Characterization of two-phase flow distribution in microchannel heat exchanger header for air-conditioning system

Redo, Mark Anthony; Jeong, Jongsoo; Giannetti, Niccolò; Enoki, Koji; Yamaguchi, Seiichi; Saito, Kiyoshi; Kim, Hyunyoung

doi:10.1016/j.expthermflusci.2019.04.021

Cited by 39 publications

(10 citation statements)

References 22 publications

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“…The same-diameter set was designed to simulate a microchannel heat exchanger with common parallel branches and had an inner diameter of 2.3 mm in all header outlets. The different-diameter set was designed to compensate for the lack of flow distribution at the top of the vertical header in the flow direction (tube number 5) considered in previous studies [24], where the header outlet gradually increases in the inner diameter from tubes 1 to 5. The details of the four header sets considered in this study are listed in Table 2.…”

Section: Test Sectionmentioning

confidence: 99%

“…This research confirmed that the effects of the mass flow rate and inlet vapor quality were more significant than those of the heat load. Redo et al [24] investigated the two-phase flow distribution according to changes in the mass flow rate and inlet quality for vertical headers with parallel microchannels. This study confirmed a relatively uniform distribution at a higher mass flow rate and a lower inlet quality.…”

Section: Introductionmentioning

confidence: 99%

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Experimental Investigation of Two-Phase Flow Distribution with Different Vertical Header Configurations

et al. 2022

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In this study, we investigated the behavior of two-phase flow distribution inside a vertical header of a microchannel heat exchanger (MCHX) that functions as an evaporator of a heat pump system. In general, the two-phase flow distribution behavior of the refrigerant differs depending on the target application, which ranges from small-scale automobile air-conditioners to large-scale building heat pump systems. Particularly, it is reported that the distribution characteristics in the vertical header of the MCHX vary extensively according to the inlet flow conditions of the refrigerant and the physical profile of the header. In this study, the physical configurations (header height, branch tube diameter) of four types of vertical headers were considered. Thereafter, the operating conditions in an experimental device that simulates an MCHX with a vertical header were selected. The experiment was performed under R410A as the working fluid, with a saturation temperature of 15 °C, inlet mass flow rate of 50–150 kg h−1 (mass flux of 908–2723 kg m−2 s−1), and an inlet vapor quality of 0.1–0.2. The liquid and vapor flow ratios and the relative standard deviation were adopted as metrics to characterize the uniformity of flow distribution. The distribution characteristics were subsequently described according to Reynolds and Froude numbers. The larger the Reynolds number and the smaller the Froude number, the more uniform the two-phase flow distribution becomes. A correlation was proposed as a function of the Reynolds and Froude numbers to predict the flow distribution characteristics for the considered vertical headers.

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Section: Test Sectionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Experimental Investigation of Two-Phase Flow Distribution with Different Vertical Header Configurations

et al. 2022

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“…As shown in Figure 5, the no-slip boundary condition does not apply to this type of flow and the fluid velocity adjacent to the wall is not equal to the solid wall. For gas flows on the solid surface, there is a Knudsen layer near the solid surface, which has a thickness in the order of λ, and this layer is not negligible in microflows with large Kn numbers [86][87][88][89][90][91][92][93][94][95]. In the slip flow regime, the Navier-Stokes and energy equations are still applicable in the bulk of the channel [96,97], and only in the vicinity of the channel known as the Knudsen boundary layer is needed to define new boundary conditions.…”

Section: Different Flow Regimesmentioning

confidence: 99%

Section: Introduction To Microstructuresmentioning

confidence: 99%

A Review of the Methods of Modeling Multi-Phase Flows within Different Microchannels Shapes and Their Applications

et al. 2021

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In industrial processes, the microtechnology concept refers to the operation of small devices that integrate the elements of operational and reaction units to save energy and space. The advancement of knowledge in the field of microfluidics has resulted in fabricating devices with different applications in micro and nanoscales. Micro- and nano-devices can provide energy-efficient systems due to their high thermal performance. Fluid flow in microchannels and microstructures has been widely considered by researchers in the last two decades. In this paper, a review study on fluid flow within microstructures is performed. The present study aims to present the results obtained in previous studies on this type of system. First, different types of flows in microchannels are examined. The present article will then review previous articles and present a general summary in each section. Then, the multi-phase flows inside the microchannels are discussed, and the flows inside the micropumps, microturbines, and micromixers are evaluated. According to the literature review, it is found that the use of microstructures enhances energy efficiency. The results of previous investigations revealed that the use of nanofluids as a working fluid in microstructures improves energy efficiency. Previous studies have demonstrated special attention to the design aspects of microchannels and micro-devices compared to other design strategies to improve their performance. Finally, general concluding remarks are presented, and the existing challenges in the use of these devices and suggestions for future investigations are presented.

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“…Nevertheless, they did not to study the internal structure of the heat exchanger. Redo et al 24 investigated the two‐phase distribution characteristics of refrigerant in vertical header, and proposed correlation to predict the distribution of refrigerant. Vladimir et al 25 used the response surface method to change the structural parameters of micro‐channel heat exchangers according to different design requirements.…”

Section: Introductionmentioning

confidence: 99%

Design and performance optimization of microchannel condensers for electric vehicles

Liu

et al. 2021

Int J Energy Res

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Summary Conventional air conditioning systems for electric vehicle have insufficient performance. Therefore, the structures on both sides of microchannel condensers must be optimized to improve their thermal hydraulic performance and enhance the COP of the air‐conditioning system in electric vehicles. Through numerical calculations and experiments, the thermal hydraulic performance of microchannel condensers were evaluated to determine the optimal values of the microchannels number, flat‐tube hole aspect ratio, flow passes, and fin pitch. The results obtained using established numerical calculation models have certain reliability with errors within ±5.6%. The results reveal that the heat exchange performance of the microchannel condensers could be enhanced by appropriately reducing the fin pitch at certain frontal air velocities. Additionally, this causes a rapid increase in air flow resistance. When the flat‐tube hole aspect ratio is 1.15 and the number of flat‐tube channels is 10, the microchannel heat exchanger demonstrates optimum thermal hydraulic performance. Experimental results show that the heat exchange capacity of the three‐ and four‐pass microchannel condenser are very close which is 36.5% greater than that of the two‐pass microchannel condenser. Meanwhile, the three‐pass condenser refrigerant flow resistance is 8.3% lower than that of the four‐pass condenser. Therefore, the microchannel condenser with three passes demonstrates the best thermal hydraulic performance.

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Characterization of two-phase flow distribution in microchannel heat exchanger header for air-conditioning system

Cited by 39 publications

References 22 publications

Experimental Investigation of Two-Phase Flow Distribution with Different Vertical Header Configurations

Experimental Investigation of Two-Phase Flow Distribution with Different Vertical Header Configurations

A Review of the Methods of Modeling Multi-Phase Flows within Different Microchannels Shapes and Their Applications

Design and performance optimization of microchannel condensers for electric vehicles

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