Enhancement of Natural Ventilation in Residential Buildings with Roof Integrated PV/T Components
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The purpose of this master thesis was to develop a design method for a combined system comprisingof an air type photovoltaic thermal system and natural ventilation for the case of a typical residentialbuilding. The prototype and model to be simulated had different air flows. The prototype availablehad a serpentine shape of the air flow, and needed a forced flow to function. Larger deviationsbetween experimental measurements and simulation output were therefore accepted. The modelwas first developed for forced flow, and then advanced to encompass natural flow. Several software programs were considered for the task. After some software obstacles, TRNSYS incombination with Matlab was chosen due to the flexibility. The PV/T component and the naturalventilation effect was programmed in Matlab. The weather file, heat transfer coefficient and thebuilding were constructed in or uploaded to TRNSYS. The simulation was performed by runningthe Matlab script in TRNSYS for each time step for the interval set in TRNSYS. Several design settings were tested for increased performance. The optimal solution was achieved byapplying the maximum area for maximum electrical production. Increased length of panel resulted ina heightened stack effect and higher air flow. A longer system will also increase outlet temperature,which is preferred in winter time. For raised outlet temperature, a small channel height was alsofound to be favoured. An increase in the channel height will enhance the natural ventilation flow.With a constant channel height, 0.5 m was the optimal height. With a seasonal optimised channelheight, the time the natural ventilation satisfied the requirements, increased with 8%. 20 degreesinclination angle proved to be the best solution for this system. In a climate like Shanghai, naturalventilation is optimal in transition seasons. In summer the ambient air is usually too warm andhumid. Increased ambient temperature led to a lower buoyancy effect, and therefore a lower airflow. During winter the ambient air can be too cold.