scholarly journals Experimental and Numerical Studies of Air Curtains for Falling Particle Receivers

2014 ◽  
Author(s):  
Clifford K. Ho ◽  
Joshua M. Christian ◽  
Adam C. Moya ◽  
Josh Taylor ◽  
Daniel Ray ◽  
...  
Keyword(s):  
Convective Heat ◽  
Flow Rate ◽  
Experimental Studies ◽  
Flow Characteristics ◽  
Heat Losses ◽  
Air Curtain ◽  
Hot Air ◽  
Numerical Studies ◽  
Release Location ◽  
The Impact

The use of an air curtain blowing across the aperture of a falling-particle receiver has been proposed to mitigate convective heat losses and to protect the flow of particles from external winds. This paper presents experimental and numerical studies that evaluate the impact of an air curtain on the performance of a falling particle receiver. Unheated experimental studies were performed to evaluate the impact of various factors (particle size, particle mass flow rate, particle release location, air-curtain flow rate, and external wind) on particle flow, stability, and loss through the aperture. Numerical simulations were performed to evaluate the impact of an air curtain on the thermal efficiency of a falling particle receiver at different operating temperatures. Results showed that the air curtain reduced particle loss when particles were released near the aperture in the presence of external wind, but the presence of the air curtain did not generally improve the flow characteristics and loss of the particles for other scenarios. Numerical results showed that the presence of an air curtain could reduce the convective heat losses, but only at higher temperatures (>600°C) when buoyant hot air leaving the aperture was significant.

scholarly journals Falling weight impact test of a new-type flexible rock-shed

2018 ◽  
Vol 38 (2) ◽  
pp. 242-252
Author(s):  
Jianrong Yang ◽  
Zhiyu Zhang
Keyword(s):  
Experimental Studies ◽  
Steel Tube ◽  
Time Interval ◽  
Explicit Finite Element ◽  
Numerical Studies ◽  
Structural Details ◽  
Tensile Forces ◽  
New Type ◽  
Falling Weight ◽  
The Impact

A new concept of a flexible rock-shed is presented for protection of the railway from falling rocks. The flexible rock-shed is made of flexible nets connected by specific spring spacer bars to an array of reinforced concrete portable frames which are linked by a longitudinal steel tube truss. To evaluate the performance of the flexible rock-shed, experimental and numerical studies are carried out in the present study. Impact tests are conducted on a full-scale partial model of the prototype structure when it is subjected to a falling block of 340 kg. The impact time interval, maximum deflection of the flexible net, tensile forces in the supporting ropes, and axial strains of spring spacer bars are recorded. To further examine the dynamic behavior of the flexible rock-shed, numerical simulations are also carried out by using the explicit finite element code ANSYS/LS-DYNA. It is found that the numerical results coincide well with the experimental data and both the numerical and experimental studies reveal that the structure can withstand impact energy of 50 kJ with all the materials working in the elastic range. The structural details are improved and the basis for the design and construction of similar structures in the future is provided.<br>

scholarly journals Reducing convective heat losses in solar dish cavity receivers through a modified air-curtain system

Solar Energy ◽  
2018 ◽  
Vol 166 ◽  
pp. 50-58 ◽  
Author(s):  
Song Yang ◽  
Jun Wang ◽  
Peter D. Lund ◽  
Siyu Wang ◽  
Chuan Jiang
Keyword(s):  
Convective Heat ◽  
Heat Losses ◽  
Air Curtain

Experimental Studies on Energy and Exergy Analysis of a Single-Pass Parallel Flow Solar Air Heater

2019 ◽  
Vol 142 (1) ◽  
Author(s):  
G. Raam Dheep ◽  
A. Sreekumar
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Air Temperature ◽  
Flow Rate ◽  
Temperature Difference ◽  
Air Flow ◽  
Experimental Studies ◽  
Solar Air Heater ◽  
Energy And Exergy

Solar air heaters (SAHs) are the simplest form of nonconcentrating thermal collectors. SAHs utilize solar thermal energy to increase the temperature of air for thermal applications of less than 80 °C. The energy efficiency of SAHs is significantly low due to poor convective heat transfer between the absorber and the air medium. In this present study, it is aimed to increase the convective heat transfer by modifying the absorber and the type of air flow inside the duct. Experimental studies were performed to study about the energy and exergy efficiencies of SAH with the absorber of longitudinal circular fins. The thermal analysis of the SAH is evaluated for five mass flow rates of 30, 45, 60, 75, and 90 kg/h m2 flowing inside the duct of thickness 100 mm. The impact of the flow rate on the absorber and air temperature, temperature difference (ΔT), energy and exergy efficiencies, irreversibility, improvement potential, sustainability, and CO2 reduction potential is studied. The experimental results show that the first and second laws of thermodynamic efficiency increase from 44.13% to 56.98% and from 24.98% to 36.62% by increasing the flow rate from 30 to 90 kg/h m2. The results conclude that the air flow duration inside the duct plays an important role in efficiency of the solar air heater. Therefore, lower flow rate is preferred to achieve maximum outlet air temperature and temperature difference.

Odour assessment: determining the optimum temperature and time for Tedlar sampling bag pre-conditioning

2012 ◽  
Vol 66 (8) ◽  
pp. 1806-1811 ◽  
Author(s):  
A. H. Bokowa
Keyword(s):  
Wastewater Treatment ◽  
Flow Rate ◽  
Wastewater Treatment Plants ◽  
Experimental Studies ◽  
Cleaning Process ◽  
Optimum Temperature ◽  
Air Flow Rate ◽  
Volatile Organic ◽  
Temperature Controlled ◽  
The Impact

Odours present in new Tedlar bags can impact the assessment of emissions from sewer collection systems and wastewater treatment plants. Conditioning protocols are needed to minimise the impact of background materials emissions on the sampling and assessment of odourous emissions. Olfactometry analysis has shown that background odour concentrations for new Tedlar bags can be as high as 130 OUE/m3. Experimental studies were undertaken to investigate the impact of different conditioning temperatures in order to determine the optimum temperature for cleaning new Tedlar bags to a level when no detectable odours were present in the sampling bags via dilution olfactometry. For the purpose of this study, new Tedlar bags were cleaned in a temperature-controlled oven that had a constant filtered air flow-rate. From the analysis of odour and volatile organic compounds (VOCs) concentrations found in new Tedlar bags during the cleaning process, it was observed that odour and VOCs concentrations decreased with time. It was also found that the temperature setting plays a significant role in the cleaning of the Tedlar bags as large concentrations of phenols and acetamide, N,N-dimethyl were found in new Tedlar bags and their concentrations decreased following the temperature pre-conditioning.

scholarly journals The Two-Phase Conical Swirl Atomizers: Spray Characteristics

Energies ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 3416 ◽  
Author(s):  
Marek Ochowiak ◽  
Andżelika Krupińska ◽  
Sylwia Włodarczak ◽  
Magdalena Matuszak ◽  
Małgorzata Markowska ◽  
...  
Keyword(s):  
Flow Rate ◽  
Discharge Coefficient ◽  
Experimental Studies ◽  
Central Area ◽  
Spray Angle ◽  
Sauter Mean Diameter ◽  
Spray Characteristics ◽  
Two Phase ◽  
Mean Diameter ◽  
The Impact

This paper presents the results of experimental studies on two-phase conical swirl atomizers. The impact of various atomizer geometries and different operational parameters of the atomization process on the spray characteristics was investigated. The influence of the mixing chamber height HS to diameter DS ratio and the volumetric flow rates of liquid and gas on the discharge coefficient values, spray angle, droplet size expressed by Sauter mean diameter D32, volumetric and radial distributions of droplet diameters in the spray stream were determined. The analysis of results showed that the discharge coefficient values depend on the Reynolds number for liquid and gas and the atomizer geometry. The spray angle increases as the flow rate of liquid and gas increases depending on the applied atomizer construction. The Sauter mean diameter value is correlated with the geometric dimensions of the atomizer swirl chamber. The rapid increase in D32 occurs after exceeding the value HS/DS ≈ 3. The Sauter mean diameter also depends on the operating parameters. A central area of stream is filled with smaller sized droplets as the gas flow rate increases.

Investigation of Engine Distortion Interaction

2016 ◽  
Author(s):  
Fabian Wartzek ◽  
Heinz-Peter Schiffer ◽  
Jakob P. Haug ◽  
Reinhard Niehuis ◽  
Martin Bitter ◽  
...  
Keyword(s):  
Numerical Models ◽  
Experimental Studies ◽  
Stability Limit ◽  
Analytical Models ◽  
Test Case ◽  
Transonic Compressor ◽  
Numerical Studies ◽  
Small Distortion ◽  
The Stability ◽  
The Impact

Inflow distortions in the compression system of a jet engine are becoming increasingly important for research focus. The investigation of the emergence of a distortion, its interaction with the rotor and the resulting impact on the rotor flow is challenging. In this work a separation in the inflow of a transonic compressor was created and the impact on stage aerodynamics investigated. The separation resulted in a total pressure distortion close to the casing within a sector of 120°. Effects were studied both numerically and experimentally in a joint collaboration project. The numerical model consisted of the full rotor-stator compressor stage, the inlet duct and the distortion generator upstream of the stage. This enables both an accurate validation of the numerical results and contributes to a deeper understanding of the flow. The results of both the numerical and experimental studies were in good agreement. The rotor is locally throttled by the inlet separation, resulting in the formation of an additional loss core at the stability limit due to a local aerodynamic overload. Considering classic distortion descriptors like the DC60, it is shown that they are not able to adequately assess the impact of a strong, but small distortion close to the tip of the rotor. The data can be considered as test case for future numerical models as well as for the validation of new analytical models. Furthermore, the results of this study reveal effects in both experimental and numerical studies that would not be realized if only a model of the separation was analyzed.

scholarly journals Modeling of a Railway Sanding System Using Vibration Fluidization

2021 ◽  
Vol 346 ◽  
pp. 03059
Author(s):  
Y.P. Bulavin ◽  
P.Y. Konovalov
Keyword(s):  
Flow Rate ◽  
Linear Dependence ◽  
Experimental Studies ◽  
Rolling Stock ◽  
Feeding System ◽  
Vibration Impact ◽  
Sand Flow ◽  
Membrane Vibrations ◽  
The Impact

The model of the sand distributor of the sand feeding system of traction rolling stock, the operation of which is based on the effect of vibration fluidization of sand, has been considered. A pneumatic pulsator was used as a source of vibration impact. Experimental studies have shown that this design allows for a continuous regulated supply of sand. The power of the sand distributor membrane vibrations at the disturbing frequency can be used as a criterion characterizing the impact of the pulsator on the sand. There is a close to linear dependence of the sand flow rate on the power of vibrations.

scholarly journals Analysis of the possibility of using high-speed pneumatic directional valves to regulate the flow of compressed air

2019 ◽  
Vol 213 ◽  
pp. 02084
Author(s):  
Jakub Takosoglu
Keyword(s):  
Flow Rate ◽  
High Speed ◽  
Flow Characteristic ◽  
Position Control ◽  
Experimental Studies ◽  
Flow Characteristics ◽  
Control Signal ◽  
Compressed Air ◽  
Flow Parameters ◽  
Proportional Flow

Most often, proportional flow valves or flow servovalves are used for position control of pneumatic drives. In case of this type of valves, flow characteristic of the valve represents a dependence of flow rate upon analogue control signal (voltage or current). The paper presents experimental studies of two high-speed pneumatic 3/2 directional valves (3-way 2-position) in order to determine the flow characteristics and flow parameters. One has analysed the option to use the directional valves to control the flow rate of compressed air using frequency-based signals.

scholarly journals The Research of the Suitability of Hydrostatic Water Level Sensor to Measure Storm Water Runoff Flow Rate with the Focus on the Influence of Sediments

2017 ◽  
pp. 336-344
Author(s):  
Vilmantė Karlavičienė ◽  
Raimondas Zaborovskis ◽  
Vaidas Vinciūnas ◽  
Mindaugas Rimeika
Keyword(s):  
Water Level ◽  
Flow Rate ◽  
Urban Areas ◽  
Experimental Studies ◽  
Storm Water ◽  
Water Runoff ◽  
Storm Water Runoff ◽  
Accuracy Of Measurements ◽  
Level Sensor ◽  
The Impact

Since most of the contaminants in surface waters fall with storm water runoff, it is very important to correctly describe the content of pollutants discharging with them (kilograms or tons) for a given unit of time (hour, shift, day, month or year). Measurements are complicated by the fact that the flow rate and pollutant concentration is very variable over time. The aim of the research was to determine the grain size of sweepings accumulated on the surfaces of the researched territory and to investigate the impact of storm water runoff sediments on the accuracy of measurements of water level height using the hydrostatic water level sensor. For the experiment four typical Vilnius city streets, two storm water runoff treatment plants and also the streets sweeping machine was chosen. Storm water runoff in urban areas has an abundance of sediment, therefore, studying the hydrostatic water level sensor DI 240 Diver suitability to determine storm water runoff flow rate, for the experimental studies the impact of sludge and sand for measuring accuracy was chosen. Particles with diameters ranging from 0.315 to 0.630 mm consisting the maximum weight (the average value of 24 g per 100 g of the sample) of street sweepings. Storm water runoff treatment plants sediments are approximately 60% of the smallest particles with a size of less than 0.05 mm. Particles of less than 0.25 mm consisting about 80% of sediment. During laboratory and full scale tests it was determined, that there is no significant affect of sediments on the accuracy of the hydrostatic water level sensor measurements. The average square error (standard deviation) was 0.567 cm when the measurement uncertainty was 0.0021 cm.

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