论文和技术资料

Indoor ventilation with good air quality control prevents infection with minimizing the spread of airborne respiratory and other infections in hospitals. CFD can be utilized to optimize flow pattern in clean rooms especially hospital clean rooms. More than two million people in Europe are infected due to Health-care Associated Infection (HAI) (Pittet et al., 2005). It is believed that transfer of infection via contact is the main cause for HAI. There are evidence that airborne bacteria may also cause infection (Brachman, 1970). This infection is by inhalation of infectious bacteria and by contamination of surfaces by bacteria (Hathway, 2008). It is useful to understand dynamics of infectious particles due to respiratory diseases such as SARS and TB.

This paper analyses air flow pattern in a one-beded hospital room. It concentrates on respiratory transmission, using a point source at the patient mouth position. Numerical simulation of air flow pattern and bio-aersol transport of clean hospital room is performed with COMSOL Multiphysics® software, version 5.1. Ventilation rate is 6ACH for health care facilities per ASHRAE standard 170.

病房里有一个抽屉，一张床，病人，医生，灯，医疗设备，入口和排气管。空气从图1所示的天花板扩散器进入房间，温度为20（°C）。空气穿过图1所示的天花板上的架子，使房间离开房间。假定房间在三个侧面及其底座进行热隔离。房间和外部之间的热交换发生在天花板和房间的第四侧。图2显示了与医生和患者相邻的温度分布和速度向量。房间的平均温度为21（°C）。由于自然对流，医生和患者旁边有向上的空气运动。我们还从患者向医生流动了空气。我们根据ASHRAE标准55-2013计算了预测的平均投票PMV，并预测了不满意的PPD的百分比。患者经历的平均空气温度和空气速度为20.8（°C）和0.06（m/s）。睡觉的患者的代谢率为1（MET）。

We assumed that the patient is wearing trousers and long-sleeve shirt therefore his clothing level is 0.61 (clo). If humidity is 50% then PMV is -1.59 and PPD is 56%. Therefore the probability of patient being dissatisfied with the room temperature is 56%, with sensation of cool. We have also simulated release of bacteria due to coughing of the patient. Coughing characteristics are obtained from “Flow dynamics and characterization of a cough” by (Gupta et al, 2009). Figure 3 shows release of bacteria; the color legend is based on velocity (m/s). Figure 4 shows transmission probability of bacteria at the exhaust; none of the bacteria leaves the room in 30 seconds after coughing. After 3 minutes 8% of the bacteria are still remaining in the room.