Nelson, Ian 1982- (2012-12). The Effect of Thermal Load Configurations on Passive Chilled Beam Performance. Doctoral Dissertation. Thesis uri icon

abstract

  • This dissertation presents the findings of a study to quantify the effect of heat source configurations on the performance of passive chilled beams. Experiments in a thermally controlled test room were conducted using thermal manikins as heat sources cooled with a 0.6 m by 2.4 m beam. The thermal manikins were arranged in a symmetric and an asymmetric configuration and tested over a range of input power to simulate a low-to-high load heat distribution of an indoor space. A computational fluid dynamics (CFD) model was developed in Star CCM+ v6.06 and used for further analysis of the flow field and to predict additional spatial arrangements of the beam, interior dimensions, and heat source configurations. The CFD model implemented a calculation for the beam cooling capacity to predict the beam performance based on the room thermal conditions. The experimental data revealed an average reduction of 15% in the passive beam cooling capacity for the asymmetrically configured thermal manikins compared to the symmetric arrangement. The CFD model was validated with the experimental data and predicted the asymmetric heat source beam performance reduction to be 17%. The reduction in performance based on the heat source arrangement was found with analysis of the CFD simulations to be a result of the above-beam air velocity field. The unbalanced thermal manikin configuration generated an unbalanced flow condition at the inlet of the beam that resulted in the room air circumventing the inlet of the passive beam, as compared to the inlet velocity field of the symmetric configuration. Additional configurations were investigated with the CFD model to include the beam position, floor area, ceiling height, and thermal manikin arrangements. The simulation results were analyzed by comparing the efficiency of beam performance using the beam cooling capacity calculation for each scenario. The predictions of additional configurations found that the efficiency increased when the beam was perpendicular to a group of heat sources and the changes in beam performance with heat source configurations was not affected by the interior dimensions of the space. However, the resulting thermal conditions in the occupied zone for the beam positions of highest efficiency may negatively impact the thermal comfort of occupants.
  • This dissertation presents the findings of a study to quantify the effect of heat source configurations on the performance of passive chilled beams. Experiments in a thermally controlled test room were conducted using thermal manikins as heat sources cooled with a 0.6 m by 2.4 m beam. The thermal manikins were arranged in a symmetric and an asymmetric configuration and tested over a range of input power to simulate a low-to-high load heat distribution of an indoor space. A computational fluid dynamics (CFD) model was developed in Star CCM+ v6.06 and used for further analysis of the flow field and to predict additional spatial arrangements of the beam, interior dimensions, and heat source configurations. The CFD model implemented a calculation for the beam cooling capacity to predict the beam performance based on the room thermal conditions.

    The experimental data revealed an average reduction of 15% in the passive beam cooling capacity for the asymmetrically configured thermal manikins compared to the symmetric arrangement. The CFD model was validated with the experimental data and predicted the asymmetric heat source beam performance reduction to be 17%. The reduction in performance based on the heat source arrangement was found with analysis of the CFD simulations to be a result of the above-beam air velocity field. The unbalanced thermal manikin configuration generated an unbalanced flow condition at the inlet of the beam that resulted in the room air circumventing the inlet of the passive beam, as compared to the inlet velocity field of the symmetric configuration.

    Additional configurations were investigated with the CFD model to include the beam position, floor area, ceiling height, and thermal manikin arrangements. The simulation results were analyzed by comparing the efficiency of beam performance using the beam cooling capacity calculation for each scenario. The predictions of additional configurations found that the efficiency increased when the beam was perpendicular to a group of heat sources and the changes in beam performance with heat source configurations was not affected by the interior dimensions of the space. However, the resulting thermal conditions in the occupied zone for the beam positions of highest efficiency may negatively impact the thermal comfort of occupants.

publication date

  • December 2012