electric field of 150 V/lm near room temperature 12 and is easily and economically fabricated, making it favorable for mass production.13 These findings point to the potential of applying EC cooling in micro-devices using polymer thin films.Direct and indirect techniques can be applied to measure the EC effect. In the indirect measurement, a differential scanning calorimeter is used to measure the heat flow under a high electric field and isothermal conditions. 14,15 This technique is best suited to bulk materials as the output heat flow signal for a thin film sample is very small. Jia and Ju 16 reported an approach for characterizing the EC effect in a thin film sitting on an insulating substrate. In this approach, the temperature response of a resistance thermometer deposited on the bottom of the EC film is monitored as an electric field is turned on and off. In the reported measurements, the temperature change is less than 10% of that expected because the heat loss from the EC film to the substrate is large. Lu et al.17 employed a specially designed calorimeter to measure the EC effect in a thin film. In this approach, the heat generated in the...

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“…In order to maintain a high temperature span in a wide temperature range, a cascade concept was realized exploiting the shift of the temperature of maximum EC activity of ceramics tailored by different sintering temperatures. A 10-fold cascade provided a temperature span of 10 K. The same operational principle can be realized using micro-electromechanical systems technology [72]. Here, the heat transfer liquid (Galden HT-70) is pumped back and forth by two diaphragm actuators, which are driven electrostatically.…”

Section: Refrigeration 34mentioning

confidence: 99%

Electrocaloric Cooling

Suchaneck¹,

Pakhomov²,

Gerlach³

2017

Refrigeration

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The electrocaloric effect describes a reversible temperature change in dielectric materials submitted to an applied electric field. Adiabatic polarization raises their temperature, and adiabatic depolarization lowers it, analogous to temperature changes that occur when a gas is compressed or expanded. For refrigerator application, the reverse Brayton cycle is currently the most promising for practical implementation. The electrocaloric effect provides a large material efficiency. However, existing refrigerator prototypes lack from the absence of efficient heat switches for thermal linkage to the load and the heat sink. Cooling power densities of a few W/cm 2 and temperature spans in the order of 20 K (in regeneration systems) are achievable at a cycle time of 100 ms.Keywords: electrocaloric effect, thermodynamic cycles, coefficient of performance, refrigeration devices IntroductionFor almost 150 years, refrigeration applications were solved by means of vapour compression. While the most efficient fluids for this approach are based on chlorofluorocarbons, hydrochlorofluorocarbons and hydrofluorocarbons, they come with the severe drawback of contributing to global warming and ozone depletion. Therefore, in 1987, the Montreal Protocol issued a ban on these chemicals providing regulations for phasing them out. Promising natural alternative substances are impractical due to their toxicity (ammonia) or-in particular-their flammability (propane) [1].Vapour compression refrigerators (VCRs) are operated as reverse Rankine cycles. They use a circulating liquid refrigerant as a medium. The refrigerant is: (i) adiabatically compressed, (ii) condensed at constant pressure undergoing a phase transition (thereby rejecting heat to the heat sink), (iii) adiabatically throttled in an expansion valve and (iv) evaporated at constant © 2017 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.pressure undergoing the reverse phase transition (thereby absorbing heat from the load). The amount of transferred heat is determined by the latent heat of the first-order phase transition. Similarly, in solid-state electrocaloric (EC) cooling, the adiabatic compression/expansion of the refrigerant is analogous to adiabatic polarization/depolarization, while the isobaric processes are replaced by isofield ones. Contrary to VCR, where the adiabatic expansion of the vapour is thermodynamically irreversible, the EC and the magnetocaloric (MC) effects are thermodynamically reversible processes that could reach the limit of the Carnot efficiency. This is another aspect making them promising for future application.Electric fields required for the EC refrigeration cycle can be supplied much easier and less expensively than the high magnetic fields required for the MC refrigeration [2]. Other advantages in compar...

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Design and modeling of a fluid-based micro-scale electrocaloric refrigeration system

Cited by 71 publications

References 20 publications

Experimentally validated finite element model of electrocaloric multilayer ceramic structures

Experimentally validated finite element model of electrocaloric multilayer ceramic structures

Electrocaloric characterization of a poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) terpolymer by infrared imaging

Electrocaloric Cooling

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