DEVELOPMENT OF ADAPTIVE VENTILATION IN MULTIFUNCTIONAL LARGE-SCALE SPACE OF PUBLIC BUILDINGS

Проанализирована актуальность строительства объектов культурно-массового назначения. Описана целесообразность проектирования многофункциональных трансформируемых помещений для общественных зданий. Приведены достоинства и недостатки применения рециркуляции воздуха как способа энергосбережения. Акцентировано внимание на поддержании чистоты воздуха в помещении и способах борьбы с бактериями и вирусами в приточном воздухе. Предложена схема многозональной общеобменной вентиляции воздуха без рециркуляции с блокированием кондиционеров для взаимозаменяемости с целью обеспечения микроклимата в многофункциональных помещениях общественных зданий. Описана последовательность работы системы вентиляции в теплый и холодный период года. Разработана система рекуперации с промежуточным холодоносителем для теплого периода года. Приведено описание работы установки кондиционирования воздуха. На примере реально существующего объекта выполнено численное исследование режимов работы системы вентиляции с рекуперацией теплоты и холода для трансформируемого помещения. Построен график для определения граничных условий работы рекуператора исходя из соотношения между интенсивностью теплообмена за счёт конвекции и интенсивностью теплообмена за счёт теплопроводности. При различных наружных температурах воздуха и расчетных температурах уходящего воздуха построены графики определения оптимальных параметров температуры воздуха на входе в утилизатор при оптимальных значениях водяного эквивалента . Выявлены и описаны режимы работы кондиционеров с теплоутилизатором в теплый период года, работающих в составе многозональной общеобменной вентиляции воздуха с блокированием кондиционеров для взаимозаменяемости. В ходе численного исследования выявлено, что наибольшая энергоэффективность системы вентиляции с рекуператором будет достигнута при принятии в качестве оптимального значения водяного эквивалента W = 3. We analyzed the relevance of cultural facilities construction. As well, we described the expediency of designing multifunctional transformable spaces for public buildings. Moreover we presented advantages and disadvantages of using air recirculation as a method of energy saving. A special attention is focused on maintaining indoor air clean and on various ways of combatting bacteria and viruses in the intake air. We offered a scheme of multi-zone forced air ventilation without recirculation with blocking air conditioners for interchangeability in order to provide a microclimate in multifunctional spaces of public buildings. We described the sequence of operations in the ventilation system in warm and cold seasons. We also developed a recuperation system with an intermediate refrigerant for warm seasons. The article presents a detailed description of the air conditioning unit operation. We carried out a numerical study of the operating modes of the ventilation system with heat and cold recovery for transformable spaces on the example of a real-existing facility. We show a graph to determine the boundary conditions of the recuperator operation based on the ratio between the intensity of heat transfer due to convection and the intensity of heat transfer due to thermal conductivity. At various outside air temperatures and design temperatures of the outgoing air, we created some graphs for determining the optimal parameters of the air temperature at the inlet to the heat exchanger at the optimal values of the water equivalent. We identified and described several modes of operation of air conditioners with a heat exchanger in warm seasons, operating as part of a multi-zone forced air ventilation with blocking air conditioners for interchangeability. In the course of a numerical study, it was revealed that the highest energy efficiency of a ventilation system with a recuperator could be achieved when the water equivalent value W = 3 is taken as the optimal value.

STATIC CONTROL OF DRAG-REDUCING AIR CAVITIES WITH VARIABLE CAVITATOR SHAPE

Air ventilation of submerged surfaces of ship hulls is a promising technique for drag reduction. To ensure high performance of air cavities in a broad range of operational conditions, the cavity properties can be controlled with help of compact hydrodynamic actuators. In this study, a potential flow theory is applied to model an air cavity formed behind a wedge-shaped cavitator under a horizontal wall imitating a ship bottom. By varying the wedge angle, it is possible to achieve states with maximum drag reduction at given operational conditions. The dependence of the optimal wedge angle on Froude number and hull trim is investigated. The air-cavity ability to reduce frictional drag is found to increase with rising flow speed and bow-down hull trim.

The question of determining installation sites for the Air purification of pig premises local system elements

The allocation of intake air stream in pig premises is not evenly. The existence of engineer-ing networks and equipment, the breaching of montage technologies of air ventilation, incorrect maintenance of air ventilation system – all these factors bring to many breaches and problems. This problem such as air exchange violation in all premises, appearing zones of stasis (aero stasis), and others. As a result of which the differential of temperature and humidity has appeared. These also appear excess maximum per-mitted concentration of dust and gases. The all-exchanged ven-tilation system can’t solve all problems in local zones in pig premises. In this local air-ventilation system become more demand. For effective work of local air ventilation, the question of deter-mining installation sites for the air purification of pig premises local system elements should be solved. Keywords: LOCAL VENTILATION, AIR CLEANING FROM DUST, DUST RELEASE, HARMFUL GAS CLEANING

VOCs Fugitive Emission Characteristics and Health Risk Assessment from Typical Plywood Industry in the Yangtze River Delta Region, China

Volatile organic compounds (VOCs) emissions from the plywood manufacturing industry in China have received concerns during recent years. A total of 115 VOCs were measured in the adhesive-making, adhesive-coating, and hot-pressing workshops of the plywood manufacturing industry to investigate fugitive emission characteristics of VOCs and assess their health risks to workers. The average concentration of total VOCs in workshops of the plywood manufacturing industry is 467 ± 359 μg/m3, whereas the value for ambient air is 81.4 μg/m3. For specific processes, the adhesive-coating and hot-pressing processes show higher VOCs concentrations (501 μg/m3–519 μg/m3) than the adhesive-making process (340 μg/m3). Formaldehyde, ethyl acetate, and dichloromethane are the three most abundant VOCs in workshops, with relative contributions to total VOCs of 55.9–63.1%, 4.3–11.0%, and 1.7–4.4%, respectively. For ozone formation potential (OFP) of VOCs, formaldehyde is the largest contributor (86.1%), followed by toluene, xylenes, and propanal. The non-cancer toxic risks (HI) and cancer risks of total VOCs (T-LCR) for three processes are calculated as 2.93–3.94 and 2.86–4.17 × 10−4 using the US EPA recommended methods, both significantly higher than threshold values (1.0 for HI and 10−4 for LCR), suggesting the highly toxic and cancer risks to workers. Formaldehyde contributes 68.1–78.2% and 91.4–93.9% of HI and T-LCR, respectively. The designed risk reduction scheme of VOCs based on air ventilation suggests that air ventilation rates of formaldehyde need to reach 4–5 times in 8 h in three processes to reduce T-LCR to 10−5. These results are useful for developing VOCs control measures and evaluating VOCs occupational health risk for workers in the plywood manufacturing industry.

Assessment of Airborne Disease Transmission Risk and Energy Impact of HVAC Mitigation Strategies

The COVID-19 pandemic has focused renewed attention on the ways in which building HVAC systems may be operated to mitigate the risk of airborne disease transmission. The most common suggestion is to increase outdoor-air ventilation rates so as to dilute the concentrations of infectious aerosol particles indoors. Although this strategy does reduce the likelihood of disease spread, it is often much more costly than other strategies that provide equivalent particle removal or deactivation. To address this tradeoff and arrive at practical recommendations, we explain how different mitigation strategies can be expressed in terms of equivalent outdoor air (EOA) to provide a common basis for energy analysis. We then show the effects of each strategy on EOA delivery and energy cost in simulations of realistic buildings in a variety of climates. Key findings are that in-duct filtration is often the most efficient mitigation strategy, while significant risk reduction generally requires increasing total airflow to the system, either through adjusted HVAC setpoints or standalone disinfection devices.

Cold traps as reliable devices for quantitative determination of SARS-CoV-2 load in aerosols

Spread of the severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) is a demanding challenge. This is of particular importance in schools and public areas of unavoidable access. New viral mutations may increase infectivity and require even better methods to identify areas of potential hazards. High-throughput SARS-CoV-2 testing and legal restrictions are not effective in order to get the current outbreak under control. The occurrence of new SARS-CoV-2 variants with a higher transmissibility requires efficient strategies for early detection and surveillance. Until today, testing focuses on nasal or pharyngeal mucosa swabs, neglecting the origin of aerosolic transmission, thus failing to detect the spread by carriers of the virus. Therefore, in this study, SARS-CoV-2 RNA levels were determined by quantitative real time PCR in aerosols collected by non-powered cold traps. SARS-CoV-2 spreading kinetics were recorded in indoor hotspots within a high-endemic area. These hotspots included a SARS-CoV-2 isolation unit, an outpatient endoscopy facility, a concert hall, and a shopping mall. For determination of viral presence aerosols were collected by cold traps positioned at different locations in the area of interest over a period of 4–6 h. Indoor SARS-CoV-2 hotspots were found in non-ventilated areas and in zones that are predisposed to a buoyancy (chimney) effect. SARS-CoV-2 RNA in those aerosols reached concentrations of 105 copies/mL, while extensive outdoor air ventilation reliably eliminated SARS-CoV-2 aerosol contamination. The method presented herein is effective for the identification of SARS-CoV-2 indoor hotspots and may help to characterize the spreading kinetics of SARS-CoV-2. Moreover, it can be used for the surveillance of emerging SARS-CoV-2 variants. Due to low costs and easy handling, the procedure might enable efficient algorithms for COVID-19 screening and prevention.

INDIKATOR PERANCANGAN OCEANARIUM TANGGAP PANDEMI

According to data compiled by Johns Hopkins University, the COVID-19 virus has spread to all countries and regions of the world, infecting and killing people globally since it first emerged in the Chinese city of Wuhan late last year. The impact of COVID-19 has caused several tourism destinations in Jakarta to be closed. One of the public facilities affected is an oceanarium recreation area which functions as a centre for public entertainment, education and scientific research. The purpose of this study was to obtain design indicators for a pandemic-responsive oceanarium to reduce the risk of spreading and transmitting the COVID-19 virus. This research was conducted using literature studies, interviews, questionnaires and direct observation of similar existing buildings, namely Seaworld Ancol, Jakarta Aquarium and Dunia Fresh Air. The reference theories used that are relevant to the theme of this research include the theory of the spread and transmission of the COVID-19 virus through the air and the HVAC system, the theory of the oceanarium, and other supporting theories. Based on the results of the analysis and discussion, it is concluded that several design indicators can be used as the basis for the concept of a design strategy, namely: 1) The importance of natural air ventilation; 2) HVAC system used; 3) Limiting the duration of visits in a closed room; 3) Design of a separate building mass; 4) Minimizing direct contact between visitors and managers and visitors with visitors; 5) Maintain distance between visitors, visitors and operators. Keywords: HVAC; Design Indicators; Oceanarium; Pandemic Response; Jakarta. AbstrakVirus COVID-19 telah menyebar ke seluruh negara dan wilayah dunia, menginfeksi dan membunuh orang secara global sejak muncul pertama kali di kota Wuhan, China, akhir tahun 2019, menurut data yang dikumpulkan oleh Universitas Johns Hopkins. Dampak COVID-19 menyebabkan sejumlah Destinasi Pariwisata di Jakarta ditutup. Salah satu fasilitas umum yang terdampak adalah tempat tempat rekreasi oceanarium yang berfungsi sebagai pusat hiburan umum, pendidikan dan penelitian ilmiah. Tujuan penelitian ini adalah untuk mendapatkan indikator-indikator desain oceanarium tanggap pandemi sehingga dapat mengurangi resiko penyebaran dan penularan virus COVID-19. Penelitian ini dilakukan dengan metode kombinasi studi pustaka, wawancara, kuesioner dan observasi langsung terhadap bangunan sejenis yang sudah ada yaitu, Seaworld Ancol, Jakarta Aquarium dan Dunia Air Tawar. Beberapa teori acuan yang digunakan yang relevan dengan tema penelitian ini diantaranya adalah, teori penyebaran dan penularan virus COVID-19 melalui udara dan sistem HVAC, teori tentang oceanarium dan teori pendukung terkait lainya. Berdasarkan hasil analisis dan pembahasan diperoleh kesimpulan beberapa indikator perancangan yang dapat digunakan sebagai landasan konsep strategi desain yaitu: 1) Pentingnya ventilasi udara alami; 2) Sistem HVAC yang digunakan; 3) Membatasi durasi kunjungan di dalam ruangan tertutup; 3) Desain masa bangunan yang dipisah-pisah; 4) Meminimalisir kontak langsung antara pengunjung dengan pengelola dan pengunjung dengan pengunjung; 5) Menjaga jarak antara sesama pengunjung, pengunjung dengan operator.

Proposal of a New Method for Controlling the Thaw of Permafrost around the China–Russia Crude Oil Pipeline and a Preliminary Study of Its Ventilation Capacity

The China–Russia crude oil pipeline (CRCOP) has been in operation for over ten years. Field observation results have shown that a thaw bulb has developed around the CRCOP which expands at a rate of more than 0.8 m∙a−1 in depth. In view of the deficits of existing measures in mitigating permafrost thaw, a new control method is proposed based on active cooling. According to the relationship between total pressure loss and the driving force of natural ventilation, the wind speed in a U-shaped air-ventilation pipe around the CRCOP is calculated. By analyzing the theoretical calculation and numerical analysis results, it is found that the influence of thermal pressure difference on the natural ventilation of the structure can be negligible, and the influences of resistance loss along the pipe and local resistance loss in the pipe are similarly negligible. Exhaust elbows greatly improve the ventilation performance of the U-shaped air-ventilated pipe. This study developed a novel structure around warm-oil pipelines in permafrost for mitigating thaw settlement along the CRCOP and other similar projects across the world.

Modelling airborne transmission of SARS-CoV-2 using CARA: Risk assessment for enclosed spaces

The global crisis triggered by the COVID-19 pandemic has highlighted the need for a proper risk assessment of respiratory pathogens in indoor settings. This paper documents the COVID Airborne Risk Assessment (CARA) methodology, to assess the potential exposure of airborne SARS-CoV-2 viruses, with an emphasis on the effect of certain virological and immunological factors in the quantification of the risk. The proposed model is the result of a multidisciplinary approach linking physical, mechanical and biological domains, benchmarked with clinical and experimental data, enabling decision makers or facility managers to perform risk assessments against airborne transmission. The model was tested against two benchmark outbreaks, showing good agreement. The tool was also applied to several everyday-life settings, in particular for the cases of a shared office, classroom and ski cabin. We found that 20% of infected hosts can emit approximately 2 orders of magnitude more viral-containing particles, suggesting the importance of super-emitters in airborne transmission. The use of surgical-type masks provides a 5-fold reduction in viral emissions. Natural ventilation through the opening of windows at all times are effective strategies to decrease the concentration of virions and slightly opening a window in the winter has approximately the same effect as a full window opening during the summer. Although vaccination is an effective protection measure, non-pharmaceutical interventions, which significantly reduce the viral density in the air (ventilation, masks), should be actively supported and included early in the risk assessment process. We propose a critical threshold value approach which could be used to define an acceptable risk level in a given indoor setting.