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  • Open Access

    ARTICLE

    The Turbulent Schmidt Number for Transient Contaminant Dispersion in a Large Ventilated Room Using a Realizable k-ε Model

    Fei Wang, Qinpeng Meng, Jinchi Zhao, Xin Wang, Yuhong Liu, Qianru Zhang*

    FDMP-Fluid Dynamics & Materials Processing, Vol.20, No.4, pp. 829-846, 2024, DOI:10.32604/fdmp.2023.026917

    Abstract Buildings with large open spaces in which chemicals are handled are often exposed to the risk of explosions. Computational fluid dynamics is a useful and convenient way to investigate contaminant dispersion in such large spaces. The turbulent Schmidt number (Sct) concept has typically been used in this regard, and most studies have adopted a default value. We studied the concentration distribution for sulfur hexafluoride (SF6) assuming different emission rates and considering the effect of Sct. Then we examined the same problem for a light gas by assuming hydrogen gas (H2) as the contaminant. When SF6 was considered as More >

  • Open Access

    ARTICLE

    NUMERICAL INVESTIGATION OF NON-NEWTONIAN FLOW AND HEAT TRANSFER IN TUBES OF HEAT EXCHANGERS WITH RECIPROCATING INSERT DEVICES*

    D. S. Martínez, J. P. Solano, J. Pérez, A. Viedma

    Frontiers in Heat and Mass Transfer, Vol.2, No.3, pp. 1-10, 2011, DOI:10.5098/hmt.v2.3.3002

    Abstract Non-Newtonian flow and heat transfer in tubes of heat exchangers with reciprocating insert devices have been numerically investigated. The heat exchanger is mechanically assisted by a reciprocating cylinder, which moves the scraping rods inserted in the tubes. An array of semi-circular elements is mounted on each rod, with a pitch p=5D. These elements fit the internal diameter of the tubes. During the reciprocating motion, they scrape the inner tube wall, avoiding fouling. Additionally, the movement of the inserted device generates macroscopic displacements of the flow, which continuously mix core regions with peripheral flow. A power More >

  • Open Access

    ARTICLE

    CONJUGATE HEAT TRANSFER FROM A FLAT PLATE WITH SHOWER HEAD IMPINGING JETS

    Rajesh Kumar Panda, B.V.S.S.S. Prasad*

    Frontiers in Heat and Mass Transfer, Vol.2, No.1, pp. 1-10, 2011, DOI:10.5098/hmt.v2.1.3008

    Abstract Conjugate heat transfer from a flat circular disk is investigated both computationally and experimentally with a constant heat flux imposed on its bottom surface and a shower head of air jets impinging on the top surface. The shower head consists of a central jet surrounded by four neighboring perimeter jets. Measured temperature data at twelve locations within the plate are compared with the conjugate heat transfer result obtained at the same locations computationally by Shear Stress Transport (SST) κ-ω turbulence model. The spacing to orifice diameter ratio (H/d = 1 to 4), the jet Reynolds… More >

  • Open Access

    ARTICLE

    Influences of the Fresh Air Volume on the Removal of Cough-Released Droplets in a Passenger Car of a High-Speed Train Using CFD

    Jun Xu1, Kai Bi1, Yibin Lu2,*, Tiantian Wang2,3, Hang Zhang2, Zeyuan Zheng3, Fushan Shi3, Yaxin Zheng3, Xiaoying Li2, Jingping Yang3

    CMES-Computer Modeling in Engineering & Sciences, Vol.138, No.3, pp. 2727-2748, 2024, DOI:10.32604/cmes.2023.031341

    Abstract The spread and removal of pollution sources, namely, cough-released droplets in three different areas (front, middle, and rear areas) of a fully-loaded passenger car in a high-speed train under different fresh air flow volume were studied using computational fluid dynamics (CFD) method. In addition, the structure of indoor flow fields was also analysed. The results show that the large eddies are more stable and flow faster in the air supply under Mode 2 (fresh air volume: 2200 m3/h) compared to Mode 1 (fresh air volume: 1100 m3/h). By analysing the spreading process of droplets sprayed at different locations… More >

  • Open Access

    ARTICLE

    STUDY OF INTERNAL FLOW CHARACTERISTICS OF INJECTOR FUELLED WITH VARIOUS BLENDS OF DIETHYL ETHER AND DIESEL USING CFD

    Vijayakumar Thulasi*, Thundil Karuppa Raj Rajagopal

    Frontiers in Heat and Mass Transfer, Vol.4, No.2, pp. 1-5, 2013, DOI:10.5098/hmt.v4.2.3007

    Abstract Researchers across the world are exploring the potential of using diethyl ether as an alternate fuel to meet the stringent emission norms due to the high oxygen content in the fuel. The spray characteristics of any injected fuel are highly influenced by its physical properties. Due to high injection pressure in CI engines the fuel tends to cavitate inside the nozzle greatly. The change in fuel properties will affect the cavitating behavior of the fuel. In this paper computational technique is used to study and compare the internal flow characteristics of a fuel injector for More >

  • Open Access

    ARTICLE

    CFD MODELLING AND VALIDATION OF COMBUSTION IN DIRECT INJECTION COMPRESSION IGNITION ENGINE FUELLED WITH JATROPHA OIL BLENDS WITH DIESEL

    Biswajit De*, Rajsekhar Panua

    Frontiers in Heat and Mass Transfer, Vol.5, pp. 1-6, 2014, DOI:10.5098/hmt.5.7

    Abstract This paper presents a pre-mixed combustion model for diesel and Jatropha oil blends combustion studies. Jatropha oil blends are considered as a mixture of diesel and Jatropha oil. CFD package, FLUENT 6.3 is used for modeling the complex combustion phenomenon in compression ignition engine. The experiments are carried out on a single cylinder, four strokes, water cooled direct injection compression ignition engine at compression ratio of 17.5 at full load condition at constant speed of 1500 rpm fuelled with diesel and jatropha oil blends with diesel. The numerical model is solved by considering pressure based,… More >

  • Open Access

    ARTICLE

    Investigation the Influence of Phase Change Material Amount on a Hot-Water Stratification in Charging Mode

    Abeer H. Falih*, Basim Freegah, Adnan A. Abdulrasool

    Frontiers in Heat and Mass Transfer, Vol.21, pp. 141-160, 2023, DOI:10.32604/fhmt.2023.01525

    Abstract Among the various techniques for enhancing the storage and consumption of energy in a thermal energy storage system, the establishment of thermal stratification in a hot-water container is an effective technology. The current study aims to assess the performance of the thermal stratification for hot-water containers using (ANSYS Fluent) R.1.0, 2022, through the study of the impact of different numbers of paraffin-filled containers, namely 3, 5, and 7, that are equivalent to 5, 7, and 9 kg of paraffin, respectively. To validate the present numerical model, a comparison between the current study results and the… More > Graphic Abstract

    Investigation the Influence of Phase Change Material Amount on a Hot-Water Stratification in Charging Mode

  • Open Access

    ARTICLE

    MODELLING AND EXPERIMENTAL VALIDATION OF COMBUSTION IN STRAIGHT INOCULATION COMPRESSION IGNITION ENGINE FUELLED WITH DIESEL AND JATROPHA METHYL ESTER BLEND

    Biswajit De*, Rajsekhar Panua

    Frontiers in Heat and Mass Transfer, Vol.6, pp. 1-6, 2015, DOI:10.5098/hmt.6.11

    Abstract An incorporated arithmetical model has been urbanized and investigated for CFD replication of a solitary cylinder, four stroke, straight inoculation, compressed ignition diesel engine of 3.5 kW for in-cylinder combustion analysis and authenticated under engine simulations at full load functioning conditions with foundation fuel diesel and 10% JME (volume basis) blend with diesel at invariable speed of 1500 rpm. For advancing the exactness of the exertion, a number of sub models, such as species transport model explaining the actual biodiesel energy content and molecular structure as soon as fuel blend is initiated, spray break-up model, More >

  • Open Access

    ARTICLE

    EFFECTS OF GEOMETRIC PARAMETERS FOR WAVY FINNED-TUBE HEAT EXCHANGER IN TURBULENT FLOW: A CFD MODELING

    Arafat A. Bhuiyana,c, M. Ruhul Aminb, Jamal Naserc, A. K. M. Sadrul Islama

    Frontiers in Heat and Mass Transfer, Vol.6, pp. 1-11, 2015, DOI:10.5098/hmt.6.5

    Abstract In this study, the effects of thermal and hydraulic characteristics of wavy fin and tube heat exchanger are investigated. Simulation has been carried out by a commercial computational fluid dynamics code, ANSYS CFX12.0. The main objective of this study is to investigate the flow characteristics in turbulent flow. Results are predicted for the turbulent flow regime (2100≤Re≤7000) and compared with author’s previous work for laminar (400 ≤Re≤1200) and transitional (1300≤Re≤2000) flow regime. Regarding turbulence, the k-ω model was used to predict the turbulent flow characteristics with 5% turbulence intensity. Predicted results were compared with the More >

  • Open Access

    ARTICLE

    EXPERIMENTAL AND 3D-CFD STUDY ON OPTIMIZATION OF CONTROL VALVE DIAMETER FOR A CONVERGENT VORTEX TUBE

    Seyed Ehsan Rafiee*, M. M. Sadeghiazad

    Frontiers in Heat and Mass Transfer, Vol.7, pp. 1-15, 2016, DOI:10.5098/hmt.7.13

    Abstract The aim of this investigation is study on separation phenomenon inside a special vortex tube affected by structural and physical factors including; throttle diameter, nozzle number and injection pressure as well as the parametric optimization based on separation efficiency using experimental and 3D-CFD methods. The results show that convergent VT with Dth=5.5mm provides 30.01% and 20.04% higher cooling and heating effectiveness compared to basic model. As another result, the higher injection pressure, the higher cooling effectiveness. The cooling effectiveness improves (16.86%) with increase in slot number up to N=4, then decreases. The maximum disagreement between More >

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