可持续保护人类免受有害气溶胶的侵害

Lessons learned from a global pandemic - and the remaining problem

Many countries worldwide recently succeeded in containing the spread of the COVID-19 disease by drastic confinements, regular testing, and an increasing vaccination rate. However, these measures are unsuitable for an extended period of time nor is it possible to vaccinate humans against every harmful aerosol. There is an urgent need for actionable and effective procedures to sustainably contain the risks of infection without harming the economy and society.

这种大流行教会了我们通过空气寄生颗粒传播的轻松和强烈病原体。世卫组织，阿斯拉（Asrae）以及几个国家建筑和公共卫生当局接受并记录了这一事实。在通风不足的封闭空间中，一个人可以轻松地感染大量其他人。然而，对传染性事件的调查反复表明，人类仅在房间的某些地区被感染，具体取决于传播人的位置和通风状况。有趣的是，感染发生时，被感染者不需要在房间里。他们留下的受污染的空气足以感染其他人进入房间的人。通过有效的通风系统改善空气质量有可能减轻空气传播的疾病的影响。这包括季节性疾病，例如流感，普通感冒和其他病毒感染。结果，适当的通风以进行优化的气流问题。

Effects & consequences of the problem - a need for action

定期新鲜空气供应降低感染风险的最新指南和建议仍然基于对个人情况的有限知识。实际上，基本影响因素及其能够有效维持空气质量的依赖性仍然没有解决：

• 基于所选通风法的空气交换有多均匀？
• 在同一空间，活动，通风配置，温度等中的人数如何影响空气质量和空气循环？
• 哪些措施可以改善空气交换的统一性？
• 在考虑相关投资的同时，采取了最大程度地降低感染风险的最有效的保护措施？

在自然通风的情况下，打开窗户：

• How wide and how many windows should be opened to exchange the air equally?
• 二氧化碳传感器可以尽早警告以使窗户打开的最佳位置是什么？
• 二氧化碳传感器可以通知可以关闭窗户可接受的新鲜空气水平的最佳位置是什么？

In the case of air filter devices:

• How effective are air filter devices to improve the air quality in the selected situation?
• What is the best number, performance, and position of air filter devices to achieve the highest effectiveness?

对这些问题的缺乏令人满意的答案导致公司努力获得对其设施的可接受风险评估。运输协会和运营商很难赢得人们对公共交通安全的信任。规划师，运营商和设施经理很难确保使用其设施的人们的安全。有必要采用解决方案方法来考虑各个环境，通风系统和占用的性质。

What are appropriate and effective protection measures?

计算流体动力学（CFD）进行预定，以提供有关气流和新鲜空气供应变化的见解。尽管如此，这项技术通常与耗时，昂贵且复杂的工作有关，以模拟空气湍流或液滴运动的动态，因此无助于支持个人评估。但是，有可能使用该技术在所考虑的空间中的任何区域分析与通风相关的气溶胶分布或空气质量，而所需的时间很少，并且信息价值很高。

基于开源CFD软件OpenFOAM，，，，ESI developed a solution that allows you to evaluate ventilation situations in a small amount of time. This solution is based on physically validated simulation models for turbulence, buoyancy, droplet size distribution, heat flux, radiation, as well as transient impulses.

We combined these underlying flow regimes in a steady-state simulation methodology which enables us to analyze the air exchange process while considering influencing factors like ventilation configuration, temperature, humidity, gravity, as well as peoples’ activities like breathing, talking, or shouting.

死空气（再循环）的区域可以通过空中模拟确定。可以看到空气交换率低于名义值的区域。这些是估计暴露于这些地区每个人的气溶胶的重要数据。用新鲜空气替换陈旧的空气所需的时间越长，携带病原体的颗粒物可以积聚。考虑到房间中任何位置受感染的人，可以相应地计算出污染的呼出气溶胶的分散和浓度。

我们可以采用这种方法的方案

Assessment of natural ventilation possibilities

Many offices, schools and universities, administrative facilities, community centers, religious and cultural facilities do not have ventilation systems and need to rely on natural ventilation. For operators and users, it is unclear at what time and to what extent the used air can be replaced by fresh air.

The introduced simulation methodology allows determining the effect of opening windows under various wind and temperature conditions on the air exchange. This enables operators to make informed decisions on meaningful ventilation intervals or the need for additional improvement measures.

验证入住建议

In open-plan offices and, even more frequently, public transportation, many people meet in confined, enclosed spaces for an extended period of time. To evaluate the risk of workers or passengers being exposed to a critical number of pathogens, further aspects must be considered in addition to the ventilation system and the number of people. These are people’s activities like breathing, talking, and shouting, as well as protection measures such as wearing a mask.

The proposed simulation methodology allows examining the air quality under these conditions and the effect of different occupancy levels and climate conditions. The comparison of manifold settings of all influencing parameters allows identifying best and worst cases scenarios as well as acceptable occupancy levels considering predefined thresholds of aerosol concentration. Also, informed decisions can be made on which additional protection measures like installing air filters or glass shields between seating rows would be necessary and effective.

Validation of safety (distance) rules under different ventilation conditions

均匀地为大厅提供新鲜空气是一个挑战。通风系统应旨在保护工厂或制造工厂中的工人免受机器上的累积废气或空中污染物的侵害，并通过避免高速速度来增加占用舒适性。

我们的仿真方法允许确定新鲜空气到达操作员的有效效率，以及从污染源中发射有害气溶胶的发射可能会影响附近工作的操作员。如果发生咳嗽或打喷嚏等极端呼吸事件，呼出颗粒的轨迹说明了环境的直接污染。此外，可以轻松地研究旨在保护工人免受潜在有毒物体过度接触潜在毒物的工作计划和工作指导的有效性虚拟现实environment and the effect of alternative ventilation configurations and designs can be evaluated comparatively.

Validation of air filters

医疗室和经营剧院中的位移通风旨在为房间受控部分提供均匀的，无扰动的空气。然而，识别重新循环的区域是有见识的，可以最大程度地减少病原性气溶胶分布的风险，以便人们可以在安全和福祉的情况下放置设备。可以轻松验证空气滤清器设备在房间各个位置改进空气质量的有效性。

Investigation of the influence of fans and diffusers on air circulation

用于通风入口的风扇类型和扩散器可能会对所考虑空间中新鲜空气的分布产生重大影响。尤其是在小房间中，有效的风扇与淋巴结组合的知情选择可以使相关区域的良好空气质量和差的空气质量之间的关键差异。

Communication and Visualization

气溶胶是人类看不见的。因此，人类无法感知危险区域，其中含有病毒的气溶胶可以积聚。

对于决策，使用可以可视化此类区域的媒体并且可以轻松理解每个人的媒体非常重要。在交互式虚拟环境中的可视化允许与所有受影响的利益相关者的直观沟通。取决于可用数据以及分析是指正在构建中的设施还是现有数据，要么虚拟现实可以是可视化的正确技术，也可以使用增强现实的现实技术来直接在真实环境的背景下直接说明结果。

很高兴知道解决方案已经可以使用并准备好使用该行业来快速分析封闭空间中的人们感染的风险，例如办公室，生产线，公共交通工具，以及在贸易展览，剧院或公共设施中的风险餐馆为自己的未来做好准备。

Do you need to know how to improve air quality in your area of responsibility?登记对于我们的免费讲习班 - 作为我们OpenFoam会议的一部分 - 于2021年10月21日：从Covid -19中学到的空气质量课程 - 由CFD和传感器数据支持的智能通风

等不及了吗？手表我们的On-Demand Workshop: COVID-19 Minimize the risk of infection & increase confidence in safety