Ventilation Fans Research Articles

Summer Energy Use and Comfort Analysis in Rural Chinese Dwellings: A Case Study of Low-Income Older Populations in Shandong

This paper aims to investigate the indoor environmental conditions and energy use behaviours of older individuals in rural cold climates of China, with a specific focus on cooling practices during the summer months in the Shandong region. This study employs a mixed-method approach, combining quantitative indoor environmental monitoring with qualitative interviews and observations, to explore the relationship between environmental factors, household living conditions, and energy use patterns across five types of elderly households: three generations living together, older people living with grandchildren, older people living with children, older couples living together, and older people living alone. Data collection was conducted over five weeks during the summer of 2023 using HOBO UX100-003 data loggers, while external weather conditions were monitored by the China Meteorological Administration. Face-to-face interviews were conducted to gain deeper insights into daily cooling behaviours and energy use. The results reveal that cooling practices and indoor environmental conditions vary significantly among the different household types. Multigenerational households showed more complex energy use dynamics, with younger family members frequently operating high-energy appliances like air conditioners, while older individuals tended to rely on natural ventilation and electric fans to reduce energy costs. In contrast, older couples and solitary older individuals demonstrated more conservative cooling behaviours, often enduring higher indoor temperatures due to limited financial resources and a desire to minimize energy expenditures. Despite the high energy use intensity in some households, many homes failed to achieve comfortable indoor environments, particularly in dwellings with minimal insulation and older building materials. This study concludes that economic status, household structure, and building characteristics play crucial roles in shaping cooling behaviours and indoor comfort during the summer.

A Study on the Influence of Mobile Fans on the Smoke Spreading Characteristics of Tunnel Fires

Mobile fans, as flexible and convenient new longitudinal ventilation and smoke extraction equipment for tunnels, demonstrate more significant effectiveness in an emergency response to tunnel fires compared to traditional smoke extraction methods. This study employs computational fluid dynamics simulation methods, selecting two fire scenarios to investigate the effects of fan inclined angles and fan airflow volumes on the longitudinal temperature distribution and smoke back-layering length in tunnels. The results indicate that when using mobile fans for longitudinal ventilation in tunnels, at a lower fan airflow volume, the temperature distribution along the longitudinal axis is nearly symmetrical. The fire source and the fan installed in the upstream are within a certain range, and it is more effective to use the horizontal angle for longitudinal ventilation. As the fan airflow volume increases, the back-layering length significantly decreases (210,000 m3/h < V < 270,000 m3/h). However, as the fan flow volume continues to increase (270,000 m3/h < V < 300,000 m3/h), the reduction in the back-layering length becomes less pronounced, the smoke spread distance of the latter is only 11% of that of the former. Therefore, selecting appropriate fan airflow volumes and fan inclined angles them can effectively enhance the performance of tunnel smoke extraction systems. Moreover, by comparing with traditional fans, we find that mobile fans provide an alternative effective strategy during firefighting by allowing adjustments in distance from the fire source and fan inclination angles, enhancing fire suppression effectiveness while reducing energy losses. The research findings can serve as a reference for tunnel fire prevention design.

Mitigating household air pollution exposure through kitchen renovation

Globally, over three billion people rely on traditional solid fuels for cooking and heating, leading to significant household air pollution and critical public health concerns. While transitioning to clean energy carriers faces challenges of accessibility and affordability—especially among low-income, rural populations—alternative strategies like kitchen layout modifications and the use of ventilation fans may effectively reduce exposure to pollutants. Here, we analyze factors influencing the adoption of separated kitchens and mechanical ventilation and evaluate changes in human exposure to PM2.5 under different kitchen renovation scenarios by conducting a nationwide survey of household kitchen characteristics in rural China. We found that although 82% of rural households have kitchens separated from other rooms, only 34% use mechanical ventilation. The adoption of ventilation fans is significantly influenced by income and education levels. We estimate that widespread implementation of ventilation fans and separated kitchen designs could prevent approximately 67400 premature deaths annually, resulting in a health benefit of about USD 19 billion per year—substantially exceeding the costs involved. These findings suggest that cost-effective kitchen renovations offer enormous potential for substantial health benefits and present a practical solution compared to the challenges of clean energy transitions in rural areas.

Recovery of electrical power from exhaust air—role of vertical axis wind turbine

AbstractThis article explores the potential of regeneration of power from unnatural wind sources with the help of vertical axis wind turbines (VAWT). Researchers are searching for urban as well as industrial wind sources, which can be useful as the natural wind source to obtain electrical energy and utilize it. The wind sources considered here are the exhaust of the cooling or ventilation fans used in buildings, industries, and other places. The Darrieus VAWT extracts wind power from the exhaust air and reduces the power consumption of the concerned electrical drives. These uncommon energy sources have an inherent capability to recover a significant amount of energy without polluting the environment with less payback period. Recovered energy can be suitably converted into electrical energy and may be fed back to the power grid without any pollution, thus minimizing the total energy consumption of the building and reducing the cost operations. A detailed study of experimental models with different types of assembly and turbine models is conducted here with power outputs and operational behaviors on the existing systems. Various parameters and factors for existing and new applications are in detail that show the system has no negative impact on regular operation.

Multimodal Hong Kong: A review of policies regarding soundscape and smellscape of Chinese temples

Many people in Hong Kong regularly visit Chinese temples, and see this not necessarily as a religious activity, but as a traditional practice. Temples represent the local intangible cultural heritage. The dense urbanity and mixed population characterise Hong Kong and make it valuable to study its sounds and smells. Most temples existed earlier than modern urban areas, which grew around them. The temple soundscape consists of drums, bells, coin donations, ventilation fans, as well as chanting, especially during festivals. The smellscape consists of ritual burning of incense and paper, fruit offerings, and building materials e.g., wood and cement. The burning causes particle pollution, health concerns, and residential nuisance, that may conflict with the wish for sustaining a valuable heritage. Smells and air quality have recently become debated, raising the question of the need for a specific regulatory framework. There is currently a lack of official provision that directly protects the sounds and smells of these temples in Hong Kong. This paper reviews the current state of Hong Kong policies in regard to soundscape and smellscape, with comparison to China and France, because of the latter's progressive agenda in preserving sensory heritage in the countryside.

Energy-saving cooling strategies in tunnel-ventilated dairy buildings: Computational fluid dynamics (CFD) simulations and validation

Ventilation is a key strategy for addressing heat stress in dairy cattle. In this study, we developed computational fluid dynamics (CFD) models for a 252-head free stall tunnel-ventilated dairy building equipped with ridge openings and circulation fans. A detailed cow model was developed for a standard 625 kg Holstein cattle. Both tube and floor cooling were developed as supplemental cooling strategies using a ground source heat pump while the ventilation fans continued to operate at a reduced air speed (30 to 65 % reduction). The average air velocity within the stalls for the control (1.4 ± 0.32 m s-1) was significantly higher than the average velocity achieved with floor cooling (1.02±0.41 m s-1) and tube cooling (0.69±0.21 m s-1) (p = 0.043). Despite lower air velocities, CFD simulations showed that the average temperature at cow resting height for tube cooling (27.9 ± 0.21 °C) was significantly lower than that for the control (28.6 ± 0.36 °C) and floor cooling (28.3 ± 0.14 °C) (p = 0.021). For 252 cows, the total electricity consumption for the control was 40,590 kWh during summer, while for floor cooling, it varied between 30,683 and 36,181 kWh, and for tube cooling, it ranged from 15,879 to 21,378 kWh. Ventilation-related greenhouse gas (GHG) emissions from the tunnel-ventilated barn were 0.12 t of CO2 eq. per cow. Future studies could investigate the impact of reduced airflow rates on air quality inside the buildings.

Analysis on typical characteristics and causes of coal mine gas explosion accidents in China.

Large-scale coal mine gas explosion (CMGE) accidents have occurred occasionally and exerted a devastating effect on society. Therefore, it is essential to systematically identify the characteristics and association rules of causes of CMGE accidents through analysis on large-scale CMGE accident reports. In this study, 298 large-scale CMGE accidents in China from 2000 to 2021 were taken as the data sample, and mathematical statistical methods were adopted to analyze their general characteristics, coupling cross characteristics, and characteristics of gas accumulation and ignition sources. Moreover, the text mining technology and the Apriori algorithm were used for exploring the formation mechanism of CMGE accidents, during which 46 main causal factors were identified and 59 strong association rules were obtained. Furthermore, an accident causation network was constructed based on the co-occurrence matrix. The key causal items and sets of CMGE accidents were clarified through network centrality analysis. According to the research results, electrical equipment failure, cable short circuit, mine lamp misfire, hot-line work, and blasting spark are the key ignition sources of CMGE. Fan failure, airflow short circuit, and local ventilation fan damage are the main causes of gas accumulation. Besides, the confidence levels of two association rules of "static spark-fan failure" and "blasting spark-airflow short circuit" are higher than 70%, indicating that they are the two dominant risk-coupling paths of gas explosions. In addition, six causes appear frequently in the shortest risk paths of gas explosion and are closely related to other causes, i.e., fan failure, local ventilation fan damage, static sparks, electrical equipment failure, self-heating ignition, and friction impact sparks. This study provides a new perspective on identifying causes of accidents and their complex association mechanisms from accident report data for practical guidance in risk assessment and accident prevention.

Environmental conditions in equine indoor arenas: A descriptive study

Indoor arenas do not always include mechanical ventilation or stirring fans and occupancy by horses and humans can be sporadic and inconsistent, which creates a challenging space for understanding and predicting variations in temperature, moisture, and airflow. To understand the interior environment within indoor arenas, monitoring was conducted at 15 facilities within 200 kilometres of Lexington, KY. Environmental monitoring of dry bulb temperature, relative humidity, dew point temperature, air speeds, and solar radiation took place over 7 days in the winter and summer to examine temporal variability. Environmental data was collected every 5 minutes using the HOBO RX3000 Remote Monitoring Station with the HOBOnet Temp/RH Sensor, HOBOnet Solar Radiation (Silicon Pyranometer) Sensor, and HOBOnet Ultrasonic Wind Speed and Direction Sensor. Clear seasonal differences and diurnal patterns were evident in all environmental conditions, but the relative humidity. The relative humidity and dew point temperatures indicated moisture could be an issue in many of the indoor arenas. High relative humidity and excess moisture can negatively impact horse and human health as well as the lifespan of the facility. Similar results to previous spatial variability indoor arena characterizations were observed during the environmental monitoring with air speeds being below the threshold for still air in livestock facilities (0.51 m s-1). Sensor technology and implementation provides a better understanding of the interior environment and how indoor arena design can impact it.

Primary Frequency Control with an Air Handling Unit

The green energy transition threatens stability of the power grid due to associated reduction in grid synchronous inertia. Primary frequency control (PFC) can compensate for the challenge; however, sufficient procurement of primary frequency capacity could depend on more extensive employment of demand-side loads for PFC. Ventilation fans in particular present a promising class of such loads because of ubiquity of variable-frequency drives and relatively slow thermal and ventilation dynamics of indoor spaces. This research proposes a novel method for PFC by an air handling unit: the open loop control is shown to have favorable dynamic characteristics, and its impact on indoor climate is shown to be tolerable. This study suggests that the largely unused primary frequency capacity of ventilation fans could be exploited to provide primary frequency response for low inertia power grids.

Noise considerations for the distributed modular-based approach to cryptocurrency data centers

While the establishment of cryptocurrency data centers becomes increasingly prevalent, the significant noise impact of these facilities on the surrounding community and environment has also become of interest. One of the most common designs for cryptocurrency mining facilities is to utilize a set of modular data centers, commonly constructed out of modified shipping containers, which are distributed over a large space. Each individual data center module can contain a large number of cryptocurrency mining computers, with each of these equipped with its own cooling fan system. The individual miner fans, coupled with the large ventilation fans required to cool the data center modules themselves, can lead to a complex, widespread acoustic environment that can be difficult to mitigate. This work presents commonly implemented noise mitigation strategies for cryptocurrency mining operations and the common issues that come along with those strategies, as well as operational limitations that must be considered when designing the proper noise control solution. Applications to regulatory constraints on noise, or lack thereof, are discussed.

Noise control tactics to balance the demand for sustainable energy storage, community tranquility, and environmental regulatory compliance

As the construction of large-scale Battery Energy Storage System (BESS) facilities increases in California, their impact on urban sprawl is also becoming more pronounced. Projects involving BESS arrangements increasingly find themselves within or near residential land uses in California, providing greater challenges for noise control and abatement to comply with state and local operational noise thresholds. This paper presents case studies of what Dudek has found to be the most efficient noise control tactics related to lowering the noise emission of BESS facilities, particularly through the implementation of onsite noise walls, direct noise attenuation applied to BESS equipment (i.e., noise attenuation for battery thermal management systems involving the operation of ventilation fans and refrigeration system components), and modified BESS equipment arrangements. These strategies are essential for ensuring that BESS projects are not only compliant with environmental standards but also socially acceptable within residential communities. By presenting practical and efficient noise mitigation techniques, this paper aims to guide planners and developers in the sustainable development of BESS facilities, balancing the demand for energy storage with the preservation of community tranquility and compliance with regulatory noise limits.

Exploration of the effect of hot smoke generated by tunnel fire on the ventilation flow field of jet fan

Abstract To reduce the hazard of hot smoke from tunnel fires, ventilation becomes a necessary control strategy. Uniform ventilation is the main method used in the study of tunnel fires, but it has obvious differences from the widely used jet fan ventilation in practice, and the two have different performances in controlling smoke. Therefore, the distribution of the upstream flow field with jet fan ventilation will be studied in a tunnel fire. Considering several parameters such as the HRR and the velocity of fan exit, numerical simulations were conducted to monitor the fire development by using a Fire dynamics simulator (FDS). The results suggest that the center-line velocity decay of a jet fan can be categorized into three regions: linear decay, power function decay, and stabilization. The decay coefficient (n) related to power function decay correlates with HRR, and therefore, a new prediction for the center-line velocity distribution of the jet fan is proposed. The predicted results correlate well with the available experimental data.

Analytical design and computational fluid dynamics analysis for optimizing fixed ventilation systems for power transformer: Numerical study and experimental validation

Despite the recognized fact that power transformers (PT) are highly efficient technology, part of their electrical energy is counted as heat losses. Therefore, the cooling system is a critical factor in the life span and performance of the PTs, and hence the adopted thermal energy design can be strongly effective. This study revolves around the innovative development of a novel generation of fixed ventilation fans for PTs, achieved through Computational Fluid Dynamics (CFD) simulations and practical experiments. The proposed CFD model was developed adopting ANSYS FLUENT 19.2. The proposed CFD model was verified by comparing the numerical and experimental results of the cooling air temperature and velocity. A standard k-ε model was used to simulate the airflow of the investigated cooling system numerically. A thermal analysis of a four-sided power transformer was performed, and an analysis of the optimum position to install the cooling fan on the radiator was presented. The most effective number of used fans was also determined. The main results showed that two fans were found to be the best performance among the tested candidate alternatives. The two cooling fans’ size, material, and cover shape were also studied and added to the proposed model. Besides, the utilization of a thermoelectric generator was considered in this study in order to recycle some of the lost heat into output power. An experimental prototype mimicking the actual cooling system for the power transformer was designed and fabricated. Results showed that the selected material has achieved a high Calculated Factor of Safety (FoS) equal to 237, indicating that the utilization of the designed parts is of high safety.

Power consumption profiles of the main fans at coal mines

Purpose. To determine the main indicators of the power consumption profiles of the main ventilation fans of coal mines under the condition of regulating their performance using controlled electric drive systems based on semiconductor elements. The methods. The methods of operations research were used to analyse technological processes in terms of compliance of the actual power consumption profiles of the main fans with their expected operating modes. The methods of mathematical statistics were used to determine the statistical parameters of the electrical loading diagrams of the main ventilation fans of coal mines. Findings. A statistical analysis of typical power consumption profiles of the main fans of coal mines with different electric drive systems has been carried out: a synchronous motor with a high-voltage frequency converter, an induction motor based on the asynchronous-thyristor cascade system, and a synchronous motor with ‘classical’ rotor excitation control without semiconductor elements. The feasibility of using adjustable electric drive systems to control the performance of main ventilation fans in terms of reducing active power consumption has been confirmed. However, at the same time, the consumption of a significant amount of reactive power is shown, which is inherent for systems based on semiconductor elements, regardless of the motor type (synchronous or asynchronous). Originality. The statistical analysis of the actual daily power consumption profiles of the main fans of coal mines with different controlled electric drive systems has shown that the standard deviation of the active load does not exceed 1% of the rated power of the drive motor and does not depend on its type (synchronous or asynchronous). Practical implementation. The practical value of the work is in determining the actual consumption of reactive power by the systems of controlled electric drive based on semiconductor elements. It shows its significant level, which should be provided by appropriate filter-compensating devices on the power supply buses of the motors of the main ventilation fans.

Numerical study on the internal ventilation of the engine room of a ship under construction

Manual welding operations are performed inside the engine room of a liquefied natural gas carrier under construction. The welders are at risk of exposure to welding fumes in case of poor ventilation. Therefore, ventilation fans are installed at shipbuilding sites to improve indoor air quality. Although ensuring the respiratory health of welders is important, studies focusing on ventilation in the ship engine room have not been conducted. Therefore, the ventilation efficiency was evaluated herein based on the placement of ventilation fans to alleviate air stagnation using a computational fluid dynamic (CFD) model operating on Fluent. The mean age of air (MAA) was computed to assess the ventilation efficiency. In addition, particles with size and physical properties similar to welding fumes were sourced assuming 30 welders in the engine room. Results revealed that ventilation fan and/or exhaust in enclosed spaces contributes significantly to alleviating the MAA level. MAA and particle distribution did not correlate well due to the different properties of air and the iron oxide particle. Therefore, to determine the optimal ventilation fan displacement, particle motion should be studied along with performing MAA analysis. The proposed CFD model potentially guides to improvement of the working environments and respiratory health of welders.

Implementation of IoT Based Gas Leakage Detection Device

In this paper, we present the design and implementation of an innovative Internet of Things (IoT)-based gas and smoke detection system aimed at enhancing safety in various environments. Gas leaks and fires pose significant risks to life, property, and the environment, necessitating effective detection and mitigation strategies. Leveraging advancements in sensor technology, wireless communication, and smart automation, our system provides real-time monitoring of gas levels and smoke presence. Upon detection of a gas leak or smoke, the system initiates automated responses, including activating an exhaust fan for ventilation, disabling electrical appliances, and triggering audible alarms to alert occupants. Additionally, the system integrates with a mobile application, enabling remote monitoring and control. Through comprehensive testing and evaluation, we demonstrate the effectiveness and reliability of our system in enhancing safety and security. Our research contributes to the advancement of IoT-based safety systems and offers insights into future developments in safety engineering. Keywords— “IoT (Internet of Things)”, “Gas Sensor, Mobile Integration”, “Safety protocols”, “MQ2 sensor”, “LM324”.

INVESTIGATION OF THE INSIDE TEMPERATURE TO ARRIVE COMFORTABLE CONDITION: CASE STUDY MECHANICAL WORKSHOP BUILDING

Mechanical workshops are considered as important buildings in faculty of engineering. It is a place for the students and teachers to get practical experiences and activities. Thermal comfort is an essential requirement in most occupied spaces because it affects the productivity, health and thermal satisfaction of the occupants. Natural ventilation, which may provide occupants with good indoor thermal comfort, and reduce energy costs, has become an important sustainable strategy in building designs. Most of the mechanical workshop buildings in countries with a hot and humid climate use a combination of natural ventilation and electrical fans are commonly used as a space cooling method to provide thermal comfort to the occupants. This article presents the results of a field measurement study that was conducted on the mechanical workshop building which is locat-ed in Faculty of Engineering, University of Aden, Yemen. The purpose of study is to investigate of the inside temperature to arrive comfortable condition of the Mechanical Workshop Building un-der the present ventilation system. The measurements were recorded within duration of one year, starting from October 2021 to September 2022 on the middle of months. The measured values were then compared to the corresponding limit as specified in the ASHRAE Standard-55. It was found that the inside temperature at the selected locations of the mechanical workshop building exceed the respective upper limits as recommended in the ASHRAE Standard-55. This shows that the existing air ventilation method via the use of natural ventilation and electrical fans in the me-chanical workshop building are not able to provide an adequate level of thermal comfort to the occupants for all the stipulated months. Therefore, an alternative ventilation method is needed to improve the thermal comfort inside the Mechanical Workshop building.

The Use of Coffee Aroma for Stress Reduction in Postgraduate Dental Students

ObjectivesThis study aimed to investigate the measure to reduce academic stress of graded oral presentation in postgraduate dental students using coffee aromatherapy. MethodsHealthy postgraduate dental students in a seminar class were divided into coffee (n = 32) or control (n = 26) group. There were three modes of aroma distribution: personal distribution with a coffee pad attached to a lanyard, a lanyard plus a personal fan for ventilation of the aroma, and the typical method of the diffuser to spread the aroma in the ambient air. The levels of salivary alpha-amylase (sAA), cortisol (sCort), and chromogranin A (sCgA) represented stress biomarkers. Pulse rates were also measured. ResultsThe levels of sAA increased 176.62 ± 30.26% between pre- and post-presentation in the control group. Inhaling coffee aroma during the presentation period significantly ameliorated sAA increase at 81.02 ± 14.90% (p = 0.015). sCort levels tended to decrease in the coffee group but not significantly. Surprisingly, sCgA levels actually increased more in the coffee group. Also, pulse rates decreased in the coffee group (-2.07 ± 2.81 bpm) and increased in the control group (6.90 ± 3.22 bpm; p = 0.035). Subgroup analysis did not reveal differences in salivary markers among three aroma distribution modes. ConclusionsCoffee aroma could have anxiolytic effect on postgraduate dental students as evidenced by sAA levels and pulse rates. Personal aroma distribution was also a useful and effective mode of aromatherapy.

Theoretical model for calculating and adjusting radon activity concentration in ventilation networks of uranium mines considering pressure drop effect

The radiation dose of workers in underground uranium mines mainly comes from radon and radon progeny. To ensure a healthy and safe work environment, it is necessary and urgent to optimize the design of ventilation systems. As such, based on the simplified radon diffusion-advection migration model of the rocks, this paper proposes 1) two methods for determining the radon exhalation rate modified by pressure drop, 2) three methods for calculating radon activity concentration of single-branch, and 3) the novel adjustment algorithm and solving procedures for calculating and adjusting the radon activity concentration in ventilation networks by modifying the radon exhalation rate, demonstrated on a specific ventilation network in a simulated underground uranium mine with calculation and analysis via MATLAB. The results show that 1) the radon exhalation rate of different branches can be modified by their pressure drop, and 2) the proposed method can be used to reveal the influences of different ventilation methods and fan pressures on the radon activity concentration in the ventilation network and the radon release rate to the atmosphere.

Experimental study on the performance of micro gas turbines under different intake environments

This article uses experimental methods to measure the operational performance and pollutant emissions of micro gas turbines in different intake environments, and analyzes the feasibility of replacing mine ventilation fans with micro gas turbines. The results show that when the compressor efficiency is increased from 70 % to 90 %, the total efficiency of the micro combustion engine is increased from 28% to 34 %, with an increase of up to 21.4 %. When the demand power is 25 kW, the fluctuation range of NOx emission concentration is within 5.4 %. When the intake opening is below 50 %, the effect is obvious. When the intake opening is reduced from 50 % to 25 %, the performance of the micro gas turbine decreases by 0.7 %; The influence of intake humidity on various operating parameters of micro gas turbines is generally within 3 %, which can meet the requirements of high humidity environment operation; The intake temperature has the greatest impact, with an increase in intake temperature leading to a decrease in power generation efficiency. After comprehensive analysis, we believe that the application of gas turbines in mines is feasible.