Superficial heat transfer by forced convection and radiation in a horizontal channel

Chérif, Y.; Joulin, Annabelle; Zalewski, Laurent; Lassue, Stéphane

doi:10.1016/j.ijthermalsci.2009.01.017

Cited by 19 publications

(20 citation statements)

References 23 publications

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“…Practically, these are CAPTEC products, whose thicknesses are about 0.2 mm and sensitivity are 120 µV W −1 m 2 . The calibration procedure, described in [69,70], permits us to calibrate these sensors with a precision of ±3% as demonstrated for the example in [71]. Secondly, the entire sample is positioned between two exchange plates in order to impose the temperature on the two main faces.…”

Section: Experimental Protocolmentioning

confidence: 99%

Efficient Characterization of Macroscopic Composite Cement Mortars with Various Contents of Phase Change Material

et al. 2019

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The determination of both the thermal and thermodynamical properties of a composite material containing phase change material is done thanks to an inverse method, which combines experimental measurements and numerical computations. Given first an in-house experiment, which allows us to test samples at a macroscopic scale (i.e., close to the real conditions) and to set various types of thermal stresses, and secondly the simulation of the corresponding thermal behavior, relying on an accurate thermodynamical modeling and taking into account the real operating parameters (e.g., thermal contact resistances and non-symmetric heat fluxes on each side), it is possible to characterize the solid and liquid thermal conductivities and heat capacities, as well as the temperature range associated with a non-isothermal phase transition and the associated latent heat. The specificity of the present approach is to allow, in a single step, a characterization of all the involved thermo-physical parameters that are usually required in simulation tools (e.g., EnergyPlus…). Moreover, the hitherto studies dealing with repeatability and uncertainties of the enthalpy characterization are generally very scant and not encountered very often or only with qualitative assessments. This is a clear caveat, especially when considering any system design. Therefore, for the first time ever, the present paper pays a special attention to the repeatability of the identification method and studies the scedasticity of the results, that is to say the deviations of the determined enthalpy curves, not only from a qualitative point of view but also by proposing quantitative arguments. Finally, the results are very promising since the agreement between all trials is excellent, the maximum error for all parameters being lower than 4%. This is far below the current quality thresholds admitted when characterizing the enthalpy of a phase change material.

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Section: Experimental Protocolmentioning

confidence: 99%

Efficient Characterization of Macroscopic Composite Cement Mortars with Various Contents of Phase Change Material

et al. 2019

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“…It is equipped with thermocouples (T-type-diameter: 0.1 mm) to measure air and surface temperatures, plus two heat fluxmeters (tangential gradient type) to measure heat flux evolution on both sides of the storage wall. The calibration procedure, described in [58,59], provides these sensors with an accuracy of ±3%. The pyranometer is located in the vertical plane of the facade receiving incident solar flux.…”

Section: Composite Solar Wall and Experimental Set-upmentioning

confidence: 99%

Numerical and Experimental Investigations of Composite Solar Walls Integrating Sensible or Latent Heat Thermal Storage

et al. 2020

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This article studies a composite solar wall with latent storage (TES) designed to heat rooms inside buildings during the cold season. No numerical model of the composite solar wall is currently available in the Dymola/Modelica software library. The first objective of this work is to develop one such model. The article describes the elementary components, along with the equations that allow modeling the heat transfers and storage phenomena governing both the thermal behavior and performance of the solar wall. This model was built by assembling various existing basic elements from the software's "Building" library (e.g., models of heat transfer by convection, radiation and conduction) and then creating new elements, such as the storage element incorporating the phase change material (PCM). To validate this solar wall model, numerical results are compared to experimental data stemming from a small-scale composite solar wall manufactured in our laboratory, and the experimental set-up could be tested under real weather conditions. After verifying the level of confidence in the model, the energy performance of two solar walls, one with a conventional storage wall (sensible heat storage) the other containing a PCM (the same as in the experiment), are compared. The result indicates that the solar wall incorporating a PCM does not in this case release any more energy in the room to be heated. first assessment by E.S. Morse in the 19th century. It was subsequently redesigned as an architectural element by F. Trombe and J. Michel [11], as frequently acknowledged in published papers on: Trombe wall, Trombe-Michel solar wall, or composite solar wall. In current research dedicated to energy and environmental contexts, passive solar wall techniques are more relevant than ever, leading to the development of various passive configurations, namely: (a) the classical Trombe wall: engineering techniques [12], theoretical and experimental investigations of heat transfer [13], comparison of the effects of air flow rate between the one-dimensional and two-dimensional models [14], and the numerical study of thermal performance [15]; (b) the PCM Trombe wall: clay bricks integrating PCM macro-capsules functioning as the storage wall [16], thermal performance of a PCM storage wall in temperate and hot climates [17], a simulation study of building walls using the collector-storage wall integrating PCMs [18], a summary of the investigation and analysis conducted on systems incorporating PCMs as storage elements [19], the heat storage wall of the studied building ventilation using black paraffin wax [20], and experimental investigations of PCM wall thermal performance improved by delta winglet vortex generators [21]; (c) a composite Trombe wall with or without PCM: the numerical study of a composite Trombe wall model both with and without PCM in relying on the Dymola/Modelica software [22], numerical studies of the comparison between two walls using sensible heat (with concrete as the storage wall) by means of TRNSYS software [23], experiment...

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“…The secondary transducer method was carried out [41,42]. The advantage of this method resides in the possibility to control thermal equilibrium by means of another uncalibrated fluxmeter [43]. The fluxmeter to be calibrated is placed on an isothermal cold plate.…”

Section: Thermal Probementioning

confidence: 99%

Frequency Methods Applied to the Characterization of the Thermophysical Properties of a Granular Material with a Cylindrical Probe

et al. 2011

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In many fields, such as in the agri-food industry or in the building industry, it is important to be able to monitor the thermophysical properties of granular materials. Regular thermal probes allow for the determination of one or several thermophysical factors. The success of the method used depends in part on the nature of the signal sent, on the type of physical model applied and eventually on the type of probe used and its implantation in the material. Although efficacious for most applications, regular thermal probes do present some limitations. It is the case, for example, when one has to know precisely the thermal contact resistance or the nature of the signal sent. In this article is presented a characterization method based on thermal impedance formalism. This method allows for the determination of the thermal conductivity, the thermal diffusivity, and the contact thermal resistance in one single test. The application of this method requires the use of a specific probe developed to enable measurement of heat flux and temperature at the interface of the probe and the studied material. Its practical application is presented for dry sand.

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Superficial heat transfer by forced convection and radiation in a horizontal channel

Cited by 19 publications

References 23 publications

Efficient Characterization of Macroscopic Composite Cement Mortars with Various Contents of Phase Change Material

Efficient Characterization of Macroscopic Composite Cement Mortars with Various Contents of Phase Change Material

Numerical and Experimental Investigations of Composite Solar Walls Integrating Sensible or Latent Heat Thermal Storage

Frequency Methods Applied to the Characterization of the Thermophysical Properties of a Granular Material with a Cylindrical Probe

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