Investigation of heat transfer and pressure drop of CO2 two-phase flow in a horizontal minichannel

Wu, Jianfeng; Koettig, T.; Franke, Ch.; Helmer, David; Eisel, T.; Haug, F.; Bremer, J.

doi:10.1016/j.ijheatmasstransfer.2010.12.009

Cited by 84 publications

(26 citation statements)

References 24 publications

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“…Amongst collected data the criterion of minichannels, i.e., Con > 0.5, is fulfilled only by the research due to Docoulombier et al [25], Wu et al [47] and Yun et al [38,39] for the case of data corresponding to d = 0.98 mm. It can therefore be concluded that in case of carbon dioxide the transition from conventional size channels to minichannels takes place at a channel diameter smaller than 1.5 mm.…”

Section: The Resultsmentioning

confidence: 99%

Prediction of flow boiling heat transfer coefficient for carbon dioxide in minichannels and conventional channels

Mikielewicz¹,

Jakubowska²

2016

Archives of Thermodynamics

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In the paper presented are the results of calculations using authors own model to predict heat transfer coefficient during flow boiling of carbon dioxide. The experimental data from various researches were collected. Calculations were conducted for a full range of quality variation and a wide range of mass velocity. The aim of the study was to test the sensitivity of the in-house model. The results show the importance of taking into account the surface tension as the parameter exhibiting its importance in case of the flow in minichannels as well as the influence of reduced pressure. The calculations were accomplished to test the sensitivity of the heat transfer model with respect to selection of the appropriate two-phase flow multiplier, which is one of the elements of the heat transfer model. For that purpose correlations due to Müller-Steinhagen and Heck as well as the one due to Friedel were considered. Obtained results show a good consistency with experimental results, however the selection of two-phase flow multiplier does not significantly influence the consistency of calculations.Keywords: Heat transfer coefficient; Flow boiling; Carbon dioxide; Minichannels Nomenclature B-blowing parameter Bo -boiling number, q/GhLG

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Section: The Resultsmentioning

confidence: 99%

Prediction of flow boiling heat transfer coefficient for carbon dioxide in minichannels and conventional channels

Mikielewicz¹,

Jakubowska²

2016

Archives of Thermodynamics

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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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“…Oh et al [68] experimentally studied five different refrigerants in mini-channels and found that CO 2 has the highest boiling HTC. Wu et al [69] and Yun et al [70] further reported that the nucleate boiling is predominant at a lower vapor quality because the heat flux and saturation temperature dictate the local HTC in this region, while the convective HTC dominates due to a high vapor velocity at a higher vapor quality. The pressure drop across the mini-channel was evaluated in Reference [69] by modifying a frictional factor developed by Cheng et al [71] to address the overprediction of a frictional pressure drop in the mist flow region.…”

Section: Evaporatormentioning

confidence: 99%

Recent Advances in Transcritical CO2 (R744) Heat Pump System: A Review

et al. 2019

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Heat pump (HP) is one of the most energy efficient tools for address heating and possibly cooling needs in buildings. Growing environmental concerns over conventional HP refrigerants, chlorofluorocarbons (CFCs), and hydrofluorocarbons (HFCs) have forced legislators and researchers to look for alternatives. As such, carbon dioxide (R744/CO2) has come to light due to its low global warming potential (GWP) and zero ozone depleting characteristics. Even though CO2 is environmentally benign, the performance of CO2 HP has been of concern since its inception. To improve the performance of CO2 HP, research has been playing a pivotal role in developing functional designs of heat exchangers, expansion devices, and compressors to suit the CO2 transcritical cycle. Different CO2 HP cycles coupled with auxiliary components, hybrid systems, and refrigerant mixtures along with advanced control strategies have been applied and tested. This paper presents a complete overview of the most recent developments of transcritical CO2 HPs, their components, and applications.

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Investigation of heat transfer and pressure drop of CO2 two-phase flow in a horizontal minichannel

Cited by 84 publications

References 24 publications

Prediction of flow boiling heat transfer coefficient for carbon dioxide in minichannels and conventional channels

Prediction of flow boiling heat transfer coefficient for carbon dioxide in minichannels and conventional channels

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

Recent Advances in Transcritical CO2 (R744) Heat Pump System: A Review

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