Air Intake Research Articles

Energy efficiency of life support systems of buildings in «green construction»

Purpose: develop an integrated air conditioning system with the environment, which will allow to reduce energy consumption due to lowering the temperature of air taken from outside from natural or artificial green areas. Methods: the basis of the solution to the task of developing an integrated system was the use of three well-known methods of greening of home territories: traditional, non-traditional and container. Because green spaces, in the warm period of the year, allow you to naturally reduce the parameters of the outside air, which are used for the needs of the building's ventilation and air conditioning systems. Findings: due to the complex use of all types of landscaping, it is possible to reduce the energy consumption for work of ventilation and air conditioning systems by reducing the temperature of air taken from the outside from natural or artificial green areas. Due to this, when developing integrated air conditioning systems, we can achieve: a decrease in the temperature of the supply air from the landscaping area, which will reduce not only the energy costs for cooling and humidification, but also the reduction of pollution of the supply air; when using trees and shrubs of certain breeds, which emit phytoncides and other beneficial secretions, in the outdoor air intake area, it will improve the quality of incoming air. Practical implication: the developed integrated air conditioning system with the environment will allow to reduce the influence of the outside air temperature on the indoor air temperature due to the integrated use of all types of greening. Originality: a review of literary sources showed that today the possibility of taking outside air from existing or artificially created green areas is not used in the design of ventilation and air conditioning systems.

The intake port of DI-engine type VIKYNO RV165 desinged using 3D-CAE software

The intake manifold profile in a marine diesel engine profoundly influences engine intake performance, which, in turn, significantly impacts the engine's power characteristics and exhaust emissions which leading to marine polution and challenging the marine sustainable development. Improving the performance of the appropriate geometric design of the intake manifold in order to optimize the study time is a key basis. This research aims to build a parametric model for the 3D profile of the VIKYNO RV165-2 engine intake line. By changing the value of parameter variables in the model through SolidWorks software, it is able to design and change the 3D profile design of the intake manifold. The 3D model of the intake line will be parameterized based on the 2D design drawings of this part provided by VIKYNO. The parameter variables used are upper inclination, lower inclination, curvature, intake valve diameter, input cross-section. Many different 3D models of intakes will be created with respect to the values of parameter variables changed by using SolidWorks software. The results of the study provided a parametric model for the 3D profile of the intake tract, linking the parametric variables of the model with Solidwork software as a basis for speeding up this detailed 3D design process. The 3D design of the intake by the parametric model compared to the 3D design of the intake manifold by direct rendering from the 2D drawing has a difference of no more than 2% in volume. This adaptability and precision are crucial for ensuring air intake efficiency for marine engines operating in diverse and challenging marine conditions.From the platform model, the change of input variables is displayed quickly on new designs, in accordance with the standard, and thereby the model is selected for the stage of researching the efficiency of air intake on the engine. Keywords: CAE, Diesel engine, intake port geometry, numerical design.

Flow Analyses of Integrated Liquid Fuel RAMJET Propulsion System

A CFD study is performed to check the seamless flow behaviour of the Liquid Fuel Ramjet Propulsion system which includes, air intakes, combustor and nozzle. Resolving both supersonic and subsonic flow scales in the same domain makes the simulations complex. Addition of combustion with stiff chemistry makes the simulations more difficult. CFD simulations are carried out using commercially available CFD software. Liquid fuel is injected as discrete phase and the flow turbulence is modelled using Realizable k-ε turbulence model. Jet-A + air combustion has been simulated using combined finite rate / eddy dissipation model. Finite rate chemistry was modelled using three step chemistry which was obtained from the published literature. Flow structures such as oblique shocks, normal shocks and combustion are observed.

Simulation Analysis of Electromagnetic Environment Effect and Shielding Effectiveness for VPX Chassis under Plane Wave Radiation

The chassis based on the VPX bus standard structure has been widely applied to the fields of vehicle, missile, radar, etc. In this paper, we analyze the electromagnetic environment effect on VPX chassis via the CST software, and investigate the electromagnetic coupling characteristics of VPX chassis under 20 v/m plane wave radiation according to the RS103 test defined in the MIL-STD-461G standard. By simulation, we analyze the electromagnetic coupling paths of the VPX chassis, find the key positions of the electromagnetic protection such as the air intake, air outlet, trapdoor, and panel gaps, and we propose the electromagnetic protective measures for the weak parts of the VPX chassis. The electromagnetic shielding effectiveness before and after protection design is evaluated. Finally, the simulation results are verified by the experiments. It has guiding significance for the electromagnetic protection design of VPX chassis.

Bird strike tests, analyses, and design optimisation of a tilt-rotor aircraft composite inlet

Collisions of aircraft with foreign objects are very common phenomena, so they must be anticipated, and their consequences must be individually checked. Since these incidents can result in severe engine damage and the engine is the aircraft's only thrust-providing system, the effect of bird strikes on engine air intakes and similar systems must be investigated and mitigated with special attention. Principally for tilt-rotor convertible aircraft, this effect is crucial in terms of operational safety, flight mechanics and overall aircraft control. The objective of this work is to demonstrate the durability of the composite air intake for a new tilt-rotor aircraft, which is experimentally verified on components of basic geometric shapes such as plate and cylindrical section. Based on computer-supported simulations, which are correlated with the basic tests, the consequences of the impact on the real air-duct were analysed and potentially dangerous regions were found. Sizing and optimisation was carried out and a design improvement proposal was developed.

The influence of ventilation on airborne transmission between stacking toilets

Multiple COVID-19 outbreaks in high-rise residential buildings have been linked to the vertical spread of the virus along the building. This study aimed to provide empirical evidence and experimental results to evaluate the effects of toilet ventilation on the spread of bathroom aerosols in high-rise residential buildings. This study explored potential transmission pathways by conducting tracer gas experiments in a full-scale mock-up toilet facility and identified effective strategies to minimize tracer gas surge and overall exposure. A novel IoT-enabled tracer gas sensing network was used to evaluate tracer gas dispersion from a lower-floor toilet to an upper-floor toilet and the roof under 32 different ventilation conditions of windows, exhaust fans, and forward-facing wind. The findings confirmed the potential for vertical airborne transmission through toilet ventilation and suggested effective ventilation strategies for forward-facing wind and no-wind conditions. This study provided novel experimental results on vertical aerosol transmission, contributing to further analysis and validation in this field. Appropriate ventilation measures were also discussed to ensure clean, virus-free air intake, reducing the risk of airborne cross-infection via the vertical transmission pathway.

A study of swirl flow measurements in a cylinder under an intake flow similar to an engine operating condition using a rotating slit disk valve

A new swirl measurement system was developed by installing bevel gears and a slit rotary valve into an impulse- type swirl measurement system of the type traditionally used to measure the swirl ratio and flow coefficient of engine intake ports. When operating this new swirl measurement system, it was confirmed that the characteristics of the intake air flow rate to the cylinders were similar to those of a typical operating engine condition. When the valve lift was limited to the cam angle range of 160 to 200 (the valve lift is maximized at a cam angle of 180°), the flow coefficient Cf increased as the cam angle increased under a constant camshaft rotation speed. Moreover, as the rotation speed of the camshaft increased, the Cf value decreased slightly. The swirl ratio NR in the cam angle range of 160 to 200 showed a nearly constant value with an increase of the cam angle at a constant camshaft rotation speed. There were also no significant changes in Cf with an increase in the camshaft rotation speed. NR measurement results while changing the camshaft rotation speed cannot be obtained by the traditional impulse swirl measurement method. NR measurement results with the new swirl measurement system can be used as basic data when calculating spray dispersion characteristics considering the engine rotation speed.

Numerical investigation of gas emission and extraction under the action of coal-oxygen recombination in longwall gobs

The emission and migration of gas in the longwall gobs are closely linked to the temperature field formed by the oxidation and exothermic behavior of coal. This work conducted gas adsorption and desorption experiments on coal particles and obtained the relationship between gas desorption rate and temperature. Additionally, the coupling relationship between multi-physical fields, including the air flow, gas and oxygen concentration, air and solid temperature has been improved. On this basis, a coupled model for gas and coal spontaneous combustion was constructed. The distribution characteristics of the gas concentration field and solid temperature field before and after extraction in gob were simulated. The optimal extraction point position was determined at 38 m from the working face, 25 m on the return air side, and a height of 11 m with an extraction negative pressure of −6 kPa. The results show that: The gas desorption rate exhibits an exponential relationship with temperature, and the coefficient and exponential factor in the exponential equation are AT and BT. The gas concentration in the gob and upper corner before extraction is high, and there is also a high-temperature area on the air intake side. After extraction, the gas concentration in the upper corner decreased from 2.94% to 0.366%, which is lower than the critical value of 0.8%. At the meanwhile, the maximum temperature only increased by 3.36 °C. Based on the field's verification, the monitoring value of gas concentration in the upper corner is 0.253%, which reduces the danger of gas in the upper corner while controlling the heating of residual coal. This work can provide basic support for the prevention and control of gas disasters in gobs.

Long-term assessment of energy consumption reduction in a building ventilation system with passive particulate matter control technology in the fresh air intake

A particulate matter (PM) control device known as aspiration efficiency reducer (AER) has been developed as an attachment to the fresh air intake in building ventilation systems to reduce building energy consumption and improve the fresh air intake’s quality. Ambient particle laden air is drawn into the fresh air inlet of a mechanically ventilated building via the air handling unit (AHU). The ventilation system particle filters become loaded and clogged with PM, increasing the load on the fan’s motor. Three novel AER devices were tested against an AHU inlet rainhood, and their long-term energy performance assessed. Furthermore, an AER attached to an AHU incorporating single-stage filtration (SSF) was compared against an AHU fitted with rainhoods employing two-stage filtration (TSF). The findings showed AER technology resulted in a 6.6–11.4 % reduction in the AHU’s energy consumption. Finally, the impact of the AER with SSF compared to a rainhood with TSF led to a lowering of the system pressure throughout the entire testing period, reduced filter and labour costs resulting in a 36.5 % reduction in the total costs. AER technology and a ventilation filtration system design tailored to the local environment will result in lower building energy consumption and CO2 emissions.

Signal Compensation Control With DDPG-Based Tuning Strategy for Electronic Throttle System

The electronic throttle system (ETS) is one of the important components of an automobile engine that adjust the engine air intake to directly affect the combustion power of the engine. In practical scenarios, Proportional-Integral-Derivative (PID) is a common and effective method. However, the traditional PID is difficult to satisfy the ETS performance requirements, e.g., the system response overshoot is not allowed to exist. Moreover, the controller gains are also difficult to tune manually. To tackle the above-mentioned issues, we propose a signal compensation control framework with an adaptive gain tuning strategy for the electronic throttle system, which consists of an upper-level to tune controller gains and a lower-level signal compensation controller to eliminate the nonlinear terms. The main feature of the signal compensation controller relies on two nonlinear compensators to remove the strong nonlinearity and uncertainty in the actual throttle system. Furthermore, we develop an adaptive gain tunning strategy based on Deep Deterministic Policy Gradient (DDPG) algorithm, and we analyze the corresponding stability and convergence properties of the proposed method. Finally, we illustrate the proposed algorithm on benchmarks and the tracking control problem using the real-world experiment platform of the ETS to show the effectiveness of the proposed algorithm.

Study on the Modified Ventilation Network on the Ventilation Effect and Ozone Migration Characteristics in Grain Pile

Grain is an important material for human survival. However, the expanding world population is contributing to a growing grain shortage. In order to reduce the loss of grain due to pests and mold during storage, mechanical ventilation as the main method of ventilation has crucial research significance. This article proposed and analyzed the ventilation effect and the migration characteristics of ozone in the grain pile under the modified ventilation network (MVN) and compared it with the original ventilation network (OVN). The study found that the temperature, moisture, and ozone concentration in the grain pile of the two ventilation networks are not evenly distributed in the vertical direction, showing a layered pattern. That is, with an increase in grain stack height, the temperature and moisture content of the grain stack are higher, and the ozone concentration is lower. Moreover, in the pre-ventilation period, the average temperature decline rate of the MVN was 1.25 °C/d, which was better than that of the OVN (0.84 °C/d), and the maximum temperature difference between the MVN and the OVN was 0.89 °C. The vertical ducts added to the MVN improved the ventilation effect, maintaining high ozone concentrations within the grain pile. Notably, on the sixth day of fumigation, the average ozone concentration of the MVN exceeded that of the OVN. The MVN can solve the shortcomings of the OVN, where air intake and fumigation gas rise slowly in the vertical direction. These findings hold substantial significance for optimizing ventilation network structures, devising effective fumigation strategies, and enhancing the insecticidal effects of grain storage.

Experiment for the performance of a thin membrane inclined automatic wicking dew-point evaporative cooling device based on simulation results

The traditional indirect evaporative coolers necessitate a continuous operation of water pumps to ensure the wetting of wet channel walls. However, excessive water spraying can lead to a thickened water film, negatively impacting heat transfer efficiency and generating an additional pressure drop. Identifying suitable water supply strategies and exploring materials for the wet channel that possess good moisture retention and evaporation characteristics has drawn research attention over the years.In this study, an automatic wicking dew-point evaporative cooling device, whose structure was determined by corresponding optimal performance simulation research, was designed and manufactured. The thin film exhibits a certain inclination angle between the dry and wet channels to form a triangular channel to enhance support and increase heat transfer area. Utilizing the automatic water absorption characteristics of the membrane for water supply instead of spraying, makes the water more uniform and heat exchange more efficient. A comprehensive study was conducted on the effects of different operating parameters (working-to-intake air ratio, intake air velocity, water temperature, intake air temperature, and intake air humidity) on the performance of the device. The results indicate that the cooler performs best in high-temperature, low-humidity environments. When the inlet temperature, humidity, and velocity are within the range of 25–45 °C, 20–80 %, and 0.5–2.5 m/s, respectively, with a water temperature of 22 °C and an air-to-water flow rate ratio of 0.5, the maximum temperature drop can reach 14.8 °C, and the cooling capacity per unit area ranges from 13 to 150 W/m2. The wet-bulb efficiency and dew-point efficiency increased from 52.4 % and 33.6 % to 110.6 % and 88.5 %, respectively. When the air velocity increases from 0.5 m/s to 2.5 m/s, the product air temperature increases by 3.1 °C, and the wet-bulb efficiency and dew-point efficiency decrease by 25.1 % and 17.5 %, respectively. However, the variation trends of unit area cooling capacity and energy efficiency ratio (EER) are opposite. The optimal operating conditions are proposed with an air volume ratio of 0.5 and a water temperature range of 22–26 °C. Finally, the temperatures of the product air and water were observed during long-term operation testing to evaluate the stability of the device.

Experimental study of materials for the filtration of the intake air of the internal combustion engine of a motor vehicle

Experimental evaluation of the properties of filter materials in the selection of material for filtration of inlet air of internal combustion engines was carried out. The filtration characteristics were determined: filtration efficiency and accuracy, as well as flow resistance depending on the dust mass load. Filter materials based on cellulose, polyester, microfiber glass, and cotton and polyester nonwoven beds were studied. Two filter beds consisting of three base filter materials were designed: composite K1 (polyester-microglass-cellulose) and composite K2 (cellulose-microglass-cellulose), and their characteristics were performed. The air filtration quality factor was used to analyze the test results. The coefficient of filtration efficiency was defined, showing the effect of the preliminary stage on the total time of the filtration process. It was shown that the K1 composite has high (dpmax = 1.5÷3 µm) filtration accuracy, high initial filtration efficiency (99.8%), which shortens the pre-stage, and extends to 96-98% the duration of the main stage of the filtration process. The K1 composite obtained more than twice the mass loading of dust (kdK1 = 148,9 g/m2), which will allow the vehicle's mileage to be extended.

Analysis of internal flow characteristics of squirrel-cage fan with multi-directional air intake impeller

The separate flow in the inlet region of the squirrel-cage fan, caused by airflow steering, hinders the further improvement of internal flow state and aerodynamic performance. This study proposes a multi-directional air intake design of the impeller to solve this problem. Specifically, a new parameter known as D* is introduced in this study to represent the axial air intake parameter of the impeller. Subsequently, the key parameters of the multi-directional air intake impeller (D*, entrance blade angle, exit blade angle) are optimally designed using an orthogonal experimental and CFD numerical simulation. These results are further validated through experimentation, demonstrating that a well-designed multi-directional air intake impeller can increase the fan's air volume, total pressure, and total efficiency by 27.3%, 12.6%, and 5.2%, respectively. Furthermore, it has been observed that the inclusion of an axial air intake in the impeller diminishes the impact of the entrance blade angle on fan efficiency. When evaluating different-sized models, the influence of the axial dimensionless parameter D* on the fan total efficiency shows a consistent pattern, which is worth noting that the efficiency does not necessarily increase with increasing values of D*, but rather the fan efficiency peaks when D* is approximately 0.5. The analysis of the flow field and entropy generation inside the fan reveal that the design can weaken the separation vortex at the inlet and shift the position of vortex core towards the impeller's leading edge, so as to eclectically enhance the uniformity of the impeller inlet and outlet, ultimately optimizing the aerodynamic characteristics within the fan. This study presents a novel approach to controlling the inlet separation flow of a squirrel-cage fan and provides a reference to elucidate the mechanism of internal flow evolution with the multi-directional air intake impeller.

Numerical Study of the Features of the Propagation of Acoustic Disturbances in an Unregulated Supersonic Air Intake

Numerical Study of the Features of the Propagation of Acoustic Disturbances in an Unregulated Supersonic Air Intake

Temperature-pressure interaction analysis of altitude ground test facility’s air intake system in negative temperature simulation

Temperature-pressure interaction analysis of altitude ground test facility’s air intake system in negative temperature simulation

CFD simulation of double-pass solar dryer with air return

An indirect solar dryer was designed and manufactured in Yamoussoukro, Côte d’Ivoire. It is equipped with three parameters including two air intake ports, a fan and a removable hot air recovery system. Vacuum CFD simulations were performed in order to observe the influence of these parameters on the effectiveness of the device. The fan switched off speeds of 9 m/s and made the air distribution uniform in the drying cabin. The natural convection operation made it possible to reach 62°C in the drying chamber compared to 55°C for the forced convection operation. The unique opening of the low air intake port in operation accentuates the temperature variations in the cabin compartments with differences of + 5°C from one level to another. The hot air return system has a positive impact on temperature trends because it allows values of 65°C to be reached inside the chamber, ideal for drying agri-food products. However, this recovery reduces the air velocity in the cabin, which is a disadvantage for the performance during products. This problem could be solved by increasing the fan power.

Study of the Vortex-Resolving Method of the Throttling Effect on Pressure Pulsation Spectra in a Paired Supersonic Air Intake

Study of the Vortex-Resolving Method of the Throttling Effect on Pressure Pulsation Spectra in a Paired Supersonic Air Intake

Analysis of abnormal operation of condenser water chamber evacuation system in nuclear power plants

During the operation of a nuclear power plant, there was no level indication in some of the condenser outlet water chamber, the level of the vacuum control tank upstream of the water chamber evacuation pump was rising frequently and unintentionally. To find out the causes of the above phenomena, a phenomenological analysis was first carried out. The cause analysis is then carried out in conjunction with the internal pressure of the condenser, the calculation of the air volume inside the condenser water chamber, and the flow pattern of the medium inside the water chamber evacuation pipeline. The final analysis concludes that a low junction point between the inlet water chamber's evacuation pipeline and the outlet can lead to the formation of an airlock at the top of the condenser's outlet water chamber. When there is a leak in the evacuation pipeline of the condenser's outlet water chamber, the increased air intake, in conjunction with gas-liquid two-phase flow, causes the liquid level in the vacuum control tank to rise unexpectedly and frequently. Thus, the factor of higher pressure at the inlet water chamber evacuation point and the influence of gas-liquid two-phase flow pattern should be taken into account when designing the evacuation pipeline.

Optimization and experimental validation of the air intake holes of the lithium-ion battery pack

Energy storage systems enable the storage of energy and provide access to carbon-neutral, environmentally friendly energy whenever or wherever it is needed. Lithium-ion batteries are currently the most preferred type among various battery technologies and are widely used in energy storage systems. Some of the features that make lithium-ion batteries advantageous include high energy density, long life, low maintenance requirements, and high operating voltage. The growing demand for energy throughout the day increases the need for batteries with high storage capacity. However, the increased capacity also leads to heating issues in lithium-ion batteries. The heating problem in lithium-ion batteries can result in nonhomogeneous temperature distribution, shortened lifespan, thermal runaway, increased internal resistance, and performance loss. Therefore, an effective thermal management system is essential for cooling lithium-ion batteries. This study aims to provide insight into the forced air cooling of prismatic 280 Ah LiFePo4 batteries, which have limited information in the literature and are more prone to overheating compared to lower-capacity batteries. In this study, five different battery pack case designs, each with different sizes and numbers of air intake holes, were determined and modelled using the SolidWorks program. Within the battery pack cases, 16 280 Ah lithium-ion batteries are placed, and an axial fan is used to cool these batteries. Initially, computational fluid dynamics analyses of the five different designs were performed in the SolidWorks Flow Simulation program. An experiment was then conducted on the design that provided the most efficient thermal management to validate the numerical results. The selected design, fulfilling the purpose of homogeneous temperature distribution and having the minimum temperature difference between batteries, was designated as Design 5. It exhibited a 62 % improvement in cooling performance with a 0.25 °C temperature difference, indicating successful temperature homogeneity between batteries. During a two-hour experiment with a 140 A discharge current, temperature measurements were taken from the surfaces of the batteries using thermocouples. Finally, the maximum error rate between experimental and numerical studies was determined to be 1.47 %, indicating successful validation of the numerical study. The air intake hole optimization, a novel design approach, prevents temperature distribution inhomogeneity caused by the distance of the batteries to the fan and offers an effective way to cool down high-capacity 280 Ah batteries.