The Open Transport Phenomena Journal最新文献_第2页

Gas-liquid flow distributions in multipass channels with vertical upward branches 具有垂直向上分支的多通道气液流动分布

The Open Transport Phenomena Journal Pub Date : 2011-06-06 DOI: 10.2174/1877729501103010017

Z. Razlan, H. Goshima, M. Hirota, Ryota Isobe, Y. Mizuno, N. Maruyama, A. Nishimura

{"title":"Gas-liquid flow distributions in multipass channels with vertical upward branches","authors":"Z. Razlan, H. Goshima, M. Hirota, Ryota Isobe, Y. Mizuno, N. Maruyama, A. Nishimura","doi":"10.2174/1877729501103010017","DOIUrl":"https://doi.org/10.2174/1877729501103010017","url":null,"abstract":"The gas-liquid flow distributions in multi-pass channels that simulate a compact evaporator used for an automobile air-conditioning system was examined experimentally. The test channel had a horizontal header with a square cross section of 20mm × 20mm and a length of 255mm, and ten upward branches with a length of 200mm were connected to it. Experiments were conducted in an isothermal air-water flow system. Special attention was directed to influences of (i) flow-inlet condition at the header entrance (stratified-flow inlet and mist-flow inlet), (ii) pressure condition at the branch outlets (uniform backpressure and non-uniform backpressure) and (iii) pressure-loss characteristics of branches (flat tubes and multi-port tubes) on the gas-liquid distribution characteristics. In addition to the gas-liquid distributions to branches, the pressure distributions in the headers were measured to make clear the pressure condition in a real evaporator. It was found that the outlet pressure condition of branches exerts great influence on the gas-liquid distributions to branches in the channel with flat tube branches, but it has only minor influence in the channel with multi- port tube branches. The flow-inlet condition at the header entrance has significant influence on the gas-liquid distribution, and the uniformity of the liquid distribution to branches is improved under the mist-flow inlet condition. The pressure in the headers showed uniform distributions in the longitudinal direction, suggesting that the uniform backpressure condition at the branch outlets is appropriate for reproducing the flow in a real compact evaporator with multi-pass channels.","PeriodicalId":373830,"journal":{"name":"The Open Transport Phenomena Journal","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115183620","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 5

Effect of Orifice Shape on Flow Behavior and Impingement Heat Transfer 孔板形状对流动特性和冲击换热的影响

The Open Transport Phenomena Journal Pub Date : 2011-03-29 DOI: 10.2174/1877729501103010009

A. Kanamori, M. Hiwada, K. Oyakawa, I. Senaha

{"title":"Effect of Orifice Shape on Flow Behavior and Impingement Heat Transfer","authors":"A. Kanamori, M. Hiwada, K. Oyakawa, I. Senaha","doi":"10.2174/1877729501103010009","DOIUrl":"https://doi.org/10.2174/1877729501103010009","url":null,"abstract":"Impingement jets are widely used in industries because they provide a high heat transfer coefficient near the stagnation region. However, few methods exist for controlling impingement heat transfer. Recently, a peculiar diffusion process called \"axis switching\" for three-dimensional free jet has begun to attract attention, and there is a novel possibility of control diffusion and mixture process using this phenomenon. In this paper, we report on the effect of non-circular polygonal orifice shapes on impingement heat transfer. In addition, we demonstrate axis-switching phenomenon by using flow visualization with hydrogen bubbles. Orifice configurations are the regular polygons with 3 to 6 sides. Heat transfer experiments covered the distance between the orifice-to-target plate is 4 to 8 and Reynolds number is 5 × 10 4 and the heat flux is 600 W/m 2 . The flow was visualized in Reynolds number 1,500. For a free jet emerging from a regular polygonal orifice, the location of axis-switching phenomenon shifts toward the orifice exit as the number of sides on the orifice is increased. The iso-Nusselt number profile tends to take the shape of a concentric circle farther upstream. However, with a decrease in the number of sides of the orifice, the iso-Nusselt number profile after axis switching remains downstream. ing the flow using hydrogen bubbles. We also investigated the heat transfer characteristics of an impinging air jet from a non-circular orifice shapes including triangle, square, penta- gon, and hexagon. Moreover, we examined the possibility of controlling impinging heat transfer by changing the orifice configuration.","PeriodicalId":373830,"journal":{"name":"The Open Transport Phenomena Journal","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131232059","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 10

Multi-scale modeling of the gas-liquid interface based on mathematical and thermodynamic approaches 基于数学和热力学方法的气液界面多尺度建模

The Open Transport Phenomena Journal Pub Date : 2010-05-18 DOI: 10.2174/1877729501002010069

Y. Yonemoto, T. Kunugi

{"title":"Multi-scale modeling of the gas-liquid interface based on mathematical and thermodynamic approaches","authors":"Y. Yonemoto, T. Kunugi","doi":"10.2174/1877729501002010069","DOIUrl":"https://doi.org/10.2174/1877729501002010069","url":null,"abstract":"A gas-liquid interface involves complex physics along with unknown phenomena related to thermodynamics, electromagnetics, hydrodynamics, and heat and mass transfer. Each phenomenon has various characteristic time and space scales, which makes detailed understanding of the interfacial phenomena very complex. Therefore, modeling the gas- liquid interface is a key issue for numerical research on multiphase flow. Currently, the continuum surface force (CSF) model is popular in modeling the gas-liquid interface in multiphase flow. However, the CSF model cannot treat the vari- ous chemical and physical phenomena at the gas-liquid interface because it is derived based only on mechanical energy balance and it assumes that the interface has no thickness. From certain experimental observations, bubble coales- cence/repulsion was found to be related to a contamination at the interface. The present study developed a new gas-liquid interfacial model based on thermodynamics via a mathematical approach, assuming that the interface has a finite thickness like a thin fluid membrane. In particular, free energy, including an elec- trostatic potential due to the contamination at the interface, is derived based on a lattice gas model. Free energy is incorpo- rated into the conventional Navier-Stokes equation as new terms using Chapman-Enskog expansion based on the multi- scale concept. Using the Navier-Stokes equation with the free energy terms, we derived a new governing equation of fluid motion that characterizes mesoscopic scale phenomena. Finally, the new governing equation was qualitatively evaluated by simulating an interaction between two microbubbles in two dimensions while also accounting for electrostatic force.","PeriodicalId":373830,"journal":{"name":"The Open Transport Phenomena Journal","volume":"55 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-05-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123208670","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 11

The effect of body acceleration on two dimensional flow of casson fluid through an artery with asymmetric stenosis 体加速度对非对称狭窄动脉卡森液二维流动的影响

The Open Transport Phenomena Journal Pub Date : 2010-05-18 DOI: 10.2174/1877729501002010055

S. Shaw, P. Murthy, S. C. Pradhan

引用次数: 34

Importance of Melt Flow in Solidifying Mushy Zone 凝固糊状区熔体流动的重要性

The Open Transport Phenomena Journal Pub Date : 2010-04-16 DOI: 10.2174/1877729501002010016

Menghuai Wu, A. Vakhrushev, G. Nummer, C. Pfeiler, A. Kharicha, A. Ludwig

引用次数: 21

Experimental investigation of heat transfer characteristics on a gas-to-gas parallel flow microchannel heat exchanger 气-气平行流微通道换热器换热特性实验研究

The Open Transport Phenomena Journal Pub Date : 2010-04-02 DOI: 10.2174/1877729501002010001

K. Koyama, Y. Asako

引用次数: 8