Accurate values of thermophysical transport properties of particle beds are necessary to accurately model heat and mass transfer processes in particle beds that under-go preferred processes and changes. The objective of this study is to use a proven analytical/numerical methodology to estimate the unknown transport properties within test cells filled with silicagel particles and compare the results with the previously published data. An experimental test cell was designed and constructed to carry out transient heat transfer tests for both step change conduction and convection heat transfer within a packed bed of silicagel particles. For a known step change in the test cell temperature boundary condition, the temporal temperature distribution within the bed during heat conduction depends only on the effective heat conduction coefficient and the thermal capacity of the particle bed. The central problem is to, using only the boundary conditions and a few time-varying temperature sensors in the test cell of particles, determine the effective thermal conductivity of the test bed and specify the resulting measurement uncertainty. A similar problem occurs when the heat convection coefficient is sought after a step change in the airflow inlet temperature for the test cell. These types of problems are known as inverse heat transfer problems (IHTP). In this thesis, IHTP method was used to estimate the convective heat transfer coefficient. Good agreement was seen in experimental and numerical temperature profiles, which were modeled by using the estimated convective heat transfer coefficient. The same methodology was used to estimate the effective thermal conductivity of the particle bed. Comparison between the experimental temperature distribution and numerical temperature distribution, which was modeled by using the estimated effective conductivity, illustrated good agreement. On the other side, applying the effective thermal conductivity, obtained from a direct steady state measurement, in the numerical simulation could not present agreement between the numerical and experimental results. It was concluded that the IHTP methodology was a successful approach to find the thermophysical properties of the particle beds, which were hard to measure directly.

The different technologies of passive cooling concepts have to rely on a good thermal coupling between a building's thermal mass and indoor air. In many cases, the ceiling is the only surface remaining for a good coupling. Further research is necessary to investigate discrepancies between existing correlations. Therefore, the overall aim of the work described in this thesis is the investigation of heat transfer at a heated ceiling in an experimental chamber. Acoustic baffles obstruct the surface of the ceiling and impede heat transfer. However, there is nearly no published data about the effect of such baffles on heat transfer. Available results from simulations should be verified with an experimental investigation. Consequently, one of the primary aims of this work was to experimentally determine the influence of such acoustic baffles. A suitable experimental chamber has been built at Biberach University of Applied Sciences. The thesis describes the experimental chamber, the experimental programme as well as results from five different test series. With a value of ±0.1Wm⁻²K⁻¹ for larger temperature differences, uncertainty in resulting convective heat transfer coefficients for natural convection is comparable to that of results from an existing recent experimental work often recommended for use. Additionally, total heat transfer (by convection and radiation) results are presented. Results are given for natural, forced and mixed convection conditions at an unobstructed heated ceiling. Furthermore, results for acoustic baffles in both an unventilated and a ventilated chamber are shown. Natural convection results show a very good agreement with existing correlations. Under mixed convection conditions, convective heat transfer at an unobstructed ceiling decreases to the limiting case described by natural convection. Installation of acoustic baffles leads to a reduction in total heat transfer (convection and radiation) between 20% and 30% when compared to the case of an unobstructed ceiling.