This study concerns the in-situ determination of the thermal resistance of a building wall. Measurements were performed in the PANISSE platform, which is a residential building with two floors located in the town of Villemomble, at about ten kilometers in the east of Paris. During a renovation, a 6cm-thick external insulating layer was fixed onto the cellular concrete walls of the house. Three methods using IR thermography were used to estimate the thermal resistance of the insulated walls. Results are compared to a standardized method (ISO 9869-1) that uses contact sensors. The comparison is made considering estimated thermal resistance values, measurement uncertainties and measurement duration.
In order to provide a method to control conformity of insulation of buildings after restoration, Protomeres project was launched under Prebat 2005 program. This work deals with the development of an experimental protocol for the diagnostic of multi-layered insulated building walls. In a previous study, a test bench was set up in order to measure front and back side temperatures of standard panels compounded of 1cm of plaster and various thicknesses of polystyrene. The panels considered have insulation thicknesses of 2, 6 and 10cm. In the present work, the panels are fixed on walls in laboratory to test real situations in constructions. The front side is painted in standardized black color and heated by two halogen lamps of 500W. A CEDIP Jade Long wave infrared camera and thermocouples are used to carry out temperature measurements during an exposure time and subsequent cooling. In a second time, a one dimensional model based on thermal quadruples and Laplace transforms was developed under Matlab environment. This model simulates a three-layered wall with a blade of air between polystyrene and concrete. Finally, a method of identification of physical parameters is implemented by performing least square minimization based on Levenberg-Marquardt method. The experimental measurements are compared to theoretical results and by minimization we obtain thermal conductivity and diffusivity as well as thickness of the two layers.
This work deals with the development of an experimental protocol for the diagnostic of multi-layered insulated building walls. First, a test bench is set up in order to measure front and back sides temperatures of standard panels. The panels considered have insulation thicknesses of 2, 6 and 10cm. The front side is heated by two halogen lamps of 500W. A CEDIP Jade Long wave infrared camera and thermocouples are used to carry out temperature measurements. In a second time, a one dimensional model based on thermal quadruples and Laplace transforms was developped under Matlab environment. Also, we developped a three dimensional model based on finite volumes using Fluent computational code. Finally, a method of identification of physical parameters is implemented by performing least square minimization based on Levenberg-Marquardt method. The experimental measurements are compared to theoretical results and by minimization we obtain thermal conductivity and diffusivity as well as thickness of the two layers.
By using quantitative thermal scanning of building surface structures, it is possible to access to the temperature field. For the further calculation of the heat flux exchanged by these structures with the environment, one must quantify as finely as possible the temperature field on the bodies' surfaces. For this purpose we have to take into account the fact that real bodies are not black which implies that a parts of the radiant energy received by the infrared camera detectors is reflected radiation. In this paper, we present a method to quantify the energy issued by all the bodies placed into e virtual hemisphere surrounding the thermal scene. The target body is a multi-layers wall, which represent a simplified version of a real building structure. In order to validate the method, we have compared the results obtained by thermocouple measurements and by computer simulation of the body with the corrected temperature field.
A study of the thermal aging of the pyroelectric properties of commercially available bioriented PVDF and P(VDF-TrFE) 75-25 mol percent films is reported. The analysis of pyrocurrent spectra has been carried out in a large temperature range of -100 degrees C up to +150 degrees C. The pyroelectric coefficient p3 shows a distinct temperature dependence below and above thermal transitions, and especially the glass transition. We consider how this dependence changes upon aging. The influence of both aging temperature and aging time was investigated. ThermoStimulated Currents spectroscopy (TSC) has been used as a complementary technique of investigation. We have paid a particular attention to the evolution of the relaxation modes associated with the glass transition and with the (alpha) c transition as a function of aging conditions. Experimental results of (beta) -PVDF show that the decay of the pyroelectric activity is linearly dependent on the annealing temperature. Identical aging conditions induce a lower decay of p3 in P(VDF-TrFE) 75-25 than in PVDF, attesting the higher stability of the macroscopic polarization in fluorinated copolymers. The evolution of the decay of p3 as a function of the aging time is more complex. Indeed, p3 decreases quickly below a short characteristic aging time, and much slower at longer times. This characteristic time is aging temperature dependent. The evolution of the relaxation mode association with the glass transition shows that irreversible crystallinity changes occur at aging temperature higher than +110 degrees C. So, crystallization phenomena do not play a major role in the decay of p3. Besides, the (alpha) c transition seems to play an important role in the aging of pyroelectricity. Indeed, any loss of pyroelectric activity is detected after aging at temperatures lower than the (alpha) c transition.
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