Flow boiling heat transfer of R134a in multi microchannels

Fayyadh, Ekhlas M.; Mahmoud, Mohamed M.; Sefiane, Khellil; Karayiannis, Tassos G.

doi:10.1016/j.ijheatmasstransfer.2017.03.057

Cited by 75 publications

(18 citation statements)

References 30 publications

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“…The experimental results and analytical correlations employed in the literature show a similar trend-as Reynolds number The experimental results for a single-phase flow are similar to those obtained by Fayyadh et al [27]. It is worth mentioning that the correlations of Shah and London [22] and Stephan and Preuber [25] were based on data for a single channel and not for a multi-microchannel configuration, as pointed out by Fayyadh et al [27]. Copeland [26] used manifold microchannel heat sinks, which greatly reduces the travel length of the working fluid through the microchannel, reducing the pressure drop for the flow.…”

Section: Resultssupporting

confidence: 83%

“…Figure 5 shows the experimental Nusselt number compared with those predicted by correlations of Shah and London [22], Stephan and Preuber [25], and Copeland [26]. The experimental results and analytical correlations employed in the literature show a similar trend-as Reynolds number The experimental results for a single-phase flow are similar to those obtained by Fayyadh et al [27]. It is worth mentioning that the correlations of Shah and London [22] and Stephan and Preuber [25] were based on data for a single channel and not for a multi-microchannel configuration, as pointed out by Fayyadh et al [27].…”

Section: Resultssupporting

confidence: 70%

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Analytical, experimental, and numerical analysis of a microchannel cooling system for high-concentration photovoltaic cells

Ortegón

Souza

Silva

et al. 2019

J Braz. Soc. Mech. Sci. Eng.

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In this work, we present the results of an analytical, numerical, and experimental analysis on the performance of a heat sink system designed as a parallel arrangement of microchannels for cooling a high-concentration photovoltaic (HCPV) cell. The analysis considered the worst-case scenario where no electricity is generated, and the solar incidence is maximum on the northwest region of the São Paulo State in Brazil. For the experimental, analytical, and numerical analysis, the considered HCPV cell has a geometrical concentration ratio of 500×, a maximum efficiency of 40% at cell's operating temperature of 41.0 °C, and a cell base area of 100 mm 2. The numerical analysis adopts the finite volume method implemented in ANSYS Fluent v15 to solve flow and energy equations with second-order upwind schemes, and the steady-state, incompressible, and laminar flow. In the experimental apparatus, the copper microchannel heat sink consists of 33 parallel rectangular channels of 10 mm in length, 200 μm in width, and 500 μm in height for each microchannel. A cartridge heater was used to simulate the on-sun test, i.e., it simulates the total heat rate supplied to the microchannel heat sink. The microchannel heat sink is capable of keeping the operating temperature of the cell below the maximum cell's operating temperature (41.0 °C). In addition, the pressure drops are slightly higher than the predicted models, but not exceeding 34%. Moreover, the energy spent in the pumping in the microchannel represents < 1% of the energy generated by the photovoltaic cell.

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Section: Resultssupporting

confidence: 83%

Section: Resultssupporting

confidence: 70%

Analytical, experimental, and numerical analysis of a microchannel cooling system for high-concentration photovoltaic cells

Ortegón

Souza

Silva

et al. 2019

J Braz. Soc. Mech. Sci. Eng.

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“…[1] for more details. Fayyadh et al [98] investigated flow boiling of R134a in a copper, multi-microchannel evaporator (0.3 × 0.7 mm) in the mass flux range 50 -300 kg/m 2 s. They reported that flow reversal depends on mass flux. For G = 50 kg/m 2 s, flow reversal was observed at boiling incipience and continued for all heat fluxes.…”

Section: Flow Instability and Reversalmentioning

confidence: 99%

Flow Boiling in Micro-Passages: Developments in Fundamental Aspects and Applications

Karayiannis

Mahmoud

2018

International Heat Transfer Conference 16

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Flow boiling in mini to micro passages located at the heat source, and as part of a thermal management system, has been identified as a possible way to remove the increasing high heat fluxes generated by high power electronic devices due to their capability of high heat transfer rates with small surface temperature variations. However, some still unresolved fundamental issues hinder the possible full adoption of this technology. These relate to the prevailing flow patterns, heat transfer rates and pressure drop in such geometries, and their dependence on key parameters. The possible major applications of flow boiling in microchannels are first mentioned in this paper, highlighting the requirements and the challenges of the thermal management of each application. The paper then presents new experimental research by the present authors as well as research reported in the literature on flow boiling in single tubes and rectangular multi microchannels to help elucidate the following fundamental issues: the definition of a microchannel, prevailing flow patterns, heat transfer mechanisms, flow instability and reversal and their effect on heat transfer rates, effect of channel material and surface characteristics (including latest research in coatings), effect of different fluid properties, and its relation to channel material, effect of channel length and aspect ratio. An appreciation of the above can help explain the interpretation of the prevailing fluid flow and heat transfer phenomena and the data scatter and discrepancies observed in past studies. In addition, models and correlations predicting flow patterns and heat transfer rates are presented.

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“…Two-phase flow boiling regimes have received extensive attention in power electronics applications in recent years. Taking advantage of the latent heat of liquid refrigerant during its boiling process, it can provide higher heat transfer coefficients, lower flow rates, more uniform surface temperatures, and lower pumping power than a single-phase cooling scheme [1], [22]- [24]. However, the refrigerant boiling requires a wise control of the pressure and temperature of the refrigerant in the evaporator, so that the flow boiling can be reached for isothermal heat absorption.…”

Section: Introductionmentioning

confidence: 99%

Microchannel Thermal Management System With Two-Phase Flow for Power Electronics Over 500 W/cm² Heat Dissipation

Hou

Zhang

Huang

et al. 2020

IEEE Trans. Power Electron.

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In this paper, a microchannel thermal management system (MTMS) with the two-phase flow using the refrigerant R1234yf with low global warming potential is presented. The thermal test vehicles (TTVs) were made of either single or multiple thermal test chips embedded in the substrates, which were then attached to the MTMS. The system included two identical aluminum microchannel heat sinks (MHSs) connected in series in the cooling loop, which also consisted of a gas flowmeter, a miniature compressor, a condenser, a throttling device, and accessory measurement components. The experimental results showed that the thermal management system could dissipate a heat flux of 526 W/cm 2 while maintaining the junction temperature below 120 ºC. For SiC MOSFET with a higher junction temperature, e.g., 175 ºC , the current system is expected to dissipate a heat flux as high as about 750 W/cm 2. The effects of the rotational speed of the compressor, the opening of the throttling device, TTV layout on MHS, and a downstream heater on the cooling performance of the system were analyzed in detail. The study shows that the present thermal management with a twophase flow system is promising cooling technology for the high heat flux SiC devices.

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Flow boiling heat transfer of R134a in multi microchannels

Cited by 75 publications

References 30 publications

Analytical, experimental, and numerical analysis of a microchannel cooling system for high-concentration photovoltaic cells

Analytical, experimental, and numerical analysis of a microchannel cooling system for high-concentration photovoltaic cells

Flow Boiling in Micro-Passages: Developments in Fundamental Aspects and Applications

Microchannel Thermal Management System With Two-Phase Flow for Power Electronics Over 500 W/cm² Heat Dissipation

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Flow boiling heat transfer of R134a in multi microchannels

Cited by 75 publications

References 30 publications

Analytical, experimental, and numerical analysis of a microchannel cooling system for high-concentration photovoltaic cells

Analytical, experimental, and numerical analysis of a microchannel cooling system for high-concentration photovoltaic cells

Flow Boiling in Micro-Passages: Developments in Fundamental Aspects and Applications

Microchannel Thermal Management System With Two-Phase Flow for Power Electronics Over 500 W/cm2 Heat Dissipation

Contact Info

Product

Resources

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Microchannel Thermal Management System With Two-Phase Flow for Power Electronics Over 500 W/cm² Heat Dissipation