一氧化碳在有隔間建築內部傳輸之物理模

A Transport Model for CO in Partitioned Buildings

因為通風不佳，家用瓦斯熱水器造成的一氧化碳中毒的事件在台灣每年皆會發生，導致人員的傷亡和家庭的破碎。前人研究大多使用計算流體動力學模式（Computational Fluid Dynamics, CFD）模擬某一棟建築物之內一氧化碳的濃度分佈，並未考慮到室外風速、風向、室內隔間對建築物內部濃度場的影響。本研究結合自然通風模式和一個質量傳輸模式來計算有隔間建築物中一氧化碳的濃度變化，並以縮尺模型之風洞實驗示蹤劑濃度衰減法驗證模式所預測之濃度場。驗證後之傳輸模式便可用來評估在自然通風情況下，通風率、初始濃度和房間的體積大小等參數對建築物之內一氧化碳的濃度和消散時間的影響。參數研究結果顯示：相鄰房間的一氧化碳最大濃度約為安裝熱水器之陽台初始濃度的50％～62％。當開口正對風向時，室外風速及開口面積愈大，通風率愈大，一氧化碳消散的時間愈短。隨著風向角增加，通風率降低，相鄰房間中一氧化碳到達最大濃度的時間和消散時間皆變長。當風向平行於開口時，室內外空氣交換率低，一氧化碳滯留室內的時間最長，需要使用機械通風來排除室內一氧化碳。本研究所發展之質量傳輸模式亦可用於其他會在室內產生之氣態污染物。

Carbon monoxide (CO) poisoning accidents caused by the gas-burning water heaters, due to poor ventilation, in redsiential buildings is one of the common mishaps in Taiwan. Most previous studies on this problem employed Computational Fluid Dynamics (CFD) models to simulate the dispersion of CO inside the buildings. Nonetheless, their results did not consider the effects of external wind speed and direction to the transport of CO inside the buildings. This study incorporates a natural ventilation model and a gas transport model to predict the ventilation rate and CO concentration in partitioned buildings. The model predictions are validated by the measured concentration, by a tracer gas technique, in wind tunnel experiments. The verified transport model is used to evaluate the influences of initial concentration, interior volume, external wind speed and direction on the concentration variation of CO in a full-scale two-room building. The results reveal that the ratio of the maximum concentration in the adjacent room to the initial concentration of CO in the room (balcony) with the source was about 50~62%. The ventilation rate increases as the wind speed and the opening area increases, this sequentially reduces the dispersion time of CO in the building when the wind direction is normal to the windward opening. The ventilation rate drops significantly and the CO concentration remains very high for a long period of time, and mechanical ventilation is needed to disperse the CO inside the building.