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.
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.
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.
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
2012 – 199 p.
Download the thesis (PDF file of 4 Mo)
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.
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
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
|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 -80Â°C to +15Â°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
CHARACTERIZATION AND MODELING OF THE NOISE
MADE BY GAS BURNERS
Author: Dr GwenaÃ«lle 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
To have information about the current laboratory of the author and
|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
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
To have information about the current laboratory of the author
STUDY AND DEVELOPMENT OF AN EXPERIMENTAL PROCEDURE FOR THE
IDENTIFICATION OF THE PARMAMETERS OF A THERMAL MODEL OF DYNAMIC AIR
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
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.