Reducing the airborne infection risk in tourist buses using medium-efficiency filters in air-conditioning systems

IF 7.1 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Building and Environment Pub Date : 2025-05-16 DOI:10.1016/j.buildenv.2025.113186

Naohide Shinohara , Koichi Tatsu , Wataru Naito , Yoshiko Murashima , Hiromu Sakurai , Takuma Kizu , Katsuhiro Kan

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Abstract

To reduce the airborne infection risk in tourist buses, medium-efficiency filters with a minimum- efficiency reporting value (MERV) of 11 or 13 are installed in the air-conditioning (AC) system inlets on the ceilings of three tourist buses, and the equivalent air-exchange rates (AERs) of artificial droplet nuclei and their behavior within buses are evaluated. Without filters, the equivalent AERs in the ventilation and internal air circulation modes are 12 and 1.5–5.2 /h, respectively, at the lowest air-flow, and 21 and 7.8–11 /h, respectively, at the highest air-flow. With filters installed and the AC system operating in the internal air circulation mode, the equivalent AERs are 10–15 and 27–042 /h at the lowest and highest airflows, respectively, demonstrating a droplet nuclei removal performance similar to or better than that of the ventilation mode. In the internal air circulation mode without filters, artificial droplet nuclei spread throughout the bus and decay slowly, even after emission ceases. Notably, with the source located in the center seat, the average in-vehicle concentration is higher when the AC system operates in the internal air circulation mode without filters than when it is turned off. Conversely, operating the AC system in the internal air circulation mode with a medium-efficiency filter considerably suppresses the spread of artificial droplet nuclei. Based on the advective spread of artificial droplet nuclei, the estimated average relative airborne infection risk, normalized with that when the AC system is turned off, in the bus was reduced to 52–79 % in the ventilation mode and 25–50 % in the internal air circulation mode with filters.

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利用空调系统中效过滤器降低旅游车空气感染风险

为了降低旅游车内空气传播的风险，在3辆旅游车顶板空调系统入口安装了最小效率报告值（MERV）为11或13的中效过滤器，并对人工飞沫核的等效空气交换率（AERs）及其在车内的行为进行了评价。不加过滤器时，最低风量下通风和内循环模式的等效aer分别为12和1.5 ~ 5.2 /h，最大风量下等效aer分别为21和7.8 ~ 11 /h。在安装过滤器和空调系统运行于内风循环模式下，最低风量和最高风量下的等效AERs分别为10-15和27-042 /h，其除核性能与通风模式相似或优于通风模式。在没有过滤器的内部空气循环模式下，人工液滴核遍布整个公共汽车，即使在排放停止后也会缓慢衰减。值得注意的是，当污染源位于中央座椅时，空调系统在无过滤器的内部空气循环模式下运行时，车内平均浓度高于关闭时。相反，在带有中等效率过滤器的内部空气循环模式下运行交流系统，可显著抑制人工液滴核的扩散。基于人工飞沫核的平流传播，与空调系统关闭时的平均相对空气传播风险归一化后，在通风模式下估计的平均相对空气传播风险降至52 - 79%，在带过滤器的内空气循环模式下估计的平均相对空气传播风险降至25 - 50%。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Building and Environment 工程技术-工程：环境

CiteScore

12.50

自引率

23.00%

发文量

1130

审稿时长

27 days

期刊介绍： Building and Environment, an international journal, is dedicated to publishing original research papers, comprehensive review articles, editorials, and short communications in the fields of building science, urban physics, and human interaction with the indoor and outdoor built environment. The journal emphasizes innovative technologies and knowledge verified through measurement and analysis. It covers environmental performance across various spatial scales, from cities and communities to buildings and systems, fostering collaborative, multi-disciplinary research with broader significance.