Vent Position Research Articles

An air‐cooled cylindrical Li‐ion 5 × 5 battery module with a novel flow‐diverting arrangement and variable vent positions for electric vehicles: A numerical thermal analysis

AbstractThermal management of lithium‐ion batteries has received a lot of interest in the automobile sector. In commercial electric motor vehicles, an efficient battery cooling arrangement, particularly active cooling approaches, has been chosen as an ideal option. When building battery cooling systems, the physical structure and arrangement of the battery pack (BP) are vital. The current study presents a revolutionary design of a BP that incorporates cylindrical cells in a square duct and an air‐cooling (AC) medium circulated in its surroundings with the help of variable vents for inlet and outlet. A forced‐AC system is used to test lithium‐ion battery cells grouped in a 5 × 5 configured battery module. To investigate the impact of heat generation on battery thermal performance, a complete thermal analysis was performed at different discharge rates of 0.5, 1, 2, 3, and 4 C. As compared with both inlet vents at an equidistance configuration with an inlet velocity of 12 m/s and a flow rate of 1.210(−2) kg/s, the results show that the proposed design minimizes heat accumulation by enhancing the heat transfer. As a result, the peak temperature and temperature disparity decreased by 6.76% and 85.32%, respectively. A flow‐dispersing disc of 30 mm in size enhances temperature uniformity in comparison to the other intake vent design, hence improving battery safety and longevity.

Simulation analysis and optimization of containerized energy storage battery thermal management system

The air-cooling system is of great significance in the battery thermal management system because of its simple structure and low cost. This study analyses the thermal performance and optimizes the thermal management system of a 1540 kWh containerized energy storage battery system using CFD techniques. The study first explores the effects of different air supply angles on the heat transfer characteristics. Second, the evaluation indexes of heat removal efficiency, air exchange efficiency, temperature and velocity uniformity coefficient are used to select the optimal air supply angle by the Topsis method. Then, the return air vent position is optimized based on the optimal air supply angle, and the optimal solution is obtained. Research indicates that increasing the air supply angle enhances air mixing within the container and simultaneously decreases the battery pack surface temperature. With a 90° air supply angle, the maximum temperature reduces to 33.58 °C, a 19.52 % reduction compared to 30°. The temperature difference across each battery surface also drops by 16.02 % to 3.46 °C. Adjusting the position of the return air vent further improves temperature uniformity and air flow distribution within the battery compartment. When the air supply angle is 90° and the return air vent evenly distributed at Z = 0.85 m next to the fire door, an optimal uniform temperature distribution is achieved. This reduces the maximum surface temperature by 16.47 %, from 36.67 °C to 30.63 °C and decreases the average temperature difference to 3.0 °C, 21.4 % lower. Thus, the present method effectively enhances the performance of the containerized energy storage battery thermal management system.

Impact of impinging jet ventilation on thermal comfort and aerosol transmission: A numerical investigation in a densely-occupied classroom with solar effect

Urgent demands for ensuring safe and healthy spaces for children have been raised due to the post-COVID-19 pandemic. This study numerically modelled a densely populated classroom with 40 students and one teacher across two layouts with different relative vent positions to assess the effectiveness of an emerging ventilation scheme, impinging jet ventilation (IJV), in balancing thermal comfort and controlling indoor transmission. The effect of solar radiation was carefully analysed. Cough-induced contaminants were expelled from the infectious teacher and were traced by the Eulerian-Lagrangian approach. The exposure risk of students was further assessed via the inhalation index (ID) based on the spatial characteristics of the released particles. The thermal comfort was evaluated by the Fanger model. The results demonstrated that IJV with Layout 2 (teacher at the supply inlet and exhaust side) was found more optimal in counterbalancing the occupants’ thermal comfort and indoor transmission control. This layout not only aligned better with ASHRAE standards for thermal comfort, showing a reduced vertical thermal gradient but also lowered student exposure risk by 18.9%–135.2%. With solar radiation, heat absorbed by the windows led to non-uniform wall temperature distributions, causing the air near the windows to also exhibit a non-uniform profile. This interaction with the cooler air from the IJV system was found to facilitate contaminant dispersion. This resulted in a 10.3% to 26% increase in students’ average exposure risk compared to those without solar radiation cases. This study aimed to investigate the practical applications of IJV system for densely-occupied classrooms.

Numerical simulation and optimisation design for ventilation and heat dissipation in high-temperature and high-load indoor substations

Under high-temperature and high-load operational conditions, inadequate ventilation and suboptimal cooling arrangements within indoor substations result in high oil temperatures, posing a threat to the secure and steady operation of transformers. In this paper, the ventilation and heat dissipation effect of a 110 kV indoor substation is studied by the computational fluid dynamics method. Initially, the three-dimensional simulation model of the main transformer chamber is constructed to mirror the actual substation structure. Subsequently, the impact of the upper outlet on ventilation and heat dissipation is explored. The results show that the proximity of the upper outlet to the fan on the side wall prompts the fan to draw air from the upper outlet, diminishing the air volume entering the lower intake outlet by 38.8 %. It proves detrimental to the transformer's heat dissipation efficiency. Lastly, with the upper outlet closed, the study delves into the impact of various configurations of intake and exhaust ports on optimizing ventilation and heat dissipation. A total of six cases of two scenarios for the air inlet location and three exhaust vent positions are explored. According to the simulation results, the optimal case of substation ventilation and heat dissipation is obtained by considering four evaluation parameters.

Optimizing the Return Vent Height for Improved Performance in Stratified Air Distribution Systems

One of the factors that strongly impacts the efficacy of stratified air distribution (STRAD) systems is the return vent height (H), for which different studies have yielded different suggested values. This theoretical research uses a displacement ventilation (DV) system as an example to examine how the H affects the efficacy of STRAD systems through analysis of the trade-offs between the cost of the vertical temperature gradient and the benefits of energy reduction. The key results are as follows: (a) The energy savings due to a lower H are smaller than the cost of the vertical temperature gradient for all STRAD systems. (b) With a supply temperature (Ts) set at 18 °C, elevated return vent positions can result in excessively cooled areas, while extremely low vent positions create a temperature gradient exceeding 3 °C between the head and ankles. (c) The TOPSIS methodology reveals that the optimal H value lies in the range of 1.5–2.3 m when Ts is 18 °C. (d) When adjusting the Ts value to achieve thermal neutrality, 2.3 m is identified as the optimal H value, demonstrating superior performance over the 1.5 m to 2.3 m range at 18 °C Ts. These findings highlight the benefit of a higher H for STRAD systems and the significance of configuring ventilation systems for thermal neutrality.

Buoyancy-Driven Ventilation in the Interior-Most Flats of an Apartment Building with Different Corridor Vent Opening Condition

In the present work, computational simulations are conducted for an apartment building to investigate the bouncy-driven airflow in the corridor and inside the rooms. Two types of corridor vent openings are provided through which the hot light air moves to the ambient. Two floors are considered for the study. The simulations are conducted with three different temperature difference conditions between walls and room inside air such as; ∆T=10OC, ∆T=15OC, ∆T=20OC for two different corridor vent opening configurations. When the corridor vent openings are kept only in front of the doors and windows, recirculation zones below the roof near the air entry region are observed and part of the air escaped through the inlet. In the case of a wide corridor vent opening, air does not escape through the inlet. With increase in ΔT, the airflow increases irrespective of vent positions. Mainly the area of the rooms is well ventilated closer to the door position. It is also observed that the lower floor is relatively well-ventilated as compared to the upper floor. The ACH increases with increase in vent opening and it also increases with increase in ∆T.

Addressing personalized thermal comfort in residential settings: A novel dual-supply vent air conditioner

A new approach was proposed for meeting diverse thermal comfort demands of different occupants by using a dual-supply vent air conditioner with independent control of the air supply parameters at each vent to establish distinct thermal environments. The feasibility of this method was tested in a living room environment, and numerical simulation was conducted to explore the differences in thermal environment at various locations under different air supply temperatures, velocities, directions, and vent positions. The results indicated that, within the targeted air supply zone, the maximum temperature difference could reach around 2.5 °C. Considering the Cooling Effect of air velocity, the maximum Equivalent Temperature difference was around 4.5 °C, which could address the differences in common personalized thermal comfort preference. Utilizing the differential air supply velocities of different vents was an effective means of achieving diverse thermal environments, although attention should be paid to local thermal discomfort caused by drafts. This approach may offer a new perspective in addressing the differing thermal comfort preferences among occupants within the same residential room, additionally providing innovative insights for improving traditional air conditioning systems.

Predicting Contamination Spread Inside a Hospital Breakroom with Multiple Occupants Using High Fidelity Computational Fluid Dynamics Simulation on a Virtual Twin

Mitigating the rise and spread of contaminants is a major challenge faced during any contagious disease outbreak. In densely occupied areas, such as a breakroom, the risk of cross-contamination between healthy and infected individuals is significantly higher, thereby increasing the risk of further spread of infectious diseases. In this study, a high fidelity transient fluid solver and Lagrangian particle-based method were used to predict the airflow distribution and contaminant transmission inside a detailed 3D virtual twin of an emergency hospital breakroom. The solver efficiently captured the contaminants emitted simultaneously from multiple talking occupants as well as their propagation inside the breakroom. The influence of airflow distribution on the aerosol spread inside the breakroom for two different air conditioning vent positions was demonstrated with all occupants and with reduced occupants. The baseline simulation with all occupants in the breakroom showed a higher risk of contamination overall as well as between adjacent occupants. It was observed that there was a 26% reduction in the contaminants received by the occupants with the proposed modified vent arrangement and a 70% reduction with the scenarios considering a reduced number of occupants. Furthermore, the fomite deposition and cross-contamination between adjacent humans significantly changed with different ventilation layouts. Based on the simulation results, areas with higher contaminant concentrations were identified, providing information for the positioning of UV lights in the breakroom to efficiently eliminate/reduce the contaminants.

Distribution of benzene and formaldehyde in tractor cabin: Effects of components, ventilation conditions, and vent positions

Tractor cabin is a relatively closed microenvironment in which operator is exposed to various pollutants that can adversely affect human health. In this study, the distribution of benzene and formaldehyde inside tractor cabin was investigated using computational fluid dynamics (CFD) method and verifying its effectiveness with field measurements. The effects of pollution source, ventilation, and vent position on the distribution of pollutants were discussed by using the validated CFD model. The results indicated that the areas with high concentration of pollutants are mostly distributed in the corners, and the ceiling contributes the most to its emission. The concentration difference of benzene and formaldehyde in the driver’s breathing area can reach a maximum of 20% by adjusting the air supply angle. It can also be reduced by 3.9% and 4.3% for every 1 m s−1 increase in air supply speed when the airflow angle emitted from the vent was 90°. In the common vent locations, the vent arranged on the front ceiling has the best pollutant reduction effect. This study provided a reliable CFD simulation method for benzene and formaldehyde distribution, offered a theoretical basis for the selection of ventilation conditions and the design of internal layout in tractor cabins for improving air quality. It also suggested that then environment and air quality of non-road mobile machinery cabs should be paid more attention in the future.

Assessing long-term tephra fallout hazard in southern Italy from Neapolitan volcanoes

Abstract. Nowadays, modeling of tephra fallout hazard is coupled with probabilistic analysis that takes into account the natural variability of the volcanic phenomena in terms of eruption probability, eruption sizes, vent position, and meteorological conditions. In this framework, we present a prototypal methodology to carry out the long-term tephra fallout hazard assessment in southern Italy from the active Neapolitan volcanoes: Somma–Vesuvius, Campi Flegrei, and Ischia. The FALL3D model (v.8.0) has been used to run thousands of numerical simulations (1500 per eruption size class), considering the ECMWF ERA5 meteorological dataset over the last 30 years. The output in terms of tephra ground load has been processed within a new workflow for large-scale, high-resolution volcanic hazard assessment, relying on a Bayesian procedure, in order to provide the mean annual frequency with which the tephra load at the ground exceeds given critical thresholds at a target site within a 50-year exposure time. Our results are expressed in terms of absolute mean hazard maps considering different levels of aggregation, from the impact of each volcanic source and eruption size class to the quantification of the total hazard. This work provides, for the first time, a multi-volcano probabilistic hazard assessment posed by tephra fallout, comparable with those used for seismic phenomena and other natural disasters. This methodology can be applied to any other volcanic areas or over different exposure times, allowing researchers to account for the eruptive history of the target volcanoes that, when available, could include the occurrence of less frequent large eruptions, representing critical elements for risk evaluations.

Scenario-based probabilistic hazard assessment for explosive events at the San Salvador volcanic complex, El Salvador

We present a scenario-based, probabilistic hazard assessment for the San Salvador volcanic complex (SSVC), a volcanic field located in the vicinity of San Salvador that includes the El Boquerón stratovolcano and 25 monogenetic vents. We define a set of likely eruption scenarios for tephra fallout and pyroclastic density currents (PDCs). The eruption scenarios range from violent Strombolian eruptions with a significant uncertainty in source position to sub-Plinian and Plinian activity fed from the central cone. The adopted methodology is mainly based on numerical modeling using Tephra2 (adopting the software TephraProb) to study tephra fallout and the branching box model and the branching energy cone model (adopting the programs BoxMapProb 2.0 and ECMapProb 2.0) to describe inertial and frictional PDCs, respectively. Despite the dominant W-WSW-trending winds, numerical results show that Plinian eruptions at El Boquerón volcano are able to deposit thick tephra layers in the metropolitan area of San Salvador city, likely reaching mass loads of the order of 100 kg/m2 (conditional probability of 50%). The simulated sub-Plinian events highlight the seasonal influence of wind patterns. In fact, the conditional probability of significant tephra sedimentation in San Salvador city is strongly reduced when eruptions occur during the rainy season. Numerical modeling of violent Strombolian eruptions is performed considering uncertainty in vent position. Results show that the conditional probability of depositing tephra mass loads higher than 10 kg/m2 at a given point reaches a maximum value of ∼7% on the NW flank of the volcano, at about 8 km from the central crater. On the other hand, very low conditional probabilities (<1%) are obtained for San Salvador city for any relevant threshold (10 kg/m2 or more) of tephra mass load during violent Strombolian events. Regarding PDCs, results show that those produced during large-scale Plinian eruptions are able to invade significant areas of the volcano surroundings, including San Salvador city. PDCs generated from the partial collapse of a sub-Plinian eruption column exhibit maximum inundation probabilities on the N, W and S flanks of the volcano. Cerro El Picacho exerts a significant shield effect on the propagation of these PDCs, with low inundation probabilities for San Salvador city (<3%). Finally, coupling published vent opening probability maps and numerical modeling of small-scale PDCs yields maximum inundation probabilities on the NW flank of the volcano, reaching maximum conditional probabilities of the order of ∼10% and values of about 5% near the village of Nuevo Sitio del Niño.

Effect of the position and the area of the vent on the hydrogen dispersion in a naturally ventilated cubiod space with one vent on the side wall

The design of ventilation system has implications for the safety of life and property, and the development of regulations and standards in the space with the hydrogen storage equipment. The impact of both the position and the area of a single vent on the dispersion of hydrogen in a cuboid space (with dimensions L x W x H = 2.90 × 0.74 × 1.22 m) is investigated with Computational Fluid Dynamics (CFD) in this study. Nine positions of the vent were compared for the leakage taking place at the floor to understand the gas dispersion. It was shown a cloud of 1% mole fraction has been formed near the ceiling of the space in less than 40 s for different positions of the vent, which can activate hydrogen sensors. The models show that the hydrogen is removed more effectively when the vent is closer to the leakage position in the horizontal direction. The study demonstrates that the vent height of 1.00 m is safer for the particular scenario considered. The area of the vent has little effect on the hydrogen concentration for all vent positions when the area of the vent is less than 0.045 m 2 and the height of the vent is less than 0.61 m. • The coupling effects of the height and the area of the vent on hydrogen diffusion were analyzed. • The average concentration of the local area of the cross-section for different vent positions was compared. • The flow for various vent positions in the horizontal direction was investigated.

Study of Four Passive Second Skin Façade Configurations as a Natural Ventilation System During Winter and Summer

The fight against climate change is a significant challenge, resulting mainly from the linear and extensive exploitation of natural resources, particularly fossil fuels. Its impacts are now recognized. The current climate models are neither sustainable nor ecological in economic and social terms, especially as we live in a century marked by galloping demography and urbanization. Researchers worldwide have paid great attention to passive solar design strategies such as double skin or Second Skin Façade. From this point, the present work aims to contribute to a better understanding of the feasibility of using a passive façade as a useful technology for natural ventilation to achieve potential energy savings and improve thermal comfort and indoor air quality. For this purpose, a parametric study was conducted for a room with four different southern facade configurations in six Moroccan climatic zones; the difference between each lies in the vent's position in the entrance and exit. This process was done by using COMSOL Multiphysics software. Velocity and volume flow rate fields were analyzed. The proposed configurations provided an average volume flow rate between 200 m3/h and 400 m3/h for a surface of 1 m2 of southern façade with an air vent area of 0.1mx0.2m.

Numerical Analysis of Inlet and Outlet Room Air Vent Position for Reaching the Best Ventilation Condition with an Energy Approach

Numerical Analysis of Inlet and Outlet Room Air Vent Position for Reaching the Best Ventilation Condition with an Energy Approach

Controlling virus droplets diffusion in an isolated room using CFD

This paper presents an isolation room model with a patient carrying acute air born disease with an effective ventilation system being functioned. Different models have been simulated with different vent position and the results have been observed. With the unruly rise in the spread of the COVID-19, it is paramount to restrain the virus propagation within the hospital premises. The purpose of the research is to control the virus dissemination caused by sneezing, by altering the position of the ventilation i.e. air inlet and outlet, by using flow across the room to direct it towards the outlet with maintaining a negative pressure. The negative strain helps in confining the air-borne transmission of the deadly virus from spreading across the room and not letting them permeate outside the isolated region. An isolation room model has been studied using computational fluid dynamics, by setting up a discrete phase model by using injection spray modelling to observe the permeation of the virus droplets. The behaviour of these aerosol droplets are studied using simple-semi implicit method for the equation associated with pressure by specifying the droplet size. By altering inlet and outlet locations we are able to minimise the spread of these harmful droplets by using the flow from the air inlet to go against the diffusing droplets. These paper aides well for a sudden isolation room setup anywhere with peruse dimensions of the inlet and outlet height at most optimum position.

Experimental study and numerical simulation of the influence of vent conditions on hydrogen explosion characteristics

ABSTRACT In order to minimize the huge loss caused by hydrogen explosion in confined space, experimental and numerical simulation methods were used to study the effects of the vent position and number on hydrogen/air explosion characteristics in a straight pipe with 7.2 m in the length and 125 mm in the inner diameter. The results showed that the continuous emission effect of the vent can provide an induction effect to the flame propagation before the flame reached the vent and produce a continuous disturbance to the flow field, which increased the flame instability. The vent position has a significant influence on the explosion venting effect. In the experiment, the explosion venting effect was the best when the vent was set near the ignition end. The maximum explosion overpressure and flame propagation velocity were reduced by 21.2 and 26.7%, respectively, compared with the pipe without vent. The explosion venting effect was slightly weak when the vent was in the back of the pipe. The reflected waves caused by the collision between the shock waves and the blind plate promoted the emission effect of the vent. When the vent was set in the middle of the pipe, the flame passed through the vent with a higher speed, which limited the emission effect of the vent and led to the worst explosion venting effect. Multistage pressure relief can effectively reduce the explosion intensity of hydrogen in the pipe. In the experiment, the maximum flame propagation velocity and explosion overpressure gradually decreased with the vent number increasing. When the vent number was three, the maximum explosion overpressure and flame propagation velocity decreased by 47.3 and 68.4%, respectively, compared with the pipe without vent. Therefore, properly increasing the vent number is beneficial to improve the explosion venting effect and ensures the safety of equipment.

Experimental and numerical evaluations on characteristics of vented methane explosion

To research the characteristics of vented explosion of methane-air mixture in the pipeline, coal mine tunnel or other closed space, the experiments and numerical simulations were carried out. In this work, explosion characteristics and flame propagation characteristics of methane in pipeline and coal mine tunnel are studied by using an explosion test system, combined with FLACS software, under different vented conditions. The numerical simulation results of methane explosion are basically consistent with the physical experiment results, which indicates that the numerical simulation for methane explosion is reliable to be applied to the practice. The results show that explosion parameters (pressure, temperature and product concentration) of methane at five volume fractions have the same change trend. Nevertheless, the explosion intension of 10.0% methane is the largest and that of 9.5% methane is relatively weak, followed by 11.0% methane, 8.0% methane and 7.0% methane respectively. Under different vented conditions, the pressure and temperature of methane explosion are the highest in the pipeline without a vent, followed by the pipeline where ignition or vent position is in each end, and those are the lowest in the pipeline with ignition and vent at the same end. There is no significant effect on final product concentration of methane explosion under three vented conditions. For coal mine tunnel, it is indicated that the maximum explosion pressure at the airproof wall in return airway with the branch roadway at 50 m from goaf is significantly decreased while that in intake airway does not change overwhelmingly. In addition, when the branch roadway is longer or its section is larger, the peak pressure of airproof wall reduces slightly.

INFLUENCE OF THE GAS VENT POSITION ON THE INITIAL MOVEMENT OF THE BOLT-CARRIER FOR THE AMPHIBIOUS RIFLES WHEN SHOOTING UNDER WATER

This paper presents a mathematical model to study the effect of the gas vent position on the movement of the bolt-carrier for the amphibious rifles when shooting under water. This mathematical model was applied for the 5.56mm amphibious rifle for different gas vent positions. The result of this research indicates that under the impact of the initial water in the barrel bore and the gas cylinder, the bolt-carrier only moves when the distance between the position of the gas vent and the muzzle is not smaller 171mm.

Numerical Simulation of the Influence of Vent Conditions on Hydrogen Flame Propagation

ABSTRACT In order to reduce the damage caused by a gas explosion in a ventilation duct, a Large Eddy Simulation (LES) model was used to simulate the hydrogen/air explosion process in the ventilation duct under different side vent. The results show that in the process of flame propagation, the large size side vent near the ignition end produces a larger discharge effect, which causes more serious distortion and longer time for the flame front passing through the side vents. The influence mechanism of the side vent on the flame propagation is different at different stages of flame propagation. When the flame front is behind the side vent, the positive flow field traction on the flame front increases the contact area between the flame front and unburned gas, and thus accelerates the flame propagation. When the side vent is 1 m away from the ignition end, with the side vent diameter increasing from 40 mm to 80 mm, the peak flame propagation speed increases by 19.02% before the flame reaches the vent. When the flame front passes through the side vent, the exhaust of the side vent and the disturbance of the vertical flow field can restrain the flame propagation. However, when the flame front is in front of the vent, the synergistic effect between turbulent vortex and reverse flow field causes the flame propagation speed to fluctuate greatly. The influence of the side vent size on the explosion relief effect is restricted by the side vent position. When the side vent is located in the pressure rising section, the pressure relief effect of the side vents with different sizes is very great and is almost unaffected by the size of the side vent. When the side vent is 1 m away from the ignition end, the peak overpressure in the tube decreased by 50.75%, 52.88% and 55.43%, respectively, when the diameter of the side vent was 40 mm, 60 mm and 80 mm. On the contrary, when the side vent is outside the pressure rising section, the pressure relief effect of the side vent will be weakened, and vents with different sizes have a great alteration to pressure relief effect. For the side vent being 5 m from the ignition end, the peak overpressure in the tube decreased by 4.49%, 13.41%, and 35.51%, respectively, when the diameter of the side vent was 40 mm, 60 mm, and 80 mm.

Mould fill time sensitivity analysis using isothermal mould filling simulations for applications in liquid composite moulding processes

Development of effective injection strategy constituting injection gates and air vents to obtain reduced mould fill time without dry spots are the primary requirements to develop mould system for an application using Liquid Composite Moulding (LCM) processes. Recent days, virtual simulation becomes promising tool in comparison to trial and error experiments due to its costing factor and timely iterations. This work demonstrates the possibility of Ansys Fluent commercial simulator to perform porous flow isothermal mould filling simulations and to quantify the sensitivity of mould fill time and flow front progression with respect to variations in process and raw material parameters. A rectangular mould of dimension 1 m × 0.5 m with an injection strategy of single point gate with 10 mm diameter and single point air vent of diameter 10 mm was used as a domain for isothermal mould filling. The sensitivity of mould fill time and flow front pattern were evaluated by varying inlet velocity, resin viscosity and orthotropic reinforcement mat permeability. From the results, it was found that the mould fill time decreases with increasing velocity, lesser viscosities and more porous preforms. Also, in all case studies, the mould fill pattern ends at the air vent position ensuring there are no dry spots formed.