Micro-channel evaporator for space applications – 1. Experimental pressure drop and heat transfer results for different orientations in earth gravity

Lee, Hyoungsoon; Park, Ilchung; Mudawar, Issam; Hasan, Mohammad M.

doi:10.1016/j.ijheatmasstransfer.2014.06.012

Cited by 55 publications

(14 citation statements)

References 49 publications

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“…This is a key feature of two-phase flow in micro-channels, which provide important advantages to space systems by greatly increasing flow inertia for a given flow rate to help resist body forces effects. These advantages were recently examined by Lee et al [67,68] who explored flow boiling of FC-72 in a test module containing 80 of 231-lm wide Â 1000-lm deep micro-channels in three flow orientations: horizontal, vertical upflow and vertical downflow. Their data showed gravity effects are negated altogether at velocities far smaller than those for macro-channels.…”

Section: Advantages Of Micro-channels In Helping Negate Body Force Efmentioning

confidence: 99%

Review of flow boiling and critical heat flux in microgravity

Konishi

Mudawar

2015

International Journal of Heat and Mass Transfer

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140

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Section: Advantages Of Micro-channels In Helping Negate Body Force Efmentioning

confidence: 99%

Review of flow boiling and critical heat flux in microgravity

Konishi

Mudawar

2015

International Journal of Heat and Mass Transfer

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140

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“…The micro-channel exchanger is just one of the methods that have been developed to solve the problems of heat flux dissipation in electronic components and chips [Rosa et al, 2009]. As a result of the search for efficient methods to cool electronic components, heat transfer and flow characteristics in micro-channels have been studied widely during the last two decades [Yun et al, 2005;Lee and Mudawar, 2008;Rosa et al, 2009;Li and Wu, 2010;Ali and Palm, 2011;Oh and Son, 2011;Wu et al, 2011;Col and Bortolin, 2012;Derby et al, 2012;Karayiannis et al, 2012;Kim and Mudawar, 2013a;Kim and Mudawar, 2013b;Balaj et al, 2014;Dai et al, 2014;Dirker et al, 2014;Lee et al, 2014]. Nowadays, more accurate predictions of heat transfer are necessary for micro-channel designs due to higher cooling load and smaller flow rates in the micro-channels which cause detriment to the temperature sensitive electronic components [Qu and Mudawar, 2002].…”

Section: Introductionmentioning

confidence: 99%

A CFD technique to investigate the chocked flow and heat transfer characteristic in a micro-channel heat sink

Azari

Bahraini

Marhamati

2015

Int. J. Comp. Mat. Sci. Eng.

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In this research, a Computational Fluid Dynamics (CFD) technique was used to investigate the effect of choking on the flow and heat transfer characteristics of a typical micro-channel heat sink. Numerical simulations have been carried out using Spalart-Allmaras model. Comparison of the numerical results for the heat transfer rate, mass flow rate and Stanton number with the experimental data were conducted. Relatively good agreement was achieved with maximum relative error 16%, and 8% for heat transfer and mass flow rate, respectively. Also, average relative error 9.2% was obtained for the Stanton number in comparison with the experimental values. Although, the results show that the majority of heat was transferred in the entrance region of the channel, but the heat transfer in micro-channels can also be affected by choking at channel exit. Moreover, the results clearly show that, the location where the flow is choked (at the vicinity of the channel exit) is especially important in determining the heat transfer phenomena. It was found that Spalart-Allmaras model is capable to capture the main features of the choked flow. Also, the effects of choking on the main characteristics of the flow was presented and discussed.

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“…Two-phase flow instabilities are commonly described as resulting from interactions between the many thermal and hydraulic phenomenon present in two-phase flows. A significant body of work investigating these phenomena exists, with key instability modes including density wave oscillations (DWOs) [46][47][48][49][50], pressure drop oscillations (PDOs) [51][52][53][54], and parallel channel instability (PCI) [55][56][57][58]. Much of the work performed is summarized in review articles, including the seminal work of Boure et al [59] and more recent reviews of Tadrist [60], Kakac and Bon [61], and Ruspini et al [62].…”

Section: Two-phase Flow Instabilitiesmentioning

confidence: 99%

Flow condensation pressure oscillations at different orientations

O’Neill

Mudawar

Hasan

et al. 2018

International Journal of Heat and Mass Transfer

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Investigation of two-phase flow dynamic behavior and instabilities has traditionally centered on phenomena present in boiling flows due to the safety critical nature of boiling in a variety of cooling applications. Analysis of pressure signals in condensing systems reveal the presence of relevant oscillatory phenomena during flow condensation as well, which may impact performance in applications concerned with precise system control. Towards this end, the present study presents results for oscillatory behavior observed in pressure measurements during flow condensation of FC-72 in a smooth circular tube in vertical upflow, vertical downflow, and horizontal flow orientations. Dynamic behavior observed within the test section is determined to be independent of other components within the flow loop, allowing it to be isolated and interpreted as resulting from physical aspects of two-phase flow with condensation. The presence of a peak oscillatory mode (one of significantly larger amplitude than any others present) is seen for 72% of vertical upflow test cases, 61% of vertical downflow, and 54% of horizontal flow. Relative intensities of this peak oscillatory mode are evaluated through calculation of Q Factor for the corresponding frequency response peak. Frequency and amplitude of peak oscillatory modes are also evaluated. Overall, vertical upflow is seen to exhibit the most significant oscillatory behavior, although in its maximum case amplitude is only seen to be 7.9% of time-averaged module inlet pressure, indicating there is little safety risk posed by oscillations under current operating conditions. Flow visualization image sequences for each orientation are also presented and used to draw parallels between physical characteristics of condensate film behavior under different operating conditions and trends in oscillatory behavior detected in pressure signals.

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Micro-channel evaporator for space applications – 1. Experimental pressure drop and heat transfer results for different orientations in earth gravity

Cited by 55 publications

References 49 publications

Review of flow boiling and critical heat flux in microgravity

Review of flow boiling and critical heat flux in microgravity

A CFD technique to investigate the chocked flow and heat transfer characteristic in a micro-channel heat sink

Flow condensation pressure oscillations at different orientations

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