Combined heat and mass transfer for laminar flow of moist air in a 3D rectangular duct: CFD simulation and validation with experimental data

Talukdar, Prabal; Iskra, Conrad R.; Simonson, Carey J.

doi:10.1016/j.ijheatmasstransfer.2007.08.034

Cited by 59 publications

(29 citation statements)

References 33 publications

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“…Pressure interpolation is second order. Since the Richardson number is well below one, buoyancy effects are negligible, as also mentioned by Talukdar et al [30]. Thereby, only forced convection is accounted for in the air-flow simulations, considering heat as a passive scalar, by which the flow field and thus also the CTCs are not strongly dependent on the thermal boundary conditions.…”

Section: Numerical Simulationmentioning

confidence: 85%

Analysis of convective heat and mass transfer coefficients for convective drying of a porous flat plate by conjugate modelling

Defraeye

Blocken

Carmeliet

2012

International Journal of Heat and Mass Transfer

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Defraeye T., Blocken B., , Analysis of convective heat and mass transfer coefficients for convective drying of a porous flat plate by conjugate modelling, International Journal of Heat and Mass Transfer 55 (1-3), 112-124. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2011. does not require knowledge of convective transfer coefficients (CTCs) but allows determining the CTCs aposteriori, hence identifying their spatial and temporal variability, which is the main focus of this study.Comparison is made with porous-material modelling using spatially and/or temporally constant CTCs. Both spatial and temporal variations of the convective boundary conditions are found to have a distinct impact on the drying behaviour: the spatial CTC variation results in two-dimensional drying of the porous material due to leading-edge effects; the temporal CTC variation identifies distinct maxima in the drying rates at the surface right before the surface dries out locally. The CTCs obtained with conjugate modelling remain approximately constant during the constant and decreasing drying rate period (CDRP and DDRP, respectively), but a distinct variation is noticed at the transition of CDRP to DDRP. The heat and mass transfer analogy is found to be valid during the CDRP and to a lesser extent during the DDRP but large discrepancies are found during the transition of CDRP to DDRP. The advantages of conjugate modelling are indicated in this study but the need for detailed modelling of convective boundary conditions is however strongly dependent on the drying behaviour of the porous material and is not always required. Nomenclature

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Section: Numerical Simulationmentioning

confidence: 85%

Analysis of convective heat and mass transfer coefficients for convective drying of a porous flat plate by conjugate modelling

Defraeye

Blocken

Carmeliet

2012

International Journal of Heat and Mass Transfer

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“…A dimensionless control parameter specifies the system, the Rayleigh number Ra. It provides a dimensionless measure of the thermal forcing, and a critical Rayleigh number Ra c indicates when this instability will occur (Talukdar et al 2008).…”

Section: Airflow Results and Daily Inversionmentioning

confidence: 99%

Evidence of daily and seasonal inversions of airflow in Petites Dales cave, Normandy, France

Masséi¹,

Magne²,

Rodet³

et al. 2017

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-Pierre Viard: Dnevni in sezonski obrati smeri zračnega toka v jami Petites Dales, Normandija, Francija V članku poročamo o podrobni mikroklimatski študiji v jami Petites Dales. V jami z enim samim vhodom smo dve leti opazovali temperaturo, vlago in porazdelitev zračnih tokov. Podrobne dnevne meritve temperature in zračnega toka kažejo na stratifikacijo in dnevni obrat smeri toka. Poleti zunanji zrak vdira v jamo pri stropu, pozimi pa pri tleh. Pri tem se pri vhodu oblikuje profil hitrosti zraka v obliki črke S, globlje v jami pa konvekcijska zanka. V vmesnih obdobjih lahko pride do preklapljanja iz dotoka pod stropom v dotok pri dnu in obratno, kar v članku obravnavamo z vidika termodinamike. V tej raziskavi smo prvič pojasnili dnevne obrate smeri zraka v primerljivih jamah. Študije jamske mikroklime so pomembne za razumevanje jamskega ekosistema, procesov v jamah ter človekovega vpliva nanje. Ključne besede: jama, mikroklima, kras, zračni tok, temperatura, spremenljivost. -entrance is presented in this paper. Two years of cave monitoring investigate temperature, weight of water vapour and airflow distributions outside and inside the cavity to determine the global behaviour of the karst cave. In addition, daily measurements of temperature and airflow demonstrate clearly the stratification of the air and inversions of the airflow during day-time. The cave air is intensively exchanged with external air during the years, with two main modes: (i) airflow enters from the ceiling during summer period and (ii) airflow enters from the floor during winter. At the entrance, an Sshaped velocity profile was observed and far from the entrance, convection loops were observed. During the other period of the year, the airflows may switch from top to bottom or conversely. The thermodynamic conditions of switching are discussed in this paper. This study provided for the first time evidence of daily airflow inversion. Study of cave climates is required in the comprehension of cave flora and fauna, thermodynamic conditions for karst processes underground, hydrogeological features of speleothems, human impact when caves are visited.

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“…The vapour density of the air stream is determined from the measured temperature and RH of the airstream while the vapour density at the surface is based on the measured water temperature and the saturated air assumption. Talukdar et al used the results of similar experiments for comparison with CFD simulations [43].…”

Section: Wind Tunnel Experiments -Convection Coefficient Experimentsmentioning

confidence: 99%

Benchmark experiments for moisture transfer modelling in air and porous materials

Belleghem

Steeman

Willockx

et al. 2011

Building and Environment

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Abstract.The presence of hygroscopic materials has a large impact on the moisture balance of buildings. Nowadays, HAM (Heat, Air and Moisture) models are widely used to investigate the role of hygroscopic materials on the performance of buildings, i.e. on the building envelope, the indoor climate and valuable objects stored within the building. Recently, these HAM models are being coupled to CFD models to study the moisture exchange between air and porous materials on a local scale (microclimates), or to BES (Building Energy Simulation) models which focus on the interaction between air and porous materials at building level. Validation of these numerical codes is essential to gain confidence in the codes. However, available experimental data are rather scarce. This paper describes the design of a new test facility for humidity experiments. A dedicated AHU system is used to provide well-controlled air (constant temperature and RH) to an airtight and well-insulated room-size test chamber. In one of the walls of the chamber a calcium silicate sample is installed. A step in RH of the supply air is imposed. Temperature and RH of the supply air, the room air and on various depths inside the sample are continuously registered during the experiments. Two types of experiments were carried out to validate a coupled CFD-HAM model and a coupled BES-HAM model. The temperature outside the test chamber was controlled and there was no temperature difference imposed across the chamber walls. Comparing the models with the measured data gave satisfactory agreement.

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Combined heat and mass transfer for laminar flow of moist air in a 3D rectangular duct: CFD simulation and validation with experimental data

Cited by 59 publications

References 33 publications

Analysis of convective heat and mass transfer coefficients for convective drying of a porous flat plate by conjugate modelling

Analysis of convective heat and mass transfer coefficients for convective drying of a porous flat plate by conjugate modelling

Evidence of daily and seasonal inversions of airflow in Petites Dales cave, Normandy, France

Benchmark experiments for moisture transfer modelling in air and porous materials

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