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Help yourself: theses

On some subjects, CETIAT welcomes doctoral students in its laboratories. You can consult here after a summary of the thesis and sometimes download the corresponding document.



 
EXPERIMENTAL STUDY AND MODELLING OF FROST FORMATION AND DEVELOPMENT ON A COLD PLANE PLATE
Author: Dr Aurélia LEONI
Doctoral thesis presented to l'Institut National des Sciences Appliquées (INSA) de Lyon: Energetic
Supervisors: Philippe HABERSCHILL and Rémi REVELLIN
Cofinanced by Ministère de la Recherche (ANRT) and CETIAT - 2017 – 216 p.

www.insa-lyon.fr

Download the thesis (PDF file 26 Mo) - in French

 
In the energy consumption and environmental impact reduction goal, heat pumps emerged as an alternative to fossil fuel systems for space heating and hot water production in residential and tertiary sectors. Manufacturers still try to improve energy performance of heat pumps. However, a non-controlled phenomenon is limiting progress : frosting. Indeed, in some outdoor air temperature and relative humidity conditions, frost can form on the heat pump evaporator surface, leading to performance reduction. On the French market, almost 98 % of the heat pumps are using outdoor air as heat source and are thus affected. Despite more and more sophisticated defrosting strategies, the frosting/defrosting cyclic operation strongly reduces heat pump performance.
or optimizing defrosting strategies, there is a need understanding frost appearance and growth mechanisms. This PhD work thus proposes to study frost formation and development on a cold plane plate. An in-depth bibliography study helped establishing databases gathering experimental points on frost thickness and frost density. Models and correlations of frost formation available in the literature have been reproduced and applied to the databases in order to evaluate their prediction capacity. The most performing models have been identified.
Meanwhile, an experimental bench allowing visualization of frost formation and development on a cold plane plate has been set up. The sensitivity analysis on air temperature, cold plate temperature, air velocity and relative humidity allowed an evaluation of these parameters impact on frost formation, and more particularly on three of its properties : thickness, density and thermal conductivity. Relative humidity and cold plate temperature have been identified as the leading parameters. One of the main results of this work was to highlight the frost crystal structure role on properties (i.e. density and thermal conductivity). Experimental data points obtained with the test bench have been compared to the results provided by literature models. Predictive methods identified as satisfying in the bibliography study gave similar results (from a statistical point of view). Perspectives for future work have also been proposed.


 
ACOUSTIC RADIATION OF A PERIODIC STRUCTURE OF FINNED-COIL TYPE - APPLICATION TO HEAT PUMPS
Author: Dr Guillaume GOSSE
Doctoral thesis presented to l'Institut National des Sciences Appliquées (INSA) de Lyon: Acoustics
Supervisor: Charles PEZERAT
Cofinanced by ADEME and CETIAT - 2012 – 125 p.

www.insa-lyon.fr

Download the thesis (PDF file 8 Mo) - in French

 
The prediction of noise from outdoor units of heat pumps, partly coming from finned coils, is an important industrial issue. The major obstacle to the study of finned coils lies in the inability to perform the acoustic calculation with classic simulation tools (Boundary Element Method) because of the huge number of required elements (about 600 fins per meter). The goal of this thesis is to exploit the periodicity of finned coils in order to calculate the total noise radiated from the radiation of a single fin, and thus get rid of the number of fins composing the structure.
The vibrations propagation is described as a wave decomposition, allowing the realization of separate calculations for each wave. The displacement at any point of the structure is calculated from the displacement of a single unit element, obtained with the Finite Element Method (FEM). An acoustic unit element is especially defined, comprising rigid baffles representing the influence of other fins of the structure. The radiation of this component is calculated for each wave using the Boundary Element Method (BEM), then spatially duplicated taking into account the propagation of the different waves. For each considered structure, a comparison with the direct calculation of the complete structure shows very good agreement with greatly reduced computation times. The influence of several parameters on the behaviour of the structure was also identified, thus highlighting some particular phenomena specific to periodic structures. In the last part of this thesis, an experimental validation of the periodic approach is proposed. Numerical results are close to vibratory and acoustic measurements done on the finned coils.


  CONTRIBUTION TO THE DETERMINATION OF THE VAPOR PRESSUR CURVE OF PURE WATER IN THE RANGE -80 °C à +100 °C WITH A VERY HIGH ACCURACY
Author: Dr Sid-Ali MOKDAD
Doctoral thesis presented to Conservatoire National des Arts et Métiers, spécialité: Laser, Métrology, Communication
Supervisor: Marc HIMBERT
www.cnam.fr
2012 – 199 p.

Download the thesis (PDF file of 4 Mo)

couverture these Mokdad
 
The determination of the physical properties of pure water, especially the vapor-pressure curve, is one of the major issues identified by the Consultative Committee for Thermometry (CCT) of the technical committee in thermometry sub-field hygrometry to improve the accuracy of the national references in humidity.
In order to achieve this objective, the LNE-CETIAT and the LNE-Cnam have jointly built a facility dedicated to the measurement of the saturation vapor pressure and temperature of pure water. The principle is based on a static measurement of the pressure and the temperature of pure water in a closed, temperature-controlled thermostat, conceived like a quasi-adiabatic calorimeter. The explored temperature range lies between 193,15 K and 373,15 K, and the pressure range between 0,06 Pa and 105 Pa.
This work presents a full description of this facility and the preliminary results obtained for its characterization. The obtained results have been compared with available literature data. The final uncertainty budget took into account several components: pressure measurements, temperature measurements and environmental error sources such as thermal transpiration and hydrostatic pressure correction. Thanks to the employment of several technical solutions, the thermal contribution to the overall uncertainty budget is reduced, and the remaining major part is mainly due to pressure measurements.

  ANALYTICAL MODELING OF AERODYNAMIC BORADBAND NOISE OF ROTATING MACHINES: USE OF AVERAGERD CALCULATIONS OF FLUID MECHANICS
Author: Dr Yannick ROZENBERG
Doctoral thesis presented to Ecole Centrale de Lyon: Acoustics
Supervisor: Michel ROGER –
Cofinanced by Valéo, Snecma and CETIAT - 2007 – 189 p.

www.ec-lyon.fr

Download the thesis (PDF file of 11 Mo) - In French

 
Noise radiated by low-speed fans or aircraft engine fans is made up of tonal noise and broadband noise, the latter being sometimes dominant. The present study suggests a hybrid method to model broadband noise based on analytical formulations using appropriate post-processings of Reynolds-Averaged Navier-Stokes equations. A bibliographic study on broadband noise radiated by airfoils is first carried out. Amiet's analytical models are presented for the turbulence-interaction noise and trailing-edge noise mechanisms, and some extensions are also proposed. Sensors are then placed into blades from a low-speed fan to measure the wall-pressure fluctuations in the vicinity of the trailing edge. The trailing-edge noise model is extended to the case of a fan blade and validated by comparing with the acoustic pressure measured in an anechoic chamber. An extension is proposed to apply the free-field aforementioned formulation to the aircraft engine fan acoustic power. In an industrial context, Reynolds-Averaged Navier Stokes simulation of the flow around fan blades provides only mean aerodynamic values. In simple cases, semi-empirical models are able to deduce the wall-pressure spectra from the aforementioned data. Since adverse pressure gradient induces a wall-pressure spectrum level increase, semi-empirical models can not be applied for airfoils or blades. An improved model is then proposed.


 
CALCULATION AND OPTIMISATION OF INDUSTRIAL LAMINAR BURNERS
Author : Dr Romain BARON
Doctoral thesis presented to the Ecole Centrale de Paris in the speciality: Energetics - Supervisor: Dominique THEVENIN - Thesis co-financed by CETIAT and ADEME - 2002 - 224 p.
In order to facilitate the design of efficient domestic burners respecting the standards, it is useful to resort to simulation. Several physical models were implemented in a laminar flames calculation code in order to make quick and accurate 2D and 3D simulations. The use of this efficient software enables to repeat the phenomena experimentally observed and to compare
the obtained results with different models. With the aim of making automatic optimisation calculations, several algorithms have been studied and implemented in a user-friendly and evolutionary software. This tool was interfaced with calculation codes in order to solve optimisation problems on reactive or non-reactive flows.
To obtain information on the laboratory having supervised the thesis:
http://www.em2c.ecp.fr


 
STUDY AND CREATION OF A NEW HUMID AIR GENERATOR
Towards a definition of a dew temperature reference
Author: Dr Bertrand BLANQUART
Doctoral thesis presented to the Conservatoire National des Arts et Métiers in the speciality: Physical Systems and Metrology
Supervisor: Marc HIMBERT - 

Thesis co-financed by CETIAT, the BNM and the Ministry of Research (ANRT) - 2001 - 170 p.
Download the thesis (PDF file of 1,22 Mo) - in French
  This documents describes the study and creation of a humid air generator in the -80°C to +15°C dew temperature field. Chapter I presents the different principles of humid air generators and the technical solutions implemented in the laboratories. Two finalities of temperature measurements are showed: the first is to determine the reference temperature ; the second one is to provide a study tool for the estimation of the generator uncertainties. The aim of chapter II is to study technical solutions adapted to each finality: standard platinum resistance thermometer and thermistors. Chapter III describes the generator design, based on the theoretical definition of the dew temperature and integrating the limits linked to the reduction of uncertainties. A method of estimation of dew temperature uncertainties is presented ; it associates the use of thermistors to the analysis of heat and mass exchanges in the generator. A first assessment of the uncertainties of the generator prototype is presented in chapter IV.



 
CONTRIBUTION TO THE STUDY OF THERMAL COUPLING OF A JET WITH AN AIR-CONDITIONED ROOM
Author: Dr Amina MESLEM
Doctoral thesis presented to INSA of Lyon in the speciality: Civil Engineering - Supervisor: Christian INARD - Thesis co-financed by CETIAT, ADEME and EDF - 1997 - 242 p.
The study deals with the dynamic and thermal qualification of the indoor environment
of air-conditioned rooms with a fan coil unit. This essentially experimental work is divided into four parts. The first part is an assessment of jets skill and gives the performance coefficients of air diffusion systems and thermal comfort. The second part explains the development of the experiment which has been used: it is a real size experimental system to which a specific velocity and temperature metrology was attached. The third part deals with the cold air jet coming from the fan coil unit. The velocity and temperature profiles measured in the latter enabled to underscore several types of behaviours depending on the initial Archimedes number. For the lowest values of this number, the jet develops itself along the vertical wall then along the ceiling. Analysing the behaviour of this type of jet enabled to distinguish the two-dimensional then axi-symmetric zone of the wall three-dimensional jet and to determine the detachment distance of the jet. When the initial Archimedes number increases, the jet does not reach the ceiling any longer and consequently the fan coil unit performance is reduced. Finally, the thermal environment was qualified thanks to a coefficient of air diffusion (ADPI) and a coefficient of thermal comfort (PPD). This is what the fourth part of this work deals with, which shows that the ADPI coefficient is indeed relating to the initial Archimedes number according to an exponential law, the best values being obtained when the initial Archimedes number values are the lowest. As for the PPD coefficient, the most important parameter is an initial Archimedes number which has been modified thanks to the heat load of the room. In those conditions, the maximum and average PPD values increase according to the modified Archimedes number.
Download a data sheet summing up the thesis (PDF document 1,78 Mo)
http://www.univ-lr.fr/labo/leptab/

 
CHARACTERIZATION AND MODELING OF THE NOISE MADE BY GAS BURNERS
Author: Dr Gwenaëlle SCHUBERT
Doctoral thesis presented to The Université de Technologie de Compiègne in the speciality: Mechanical Sciences for the engineer - Supervisor: Peter WAGSTAFF - Thesis co-financed by CETIAT, Chaffoteaux et Maury and the Ministry of Research (ANRT) - 1997 - 206 p.
The aim of the study is the characterisation and modelling of the noise made by a burner of an atmospheric gas boiler. A bibliographic study gives information on the creation of the flames noise as well as on parameters having an influence on the noise of combustion. The noise made by a burner is composed of the noise of combustion on the one hand, the noise of air flows on the other hand. An experimental study on burners enables to check that the influence of parameters such as the type of gas is in accordance with the bibliography. Noise evolution rules are deducted from the experiments led on three types of burners and compared with the mathematical expressions linking the acoustic power to the running parameters. The second part is a study about the application of the techniques of identification and sources localisation. None of these existing techniques may be used in the case of sources of noise which are shut inside a combustion chamber.
A new method, based on the reverse techniques, was developed in order to model those sources of noise. The fundamental principle may be summarised by the model of a system with m inlets (sources) and n outlets (answers). The auto-spectra and inter-spectra of the n outlets are measured thanks to microphones placed around the operating boiler. Frequency response functions (FRFs) between the "source" points in the flames and the outlet points are measured
thanks to a mono-polar source placed at the outlet point and to several high temperature microphones. Those microphones measure the pressure in the flames stemming from
  the mono-polar source ; the calculation of the FRF functions linking flames to external pressure is done using the reciprocity principle. The inversion of the FRFs matrix is done with the help of the singular values decomposition. This inversed matrix and the matrix of acoustic answers at the n outlet points enable to come back up to a spatial and spectral model of the sources of noise. A study on known sources is performed in order to check that this technique works in the acoustic field. The technique is then validated on a burner and its combustion chamber then on a complete boiler. The modelling of the burner sources of noise is satisfactory up to 2000 Hz.

 
STUDY OF THE DRYING BY INFRARED RADIATION
Application to a capillary-porous product and to a coating
Author: Dr Philippe NAVARRI
Doctoral thesis presented to the University Claude Bernard Lyon I in the speciality: Processes engineering - Supervisor: Julien ANDRIEU - Thesis co-financed by CETIAT, ADEME and EDF - 1992 - 214 p.
Electric infrared panels were used as heat sources during the drying under strong power densities of two types of model materials: a non-thermosensitive granular product (sand) and a coating (hydrosoluble glue) for which the thermo-physical characteristics, the radiation properties and the received illuminations were obtained by appropriate techniques. At first, the sand drying kinetics were determined according to the main variables of the process: power density and spectral distribution of the radiation (short and average wavelengths infrared), air velocity. The results analysis enabled to check the validity of Colburn analogy and the existence of a characteristic drying curve in the presence of very intense streams of material and heat flows. The sand drying and temperature curves were then interpreted by an intermediary front knowledge model, with no adjustable parameter, in which the product is supposed to be impervious to radiant energy. In a second part, the experimental study was extended to the case of an hydrosoluble glue, a thin and semitransparent product. Those tests, associated with a diffusive model written in Lagrangian coordinates and taking into account the warping of the product, enabled to identify the water apparent diffusion coefficient according to temperature and moisture rate. The model, associated with a global thermal assessment, was successfully used to simulate drying curves and the curves of evolution of the film average temperature, obtained in other operational conditions. Extended to the scale of the continuous dryer, those models represent an interesting tool for the dimensioning or the management of industrial installations using several heat supply modes ; the advantage presented by an intense radiant heating is clearly showed in terms of length of equipment.
Download two data sheets summing up the thesis (sand drying, glue drying).
To have information about the current laboratory of the author and supervisor:
http://www-lagep.univ-lyon1.fr

 
CONTRIBUTION TO THE STUDY OF THE THERMAL COUPLING OF A HEAT EMITTER WITH A ROOM
Author: Dr Christian INARD
Doctoral thesis presented to the INSA de Lyon in the speciality: Civil Engineering and Building sciences - Supervisor: Francis ALLARD - Thesis co-financed by CETIAT and AFME - 1988 - 449 p.
The research work presented is structured around experimental analyses of plumes stemming from heat emitters and of thermal coupling of the latter with rooms. The first part is dedicated to a review of the models presently available for the treatment of the thermal coupling between a heating system and a dwelling cell. This synthesis enables to notice the lack of data available to integrate the heating elements in predictive models. The second chapter describes the experimental device developed by CETIAT. It first gives an accurate analysis of the selected metrology principles, then presents the experiments performed for different characteristic types of radiators as well as the results obtained. The third chapter leads to a detailed analysis of the thermal plumes coming from heat emitters and to an identification of their main characteristics. The results obtained show a good coherence compared with more classical studies performed on linear sources. After having presented the second experimental device used, the fourth chapter underscores the essential influence of the rear wall cooling.
The precise description of thermal exchanges between the transmitter and the MINIBAT cell of the CETHIL also enables to provide essential data for the coherent modelling of the couplings existing between a heat emitter and a dwelling room. The last chapter gives a synthesis of the experimental results and ends on the perspectives offered by this research work.
To have information about the current laboratory of the author and supervisor:
http://www.univ-lr.fr/labo/leptab/

  STUDY AND DEVELOPMENT OF AN EXPERIMENTAL PROCEDURE FOR THE IDENTIFICATION OF THE PARMAMETERS OF A THERMAL MODEL OF DYNAMIC AIR SOLAR COLLECTORS
Author: Dr Jean-Louis DUFRESNE
Doctoral thesis presented to University Paris VII in the speciality:
Energetics - Supervisor: Louis-Marie CHOUNET - Thesis co-financed by CETIAT, AFME and CNRS - 1987- 428 p.

In the context of this thesis, a test installation was built in CETIAT, enabling to characterise the running of a dynamic air solar collector, in particular with illumination and air flow rate highly variable. The paper describes the conception of this installation, of its control and data acquisition systems. From the test results of solar air collector, it also provides an identification method for the ten parameters necessary to model this dynamic collector.

 
STUDY OF WOOD BOILERS: CONTRIBUTION TO THE MEASUREMENT OF UNBURNED COMPOUNDS EMISSION, TO THE EVALUATION OF ENERGY EFFICIENCY AND TO THE MODELLING OF THE COMBUSTION
Author: Dr Patrick DUSSERRE
Doctoral thesis presented to INSA de Lyon in the speciality: Waste Treatment and Disposal - Supervisor: J. VERON - Thesis co-financed by CETIAT, ELF and AFME - 1986 - 288 p.
This study has allowed to evaluate the impact of wood combustion on the environment and to characterize the energy power of unburned compounds emissions, to design a sampling chain in the fumes to separate dust, tars and aqueous condensates, to improve calculations of efficiencies applied on pseudo-stationary tests of wood boilers, to test the behaviour of new fuels (briquettes, pellets, "roasted" wood) and to bring out the energy gains linked to the trial of a modulating control, to adapt the pyrolysis kinetic models and combustion models to the running of a burner fed with divided wood.

 
DIFFICULTIES MET IN THE DEVELOPMENT OF POISEUILLE FLOW - APPLICATION TO THE MEASUREMENT OF LOW VELOCITIES
Author: Dr Moustapha MOUHAMED-ALI
Doctoral thesis presented to University Paris VI in the speciality: Aerodynamics and Thermal Sciences - Supervisor: André FORTIER - Thesis financed by CETIAT- 276 p.
This thesis enabled to model a laminar flow wind tunnel which was used as a reference until the end of the 90's for the calibration of low velocities air anemometers.
 
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