Two-axis solar tracking accomplished through small lateral translations.
Hallas, Justin M; Baker, Katherine A; Karp, Jason H; Tremblay, Eric J; Ford, Joseph E
2012-09-01
High-concentration solar-power optics require precise two-axis tracking. The planar micro-optic solar concentrator uses a lenslet array over a planar waveguide with small reflective facets at the focal point of each lenslet to couple incident light into the waveguide. The concentrator can use conventional tracking, tilting the entire assembly, but the system geometry also allows tracking by small lateral translation of the lenslet relative to the waveguide. Here, we experimentally demonstrate such microtracking with the existing concentrator optics and present optimized optical designs for systems with higher efficiency and angle range.
Efficiency of liquid flat-plate solar energy collector with solar tracking system
Directory of Open Access Journals (Sweden)
Chekerovska Marija
2015-01-01
Full Text Available An extensive testing programme is performed on a solar collector experimental set-up, installed on a location in Shtip (Republic of Macedonia, latitude 41º 45’ and longitude 22º 12’, in order to investigate the effect of the sun tracking system implementation on the collector efficiency. The set-up consists of two flat plate solar collectors, one with a fixed surface tilted at 30о towards the South, and the other one equipped with dual-axis rotation system. The study includes development of a 3-D mathematical model of the collectors system and a numerical simulation programme, based on the computational fluid dynamics (CFD approach. The main aim of the mathematical modelling is to provide information on conduction, convection and radiation heat transfer, so as to simulate the heat transfer performances and the energy capture capabilities of the fixed and moving collectors in various operating modes. The feasibility of the proposed method was confirmed by experimental verification, showing significant increase of the daily energy capture by the moving collector, compared to the immobile collector unit. The comparative analysis demonstrates a good agreement between the experimental and numerically predicted results at different running conditions, which is a proof that the presented CFD modelling approach can be used for further investigations of different solar collectors configurations and flow schemes.
A Two-Axis Goniometric Sensor for Tracking Finger Motion.
Wang, Lefan; Meydan, Turgut; Williams, Paul Ieuan
2017-04-05
The study of finger kinematics has developed into an important research area. Various hand tracking systems are currently available; however, they all have limited functionality. Generally, the most commonly adopted sensors are limited to measurements with one degree of freedom, i.e., flexion/extension of fingers. More advanced measurements including finger abduction, adduction, and circumduction are much more difficult to achieve. To overcome these limitations, we propose a two-axis 3D printed optical sensor with a compact configuration for tracking finger motion. Based on Malus' law, this sensor detects the angular changes by analyzing the attenuation of light transmitted through polarizing film. The sensor consists of two orthogonal axes each containing two pathways. The two readings from each axis are fused using a weighted average approach, enabling a measurement range up to 180 ∘ and an improvement in sensitivity. The sensor demonstrates high accuracy (±0.3 ∘ ), high repeatability, and low hysteresis error. Attaching the sensor to the index finger's metacarpophalangeal joint, real-time movements consisting of flexion/extension, abduction/adduction and circumduction have been successfully recorded. The proposed two-axis sensor has demonstrated its capability for measuring finger movements with two degrees of freedom and can be potentially used to monitor other types of body motion.
Research on electromechanical resonance of two-axis tracking system
Zhao, Zhi-ming; Xue, Ying-jie; Zeng, Shu-qin; Li, Zhi-guo
2017-02-01
The multi-axes synchronous system about the spatial two-axis turntable is the key equipment for semi-physical simulation and test in aerospace. In this paper, the whole structure design of the turntable is created by using Solidworks, then putting the three-dimensional solid model into ANSYS to build the finite element model. The software ANSYS is used to do the simulation about the static and dynamic analysis of two-axis turntable. Based on the modal analysis, we can forecast the inherent frequencies and the mode of vibration during the launch conditions which is very important to the design and safety of the structure.
Two-axis tracking using translation stages for a lens-to-channel waveguide solar concentrator.
Liu, Yuxiao; Huang, Ran; Madsen, Christi K
2014-10-20
A two-axis tracking scheme designed for concentration realized by a single-axis mechanical tracker and a translation stage is discussed. The translation stage is used for adjusting positions for seasonal sun movement. It has two-dimensional x-y tracking instead of horizontal movement x-only. This tracking method is compatible with planar waveguide solar concentrators. A prototype system with 50x concentration shows >75% optical efficiency throughout the year in simulation and >65% efficiency experimentally. This efficiency can be further improved by the use of anti-reflection layers and a larger waveguide refractive index.
Solar Tracking Systems and A Two-Axis Active Prototype With Stepwise Movement
Gökhan ORAL; Osman N. UÇAN
2014-01-01
In this work, criteria for a two-axis solar tracking system that provides a higher voltage and power output than a fixed solar panel, are determined and a prototype is realized with stepwise movement. From that point on, to design a practical solar tracker, extensive research studies were conducted which resulted in determination of optimal techniques and components. As a result, by using a small scale solar panel, servo motors as drive elements, Arduino processor as the controller, and a wir...
Development of Intelligent Fuzzy Controller for a Two-Axis Solar Tracking System
Directory of Open Access Journals (Sweden)
Cong-Hui Huang
2016-05-01
Full Text Available This paper proposes the development of a two-axis sun tracking solar energy system using fuzzy logic as intelligent quality policy. To achieve maximum efficiency for solar panels, it is necessary to follow the sun’s path in the sky. Therefore, the architecture for the two-axis sun tracking solar energy system uses software to control the hardware. The hardware comprises (i solar cells; (ii lead-acid batteries; (iii a gear box; (iv a stepping motor; and (v a light detection circuit, while the software comprises (i a detection system; (ii a fuzzy tracking controller; and (iii a database system. A fuzzy logic controller is designed as the software architecture of the system to decide the timing for tracking the sun. The nearest position that results in receiving direct sunlight is obtained from the database. Our system is fully automatic in a changing environment and takes into account meteorological changes and the effects of the external environment arising from a malfunction. This approach reduces the number of starting motors and results in smaller energy loss in cloudy, cloud mask, or unstable weather conditions.
Two-axis Beam Steering Mirror Control system for Precision Pointing and Tracking Applications
Energy Technology Data Exchange (ETDEWEB)
Ulander, Klaus [California Polytechnic State Univ. (CalPoly), San Luis Obispo, CA (United States)
2006-01-01
Precision pointing and tracking of laser beams is critical in numerous military and industrial applications. This is particularly true for systems requiring atmospheric beam propagation. Such systems are plagued by environmental influences which cause the optical signal to break up and wander. Example applications include laser communications, precision targeting, active imaging, chemical remote sensing, and laser vibrometry. The goal of this project is to build a beam steering system using a two-axis mirror to maintain precise pointing control. Ultimately, position control to 0.08% accuracy (40 {micro}rad) with a bandwidth of 200 Hz is desired. The work described encompasses evaluation of the instrumentation system and the subsequent design and implementation of an analog electronic controller for a two-axis mirror used to steer the beam. The controller operates over a wide temperature range, through multiple mirror resonances, and is independent of specific mirrors. The design was built and successfully fielded in a Lawrence Livermore National Laboratory free-space optics experiment. All measurements and performance parameters are derived from measurements made on actual hardware that was built and field tested. In some cases, specific design details have been omitted that involve proprietary information pertaining to Lawrence Livermore National Laboratory patent positions and claims. These omissions in no way impact the general validity of the work or concepts presented in this thesis.
Pneu-Scan - A novel, lightweight two-axis telemetry tracking system
Sullivan, A.
The development of Pneu-Scan, a conically scanning tracking antenna feed for telemetry applications, is described. Pneu-Scan has the advantage of being pneumatically driven, thereby eliminating the need for a heavy electric drive motor. Air from the dehydrator/pressurizer system is used to drive the Pneu-Scan pedestal at a scan speed which is proportional to the continuously varying pressure. The S-band tracking feed of the Pneu-Scan is less than five inches in diameter and is considerably lighter than single-channel monopulse (SCM) feeds. Aperture blocking of Pneu-Scan is more than two times smaller than conventional SCM designs. The antenna reflector of the Pneu-Scan system is a lightweight 5-foot graphite-epoxy parabolical reflector positioned by an elevator-over-azimuth pedestal. The elevation assembly is surrounded by an inflatable rotodome which rotates with azimuth. The rotating sphere was designed to have a minimum wind-induced torque, thereby minimizing the required drive power. The weight of the entire system is less than 135 pounds. The principle characteristics of the Pneu-Scan system are summarized in a table.
Seguidor Solar de Dos Ejes para un Horno Solar Two-Axis Sun Tracking System for a Solar Furnace
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Gabriel Villeda
2011-01-01
Full Text Available Se presenta el diseño y fabricación de un seguidor solar de dos ejes (rotación-elevación, el cual controla un helióstato de un horno solar para la cocción de tabiques de arcilla. El sistema trabaja con motores controlados desde una computadora personal. El algoritmo para el seguidor solar se desarrolló en un lenguaje de programación visual, calcula los ángulos de seguimiento primario y secundario del helióstato y los despliega en una pantalla. El microcontrolador está programado para controlar el funcionamiento de los motores a pasos, los cuales mueven el helióstato del horno solar. El seguimiento primario y secundario es el mismo para los equinoccios, mientras que para los solsticios son diferentes debido a que durante el verano en el hemisferio norte existe mayor altura solar que en invierno. El seguidor solar permite una captación más eficiente de la radiación solar debido a que sigue minuto a minuto el movimiento aparente del Sol.The design and manufacture of a two-axis sun tracking system (rotation-elevation, which controls a heliostat of a solar furnace for clay brick firing is presented. The system works with motors controlled through a personal computen The algorithm for the sun tracking system was developed in a visual programming language, calculates the primary and secondary tracking angles of the heliostat and shows them in a screen. The microcontroller is programmed to control the step driver engines, which move the heliostat of the solar furnace. The primary and secondary tracking is the same for the equinoxes, whereas for the solstices are different because the solar altitude is greater in summer than in winter in the northern hemisphere. The sun tracking system permits a more efficient capture of the solar radiation since it continuously follows the apparent movement of the Sun.
High performance flat plate solar collector
Lansing, F. L.; Reynolds, R.
1976-01-01
The potential use of porous construction is presented to achieve efficient heat removal from a power producing solid and is applied to solar air heaters. Analytical solutions are given for the temperature distribution within a gas-cooled porous flat plate having its surface exposed to the sun's energy. The extracted thermal energy is calculated for two different types of plate transparency. Results show the great improvement in performance obtained with porous flat plate collectors as compared with analogous nonporous types.
Burhan, Muhammad
2016-08-31
The conventional CPV systems, as big unit design, are only suitable to be installed in the open regions, like desert areas. This gigantic system design restricts their use on the rooftop of commercial and residential buildings, unlike the conventional PV systems. This paper proposes a compact but highly accurate and cheap two axis solar tracking system, designed for CPV system field operation. The proposed system is designed and verified for tracking accuracy requirement of 0.3 degrees, and has maximum capability of as high as 0.1 degrees tracking accuracy. High tracking accuracy is ensured using in-house built double lens collimator solar feedback sensor, within a fraction of the cost of commercial solar tracking sensors. A hybrid tracking algorithm is developed in C-programming using astronomical and optical solar tracking methods. As compact CPV system design demands larger number of tracking units, for same power capacity of system. Therefore, a master slave control configuration is also proposed for the CPV field operation. Only master tracker will be equipped with the expensive tracking devices, while the required tracking information will be sent to all of the slave trackers using wireless communication through ZigBee devices. With detailed optical design, simulation and control strategy, a prototype of the proposed CPV tracking system is developed, experimentally investigated and verified for tracking accuracy for outdoor operation at the rooftop. (C) 2016 Elsevier Ltd. All rights reserved.
Designing and Simulation of a Two-Axis Solar Tracking System by Exact Relations of Solar Angles
Directory of Open Access Journals (Sweden)
Faezeh Esmaili Ranjbar
2013-01-01
Full Text Available In this study, a system has been designed and simulated to track sunlight, which identifies sun location based on the exact relations of solar angles and without any optical sensor. In fact the relations which have been used in this study are far more accurate compared to similar cases, because of using the "equation of time" and reducing the tracking time of every 15 minutes. In this system, an economical micro-controller has been used to generate the necessary orders to control system and two stepper motors for powering solar array. By adding a real-time clock IC (RTC to angle differentiation circuit, dynamic plane has improved.
Measurements of Flat-Plate Milk Coolers
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Vlastimil Nejtek
2014-01-01
Full Text Available Measuring in laboratory conditions was performed with the aim to collect a sufficient quantity of measured data for the qualified application of flat-plate coolers in measuring under real operating conditions. The cooling water tank was filled with tap water; the second tank was filled with water at a temperature equivalent to freshly milked milk. At the same time, pumps were activated that delivered the liquids into the flat-plate cooler where heat energy was exchanged between the two media. Two containers for receiving the run-out liquid were placed on the outputs from the cooler; here, temperature was measured with electronic thermometer and volume was measured with calibrated graduated cylinder. Flow rate was regulated both on the side of the cooling fluid and on the side of the cooled liquid by means of a throttle valve. The measurements of regulated flow-rates were repeated several times and the final values were calculated using arithmetic average. To calculate the temperature coefficient and the amount of brought-in and let-out heat, the volume measured in litres was converted to weight unit. The measured values show that the volume of exchanged heat per weight unit increases with the decreasing flow-rate. With the increasing flow-rate on the throttled side, the flow-rate increases on the side without the throttle valve. This phenomenon is caused by pressure increase during throttling and by the consequent increase of the diameter of channels in the cooler at the expense of the opposite channels of the non-throttled part of the circuit. If the pressure is reduced, there is a pressure decrease on the external walls of opposite channels and the flow-rate increases again. This feature could be utilised in practice: a pressure regulator on one side could regulate the flow-rate on the other side. The operating measurement was carried out on the basis of the results of laboratory measurements. The objective was to determine to what extent the
Directory of Open Access Journals (Sweden)
Yasir Khudhair Abbas
2012-01-01
Full Text Available In this paper, an intelligent tracking control system of both single- and double-axis Piezoelectric Micropositioner stage is designed using Genetic Algorithms (GAs method for the optimal Proportional-Integral-Derivative (PID controller tuning parameters. The (GA-based PID control design approach is a methodology to tune a (PID controller in an optimal control sense with respect to specified objective function. By using the (GA-based PID control approach, the high-performance trajectory tracking responses of the Piezoelectric Micropositioner stage can be obtained. The (GA code was built and the simulation results were obtained using MATLAB environment. The Piezoelectric Micropositioner simulation model with the (GA-based PID control is illustrated to show the validity of the proposed control method for practical applications, such as scanning microscopy.
System Advisor Model: Flat Plate Photovoltaic Performance Modeling Validation Report
Energy Technology Data Exchange (ETDEWEB)
Freeman, J.; Whitmore, J.; Kaffine, L.; Blair, N.; Dobos, A. P.
2013-12-01
The System Advisor Model (SAM) is a free software tool that performs detailed analysis of both system performance and system financing for a variety of renewable energy technologies. This report provides detailed validation of the SAM flat plate photovoltaic performance model by comparing SAM-modeled PV system generation data to actual measured production data for nine PV systems ranging from 75 kW to greater than 25 MW in size. The results show strong agreement between SAM predictions and field data, with annualized prediction error below 3% for all fixed tilt cases and below 8% for all one axis tracked cases. The analysis concludes that snow cover and system outages are the primary sources of disagreement, and other deviations resulting from seasonal biases in the irradiation models and one axis tracking issues are discussed in detail.
Design of two-axis tracking system of solar streetlamp%太阳能路灯双轴跟踪系统设计
Institute of Scientific and Technical Information of China (English)
刘日平; 任天平; 吕寻浩
2014-01-01
针对当前太阳能路灯转换效率低的弊端，介绍了一种太阳能路灯双轴跟踪系统，通过实时检测光强的变化驱动执行机构，保证太阳能电池板始终垂直于太阳光线，从而提高太阳能利用效率。实验表明，太阳能电池板在双轴跟踪情况下，发电量要比最佳角度固定安装提高34%。%Due to the low conversion efficiency of solar tracker, the paper introduces a kind of two-axis tracking system. It tests the change of light and droved actuator on time to make sure the solar panels and sun light meet each other at right angles to increase the conversion efficiency of solar tracker. According to experiments , the two-axis tracker can increase the power output by 34 percent.
REVIEW OF PERFORMANCE AND ANALYSIS ISI FLAT PLATE COLLECTOR WITH MODIFIED FLAT PLATE COLLECTOR
Directory of Open Access Journals (Sweden)
MR.Y.Y.NANDURKAR
2012-03-01
Full Text Available The market of solar water heater of natural circulation type (thermo-siphon is fast growing in India. Initial cost of the solar water heater system at present is high because of store type design. It is necessary to make the product more popular by reducing the cost. This is possible by reducing area of liquid flat plate collector by increasing tube diameter and reducing riser length. Hence it is essential to make solar water heater in affordable range of the general public class. Present work is based on review of comparative performance and analysis of ISI flat plate collector with modified flat plat collector. The paper will be helpful for those who are working in the area of solar water heating system and their use in domestic areas.
Flexural Behavior of Posttensioned Flat Plates Depending on Tendon Layout
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Min Sook Kim
2016-01-01
Full Text Available This paper discusses the experimental results on the flexural behavior and deflections of posttensioned concrete flat plates depending on tendon layout. One reinforced concrete flat plate and two posttensioned concrete flat plates were manufactured and tested. One-way posttensioning layout and two-way posttensioning layout were considered in this paper. The load-deflection behavior and modes of crack are presented from the test results. Posttension systems effectively controlled crack and deflection. One-way and two-way posttensioning layouts both showed similar maximum load. However, serviceability improved with two-way posttensioning layout compared to one-way posttensioning layout. Also, the yield-line theory was applied to predict the ultimate load for the posttensioned flat plates. The comparison between the test results and estimation by yield-line analysis generally showed good agreement.
Analysis of Flat-Plate Solar Array and Solar Lantern
Directory of Open Access Journals (Sweden)
P. L. N. V. Aashrith
2014-05-01
Full Text Available A very detailed theortical analysis of a solar array has been carried out based on established values of solar radiation data to predict the performance of solar lamp . The analysis is based on established theory about flat-plate collectors. Top heat loss coefficient (Ut, Bottom heat loss coefficient (Ub, Overall heat loss coefficient (Ul, Useful energy (Qu, efficiency (hp of the flat-plate solar array and efficiency (hl of the solar lantern has been calculated.
Laminar film boiling on inclined isothermal flat plates.
Nagendra, H. R.
1973-01-01
Laminar film boiling from an inclined flat plate has been investigated analytically. Using the singular perturbation scheme, the complete set of Navier-Stokes equations is solved. The zeroth-order perturbation coinciding with the boundary-layer equations for vertical flat plates governs the problem. The higher-order perturbations become important near the leading edge and for large values of the inclination angle from the vertical. The assumption of zero interfacial velocity shows that, except for fluids having large (rho x mu) ratios, the results can be predicted using the vertical flat plate results by defining a modified Grashof parameter containing a cos phi term. When the interfacial shear is considered, the solutions indicate that for fluids having large (rho x mu) ratios, the heat transfer rates will be larger (approximately 15% maximum) than those predicted by the simplified model using zero interfacial velocity. In general, the inclination decreases the rate of heat transfer as well as the rate of evaporation.
Performance Study of a Double-Pass Thermoelectric Solar Air Collector with Flat-Plate Reflectors
Lertsatitthanakorn, C.; Rungsiyopas, M.; Therdyothin, A.; Soponronnarit, S.
2012-06-01
In this paper the results of the influence of flat-plate reflectors made of aluminum foil on the performance of a double-pass thermoelectric (TE) solar air collector are presented. The proposed TE solar collector with reflectors was composed of transparent glass, an air gap, an absorber plate, TE modules, a rectangular fin heat sink, and two flat-plate reflectors. The flat-plate reflectors were placed on two sides of the TE solar collector (east and west directions). The TE solar collector was installed on a one-axis sun-tracking system to obtain high solar radiation. Direct and reflected incident solar radiation heats up the absorber plate so that a temperature difference is created across the TE modules to generate a direct current. Only a small part of the absorbed solar radiation is converted to electricity, while the rest increases the temperature of the absorber plate. Ambient air flows through the heat sink located in the lower channel to gain heat. The heated air then flows to the upper channel, where it receives additional heating from the absorber plate. Improvements to the thermal energy and electrical power outputs of the system can be achieved by the use of the double-pass collector system with reflectors and TE technology. It was found that the optimum position of the reflectors is 60°, which gave significantly higher thermal energy and electrical power outputs compared with the TE solar collector without reflectors.
Shear flow past a flat plate in hydromagnetics
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S. R. N. Sastry
1980-01-01
Full Text Available The problem of simple shear flow past a flat plate has been extended to the hydromagnetic case in which a viscous, electrically conducting, incompressible fluid flows past an electrically insulated flat plate with a magnetic field parallel to the plate. For simplicity all physical parameters are assumed constant. A series solution for the velocity field has been developed for small values of a magnetic parameter. The equations governing this flow field were integrated numerically It is found that the effect of the magnetic field is to diminish and increase respectively, the first and second order contributions for the skin friction.
Certification and verification for calmac flat plate solar collector
Energy Technology Data Exchange (ETDEWEB)
1978-01-27
This document contains information used in the certification and verification of the Calmac Flat Plate Collector. Contained are such items as test procedures and results, information on materials used, Installation, Operation, and Maintenance Manuals, and other information pertaining to the verification and certification.
The structure of subsonic air wakes behind a flat plate
Energy Technology Data Exchange (ETDEWEB)
Barreras, F.; Dopazo, C. [Centro Politecnico Superior de Ingenieros Area de Mecanica de Fluidos, Zaragoza (Spain); Lozano, A.; Yates, A.J. [LITEC/CSIC, Maria de Luna 3 E-50015-Zaragoza (Spain)
1999-04-01
Acetone vapor planar laser-induced fluorescence has been used to visualize the structure of a subsonic air wake behind a flat plate. Longitudinal and transversal wavelengths have been directly measured from the acquired images. The ratio between them has been calculated to be 2/5. (orig.) With 3 figs., 1 tab., 10 refs.
Detailed Modeling of Flat Plate Solar Collector with Vacuum Glazing
Directory of Open Access Journals (Sweden)
Viacheslav Shemelin
2017-01-01
Full Text Available A theoretical analysis of flat plate solar collectors with a vacuum glazing is presented. Different configurations of the collector have been investigated by a detailed theoretical model based on a combined external and internal energy balance of the absorber. Performance characteristics for vacuum flat plate collector alternatives have been derived. Subsequently, annual energy gains have been evaluated for a selected variant and compared with state-of-the-art vacuum tube collectors. The results of modeling indicate that, in the case of using advanced vacuum glazing with optimized low-emissivity coating (emissivity 0.20, solar transmittance 0.85, it is possible to achieve efficiency parameters similar to or even better than vacuum tube collectors. The design presented in this paper can be considered promising for the extension of the applicability range of FPC and could be used in applications, which require low-to-medium temperature level.
A dynamic simulation of a flat-plate collector system
Annino, A.
1983-04-01
A numerical model for the performance of a flat plate solar collector array is presented, with account taken of thermal transients and calculation on a microcomputer. The system modeled consists of a flat plate array, the heat transfer fluid, an insulated storage tank, an exchange loop for heating a secondary fluid, and a load maintained by a pump. The one-dimensional analysis includes equations for the energy balances, with consideration given to heat losses to the outside. A function is defined for the total incident solar radiation, and behavior is simulated over the entire 24-hr day, weighted by the highest and lowest recorded temperatures. Good agreement has been found with experimental data.
Flat Plate Reduction in a Water Tunnel Using Riblets
1987-05-01
II ~Ci +c SE- 2 8 0Lg E (D so (wwI) 10 DRAG CALCULATIONS The drag on the flat plate was calculated using D = bpU 20 The drag reduction over the...described in the previous section, are used so that bpU 2. is a constant, and that the drag upstream of the leading edge of the test surface is the same
EM Scattering from Conducting Flat Plates Coated with Thin RAM
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
According to the equivalence principles, high frequency approximation and boundary conditions, a method has been developed to deal with the EM scattering by a rectangular conducting flat plate coated with uniaxial anisotropic radar absorbing material (RAM). The simple and effective method is available to the system of RCS prediction in which the large complex targets modeled by facets and wedges. Numerical results show some properties of EM scattering by conducting plate coated with thin uniaxial anisotropic RAM.
Energy Technology Data Exchange (ETDEWEB)
Vaughn, Mark R. (Albuquerque, NM); Robinett, III, Rush D. (Tijeras, NM); Phelan, John R. (Albuquerque, NM); Van Zuiden, Don M. (Albuquerque, NM)
1997-01-21
A new class of coplanar two-axis angular effectors. These effectors combine a two-axis rotational joint analogous to a Cardan joint with linear actuators in a manner to produce a wider range of rotational motion about both axes defined by the joint. This new class of effectors also allows design of robotic manipulators having very high strength and efficiency. These effectors are particularly suited for remote operation in unknown surroundings, because of their extraordinary versatility. An immediate application is to the problems which arise in nuclear waste remediation.
Energy Technology Data Exchange (ETDEWEB)
Vaughn, M.R.; Robinett, R.D. III; Phelan, J.R.; Zuiden, D.M. Van
1997-01-21
A new class of coplanar two-axis angular effectors is described. These effectors combine a two-axis rotational joint analogous to a Cardan joint with linear actuators in a manner to produce a wider range of rotational motion about both axes defined by the joint. This new class of effectors also allows design of robotic manipulators having very high strength and efficiency. These effectors are particularly suited for remote operation in unknown surroundings, because of their extraordinary versatility. An immediate application is to the problems which arise in nuclear waste remediation. 11 figs.
Unsteady Reversed Stagnation-Point Flow over a Flat Plate
Sin, Vai Kuong; Chio, Chon Kit
2012-01-01
This paper investigates the nature of the development of two-dimensional laminar flow of an incompressible fluid at the reversed stagnation-point. ". In this study, we revisit the problem of reversed stagnation-point flow over a flat plate. Proudman and Johnson (1962) first studied the flow and obtained an asymptotic solution by neglecting the viscous terms. This is no true in neglecting the viscous terms within the total flow field. In particular it is pointed out that for a plate impulsivel...
Unsteady Reversed Stagnation-Point Flow over a Flat Plate
Sin, Vai Kuong
2013-01-01
This paper investigates the nature of the development of two-dimensional laminar flow of an incompressible fluid at the reversed stagnation-point. ". In this study, we revisit the problem of reversed stagnation-point flow over a flat plate. Proudman and Johnson (1962) first studied the flow and obtained an asymptotic solution by neglecting the viscous terms. This is no true in neglecting the viscous terms within the total flow field. In particular it is pointed out that for a plate impulsively accelerated from rest to a constant velocity V0 that a similarity solution to the self-similar ODE is obtained which is noteworthy completely analytical.
High Performance Flat Plate Solar Thermal Collector Evaluation
Energy Technology Data Exchange (ETDEWEB)
Rockenbaugh, Caleb [National Renewable Energy Lab. (NREL), Golden, CO (United States); Dean, Jesse [National Renewable Energy Lab. (NREL), Golden, CO (United States); Lovullo, David [National Renewable Energy Lab. (NREL), Golden, CO (United States); Lisell, Lars [National Renewable Energy Lab. (NREL), Golden, CO (United States); Barker, Greg [National Renewable Energy Lab. (NREL), Golden, CO (United States); Hanckock, Ed [National Renewable Energy Lab. (NREL), Golden, CO (United States); Norton, Paul [National Renewable Energy Lab. (NREL), Golden, CO (United States)
2016-09-01
This report was prepared for the General Services Administration by the National Renewable Energy Laboratory. The Honeycomb Solar Thermal Collector (HSTC) is a flat plate solar thermal collector that shows promising high efficiencies over a wide range of climate zones. The technical objectives of this study are to: 1) verify collector performance, 2) compare that performance to other market-available collectors, 3) verify overheat protection, and 4) analyze the economic performance of the HSTC both at the demonstration sites and across a matrix of climate zones and utility markets.
Calculating the Solar Energy of a Flat Plate Collector
Directory of Open Access Journals (Sweden)
Ariane Rosario
2014-09-01
Full Text Available The amount of solar energy that could be obtained by a flat plate solar collector of one square meter dimension is calculated in three different locations: Tampa FL, Fairbanks AL, and Pontianak Indonesia, considering the varying sunset time for each day of the year. The results show that if the collectors are placed near the equator, more total energy could be obtained. In fact, by placing a solar collector in Pontianak, Indonesia 12.42% more solar energy can be obtained than by placing it in Tampa and 96.9% more solar energy than Alaska.
Efficiencies of flat plate solar collectors at different flow rates
DEFF Research Database (Denmark)
Chen, Ziqian; Furbo, Simon; Perers, Bengt;
2012-01-01
Two flat plate solar collectors for solar heating plants from Arcon Solvarme A/S are tested in a laboratory test facility for solar collectors at Technical University of Denmark (DTU). The collectors are designed in the same way. However, one collector is equipped with an ETFE foil between...... the absorber and the cover glass and the other is without ETFE foil. The efficiencies for the collectors are tested at different flow rates. On the basis of the measured efficiencies, the efficiencies for the collectors as functions of flow rate are obtained. The calculated efficiencies are in good agreement...
Haney, Michael W.
2015-12-01
The economies-of-scale and enhanced performance of integrated micro-technologies have repeatedly delivered disruptive market impact. Examples range from microelectronics to displays to lighting. However, integrated micro-scale technologies have yet to be applied in a transformational way to solar photovoltaic panels. The recently announced Micro-scale Optimized Solar-cell Arrays with Integrated Concentration (MOSAIC) program aims to create a new paradigm in solar photovoltaic panel technology based on the incorporation of micro-concentrating photo-voltaic (μ-CPV) cells. As depicted in Figure 1, MOSAIC will integrate arrays of micro-optical concentrating elements and micro-scale PV elements to achieve the same aggregated collection area and high conversion efficiency of a conventional (i.e., macro-scale) CPV approach, but with the low profile and mass, and hopefully cost, of a conventional non-concentrated PV panel. The reduced size and weight, and enhanced wiring complexity, of the MOSAIC approach provide the opportunity to access the high-performance/low-cost region between the conventional CPV and flat-plate (1-sun) PV domains shown in Figure 2. Accessing this portion of the graph in Figure 2 will expand the geographic and market reach of flat-plate PV. This talk reviews the motivation and goals for the MOSAIC program. The diversity of the technical approaches to micro-concentration, embedded solar tracking, and hybrid direct/diffuse solar resource collection found in the MOSAIC portfolio of projects will also be highlighted.
Pure and aerated water entry of a flat plate
Ma, Z. H.; Causon, D. M.; Qian, L.; Mingham, C. G.; Mai, T.; Greaves, D.; Raby, A.
2016-01-01
This paper presents an experimental and numerical investigation of the entry of a rigid square flat plate into pure and aerated water. Attention is focused on the measurement and calculation of the slamming loads on the plate. The experimental study was carried out in the ocean basin at Plymouth University's COAST laboratory. The present numerical approach extends a two-dimensional hydro-code to compute three-dimensional hydrodynamic impact problems. The impact loads on the structure computed by the numerical model compare well with laboratory measurements. It is revealed that the impact loading consists of distinctive features including (1) shock loading with a high pressure peak, (2) fluid expansion loading associated with very low sub-atmospheric pressure close to the saturated vapour pressure, and (3) less severe secondary reloading with super-atmospheric pressure. It is also disclosed that aeration introduced into water can effectively reduce local pressures and total forces on the flat plate. The peak impact loading on the plate can be reduced by half or even more with 1.6% aeration in water. At the same time, the lifespan of shock loading is prolonged by aeration, and the variation of impulse is less sensitive to the change of aeration than the peak loading.
Experiments to investigate lift production mechanisms on pitching flat plates
Stevens, P. R. R. J.; Babinsky, H.
2017-01-01
Pitching flat plates are a useful simplification of flapping wings, and their study can provide useful insights into unsteady force generation. Non-circulatory and circulatory lift producing mechanisms for low Reynolds number pitching flat plates are investigated. A series of experiments are designed to measure forces and study the unsteady flowfield development. Two pitch axis positions are investigated, namely a leading edge and a mid-chord pitch axis. A novel PIV approach using twin laser lightsheets is shown to be effective at acquiring full field of view velocity data when an opaque wing model is used. Leading-edge vortex (LEV) circulations are extracted from velocity field data, using a Lamb-Oseen vortex fitting algorithm. LEV and trailing-edge vortex positions are also extracted. It is shown that the circulation of the LEV, as determined from PIV data, approximately matches the general trend of an unmodified Wagner function for a leading edge pitch axis and a modified Wagner function for a mid-chord pitch axis. Comparison of experimentally measured lift correlates well with the prediction of a reduced-order model for a LE pitch axis.
Unsteady Aerodynamics on a Pitching Plunging Flat Plate
Hart, Adam; Ukeiley, Lawrence
2010-11-01
Biology has shown that natural fliers utilize unsteady flow mechanisms to enhance their lift characteristics in low Reynolds number flight regimes. This study will investigate the interaction between the leading edge vortices (LEVs) and tip vortices over a low aspect ratio flat plate being subjected to a pitch-plunge kinematic motion. Previous studies have shown the creation of stable vortices off the leading edge at the three quarter span location between times 0.25 and 0.50 in the kinematic motion. This study furthers previous knowledge by mapping the flow field around these vortex cores. This will allow for an understanding into the interaction of the LEV with tip vortices and how the LEVs convect downstream. Specifically we look to validate the interactions between these vortex systems leading to enhanced lift as has been demonstrated in very low Reynolds number numerical simulations. A combination of two dimensional and stereo Particle Image Velocimetery (PIV) is used to measure the flow field around the flat plate at various spanwise and chordwise locations. The PIV measurements are triggered by the dynamic motion rig allowing for phase averaging at key locations throughout the motion cycle.
Modal characterization of composite flat plate models using piezoelectric transducers
Oliveira, É. L.; Maia, N. M. M.; Marto, A. G.; da Silva, R. G. A.; Afonso, F. J.; Suleman, A.
2016-10-01
This paper aims to estimate the modal parameters of composite flat plate models through Experimental Modal Analysis (EMA) using piezoelectric transducers. The flat plates are composed of three ply carbon-epoxy fibers oriented in the same direction. Five specimens with different unidirectional fiber nominal orientations θk (0o, 30o, 45o, 60o and 90o) were tested. These models were instrumented with one PZT (Lead Zirconate Titanate) actuator and one PVDF (Polyvinylidene Fluoride) sensor and an EMA was performed. The natural frequencies and damping factors estimated using only a single PVDF response were compared with the estimated results using twelve measurement points acquired by laser doppler vibrometry. For comparison purposes, the percentage error of each natural frequency estimation and the percentage error of the damping factor estimations were computed, as well as their averages. Even though the comparison was made between a SISO (Single-Input, Single-Output) and a SIMO (Single-Input, Multiple-Output) techniques, both results are very close. The vibration modes were estimated by means of laser measurements and were used in the modal validation. In order to verify the accuracy of the modal parameters, the Modal Assurance Criterion (MAC) was employed and a high correlation among mode shapes was observed.
A high performance porous flat-plate solar collector
Lansing, F. L.; Clarke, V.; Reynolds, R.
1979-01-01
A solar collector employing a porous matrix as a solar absorber and heat exchanger is presented and its application in solar air heaters is discussed. The collector is composed of a metallic matrix with a porous surface which acts as a large set of cavity radiators; cold air flows through the matrix plate and exchanges heat with the thermally stratified layers of the matrix. A steady-state thermal analysis of the collector is used to determine collector temperature distributions for the cases of an opaque surface matrix with total absorption of solar energy at the surface, and a diathermanous matrix with successive solar energy absorption at each depth. The theoretical performance of the porous flat plate collector is shown to exceed greatly that of a solid flat plate collector using air as the working medium for any given set of operational conditions. An experimental collector constructed using commercially available, low cost steel wool as the matrix has been found to have thermal efficiencies from 73 to 86%.
The Effect of the Configuration of the Absorber on the Performance of Flat Plate Thermal Collector
Yan, Moyu; Qu, Ming; Peng, Steve
2016-01-01
In this study, a numerical thermal analysis for a new designed flat plate thermal collector was conducted through modeling. The new flat plate thermal collector has ellipse shaped tubes inside a wavy shaped absorber, which is made of stainless steel. For the comparison, the conventional flat plate thermal collector with circular copper tubes served as a base case was also modeled. Hottel-Whillier equations were utilized to formulate thermal networks for both models developed in Engineering Eq...
Characterizing a burst leading-edge vortex on a rotating flat plate wing
Jones, Anya R.; Medina, Albert; Spooner, Hannah; Mulleners, Karen
2016-04-01
Identifying, characterizing, and tracking incoherent vortices in highly separated flows is of interest for the development of new low-order models for unsteady lift prediction. The current work examines several methods to identify vortex burst and characterize a burst leading-edge vortex. Time-resolved stereoscopic PIV was performed on a rotating flat plate wing at Re = 2500. The burst process was found to occur at mid-span and is characterized by axial flow reversal, the entrainment of opposite-sign vorticity, and a rapid expansion of vortex size. A POD analysis revealed that variations in certain mode coefficients are indicative of the flow state changes characteristics of burst. During burst, the leading-edge vortex evolves to a region of inhomogeneous vorticity distributed over a large area. Several methods of defining the vortex size and circulation are evaluated and a combination of these can be used to characterize the leading-edge vortex both pre- and post-burst.
Waksman, D.; Thomas, W. C.
1984-12-01
The results of studies, by the National Bureau of Standards, of the reliability and durability of eight different types of flat plate solar collectors representative of equipment available in 1977 are reported. The installations were made in four sites believed to typify various U.S. climates. The stability of the thermal performance and material properties was tracked, and measured again after moving the units inside for exposure to artificial sunlight. The stagnation measurement techniques employed to evaluate the collectors were judged adequate, provided the tests are made on-site and out of doors. It is noted that the instrumentation used to gather sufficient data for valid analyses may experience performance decrements due to the necessarily long monitoring intervals, i.e., several years.
Wind loads on flat plate photovoltaic array fields (nonsteady winds)
Miller, R. D.; Zimmerman, D. K.
1981-01-01
Techniques to predict the dynamic response and the structural dynamic loads of flat plate photovoltaic arrays due to wind turbulence were analyzed. Guidelines for use in predicting the turbulent portion of the wind loading on future similar arrays are presented. The dynamic response and the loads dynamic magnification factor of the two array configurations are similar. The magnification factors at a mid chord and outer chord location on the array illustrated and at four points on the chord are shown. The wind tunnel test experimental rms pressure coefficient on which magnification factors are based is shown. It is found that the largest response and dynamic magnification factor occur at a mid chord location on an array and near the trailing edge. A technique employing these magnification factors and the wind tunnel test rms fluctuating pressure coefficients to calculate design pressure loads due to wind turbulence is presented.
Validation of CFD simulation for flat plate solar energy collector
Energy Technology Data Exchange (ETDEWEB)
Selmi, Mohamed; Al-Khawaja, Mohammed J.; Marafia, Abdulhamid [Department of Mechanical Engineering, University of Qatar, P.O. Box 2713, Doha, State of Qatar (Qatar)
2008-03-15
The problem of flat plate solar energy collector with water flow is simulated and analyzed using computational fluid dynamics (CFD) software. The considered case includes the CFD modeling of solar irradiation and the modes of mixed convection and radiation heat transfer between tube surface, glass cover, side walls, and insulating base of the collector as well as the mixed convective heat transfer in the circulating water inside the tube and conduction between the base and tube material. The collector performance, after obtaining 3-D temperature distribution over the volume of the body of the collector, was studied with and without circulating water flow. An experimental model was built and experiments were performed to validate the CFD model. The outlet temperature of water is compared with experimental results and there is a good agreement. (author)
Increasing thermal efficiency of solar flat plate collectors
Pona, J.
A study of methods to increase the efficiency of heat transfer in flat plate solar collectors is presented. In order to increase the heat transfer from the absorber plate to the working fluid inside the tubes, turbulent flow was induced by installing baffles within the tubes. The installation of the baffles resulted in a 7 to 12% increase in collector efficiency. Experiments were run on both 1 sq ft and 2 sq ft collectors each fitted with either slotted baffles or tubular baffles. A computer program was run comparing the baffled collector to the standard collector. The results obtained from the computer show that the baffled collectors have a 2.7% increase in life cycle cost (LCC) savings and a 3.6% increase in net cash flow for use in domestic hot water systems, and even greater increases when used in solar heating systems.
Initial stage of flat plate impact onto liquid free surface
Iafrati, Alessandro; Korobkin, Alexander A.
2004-07-01
The liquid flow and the free surface shape during the initial stage of flat plate impact onto liquid half-space are investigated. Method of matched asymptotic expansions is used to derive equations of motion and boundary conditions in the main flow region and in small vicinities of the plate edges. Asymptotic analysis is performed within the ideal and incompressible liquid model. The liquid flow is assumed potential and two dimensional. The ratio of the plate displacement to the plate width plays the role of a small parameter. In the main region the flow is given in the leading order by the pressure-impulse theory. This theory provides the flow field around the plate after a short acoustic stage and predicts unbounded velocity of the liquid at the plate edges. In order to resolve the singular flow caused by the normal impact of a flat plate, the fine pattern of the flow in small vicinities of the plate edges is studied. It is shown that the initial flow close to the plate edges is self-similar in the leading order and is governed by nonlinear boundary-value problem with unknown shape of the free surface. The Kutta conditions are imposed at the plate edges, in order to obtain a nonsingular inner solution. This boundary-value problem is solved numerically by iterations. At each step of iterations the "inner" velocity potential is calculated by the boundary-element method. The asymptotics of the inner solution in both the far field and the jet region are obtained to make the numerical algorithm more efficient. The numerical procedure is carefully verified. Agreement of the computed free surface shape with available experimental data is fairly good. Stability of the numerical solution and its convergence are discussed.
General Observations of the Time-Dependent Flow Field Around Flat Plates in Free Fall
DEFF Research Database (Denmark)
Hærvig, Jakob; Jensen, Anna Lyhne; Pedersen, Marie Cecilie
2015-01-01
The free fall trajectories of flat plates are investigated in order to improve understanding of the forces acting on falling blunt objects. The long term goal is to develop a general applicable model to predict free fall trajectories. Numerically the free fall of a flat plate is investigated usin...
On the rotation and pitching of flat plates
Jin, Yaqing; Ji, Sheng; Chamorro, Leonardo P.
2016-11-01
Wind tunnel experiments were performed to characterize the flow-induced rotation and pitching of various flat plates as a function of the thickness ratio, the location of the axis of rotation and turbulence levels. High-resolution telemetry, laser tachometer, and hotwire were used to get time series of the plates motions and the signature of the wake flow at a specific location. Results show that a minor axis offset can induce high-order modes in the plate rotation under low turbulence due to torque unbalance. The spectral decomposition of the flow velocity in the plate wake reveals the existence of a dominating high-frequency mode that corresponds to a static-like vortex shedding occurring at the maximum plate pitch, where the characteristic length scale is the projected width at maximum pitch. The plate thickness ratio shows inverse relation with the angular velocity. A simple model is derived to explain the linear relation between pitching frequency and wind speed. The spectra of the plate rotation show nonlinear relation with the incoming turbulence, and the dominating role of the generated vortices in the plate motions.
Wind loads on flat plate photovoltaic array fields
Miller, R. D.; Zimmerman, D. K.
1981-01-01
The results of an experimental analysis (boundary layer wind tunnel test) of the aerodynamic forces resulting from winds acting on flat plate photovoltaic arrays are presented. Local pressure coefficient distributions and normal force coefficients on the arrays are shown and compared to theoretical results. Parameters that were varied when determining the aerodynamic forces included tilt angle, array separation, ground clearance, protective wind barriers, and the effect of the wind velocity profile. Recommended design wind forces and pressures are presented, which envelop the test results for winds perpendicular to the array's longitudinal axis. This wind direction produces the maximum wind loads on the arrays except at the array edge where oblique winds produce larger edge pressure loads. The arrays located at the outer boundary of an array field have a protective influence on the interior arrays of the field. A significant decrease of the array wind loads were recorded in the wind tunnel test on array panels located behind a fence and/or interior to the array field compared to the arrays on the boundary and unprotected from the wind. The magnitude of this decrease was the same whether caused by a fence or upwind arrays.
Experimental Modal Analysis of a Flat Plate Subjected To Vibration
Directory of Open Access Journals (Sweden)
Owunna Ikechukwu
2016-07-01
Full Text Available Modal analysis is significant in evaluating the mode shapes generated by a component under vibrational excitation, as the mode shapes can be used to determine the displacement or response of the component under the influence vibration in real life application. Result obtained from the modal analysis will generate a number of resonances which the frequency and damping effect can be determined by measurement. However, determining the accuracy of modal analysis result is somewhat difficult as the experimental results and the results generated by Finite Element Analysis (FEA solvers can be affected by a number of factors pointed out in this paper. In this study, a flat plate was mounted on an electromagnetic shaker which enabled the excitation of the plate, while results of the response were measured using a transducer attached to the plate. The plate was also modelled using CATIA software and the files transferred to the different FEA solvers such as HYPERMESH, ANSYS 6 Degree of Freedom (DOF as well as ANSYS 5 degree of freedom, in which the same analysis was carried out to obtain a set of results other than the experimental results. Each FEA solver generated results that were in close proximity with the experimental results, particularly the results generated by ANSYS 5 Degree of freedom. Hence, to ascertain the accuracy of the results obtained from modal analysis experimental procedure, it is important to match up the results generated from different FEA solvers with the experimental results.
Spatially developing turbulent boundary layer on a flat plate
Lee, J H; Hutchins, N; Monty, J P
2012-01-01
This fluid dynamics video submitted to the Gallery of Fluid motion shows a turbulent boundary layer developing under a 5 metre-long flat plate towed through water. A stationary imaging system provides a unique view of the developing boundary layer as it would form over the hull of a ship or fuselage of an aircraft. The towed plate permits visualisation of the zero-pressure-gradient turbulent boundary layer as it develops from the trip to a high Reynolds number state ($Re_\\tau \\approx 3000$). An evolving large-scale coherent structure will appear almost stationary in this frame of reference. The visualisations provide an unique view of the evolution of fundamental processes in the boundary layer (such as interfacial bulging, entrainment, vortical motions, etc.). In the more traditional laboratory frame of reference, in which fluid passes over a stationary body, it is difficult to observe the full evolution and lifetime of turbulent coherent structures. An equivalent experiment in a wind/water-tunnel would requ...
Start-up vortex flow past an accelerated flat plate
Xu, Ling
2014-01-01
Viscous flow past a finite flat plate moving in direction normal to itself is studied numerically.The plate moves with velocity $at^p$, where $p=0,0.5,1,2$. We present the evolution of vorticity profiles, streaklines and streamlines, and study the dependence on the acceleration parameter $p$. Four stages in the vortex evolution, as proposed by Luchini & Tognaccini (2002), are clearly identified. The initial stage, in which the vorticity consists solely of a Rayleigh boundary layer, is shown to last for a time-interval whose length shrinks to zero like $p^3$, as $p \\to 0$. In the second stage, a center of rotation develops near the tip of the plate, well before a vorticity maximum within the vortex core develops. Once the vorticity maximum develops, its position oscillates and differs from the center of rotation. The difference between the two increases with increasing $p$, and decreases in time. In the third stage, the center of rotation and the shed circulation closely satisfy self-similar scaling laws f...
Natural convection characteristics of flat plate collectors. Progress report
Energy Technology Data Exchange (ETDEWEB)
Randall, K.R.; Wl-Wakil, M.M.; Mitchell, J.W.
1977-09-01
The results of an experimental investigation into the convective heat losses in large aspect ratio flat-plate solar collectors are described. An experimental study has been undertaken on a specially designed test cell using a 3 inch Mach-Zehnder interferometer. Air at atmospheric pressure was used as the heat-transfer fluid. The experimental results include interferograms which show the thermal boundary layer formations and the temperature profiles. Local temperature profiles have been analyzed through the use of an optical comparator to determine local Nusselt number profiles, which have, in turn, been integrated to give average heat-transfer results. Angles of inclination from the horizontal of 45, 60, 75 and 90 degrees have been investigated. Aspect ratios from 9 to 36 were examined over a Rayleigh number range of 4,000 to 310,000. Finally, heat-transfer correlations have been developed for the prediction of local Nusselt numbers in the starting and departure corners and for the average heat-transfer results as a function of collector tilt angle.
A dynamic performance simulation model of flat-plate solar collectors for a heat pump system
Energy Technology Data Exchange (ETDEWEB)
Arinze, E.A.; Schoenau, G.J.; Sokhansanj, S. (Saskatchewan Univ., Saskatoon, SK (Canada). College of Engineering); Adefila, S.S.; Mumah, S.M. (Ahmadu Bello Univ., Zaria (Nigeria). Dept. of Chemical Engineering)
1993-01-01
Flat-plate collectors are inherently exposed to time-varying meteorological and system parameters. Thus, dynamic modeling, rather than the commonly used steady-state models, is a more accurate approach for the design and performance evaluation of flat-plate solar collectors. The dynamic model presented in this study describes the fluid, plate and cover temperatures of the collector by three different differential equations. Taylor series expansion and the Runge-Kutta method are used in the solution of the differential equations. The accuracy of the dynamic model was tested by comparing the results predicted by the model with experimental performance data obtained for a liquid-cooled flat-plate solar collector with a corrugated transparent fiberglass cover. The predicted results by the dynamic model agreed favorably with the measured experimental data for the flat-plate solar collector. Experimentally determined collector temperatures varied by a maximum of [+-]3[sup o]C from values predicted by the model. (Author)
On the instability of hypersonic flow past a flat plate
Blackaby, Nicholas; Cowley, Stephen; Hall, Philip
1990-01-01
The instability of hypersonic boundary-layer flows over flat plates is considered. The viscosity of the fluid is taken to be governed by Sutherland's law, which gives a much more accurate representation of the temperature dependence of fluid viscosity at hypersonic speeds than Chapman's approximate linear law; although at lower speeds the temperature variation of the mean state is less pronounced so that the Chapman law can be used with some confidence. Attention is focussed on the so-called (vorticity) mode of instability of the viscous hypersonic boundary layer. This is thought to be the fastest growing inviscid disturbance at hypersonic speeds; it is also believed to have an asymptotically larger growth rate than any viscous or centrifugal instability. As a starting point the instability of the hypersonic boundary layer which exists far downstream from the leading edge of the plate is investigated. In this regime the shock that is attached to the leading edge of the plate plays no role, so that the basic boundary layer is non-interactive. It is shown that the vorticity mode of instability of this flow operates on a significantly different lengthscale than that obtained if a Chapman viscosity law is assumed. In particular, it is found that the growth rate predicted by a linear viscosity law overestimates the size of the growth rate by O(M(exp 2). Next, the development of the vorticity mode as the wavenumber decreases is described, and it is shown that acoustic modes emerge when the wavenumber has decreased from it's O(1) initial value to O(M (exp -3/2). Finally, the inviscid instability of the boundary layer near the leading edge in the interaction zone is discussed and particular attention is focussed on the strong interaction region which occurs sufficiently close to the leading edge. It is found that the vorticity mode in this regime is again unstable, and that it is concentrated in the transition layer at the edge of the boundary layer where the temperature
Hiroshi Tanaka
2015-01-01
Augmentation of solar radiation absorbed on a flat plate solar thermal collector by a flat plate bottom reflector was numerically determined when there was a gap between the collector and reflector. The inclination of both the collector and reflector was assumed to be adjustable according to the season. A mirror-symmetric plane of the collector to the reflector was introduced, and a graphical model was proposed to calculate the amount of solar radiation reflected by the reflector and then abs...
Vortex dynamics and surface pressure fluctuations on a normal flat plate
Hemmati, Arman; Wood, David H.; Martinuzzi, Robert J.; Ferrari, Simon W.; Hu, Yaoping
2016-11-01
The effect of vortex formation and interactions on surface pressure fluctuations is examined in the wake of a normal flat plate by analyzing Direct Numerical Simulations at Re =1200. A novel local maximum score-based 3D method is used to track vortex development in the region close to the plate where the major contributions to the surface pressure are generated. Three distinct vortex shedding regimes are identified by changes in the lift and drag fluctuations. The instances of maximum drag coincide with impingement of newly formed vortices on the plate. This results in large and concentrated areas of rotational and strain contributions to generation of pressure fluctuations. Streamwise vortex straining and chordwise stretching are correlated with the large ratios of streamwise to chordwise normal stresses and regions of significant rotational contribution to the pressure. In contrast at the minimum drag, the vorticity field close to the plate is disorganized, and vortex roll-up occurs farther downstream. This leads to a uniform distribution of pressure. This study was supported by Alberta Innovates Technology Futures (AITF) and Natural Sciences and Engineering Research Council of Canada (NSERC).
Phenomenological model for torsional galloping of an elastic flat plate due to hydrodynamic loads
Institute of Scientific and Technical Information of China (English)
FERNANDES Antonio Carlos; ARMANDEI Mohammadmehdi
2014-01-01
This study investigates the torsional galloping phenomenon, an instability type flow-induced oscillation, in an elastic stru-cture due to hydrodynamic loads into the water current. The structure applied here is a rectangular flat plate with an elastic axis in its mid-chord length. The elasticity is provided by torsion spring. The flat plate has only one degree of freedom which is rotation in pure yaw about its axis. It is observed that as the current speed is higher than a critical velocity, the flat plate becomes unstable. The instability leads to torsional galloping occurrence, as a result of which the flat plate begins to yaw about the elastic axis. By testing two different chord lengths each with several torsion spring rates, the flat plate behavior is investigated and three different responses are recognized. Then, a phenomenological model is developed with the original kernel in the form of the van der Pol-Duffing equa-tion. The model explains these three responses observed experimentally.
The Flat Plate Solar Array Project, focuses on advancing technologies relevant to the design and construction of megawatt level central station systems. Photovoltaic modules and arrays for flat plate central station or other large scale electric power production facilities require the establishment of a technical base that resolves design issues and results in practical and cost effective configurations. Design, qualification and maintenance issues related to central station arrays derived from the engineering and operating experiences of early applications and parallel laboratory reserch activities are investigated. Technical issues are examined from the viewpoint of the utility engineer, architect/engineer and laboratory researcher. Topics on optimum source circuit designs, module insulation design for high system voltages, array safety, structural interface design, measurements, and array operation and maintenance are discussed.
Performance of streamlined bridge decks in relation to the aerodynamics of a flat plate
DEFF Research Database (Denmark)
Larose, Guy; Livesey, Flora M.
1997-01-01
The aerodynamics of three modern bridge decks are compared to the aerodynamics of a 16:1 flat plate. The comparisons are made on the basis of the analytical evaluation of the performance of each cross-section to the buffeting action of the wind. In general, the closed-box girders studied in this ...... in this paper showed buffeting responses similar to a flat plate with the exception of the multi-box girder which performed much better aerodynamically.......The aerodynamics of three modern bridge decks are compared to the aerodynamics of a 16:1 flat plate. The comparisons are made on the basis of the analytical evaluation of the performance of each cross-section to the buffeting action of the wind. In general, the closed-box girders studied...
A diagram for defined solar radiation absorbed per unit area of flat plate solar collectors
Energy Technology Data Exchange (ETDEWEB)
Tekin, Y.; Altuntop, N. [Erciyes University, Dept. of Mechanical Engineering (Turkey); Cengel, Y.A. [Nevada Reno University, Dept. of Mechanical Engineering, NV (United States); Cengel, Y.A. [Nevada University, Dept. Mechanical Engineering, Reno, NV (United States)
2000-07-01
In Erciyes University, the Solar House (28.75 m{sup 2}) is heated from the floor by using flat plate liquid solar collectors. Required solar radiation for heating and heat losses are calculated. In this work, the required calculations for Erciyes Solar House were generalized and required calculation were done to evaluate absorbed solar radiation per unit surface of the flat plate liquid collector. At the end, three generalized diagrams for nine different months are obtained using obtained numerical values. The goal of preparing diagrams is to determine absorbed solar radiation per unit surface area of flat plate liquid collector at any instant at any latitude, In this work, the diagram is explained by means of sample calculations for November. This diagram was prepared to find out absorbed solar radiation per unit area of black surface collector by means obtained equations. With this diagram, all instant solar radiation can be evaluated in 19 steps. (authors)
Interacting wakes of a narrow and a wide flat plate in tandem arrangement
Energy Technology Data Exchange (ETDEWEB)
Hacışevki, H; Teimourian, A, E-mail: hasan.hacisevki@emu.edu.tr [Department of Mechanical Engineering, Eastern Mediterranean University, Mağusa, North Cyprus, Mersin 10 (Turkey)
2016-02-15
Flow structures behind two different sized flat plates in tandem arrangement normal to flow at high Reynolds number have been investigated experimentally. A narrow flat plate, as a control plate, has been placed upstream of a wide plate to investigate the interacting wakes behind the wide flat plate. The near wake downstream of the wide plate has been measured by employing constant-temperature hot wire anemometer, quantitatively. The effects of different width ratio (h/D) range from 0.1 to 1.0 together with gap ratio (g/D) ranging from 0.5 to 2.0 have been probed. It was found that Strouhal number variation is directly proportional to gap ratio between the plates. Moreover, it was observed that turbulent kinetic energy production is mostly contributed by transverse normal turbulent stress and therefore follows the transverse stress pattern rather than the stream wise stress. (paper)
Vairamani, K.; Venkatesh, K. Arun; Mathivanan, N.
2011-01-01
Computing the efficiency of flat-plate collector is vital in solar thermal system testing. This paper presents the design of ZigBee enabled data acquisition system for instantaneous flat-plate collector efficiency calculation. It involves measurement of parameters like inlet and outlet fluid temperatures, ambient temperature and solar radiation intensity. The designed system has a base station and a sensor node. ZigBee wireless communication protocol is used for communication between the base station and the sensor node for wireless data acquisition. The wireless sensor node which is mounted over the collector plate includes the necessary sensors and associated signal-conditioners. An application program has been developed on LabVIEW platform for data acquisition, processing and analysis and is executed in base station PC. Instantaneous flat-plate collector efficiency is computed and reported.
Studies on solar flat plate collector evaporation systems for tannery effluent (soak liquor)
Institute of Scientific and Technical Information of China (English)
SRITHAR K.; MANIA.
2006-01-01
Heat and mass transfer analysis of an incompressible, laminar boundary layer over solar flat plate collector evaporation systems for tannery effluent (soak liquor) is investigated. The goveming equations are solved for various liquid to air velocity ratios. Profiles of velocity, temperature and concentration as well as their gradients are presented. The heat transfer and mass transfer coefficients thus obtained are used to evaluate mass of water evaporated for an inclined fibre-reinforced plastic (FRP)solar flat plate collector (FPC) with and without cover. Comparison of these results with the experimental performance shows encouraging trend of good agreement between them.
Study on characteristics of double surface VOC emissions from dry flat-plate building materials
Institute of Scientific and Technical Information of China (English)
WANG Xinke; ZHANG Yinping; ZHAO Rongyi
2006-01-01
This paper sets up an analytic model of double surface emission of volatile organic compound (VOC) from dry, flat-plate building materials. Based on it, the influence of factors including air change rate, loading factor of materials in the room, mass diffusion coefficient, partition coefficient, convective mass transfer coefficient, thickness of materials, asymmetric convective flow and initial VOC concentration distribution in the building material on emission is discussed. The conditions for simplifying double surface emission into single surface emission are also discussed. The model is helpful to assess the double surface VOC emission from flat-plate building materials used in indoor furniture and space partition.
A Numerical Study on the Performance of an Open-type Flat-plate Solar Collector
Song, Baoyin; Inaba, Hideo; Horibe, Akihiko
1999-01-01
A set mathematical models was developed for predicting the performance of an open-type flat-plate solar collector, and solved numerically through an implicit difference method. The effects of various parameters on the absorption of solar energy for the collector were investigated. The results showed that the solar energy absorptance of the open-type flat-plate collector was relatively high especially for the region where the weather was humid and hot, and there were an optimum length and an o...
Experimental study on flat plate air solar collector using a thin sand layer
Lati, Moukhtar; Boughali, Slimane; Bouguettaia, Hamza; Mennouche, Djamel; Bechki, Djamel
2016-07-01
A flat plate air solar collector was constructed in the laboratory of New and Renewable Energy in Arid Zones LENREZA, Ouargla University-South East Algeria. The absorber of the flat plate air solar collector was laminated with a thin layer of local sand. This acted as a thermal storage system (packed bed) with a collecting area of 2.15 m2 (0.86 m × 2.5 m). It was noticed that the solar heater integrated with the thermal storage material delivered comparatively higher temperatures; thus, giving a better efficiency than the air heater without the thermal storage system.
Directory of Open Access Journals (Sweden)
R. Sivakumar
2016-07-01
Full Text Available Flat Plate Solar Water Heater (FPSWH is commonly used to harvest solar energy. Solar concentration techniques help to achieve higher temperatures of energy. The aim of this article is to compare the performance of a Fresnel lens glazed Flat Plate Solar Water Heater with Phase Change Material (PCM with that provided with an ordinary glazing. The effect of solar concentration using Fresnel lens on energy storage in PCM and heat gained by water are studied and compared with that having an ordinary glazing. Experiments showed 47% improvements in the heat gained by water.
A figure of merit for selective absorbers in flat plate solar water heaters
CSIR Research Space (South Africa)
Roberts, DE
2013-12-01
Full Text Available We derive from first principles an analytical expression for a figure of merit (FM) for a selective solar absorber in a single glazed flat plate water heater. We first show that the efficiency of a collector with an absorber with absorptance α...
Production of fatty acids and protein by nannochloropsis in flat-plate photobioreactors
Hulatt, Chris J.; Wijffels, René H.; Bolla, Sylvie; Kiron, Viswanath
2017-01-01
Nannochloropsis is an industrially-promising microalga that may be cultivated for alternative sources of nutrition due to its high productivity, protein content and lipid composition. We studied the growth and biochemical profile of Nannochloropsis 211/78 (CCAP) in optimized flat-plate photobioreact
Internal (Annular) and Compressible External (Flat Plate) Turbulent Flow Heat Transfer Correlations.
Energy Technology Data Exchange (ETDEWEB)
Dechant, Lawrence [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Smith, Justin [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2016-01-01
Here we provide a discussion regarding the applicability of a family of traditional heat transfer correlation based models for several (unit level) heat transfer problems associated with flight heat transfer estimates and internal flow heat transfer associated with an experimental simulation design (Dobranich 2014). Variability between semi-empirical free-flight models suggests relative differences for heat transfer coefficients on the order of 10%, while the internal annular flow behavior is larger with differences on the order of 20%. We emphasize that these expressions are strictly valid only for the geometries they have been derived for e.g. the fully developed annular flow or simple external flow problems. Though, the application of flat plate skin friction estimate to cylindrical bodies is a traditional procedure to estimate skin friction and heat transfer, an over-prediction bias is often observed using these approximations for missile type bodies. As a correction for this over-estimate trend, we discuss a simple scaling reduction factor for flat plate turbulent skin friction and heat transfer solutions (correlations) applied to blunt bodies of revolution at zero angle of attack. The method estimates the ratio between axisymmetric and 2-d stagnation point heat transfer skin friction and Stanton number solution expressions for sub-turbulent Reynolds numbers %3C1x10 4 . This factor is assumed to also directly influence the flat plate results applied to the cylindrical portion of the flow and the flat plate correlations are modified by
Analysis of Blasius Equation for Flat-Plate Flow with Infinite Boundary Value
DEFF Research Database (Denmark)
Miansari, M. O.; Miansari, M. E.; Barari, Amin;
2010-01-01
This paper applies the homotopy perturbation method (HPM) to determine the well-known Blasius equation with infinite boundary value for Flat-plate Flow. We study here the possibility of reducing the momentum and continuity equations to ordinary differential equations by a similarity transformatio...
Analytical Solution of Forced-Convective Boundary-Layer Flow over a Flat Plate
DEFF Research Database (Denmark)
Mirgolbabaei, H.; Barari, Amin; Ibsen, Lars Bo
2010-01-01
In this letter, the problem of forced convection heat transfer over a horizontal flat plate is investigated by employing the Adomian Decomposition Method (ADM). The series solution of the nonlinear differential equations governing on the problem is developed. Comparison between results obtained...
Energy Technology Data Exchange (ETDEWEB)
NONE
1998-03-01
The bibliography contains citations concerning the design and thermal efficiency of air and liquid type flat plate solar collectors. Topics include convection characteristics, methods to reduce heat loss, optical coatings, and corrosion prevention. Emphasis is on research and modeling. (Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)
Energy Technology Data Exchange (ETDEWEB)
NONE
1997-05-01
The bibliography contains citations concerning the design and thermal efficiency of air and liquid type flat plate solar collectors. Topics include convection characteristics, methods to reduce heat loss, optical coatings, and corrosion prevention. Emphasis is on research and modeling. (Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)
Flat plate solar collector design and performance. Citations from the NTIS data base
Hundemann, A. S.
1980-09-01
Federally funded research on the design and thermal efficiency of air and liquid type flat plate collectors is discussed. Topic areas cover convection characteristics, methods to reduce heat loss, optical coatings, and corrosion control. Emphasis of the bibliography is on basic research studies. This updated bibliography contains 196 citations, 36 of which are new entries to the previous edition.
Three-dimensional flow structures and unsteady forces on pitching and surging revolving flat plates
Percin, M.; Van Oudheusden, B.W.
2015-01-01
Tomographic particle image velocimetry was used to explore the evolution of three-dimensional flow structures of revolving low-aspect-ratio flat plates in combination with force measurements at a Reynolds number of 10,000. Two motion kinematics are compared that result in the same terminal condition
Hasheminejad, S. M.
2016-01-05
A series of flow visualizations were conducted to qualitatively study the development of streamwise counter-rotating vortices over a flat plate induced by triangular patterns at the leading edge of a flat plate. The experiments were carried out for a Reynolds number based on the pattern wavelength (λ) of 3080. The results depict the onset, development and breakdown of the vortical structures within the flat plate boundary layer. Moreover, the effect of one spanwise array of holes with diameter of 0.2λ (=3 mm) was examined. This investigation was done on two different flat plates with holes placed at the location x/λ = 2 downstream of the troughs and peaks. The presence of holes after troughs does not show any significant effect on the vortical structures. However, the plate with holes after peaks noticeably delays the vortex breakdown. In this case, the “mushroom-like” vortices move away from the wall and propagate downstream with stable vortical structures. The vortex growth is halted further downstream but start to tilt aside.
A Didactic Experiment and Model of a Flat-Plate Solar Collector
Gallitto, Aurelio Agliolo; Fiordilino, Emilio
2011-01-01
We report on an experiment performed with a home-made flat-plate solar collector, carried out together with high-school students. To explain the experimental results, we propose a model that describes the heating process of the solar collector. The model accounts quantitatively for the experimental data. We suggest that solar-energy topics should…
Analytical Solution of Forced-Convective Boundary-Layer Flow over a Flat Plate
DEFF Research Database (Denmark)
Mirgolbabaei, H.; Barari, Amin; Ibsen, Lars Bo;
2010-01-01
In this letter, the problem of forced convection heat transfer over a horizontal flat plate is investigated by employing the Adomian Decomposition Method (ADM). The series solution of the nonlinear differential equations governing on the problem is developed. Comparison between results obtained...
Lift Enhancement of a Vortex-Sink Attached to a Flat Plate
Xia, Xi; Mohseni, Kamran
2012-01-01
As observed in natural fliers, stabilized vortices on the surface of an airfoil or wing could provide lift enhancement. Similar concept can be applied in fixed lifting surfaces. Potential flow theory is employed to model lift enhancement by attaching a vortex-sink pair to the top surface of a flat plate in a pseudo-steady flow. Using this flow model, a parametric study on the location of the vortex-sink pair is performed in order to optimize lift enhancement. Lift coefficient calculations are presented for a range of vortex-sink positions, vortex-sink strengths, and flat-plate angles of attack. It is shown that beyond the lift contribution terms due to the vortex-sink strength, lift enhancement could be also achieved by a translating velocity of the vortex-sink in a non-equilibrium position. This vortex-sink velocity term is more pronounced when the vortex-sink is placed close to the top surface of the flat-plate near the leading or the trailing edges of the flat plate. It is concluded that increasing the vor...
Hot-air flat-plate solar collector-design package
1979-01-01
Report contains design data, performance specifications, and drawings for hot-air flat-plate solar-energy collector. Evaluation consists of tests on thermal performance time constance, and incidence angle modifier test. Results are presented in table and graph form and are analyzed in detail.
Three-dimensional flow structures and unsteady forces on pitching and surging revolving flat plates
Percin, M.; Van Oudheusden, B.W.
2015-01-01
Tomographic particle image velocimetry was used to explore the evolution of three-dimensional flow structures of revolving low-aspect-ratio flat plates in combination with force measurements at a Reynolds number of 10,000. Two motion kinematics are compared that result in the same terminal condition
Simulation techniques for spatially evolving instabilities in compressible flow over a flat plate
Wasistho, B.; Geurts, B.J.; Kuerten, J.G.M.
1997-01-01
In this paper we present numerical techniques suitable for a direct numerical simulation in the spatial setting. We demonstrate the application to the simulation of compressible flat plate flow instabilities. We compare second and fourth order accurate spatial discretization schemes in combination w
Hot-air flat-plate solar collector-design package
1979-01-01
Report contains design data, performance specifications, and drawings for hot-air flat-plate solar-energy collector. Evaluation consists of tests on thermal performance time constance, and incidence angle modifier test. Results are presented in table and graph form and are analyzed in detail.
Repair of R/C flat plates failing in punching by vertical studs
Directory of Open Access Journals (Sweden)
Hamed S. Askar
2015-09-01
Test results showed that using the proposed system on repairing damaged flat plates due to punching shear is very efficient. Theoretical results obtained based on the formulas adopted by different codes and from the critical shear crack theory (CSCT, showed a satisfactory agreement with test results.
Hydrodynamics of the interceptor on a 2-D flat plate by CFD and experiments
Institute of Scientific and Technical Information of China (English)
MANSOORI M; FERNANDES A C
2015-01-01
Nowadays, the use of interceptor by both partial and total dynamic lift crafts is quite common. In this article, a lot of evidence is given regarding the effectiveness of interceptor. The interceptor, when placed at the stern region, changes the pressure distribution around the craft. Its presence affects drag force, lifting force and the position of pressure’s center leading to a new trim. This study focuses on hydrodynamic effects of interceptors on a 2-D flat plate based on both computational fluid dynamic (CFD) and experimental approaches. The Reynolds average Navier-Stokes (RANS) equations are used to model the flow around a fixed flat plate with an interceptor at different heights and attack angles. Based on finite volume method and SIMPLE algorithm which uses static structures, this model can be analyzed and the RANS results can be compared with the experimental data obtained in the current channel of the laboratory of waves and current of COPPE/UFRJ (LOC in Portuguese acronym). According to the results, the increase of pressure at the end of the flat plate was proportional to the interceptor height. In addition, the existence of interceptors can significantly increase the lift force coefficient at high angles of attack also proportional to the interceptor height. The presence of interceptor at the end of the flat plate increased both the lift coefficient and the drag coefficient but hydrodynamic drag did not grow as fast as the lift coefficient did. The lift coefficient increased much more. Furthermore, the results showed that the interceptor effectiveness is proportional to the boundary layer thickness at the end of the flat plate. As the interceptor was inside the boundary layer alterations of flow speed led to changes in boundary layer thickness, directly affecting interceptor’s efficiency. Optimum choice of interceptor height had a great effect on its efficiency, and in choosing it the flow speed and length of the boat must be taken into
Energy Technology Data Exchange (ETDEWEB)
None
1983-01-01
The Flat-Plate Solar Array Project, managed by the Jet Propulsion Laboratory for the US Department of Energy, has focused on advancing technologies relevant to the design and construction of megawatt-level central-station systems. Photovoltaic modules and arrays for flat-plate central-station or other large-scale electric power production facilities require the establishment of a technical base that resolves design issues and results in practical and cost-effective configurations. The Central Station Research Forum addressed design, qualification and maintenance issues related to central-station arrays derived from the engineering and operating experiences of early applications and parallel laboratory research activities. Technical issues were examined from the viewpoint of the utility engineer, architect-engineer and laboratory researcher. The forum included presentations on optimum source-circuit designs, module insulation design for high system voltages, array safety, structural interface design, measurements and array operation and maintenance. The Research Forum focused on current capabilities as well as design difficulties requiring additional technological thrusts and/or continued research emphasis. Session topic summaries highlighting major points during group discussions, identifying promising technical approaches or areas of future research, are presented.
Two-axis joint assembly and method
Le, Thang D. (Inventor); Lewis, James L. (Inventor); Carroll, Monty B. (Inventor)
2010-01-01
In an embodiment, a two-axis joint that utilizes planar reactions to handle moments applied to the side of the joint thereby allowing the device to remain low profile and compact with minimal intrusion to the mounting surface of the two-axis joint. To handle larger moments, the diameter of the planar member can be increased without increasing the overall height of the joint assembly thereby retaining the low profile thereof. Upper and lower antifriction bearings may be positioned within a housing engage the planar member to reduce rotational friction. The upper and lower bearings and a hub which supports the planar member transfer forces produced by moments applied to the side of the joint so as to spread the forces over the area of the housing.
Investigation of Shear Stud Performance in Flat Plate Using Finite Element Analysis
Directory of Open Access Journals (Sweden)
T.S. Viswanathan
2014-09-01
Full Text Available Three types of shear stud arrangement, respectively featuring an orthogonal, a radial and a critical perimeter pattern, were evaluated numerically. A numerical investigation was conducted using the finite element software ABAQUS to evaluate their ability to resist punching shear in a flat plate. The finite element analysis here is an application of the nonlinear analysis of reinforced concrete structures using three-dimensional solid finite elements. The nonlinear characteristics of concrete were achieved by employing the concrete damaged plasticity model in the finite element program. Transverse shear stress was evaluated using finite element analysis in terms of shear stress distribution for flat plate with and without shear stud reinforcement. The model predicted that shear studs placed along the critical perimeter are more effective compared to orthogonal and radial patterns.
Flat plate vs. concentrator solar photovoltaic cells - A manufacturing cost analysis
Granon, L. A.; Coleman, M. G.
1980-01-01
The choice of which photovoltaic system (flat plate or concentrator) to use for utilizing solar cells to generate electricity depends mainly on the cost. A detailed, comparative manufacturing cost analysis of the two types of systems is presented. Several common assumptions, i.e., cell thickness, interest rate, power rate, factory production life, polysilicon cost, and direct labor rate are utilized in this analysis. Process sequences, cost variables, and sensitivity analyses have been studied, and results of the latter show that the most important parameters which determine manufacturing costs are concentration ratio, manufacturing volume, and cell efficiency. The total cost per watt of the flat plate solar cell is $1.45, and that of the concentrator solar cell is $1.85, the higher cost being due to the increased process complexity and material costs.
Influences of the Twisted Strips Insertion on the Performance of Flat Plate Water Solar Collector
Directory of Open Access Journals (Sweden)
Jafar M. Hassan
2015-09-01
Full Text Available In order to enhance the efficiency of flat plate solar water collectors without changing in its original shape and with low additional cost, twisted strips are inserted inside its riser pipes. Three flat plate collectors are used for test. Family of twisted strips are inserted inside each collector risers with different twisted ratios (TR=3,4,5. The collectors are connected in parallel mode (Z-Configuration and are exposed to the same conditions (solar radiation and ambient temperature .The experimental results show that, the highest heat transfer rate occurs at twisted ratio (3 .Consequently, for the same twisted ratio the daily efficiencies for the solar collector at different flow rate used (60,100 and 150 ℓ /hr. were 49 %, 57% and 63% respectively.
Recommendations for the performance rating of flat plate terrestrial photovoltaic solar panels
Treble, F. C.
1976-01-01
A review of recommendations for standardizing the performance rating of flat plate terrestrial solar panels is given to develop an international standard code of practice for performance rating. Required data to characterize the performance of a solar panel are listed. Other items discussed are: (1) basic measurement procedures; (2) performance measurement in natural sunlight and simulated sunlight; (3) standard solar cells; (4) the normal incidence method; (5) global method and (6) definition of peak power.
Simon, F.
1975-01-01
A Soltex flat plate solar collector was tested with a solar simulator for inlet temperatures of 77 to 201 F, flux levels of 240 and 350 Btu/hr-sq ft, a collant flow rate of 10.5 lb/hr sq ft, and incident angles of 0 deg, 41.5 deg, and 65.2 deg. Collector performance is correlated in terms of inlet temperature, flux level, and incident angle.
Energy Technology Data Exchange (ETDEWEB)
None
1983-11-15
A Photovoltaic Metallization Research Forum, under the sponsorship of the Jet Propulsion Laboratory's Flat-Plate Solar Array Project and the US Department of Energy, was held March 16-18, 1983 at Pine Mountain, Georgia. The Forum consisted of five sessions, covering (1) the current status of metallization systems, (2) system design, (3) thick-film metallization, (4) advanced techniques and (5) future metallization challenges. Twenty-three papers were presented.
A DC corona discharge on a flat plate to induce air movement
Magnier, Pierre; Hong, Dunpin; Leroy-Chesneau, Annie; Pouvesle, Jean-Michel; Hureau, Jacques
2007-01-01
International audience; This paper describes a DC surface corona discharge designed to modify the airflow around a flat plate. The electrode configuration consisted of two thin copper layers placed on each side of the plate's attack edge. Discharge optical measurements with a photomultiplier tube indicated that the light emitted by the plasma is pulsating, at a frequency that increases with applied voltage. Moreover, with voltage higher than a threshold value, the electric discharge changes r...
Thermal performance optimization of a flat plate solar air heater using genetic algorithm
Energy Technology Data Exchange (ETDEWEB)
Varun; Siddhartha [Department of Mechanical Engineering, National Institute of Technology, Hamirpur 177 005 (H.P.) (India)
2010-05-15
Thermal performance of solar air heater is low and different techniques are adopted to increase the performance of solar air heaters, such as: fins, artificial roughness etc. In this paper an attempt has been done to optimize the thermal performance of flat plate solar air heater by considering the different system and operating parameters to obtain maximum thermal performance. Thermal performance is obtained for different Reynolds number, emissivity of the plate, tilt angle and number of glass plates by using genetic algorithm. (author)
Flat Plate Wake Velocity Statistics Obtained With Circular And Elliptic Trailing Edges
Rai, Man Mohan
2016-01-01
The near wake of a flat plate with circular and elliptic trailing edges is investigated with data from direct numerical simulations. The plate length and thickness are the same in both cases. The separating boundary layers are turbulent and statistically identical. Therefore the wake is symmetric in the two cases. The emphasis in this study is on a comparison of the wake-distributions of velocity components, normal intensity and fluctuating shear stress obtained in the two cases.
A graphical approach to the efficiency of flat-plate collectors
Selcuk, M. K.
1978-01-01
A nomogram is described which can be used to determine the thermal performance of flat plate solar collectors, resulting in two performance factors: the net absorptance and the net heat loss coefficient. The nomogram takes into account angle of incidence, collector slope, absorber plate design, insulating materials, thicknesses, optical properties of absorbing surfaces and glazing materials, and flow factors. A case example is given to illustrate the use of the nomogram.
A Dynamic Multinode Model for Component-Oriented Thermal Analysis of Flat-Plate Solar Collectors
Reiter, Christoph N.; Christoph Trinkl; Wilfried Zörner; Hanby, Vic I.
2015-01-01
A mathematical model of a flat-plate solar collector was developed on the basis of the physical principles of optics and heat transfer in order to determine collector’s component temperatures as well as collector efficiency. In contrast to many available models, the targeted use of this dynamic model is the detailed, theoretical investigation of the thermal behaviour of newly developed or adjusted collector designs on component level, for example, absorber, casing, or transparent cover. The d...
Semicoarsening and Implicit Smoothers for the Simulation of a Flat Plate at Yaw
2001-05-01
Semicoarsening and Implicit Smoothers for the Simulation of a Flat Plate at Yaw Ruben S. Montero and Ignacio M. Llorente Universidad Complutense , Madrid...yDepartamento de Arquitectura de Computadores y Automatica, Universidad Complutense , 28040 Madrid, Spain zDepartamento de Arquitectura de Computadores...y Automatica, Universidad Complutense , 28040 Madrid, Spain xICASE, Mail Stop 132C, NASA Langley Research Center, Hampton, VA 23681-2199 1
Design and performance of tubular flat-plate solid oxide fuel cell
Energy Technology Data Exchange (ETDEWEB)
Matsushima, T.; Ikeda, D.; Kanagawa, H. [NTT Integrated Information & Energy Systems Labs., Tokyo (Japan)] [and others
1996-12-31
With the growing interest in conserving the environmental conditions, much attention is being paid to Solid Oxide Fuel Cell (SOFC), which has high energy-conversion efficiency. Many organizations have conducted studies on tubular and flat type SOFCs. Nippon Telegraph and Telephone Corporation (NTT) has studied a combined tubular flat-plate SOFC, and already presented the I-V characteristics of a single cell. Here, we report the construction of a stack of this SOFC cell and successful generation tests results.
Tahavvor, Ali Reza
2016-06-01
In the present study artificial neural network and fractal geometry are used to predict frost thickness and density on a cold flat plate having constant surface temperature under forced convection for different ambient conditions. These methods are very applicable in this area because phase changes such as melting and solidification are simulated by conventional methods but frost formation is a most complicated phase change phenomenon consists of coupled heat and mass transfer. Therefore conventional mathematical techniques cannot capture the effects of all parameters on its growth and development because this process influenced by many factors and it is a time dependent process. Therefore, in this work soft computing method such as artificial neural network and fractal geometry are used to do this manner. The databases for modeling are generated from the experimental measurements. First, multilayer perceptron network is used and it is found that the back-propagation algorithm with Levenberg-Marquardt learning rule is the best choice to estimate frost growth properties due to accurate and faster training procedure. Second, fractal geometry based on the Von-Koch curve is used to model frost growth procedure especially in frost thickness and density. Comparison is performed between experimental measurements and soft computing methods. Results show that soft computing methods can be used more efficiently to determine frost properties over a flat plate. Based on the developed models, wide range of frost formation over flat plates can be determined for various conditions.
Tahavvor, Ali Reza
2017-03-01
In the present study artificial neural network and fractal geometry are used to predict frost thickness and density on a cold flat plate having constant surface temperature under forced convection for different ambient conditions. These methods are very applicable in this area because phase changes such as melting and solidification are simulated by conventional methods but frost formation is a most complicated phase change phenomenon consists of coupled heat and mass transfer. Therefore conventional mathematical techniques cannot capture the effects of all parameters on its growth and development because this process influenced by many factors and it is a time dependent process. Therefore, in this work soft computing method such as artificial neural network and fractal geometry are used to do this manner. The databases for modeling are generated from the experimental measurements. First, multilayer perceptron network is used and it is found that the back-propagation algorithm with Levenberg-Marquardt learning rule is the best choice to estimate frost growth properties due to accurate and faster training procedure. Second, fractal geometry based on the Von-Koch curve is used to model frost growth procedure especially in frost thickness and density. Comparison is performed between experimental measurements and soft computing methods. Results show that soft computing methods can be used more efficiently to determine frost properties over a flat plate. Based on the developed models, wide range of frost formation over flat plates can be determined for various conditions.
REVIEW ON POROUS AND NON-POROUS FLAT PLATE AIR COLLECTOR WITH MIRROR ENCLOSURE
Directory of Open Access Journals (Sweden)
M. PRADHAPRAJ,
2010-09-01
Full Text Available In solar air heater, flat plat collectors are the best heat transferring devices. But the effectiveness of these collectorsis very low because of lack of technology. Solar assisted heated air is successfully used for drying applications and space heating under controlled conditions. From the solar flat plate air heater the hot air is transferred to a conventional dryer or to the combined heater and drying chamber directly. Hence, solar assisted air heaters arecheaper and reliable. The important factors affecting these systems are the solar radiation, mechanical loading, temperature and leakage. The air heater efficiency depends on the design of the system as well as the construction materials and the assembly. The solar air heating systems has acceptable life span of 15 to 20 years. The addition ofside mirror enclosures is to increase the amount of solar radiation absorption at the collector plate so that the collector increases the yield and operate in a higher temperature range. Therefore with the addition of side mirrors one can able to maximize the output of fixed flat plate collectors. A flat plate air collector will be more efficient if it is made up of porous medium when comparing it with the non porous collectors according to the study. In this paper, the performances of porous and non-porous absorber plates are discussed. Also the possible methods of finding out air leakages and the methodology adopted for the performance and efficiency calculations are also discussed.
Shaw, C. S.; Margason, R. J.
1973-01-01
The induced static pressures due to a highly underexpanded sonic jet ejecting normally from a flat plate into a subsonic crosswind have been investigated. These pressure data have been recorded on the flat plate for a range of nominal jet-to-free-stream dynamic-pressure ratios from 0 to 1000 at free-stream Mach numbers of 0.1, 0.2, 0.4, and 0.6. The static pressure data measured on the flat plate are presented and correlated based upon the Riemann shock geometry in the jet plume. This data correlation improves with increasing free-stream Mach number.
Optimization of a flat plate glass reactor for mass production of Nannochloropsis sp. outdoors.
Richmond, A; Cheng-Wu, Z
2001-02-23
The relationships between areal (g m(-2) per day) and volumetric (g l(-1) per day) productivity of Nannochloropsis sp. as affected by the light-path (ranging from 1.3 to 17.0 cm) of a vertical flat plate glass photobioreactor were elucidated. In general, the shorter the length of the light-path (LP), the smaller the areal volume and the higher the volumetric productivity. The areal productivity in relation to the light-path, in contrast, yielded an optimum curve, the highest areal productivity was obtained in a 10 cm LP reactor, which is regarded, therefore, optimal for mass production of Nannochloropsis. An attempt was made to identify criteria by which to assess the efficiency of a photobioreactor in utilizing strong incident energy. Two basic factors which relate to reactor efficiency and its cost-effectiveness have been defined as (a) the total illuminated surface required to produce a set quantity of product and (b) culture volume required to produce that quantity. As a general guide line, the lower these values are, the more efficient and cost-effective the reactor would be. An interesting feature of this analysis rests with the fact that an open raceways is as effective in productivity per illuminated area as a flat-plate reactor with an optimal light path, both cultivation systems requiring ca. 85 m(2) of illuminated surface to produce 1 kg dry cell mass of Nannochloropsis sp. per day. The difference in light utilization efficiency between the two very different production systems involves three aspects - first, the open raceway requires ca. 6 times greater volume than the 10 cm flat plate reactor to produce the same quantity of cell-mass. Second, the total ground area (i.e. including the ground area between reactors) for the vertical flat plate reactor is less than one half of that occupied by an open raceway, indicating the former is more efficient, photosynthetically, compared with the latter. Finally, the harvested cell density is close to one order of
On the Design of an Optimal Waveform to Maximize Scattering from a Flat Plate and a Cone
2007-11-02
direction. This report examines such a possibility. To simplify the problem, the edge effect and creeping waves are neglected. We first review the general scattering problem of a flat plate and a cone.
Digital Repository Service at National Institute of Oceanography (India)
Murty, T.V.R.
Thermal boundary layer on a continuously moving semi-infinite flat plate in the presence of transverse magnetic field with heat flux has been examined. Similarity solutions have been derived and the resulting equations are integrated numerically...
Schwarz, Mark A.; Kent, Craig J.; Bousquet, Robert; Brown, Steven W.
2015-01-01
This work describes the development of an improved vacuum compatible flat plate radiometric source used for characterizing and calibrating remote optical sensors, in situ, throughout their testing period. The original flat plate radiometric source was developed for use by the VIIRS instrument during the NPOESS Preparatory Project (NPP). Following this effort, the FPI has had significant upgrades in order to improve both the radiometric throughput and uniformity. Results of the VIIRS testing with the reconfigured FPI are reported and discussed.
A SIMILARITY METHOD FOR LAMINAR WAKE OF POWER-LAW FLUID FLOW AROUND A FLAT PLATE
Institute of Scientific and Technical Information of China (English)
Liu Cun-fang; Wang Mei-xia
2003-01-01
Based on the characteristic equation for power-law fluid and the Prandtl boundary layer equation, using the similarity method similar to that of Newtonian fluids, two similarity variables were given and a normal differential equation was derived for the laminar wake of power-law fluid flow produced by a flat plate. And numerical results were obtained. The results show that the power-law index n has evident influence on the velocity distribution in the wake. In the wake, velocity gradient is larger, and the wake is narrower for larger n.
Heat transfer from impinging jets to a flat plate with conical and ring protuberances
Hrycak, P.
1984-01-01
An experimental investigation of heat transfer from round jets, impinging normally on a flat plate with exchangeable, heat transfer enhancing protuberances, has been carried out, and the pertinent literature surveyed, for Reynolds numbers ranging from 14,000 to 67,000, and nozzle diameters from 3.18 to 9.52 mm. The experimental data at the stagnation point indicated laminar flow, and a significant enhancement of heat transfer there, due to the introduction of the spike protuberance; the ring protuberance reduced the local heat flux somewhat. Data have also been correlated by means of dimensional analysis and compared with the conical flow theory.
Stall flutter and nonlinear divergence of a two-dimensional flat plate wing
Dugundji, J.; Aravamudan, K.
1976-01-01
Tests were conducted in a small wind tunnel to study the torsional stall flutter behavior of a two-dimensional flat-plate wing pivoted about the midchord. The nonlinear static divergence equilibrium properties of the wing were well predicted from the measured static moment characteristics. Large amplitude limit cycles ranging from plus or minus 11 degrees to plus or minus 100 degrees were observed. Stall flutter occurred above a critical value of a reduced frequency of about 2. Self-excitation occurred for initial angles of attack between 0 and 8 degrees. Nondimensional harmonic coefficients were extracted from the free transient vibration tests for amplitudes up to 80 degrees.
Evaluation of All-Day-Efficiency for selected flat plate and evacuated tube collectors
1981-01-01
An evaluation of all day efficiency for selected flat plate and evacuated tube collectors is presented. Computations are based on a modified version of the NBSIR 78-1305A procedure for all day efficiency. The ASHMET and NOAA data bases for solar insolation are discussed. Details of the algorithm used to convert total (global) horizontal radiation to the collector tilt plane of the selected sites are given along with tables and graphs which show the results of the tests performed during this evaluation.
Monitoring of a flat plate solar thermal field supplying process heat
Directory of Open Access Journals (Sweden)
Cozzini Marco
2016-01-01
Full Text Available The article reports the performance data of a flat plate collector field installed in Austria and supplying process heat to a meat factory, up to a temperature of about 95 °C. The presented data span an entire year, thereby including seasonal effects and allowing for a full characterization of the system performances. Sensor uncertainty is also discussed in detail. Finally, a bin method analysis of the field efficiency is provided. To this purpose, different operating conditions are concisely represented by the so-called reduced temperature, typically used in solar collector applications.
Merges, V.; Klippel, E.
1983-12-01
A solar plant with 21 sq m of highly efficient flat plate collectors and which requires no electricity is described. Heat transport is provided by saturated steam that condenses in a four cubic meter storage tank. The operation temperature is set by the buffer gas pressure between 100 and 140 C, and an absorption chiller is simulated as a heat consumer. The solar collectors were observed to exhibit high performance. Heat transport and temperature control offered high reliability and the thermal stratification in the tank was satisfactory. The positive result permits the design and construction of larger solar plants following the same technical principles.
DEFF Research Database (Denmark)
Hosseinzadeh, Elham; Taherian, Hessam
2012-01-01
On an average about 40% of world energy is used in residential buildings and the largest energy consumption is allocated to the cooling and air-conditioning systems. So every attempt to economize energy consumption is very valuable. In this research a nocturnal radiative cooling system with flat...... as a guideline to derive the governing equations of a night sky radiator. Then, a cooling loop, including a storage tank, pump, connecting pipes, and a radiator has been studied experimentally. The water is circulated through the unglazed flat-plate radiator having 4 m2 of collector area at night to be cooled...
Koller, Anja Pia; Löwe, Hannes; Schmid, Verena; Mundt, Sabine; Weuster-Botz, Dirk
2017-02-01
Light-dependent growth of microalgae can vary remarkably depending on the cultivation system and microalgal strain. Cell size and the pigmentation of each strain, as well as reactor geometry have a great impact on absorption and scattering behavior within a photobioreactor. In this study, the light-dependent, cell-specific growth kinetics of a novel green algae isolate, Scenedesmus obtusiusculus, was studied in a LED-illuminated flat-plate photobioreactor on a lab-scale (1.8 L, 0.09 m(2) ). First, pH-controlled batch processes were performed with S. obtusiusculus at different constant incident photon flux densities. The best performance was achieved by illuminating S. obtusiusculus with 1400 μmol photons m(-2) s(-1) at the surface of the flat-plate photobioreactor, resulting in the highest biomass concentration (4.95 ± 0.16 gCDW L(-1) within 3.5 d) and the highest specific growth rate (0.22 h(-1) ). The experimental data were used to identify the kinetic parameters of different growth models considering light inhibition for S. obtusiusculus. Light attenuation within the flat-plate photobioreactor was considered by varying light transfer models. Based on the identified kinetic growth model of S. obtusiusculus, an optimum growth rate of 0.22 h(-1) was estimated at a mean integral photon flux density of 1072 μmol photons m(-2) s(-1) with the Beer-Lambert law and 1590 μmol photons m(-2) s(-1) with Schuster's light transfer model in the flat-plate photobioreactor. LED illumination was, thus, increased to keep the identified optimum mean integral photon flux density constant in the batch process assuming Schuster's light transfer model. Compared to the same constant incident photon flux density (1590 μmol photons m(-2) s(-1) ), biomass concentration was up to 24% higher using the lighting profile until a dry cell mass concentration of 14.4 ± 1.4 gCDW L(-1) was reached. Afterward, the biomass concentration remained
A Study of Under-expanded Moist Air Jet Impinging on a Flat Plate
Institute of Scientific and Technical Information of China (English)
Yumiko OTOBE; Shigeru MATSUO; Masanori TANAKA; Hideo KASHIMURA; Heuy-Dong KIM; Toshiaki SETOGUCHI
2005-01-01
When a gas expands through a convergent nozzle in which the ratio of the ambient to the stagnation pressures is higher than that of the critical one, the issuing jet from the nozzle is under-expanded. If a flat plate is placed normal to the jet at a certain distance from the nozzle, a detached shock wave is formed at a region between the nozzle exit and the plate. In general, supersonic moist air jet technologies with non-equilibrium condensation are very often applied to industrial manufacturing processes. In spite of the importance in major characteristics of the supersonic moist air jets impinging to a solid body, its qualitative characteristics are not known satisfactorily. In the present study, the effect of the non-equilibrium condensation on the under-expanded air jet impinging on a vertical flat plate is investigated numerically in the case with non-equilibrium condensation, frequency of oscillation for the flow field becomes larger than that without the non-equilibrium condensation, and amplitudes of static pressure become small compared with those of dry air. Furthermore, the numerical results are compared with experimental ones.
Relaminarization of the boundary layer over a flat plate in shock tube experiments
Hinckel, J. N.; Nagamatsu, H. T.
1986-01-01
The relaminarization of the boundary layer over a flat plate in the shock tube was investigated by using the partially reflected shock wave technique. The flow Mach number was approximately 0.14, which corresponds to the inleft flow Mach number for the first row of vanes in a gas turbine. The thin film platinum heat gauges were used to measure the heat transfer rate and the Stanton number was calculated from the oscilloscope voltage traces. The Reynolds number was varied by changing the operation pressure of the shock tube and the values varied from 2.3 x 10 to the 4th to 5.3 x 10 to the 5th. For a Reynolds number range of 7 x 10 to the 4th to 3.5 x 10 to the 5th, the relaminarization of the boundary layer was observed. This phenomenon is due to the decay of the turbulence level in the flow as the reflected shock wave moves upstream from the flat plate. As the Reynolds number increased, the relaminarization was delayed and the delay was related to the turbulence generated by the reflected shock wave.
Experimental testing of various heat transfer structures in a flat plate thermal energy storage unit
Johnson, Maike; Fiß, Michael; Klemm, Torsten
2016-05-01
For solar process heat applications with steam as the working fluid and varying application parameters, a novel latent heat storage concept has been developed using an adaptation of a flat plate heat exchanger as the storage concept. Since the pressure level in these applications usually does not exceed 30 bar, an adaptation with storage material chambers arranged between heat transfer medium chambers is possible. Phase change materials are used as the storage medium, so that the isothermal evaporation of steam during discharging of the storage is paired with the isothermal solidification of the storage material. Heat transfer structures can be inserted into the chambers to adjust the power level for a given application. By combining the required number of flat plate heat exchanger compartments and inserting the appropriate heat transfer structure, the design can easily be adjusted for the required power level and capacity for a specific application. Within this work, the technical feasibility of this concept is proven. The dependence of the operating characteristics on the geometry of the heat exchanger is identified. A focus is on varying the power density by integrating conductive heat structures in the PCM.
Three-Dimensional Stress and Stress Intensity for Tensioned Flat Plates with Edge Cracks
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
The stress in the thickness direction is an important factor influencing the fracture behavior of structural members. A stress бy tensioned flat plate with edge cracks is widely used as an analysis model. The stresses бx and бy for the plate model can be acquired from Neuber's solution. However, the solution is applicable only for a perfect plane stress or plane strain state. As a consequence of the thickness of the plate a three-dimensional (3-D) stress state will arise near the crack tip, resulting in a variation of the distribution of бx and бy stresses. A full analysis for the 3-D stress fields for a tensioned flat plate with edge cracks has been therefore carried out. The results show that the 3-D stress field near the crack tip is mainly determined by two factors: the thickness of the plate and the curvature radius at the crack tip. A further analysis has been carried out for the stress intensity near the crack tip. In this paper we give some equations matching to the 3-D stress and stress intensity, which describe precisely the stress state near the crack tip, and which can be applied effectively in engineering analysis.
Development of electromagnetic welding facility of flat plates for nuclear industry
Kumar, Rajesh; Sahoo, Subhanarayan; Sarkar, Biswanath; Shyam, Anurag
2017-04-01
Electromagnetic pulse welding (EMPW) process, one of high speed welding process uses electromagnetic force from discharged current through working coil, which develops a repulsive force between the induced current flowing parallel and in opposite direction. For achieving the successful weldment using this process the design of working coil is the most important factor due to high magnetic field on surface of work piece. In case of high quality flat plate welding factors such as impact velocity, angle of impact standoff distance, thickness of flyer and overlap length have to be chosen carefully. EMPW has wide applications in nuclear industry, automotive industry, aerospace, electrical industries. However formability and weldability still remain major issues. Due to ease in controlling the magnetic field enveloped inside tubes, the EMPW has been widely used for tube welding. In case of flat components control of magnetic field is difficult. Hence the application of EMPW gets restricted. The present work attempts to make a novel contribution by investigating the effect of process parameters on welding quality of flat plates. The work emphasizes the approaches and engineering calculations required to effectively use of actuator in EMPW of flat components.
MHD Boundary Layer Slip Flow and Heat Transfer over a Flat Plate
Institute of Scientific and Technical Information of China (English)
Krishnendu Bhattacharyya; Swati Mukhopadhyay; G.C.Layek
2011-01-01
An analysis of magnetohydrodynamic (MHD) boundary layer flow and heat transfer over a flat plate with slip condition at the boundary is presented. A complete self-similar set of equations are obtained from the governing equations using similarity transformations and are solved by a shooting method. In the boundary slip condition no local similarity occurs. Velocity and temperature distributions within the boundary layer are presented. Our analysis reveals that the increase of magnetic and slip parameters reduce the boundary layer thickness and also enhance the heat transfer from the plate.%@@ An analysis of magnetohydrodynamic (MHD) boundary layer flow and heat transfer over a flat plate with slip condition at the boundary is presented.A complete self-similar set of equations are obtained from the governing equations using similarity transformations and are solved by a shooting method.In the boundary slip condition no local similarity occurs.Velocity and temperature distributions within the boundary layer are presented.Our analysis reveals that the increase of magnetic and slip parameters reduce the boundary layer thickness and also enhance the heat transfer from the plate.
Flat-plate solar-collector performance data base and user's manual
Kirkpatrick, D. L.; Kolar, W. A.
1983-07-01
The reader is provided with a thorough understanding on the type of collector thermal performance information which is required in active system design and analysis. Thermal performance test data on 109 commercially available solar collectors which were evaluated in a single, uniform test program, the Interim Solar Collector Test (ISCT) Program are given. In addition to recounting the ISCT program and its results, the an introduction is given on the engineering and physics of a flat-plate solar collector operation. A step-by-step analysis of heat gains and losses is provided to help the reader understand both the source and applicability of the parameters used to describe collector thermal performance. A brief description of the engineering basis for the ASHRAE Standard 93-77 test procedure and the method are included. To demonstrate the sensitivity to variations of collector performance parameters of the annual output of representative solar heating systems, three sets of F-Chart (4.0) system performance predictions are given. Finally, a sensitivity analysis study is presented which considers the heat loss and optical gain parameters of flat-plate collectors, in terms of how they affect the overall solar heating system solar fraction.
Directory of Open Access Journals (Sweden)
Hiroshi Tanaka
2015-11-01
Full Text Available Augmentation of solar radiation absorbed on a flat plate solar thermal collector by a flat plate bottom reflector was numerically determined when there was a gap between the collector and reflector. The inclination of both the collector and reflector was assumed to be adjustable according to the season. A mirror-symmetric plane of the collector to the reflector was introduced, and a graphical model was proposed to calculate the amount of solar radiation reflected by the reflector and then absorbed on the collector. The performance was analyzed for three typical days at a latitude of 30°N. Solar radiation absorbed on the collector can be increased by the bottom reflector even if there is a gap between the collector and reflector. The optimum inclinations of both the collector and reflector are almost the same while the gap length is less than the lengths of the collector and reflector. However, the range of inclination of the reflector that can increase the solar radiation absorbed on the collector decreases with an increase in gap length, and the solar radiation absorbed on the collector rapidly decreased with an increase in the gap length when the reflector and/or collector were not set at a proper angle.
Directory of Open Access Journals (Sweden)
Mohamed Hassan
2017-03-01
Full Text Available Flat plates are favor structure systems usually used in parking garages and high-rise buildings due to its simplicity for construction. However, flat plates have some inherent structural problems, due to high shear stress surrounding the supporting columns which cause a catastrophic brittle type of failure called "Punching Shear Failure". Several solutions are used to avoid punching shear failure, including the use of drop panels or punching shear reinforcement. The latter is being a more sophisticated solution from the structural ductility, the architectural and the economical point of view. This study aims at investigating the effect of stirrups as shear reinforcement in enhancing the punching strength of interior slab-column connections. A total of four full-scale interior slab-column connections were tested up to failure. All slabs had a side length of 1700 mm and 160 mm thickness with 200 mm x 200 mm square column. The test parameters were the presence of shear reinforcement and stirrups concentration around the supporting column. The test results showed that the distribution of stirrups over the critical punching shear zone was an efficient solution to enhance not only the punching shear capacity but also the ductility of the connection. Furthermore, the concentrating of stirrups shear reinforcement in the vicinity of the column for the tested slabs increases the punching shear capacity by 13 % compared to the uniform distribution at same amount of shear reinforcement.
Schwarz, Mark A.; Kent, Craig J.; Bousquet, Robert; Brown, Steven W.
2016-09-01
In this work, we describe an improved thermal-vacuum compatible flat plate radiometric source which has been developed and utilized for the characterization and calibration of remote optical sensors. This source is unique in that it can be used in situ, in both ambient and thermal-vacuum environments, allowing it to follow the sensor throughout its testing cycle. The performance of the original flat plate radiometric source was presented at the 2009 SPIE1. Following the original efforts, design upgrades were incorporated into the source to improve both radiometric throughput and uniformity. The pre-thermal-vacuum (pre-TVAC) testing results of a spacecraft-level optical sensor with the improved flat plate illumination source, both in ambient and vacuum environments, are presented. We also briefly discuss potential FPI configuration changes in order to improve its radiometric performance. Keywords: Calibration, radiometry, remote sensing, source.
Institute of Scientific and Technical Information of China (English)
Zhongmin WAN; Wei LIU; Zhaoqing ZHENG; A. Nakayama
2007-01-01
An overall two-dimensional numerical model of the miniature flat plate capillary pumped loop (CPL) evaporator is developed to describe the liquid and vapor flow, heat transfer and phase change in the porous wick structure,liquid flow and heat transfer in the compensation cavity and heat transfer in the vapor grooves and metallic wall.The entire evaporator is solved with SIMPLE algorithm as a conjugate problem. The effect of heat conduction of metallic side wall on the performance of miniature flat plate CPL evaporator is analyzed, and side wall effect heat transfer limit is introduced to estimate the performance of evaporator. The shape and location of vapor-liquid interface inside the wick are calculated and the influences of applied heat flux, liquid subcooling, wick material and metallic wall material on the evaporator performance are investigated in detail. The numerical results obtained are useful for the miniature flat plate evaporator performance optimization and design of CPL.
DSMC simulations of leading edge flat-plate boundary layer flows at high Mach number
Pradhan, Sahadev, , Dr.
2017-01-01
The flow over a 2D leading-edge flat plate is studied at Mach number Ma = (Uinf /√{kBTinf / m }) in the range Boltzmann constant. The variation of streamwise velocity, temperature, number-density, and mean free path along the wall normal direction away from the plate surface is studied. The qualitative nature of the streamwise velocity at high Mach number is similar to those in the incompressible limit (parabolic profile). However, there are important differences. The amplitudes of the streamwise velocity increase as the Mach number increases and turned into a more flatter profile near the wall. There is significant velocity and temperature slip at the surface of the plate, and the slip increases as the Mach number is increased. It is interesting to note that for the highest Mach numbers considered here, the streamwise velocity at the wall exceeds the sound speed, and the flow is supersonic throughout the flow domain.
Numerical analysis on thermal hydraulic performance of a flat plate heat pipe with wick column
Lu, Longsheng; Liao, Huosheng; Liu, Xiaokang; Tang, Yong
2015-08-01
A simplified thermal hydraulic model is developed to investigate the influence of wick column on the performance of a flat plate heat pipe (FPHP). The governing equations of the FPHP are solved by using the computational fluid dynamics package FLUENT. The temperature, velocity and pressure fields are obtained. The validity of the model is confirmed by comparing the present solutions with the open literature data. The numerical results show that with the increase of the wick column size, the maximum velocity of the liquid and vapor decreases while the total thermal resistance and capillary heat transfer limit of the FPHP increases gradually. The performance of the FPHP may degrade if the wick column is placed inside the vapor core asymmetrically.
Analytical and Numerical Solutions of Vapor Flow in a Flat Plate Heat Pipe
Directory of Open Access Journals (Sweden)
Mohsen GOODARZI
2012-03-01
Full Text Available In this paper, the optimal homotopy analysis method (OHAM and differential transform method (DTM were applied to solve the problem of 2D vapor flow in flat plate heat pipes. The governing partial differential equations for this problem were reduced to a non-linear ordinary differential equation, and then non-dimensional velocity profiles and axial pressure distributions along the entire length of the heat pipe were obtained using homotopy analysis, differential transform, and numerical fourth-order Runge-Kutta methods. The reliability of the two analytical methods was examined by comparing the analytical results with numerical ones. A brief discussion about the advantages of the two applied analytical methods relative to each other is presented. Furthermore, the effects of the Reynolds number and the ratio of condenser to evaporator lengths on the flow variables were discussed.Graphical abstract
Slip effects on MHD flow and heat transfer of ferrofluids over a moving flat plate
Ramli, Norshafira; Ahmad, Syakila; Pop, Ioan
2017-08-01
In this study, the problem of MHD flow and heat transfer of ferrofluids over a moving flat plate with slip effect and uniform heat flux is considered. The governing ordinary differential equations are solved via shooting method. The effect of slip parameter on the dimensionless velocity, temperature, skin friction and Nusselt numbers are numerically studied for the three selected ferroparticles; magnetite (Fe3O4), cobalt ferrite (CoFe2O4) and Mn-Zn ferrite (Mn-ZnFe2O4) with water-based fluid. The results indicate that dual solutions exist for a plate moving towards the origin. It is found that the slip process delays the boundary layer separation. Moreover, the velocity and thermal boundary-layer thicknesses decrease in the first solution while increase with the increase of the value of slip parameters in second solution.
Simulation and Experimental Investigation of Thermal Performance of a Miniature Flat Plate Heat Pipe
Directory of Open Access Journals (Sweden)
R. Boukhanouf
2013-01-01
Full Text Available This paper presents the results of a CFD analysis and experimental tests of two identical miniature flat plate heat pipes (FPHP using sintered and screen mesh wicks and a comparative analysis and measurement of two solid copper base plates 1 mm and 3 mm thick. It was shown that the design of the miniature FPHP with sintered wick would achieve the specific temperature gradients threshold for heat dissipation rates of up to 80 W. The experimental results also revealed that for localised heat sources of up to 40 W, a solid copper base plate 3 mm thick would have comparable heat transfer performances to that of the sintered wick FPHP. In addition, a marginal effect on the thermal performance of the sintered wick FPHP was recorded when its orientation was held at 0°, 90°, and 180° and for heat dissipation rates ranging from 0 to 100 W.
Experimental and numerical investigation of a flat-plate solar collector
Energy Technology Data Exchange (ETDEWEB)
Alvarez, A. [Departamento de Construcciones Navales, E.U. Politecnica, Universidade da Coruna, 15405 Ferrol (Spain); Cabeza, O. [Departamento de Fisica, Universidade da Coruna, 15072 A Coruna (Spain); Muniz, M.C. [Departamento de Matematica Aplicada, Universidade de Santiago de Compostela, 15782 Santiago de Compostela (Spain); Varela, L.M. [Departamento de Fisica de la Materia Condensada, Universidade de Santiago de Compostela, 15782 Santiago de Compostela (Spain)
2010-09-15
In the present paper we present an experimental analysis and a thermal and hydrodynamic modelling of a newly designed flat-plate solar collector characterized by its corrugated channel and by the high surface area directly in contact with the heat transport fluid. The thermal and hydrodynamic modelling of the collector has been performed by means of the Finite Element Method (FEM), validated with analytical results for a well-known fin-and-tube type solar collector. The thermodynamic efficiency of the collector is analyzed by means of its experimental heating curves. The yield of the new collector has been compared to a previously existing commercial collector of related geometry but with less area in direct contact with the heat transport fluid. The experimental results are seen to adequately fit the simulation predictions, and a methodology to use in order to compute the parameters characterizing the thermal behavior of the collector is introduced. (author)
Boundary Layer Flow and Heat Transfer of FMWCNT/Water Nanofluids over a Flat Plate
Directory of Open Access Journals (Sweden)
Mohammad Reza Safaei
2016-09-01
Full Text Available In the present study, the heat transfer and flow of water/FMWCNT (functionalized multi-walled carbon nanotube nanofluids over a flat plate was investigated using a finite volume method. Simulations were performed for velocity ranging from 0.17 mm/s to 1.7 mm/s under laminar regime and nanotube concentrations up to 0.2%. The 2-D governing equations were solved using an in-house FORTRAN code. For a specific free stream velocity, the presented results showed that increasing the weight percentage of nanotubes increased the Nusselt number. However, an increase in the solid weight percentage had a negligible effect on the wall shear stress. The results also indicated that increasing the free stream velocity for all cases leads to thinner boundary layer thickness, while increasing the FMWCNT concentration causes an increase in the boundary layer thickness.
Flat plate heat transfer for laminar transition and turbulent boundary layers using a shock tube
Brostmeyer, J. D.; Nagamatsu, H. T.
1984-01-01
Heat transfer results are presented for laminar, transition, and turbulent boundary layers for a Mach number of 0.12 with gas temperatures of 425 K and 1000 K over a flat plate at room temperature. The measurements were made in air for a Reynolds number range of 600 to 6 million. The heat transfer measurements were conducted in a 70-ft long, 4 in. diameter shock tube. Reflecting wedges were used to reflect the incident shock wave to produce a flow Mach number of 0.12 behind the reflected shock wave. Thin film platinum heat gages were mounted on the plate surface to measure the local heat flux. The laminar results for gas temperatures of 425 K to 1000 K agree well with theory. The turbulent results are also close to incompressible theory, with the 1000 K flow case being slightly higher. The transition results lie between the laminar and turbulent predictions.
Oki, Sae; Suzuki, Ryosuke O.
2016-09-01
The performance of a flat-plate thermoelectric (TE) module consisting of square truncated pyramid elements is simulated using commercial software and original TE programs. Assuming that the temperatures of both the hot and cold surfaces are constant, the performance can be varied by changing the element shape and element alignment pattern. When the angle between the edge and the base is 85° and the small square surfaces of all n-type element faces are connected to the low-temperature surface, the efficiency becomes the largest among all the 17 examined shapes and patterns. By changing the shape to match the temperature distribution, the performance of the TE module is maximized.
Flat-plate techniques for measuring reflectance of macro-algae (Ulva curvata)
Ramsey, Elijah W.; Rangoonwala, Amina; Thomsen, Mads Solgaard; Schwarzschild, Arthur
2012-01-01
We tested the consistency and accuracy of flat-plate spectral measurements (400–1000 nm) of the marine macrophyte Ulva curvata. With sequential addition of Ulva thallus layers, the reflectance progressively increased from 6% to 9% with six thalli in the visible (VIS) and from 5% to 19% with ten thalli in the near infrared (NIR). This progressive increase was simulated by a mathematical calculation based on an Ulva thallus diffuse reflectance weighted by a transmittance power series. Experimental and simulated reflectance differences that were particularly high in the NIR most likely resulted from residual water and layering structure unevenness in the experimental progression. High spectral overlap existed between fouled and non-fouled Ulva mats and the coexistent lagoon mud in the VIS, whereas in the NIR, spectral contrast was retained but substantially dampened by fouling.
Near Continuum Velocity and Temperature Coupled Compressible Boundary Layer Flow over a Flat Plate
He, Xin; Cai, Chunpei
2017-04-01
The problem of a compressible gas flows over a flat plate with the velocity-slip and temperature-jump boundary conditions are being studied. The standard single- shooting method is applied to obtain the exact solutions for velocity and temperature profiles when the momentum and energy equations are weakly coupled. A double-shooting method is applied if these two equations are closely coupled. If the temperature affects the velocity directly, more significant velocity slip happens at locations closer to the plate's leading edge, and inflections on the velocity profiles appear, indicating flows may become unstable. As a consequence, the temperature-jump and velocity-slip boundary conditions may trigger earlier flow transitions from a laminar to a turbulent flow state.
Fixed flat plate collector with a reversible vee-trough concentrator
Selcuk, M. K.
1976-01-01
An asymmetrical-reversible vee-trough concentrator for use both with nonevacuated and evacuated receivers is proposed in order to improve the performance of a fixed flat plate collector. The device is capable of maintaining a year-round concentration factor of about 2 while eliminating the complications of the tilt adjustments of the collector box assembly. Efficiency improvements and cost reductions for temperatures of about 100 and 200 C are offered for the nonvacuum and vacuum tube versions, respectively. A major advantage of the vee-trough is the enhancement of the incident flux, thus extending the collection period. The vacuum collector is suitable for supplying heat to solar Rankine systems, while the nonvacuum version can be used for air conditioning purposes via an absorption air conditioner.
Wake interference behind two flat plates normal to the flow - A finite-element study
Behr, M.; Tezduyar, T. E.; Higuchi, H.
1991-01-01
A finite-element model of the Navier-Stokes equations is used for numerical simulation of flow past two normal flat plates arranged side by side at Reynolds number 80 and 160. The results from this simulation indicate that when the gap between the plates is twice the width of a single plate, the individual wakes of the plates behave independently, with the antiphase vortex shedding being dominant. At smaller gap sizes, the in-phase vortex shedding, with strong wake interaction, is favored. The gap flow in those cases becomes biased, with one of the wakes engulfing the other. The direction of the biased flow was found to be switching at irregular intervals, with the time histories of the indicative flow parameters and their power spectra resembling those of a chaotic system.
Comparison of DAC and MONACO DSMC Codes with Flat Plate Simulation
Padilla, Jose F.
2010-01-01
Various implementations of the direct simulation Monte Carlo (DSMC) method exist in academia, government and industry. By comparing implementations, deficiencies and merits of each can be discovered. This document reports comparisons between DSMC Analysis Code (DAC) and MONACO. DAC is NASA's standard DSMC production code and MONACO is a research DSMC code developed in academia. These codes have various differences; in particular, they employ distinct computational grid definitions. In this study, DAC and MONACO are compared by having each simulate a blunted flat plate wind tunnel test, using an identical volume mesh. Simulation expense and DSMC metrics are compared. In addition, flow results are compared with available laboratory data. Overall, this study revealed that both codes, excluding grid adaptation, performed similarly. For parallel processing, DAC was generally more efficient. As expected, code accuracy was mainly dependent on physical models employed.
Coherent Structures in Transition of a Flat-Plate Boundary Layer at Ma=0.7
Institute of Scientific and Technical Information of China (English)
ZHOU Ying; LI Xin-Liang; FU De-Xun; MA Yan-Wen
2007-01-01
@@ Direct numerical simulation (DNS) of a spatially evolving flat-plate boundary layer transition process at free stream Mach number 0.7 is performed. Tollmien-Schlichting (T-S) waves are added on the inlet boundary as the disturbances before transition. Typical coherent structures in the transition process are investigated based on the second invariant of velocity gradient tensor. The instantaneous shear stress and the mean velocity profile in the transition region are studied. In our view, the fact that the peak value of shear stress in the stress concentration area increases and exceeds a threshold value during the later stage of the transition process plays an important role in the laminar breakdown process.
MHD Natural Convection with Convective Surface Boundary Condition over a Flat Plate
Directory of Open Access Journals (Sweden)
Mohammad M. Rashidi
2014-01-01
Full Text Available We apply the one parameter continuous group method to investigate similarity solutions of magnetohydrodynamic (MHD heat and mass transfer flow of a steady viscous incompressible fluid over a flat plate. By using the one parameter group method, similarity transformations and corresponding similarity representations are presented. A convective boundary condition is applied instead of the usual boundary conditions of constant surface temperature or constant heat flux. In addition it is assumed that viscosity, thermal conductivity, and concentration diffusivity vary linearly. Our study indicates that a similarity solution is possible if the convective heat transfer related to the hot fluid on the lower surface of the plate is directly proportional to (x--1/2 where x- is the distance from the leading edge of the solid surface. Numerical solutions of the ordinary differential equations are obtained by the Keller Box method for different values of the controlling parameters associated with the problem.
Multi-objective genetic algorithm for the optimization of a flat-plate solar thermal collector.
Mayer, Alexandre; Gaouyat, Lucie; Nicolay, Delphine; Carletti, Timoteo; Deparis, Olivier
2014-10-20
We present a multi-objective genetic algorithm we developed for the optimization of a flat-plate solar thermal collector. This collector consists of a waffle-shaped Al substrate with NiCrOx cermet and SnO(2) anti-reflection conformal coatings. Optimal geometrical parameters are determined in order to (i) maximize the solar absorptance α and (ii) minimize the thermal emittance ε. The multi-objective genetic algorithm eventually provides a whole set of Pareto-optimal solutions for the optimization of α and ε, which turn out to be competitive with record values found in the literature. In particular, a solution that enables α = 97.8% and ε = 4.8% was found.
Exergy efficiency analysis of a flat plate solar collector using graphene based nanofluid
Said, Z.; Alim, M. A.; Janajreh, Isam
2015-10-01
The thermal efficiency of a flat plate solar thermal collector is largely affected by the thermal conductivity of the fluid used. In this paper, we theoretically analyzed the heat transfer performance, the entropy generation rate, and the exergy efficiency of the two different graphene based nanofluids (graphene/Acetone and graphene/water). From the analyses, it is revealed that by inserting a small amount of graphene nanoparticles in water, exergy efficiency could be enhanced by 21%, comparing to conventional fluids and entropy generation is decreased by 4%. However, the graphene/water nanofluid shows a lower entropy generation. This characteristic suggests that graphene/water nanofluid is a better candidate for flat solar thermal application.
Potential of size reduction of flat-plate solar collectors when applying MWCNT nanofluid
Faizal, M.; Saidur, R.; Mekhilef, S.
2013-06-01
Flat-plate solar collector is the most popular type of collector for hot water system to replace gas or electric heater. Solar thermal energy source is clean and infinite to replace fossil fuel source that is declining and harmful to the environment. However, current solar technology is still expensive, low in efficiency and takes up a lot of space. One effective way to increase the efficiency is by applying high conductivity fluid as nanofluid. This paper analyzes the potential of size reduction of solar collector when MWCNT nanofluid is used as absorbing medium. The analysis is based on different mass flow rate, nanoparticles mass fraction, and presence of surfactant in the fluid. For the same output temperature, it can be observed that the collector's size can be reduced up to 37% of its original size when applying MWCNT nanofluid as the working fluid and thus can reduce the overall cost of the system.
Direct numerical simulation of laminar-turbulent flow over a flat plate at hypersonic flow speeds
Egorov, I. V.; Novikov, A. V.
2016-06-01
A method for direct numerical simulation of a laminar-turbulent flow around bodies at hypersonic flow speeds is proposed. The simulation is performed by solving the full three-dimensional unsteady Navier-Stokes equations. The method of calculation is oriented to application of supercomputers and is based on implicit monotonic approximation schemes and a modified Newton-Raphson method for solving nonlinear difference equations. By this method, the development of three-dimensional perturbations in the boundary layer over a flat plate and in a near-wall flow in a compression corner is studied at the Mach numbers of the free-stream of M = 5.37. In addition to pulsation characteristic, distributions of the mean coefficients of the viscous flow in the transient section of the streamlined surface are obtained, which enables one to determine the beginning of the laminar-turbulent transition and estimate the characteristics of the turbulent flow in the boundary layer.
Numerical 3-D heat flux simulations on flat plate solar collectors
Energy Technology Data Exchange (ETDEWEB)
Villar, N. Molero; Lopez, J.M. Cejudo; Munoz, F. Dominguez; Garcia, E. Rodriguez; Andres, A. Carrillo [Grupo de Energetica, Escuela Tecnica Superior de Ingenieros Industriales, UMA, Plaza El Ejido s/n, 29013 Malaga (Spain)
2009-07-15
A transient 3-D mathematical model for solar flat plate collectors has been developed. The model is based on setting mass and energy balances on finite volumes. The model allows the comparison of different configurations: parallel tubes collectors (PTC), serpentine tube collectors (STC), two parallel plate collectors (TPPC), and other non-usual possibilities like the use of absorbent fluids with semitransparent or transparent plates. Transparent honeycomb insulation between plate and cover can also be modelled. The effect of temperature on the thermal properties of the materials has also been considered. The model has been validated experimentally with a commercial PTC. The model is a useful tool to improve the design of plate solar collectors and to compare different configurations. In order to show the capabilities of the model, the performance of a PTC collector with non-uniformity flow is analysed and compared with experimental data from literature with good agreement. (author)
Xiao, Lan; Wu, Shuang-Ying; Zhang, Qiao-Ling; Li, You-Rong
2012-07-01
Based on the heat transfer characteristics of absorber plate and the heat transfer effectiveness-number of heat transfer unit method of heat exchanger, a new theoretical method of analyzing the thermal performance of heat pipe flat plate solar collector with cross flow heat exchanger has been put forward and validated by comparisons with the experimental and numerical results in pre-existing literature. The proposed theoretical method can be used to analyze and discuss the influence of relevant parameters on the thermal performance of heat pipe flat plate solar collector.
Batubara, Fatimah; Misran, Erni; Dina, Sari Farah; Heppy
2017-06-01
Research on potato drying using the indirect solar dryer with flat-plate finned collector and forced convection has been done. The research was conducted at the outdoor field of Laboratory of Institute for Research and Standardization of Industry on June 14th-23rd, 2016 from 9:00 am to 4:00 pm. This research aims to obtain the drying kinetics model of potato (Solanumtuberosum L.) using an indirect solar dryer's (ISD) with flat plate-finned collector and forced convection. The result will be compared to the open sun drying (OSD) method. Weather conditions during the drying process took place as follows; surrounding air temperature was in the range 27 to 34.7 °C, relative humidity (RH) 29.5 to 61.0% and the intensity of solar radiation 105.6 to 863.1 Watt/m2. The dried potato thicknesses were 1.0 cm, 1.5 cm and 2.0 cm, with the average initial water content of 76.46%. The average temperature in the collector chamber ranged from 42.2 to 57.4 °C and the drying chamber was at 46.2 °C. The best drying result was obtained from a sample size of 1 cm thickness using the IDS method with an average drying rate of 0.018 kg H2O per kg dry-weight.hour and the water content was constant at 5.02% in 21 hours of drying time. The most suitable kinetics model is Page model, equation MR = exp (-0.049 t1,336) for 1.0 cm thickness, exp (-0.066 t1,222) for 1.5 cm thickness and exp (-0.049 t1,221) for 2.0 cm thickness. The quality of potato drying using ISD method is better than using OSD which can be seen from the color produced.
Sensitivity analysis of thermal performances of flat plate solar air heaters
Njomo, Donatien; Daguenet, Michel
2006-10-01
Sensitivity analysis is a mathematical tool, first developed for optimization methods, which aim is to characterize a system response through the variations of its output parameters following modifications imposed on the input parameters of the system. Such an analysis may quickly become laborious when the thermal model under consideration is complex or the number of input parameters is high. In this paper, we develop a mathematical model to analyse the heat exchanges in four different types of solar air collectors. When building this thermal model we show that for each collector, at quasi-steady state, the energy balance equations of the components of the collector cascade into a single first-order non-linear differential equation that is able to predict the thermal behaviour of the collector. Our heat transfer model clearly demonstrates the existence of an important dimensionless parameter, referred to as the thermal performance factor of the collector, that compares the useful thermal energy which can be extracted from the heater to the overall thermal losses of that collector for a given set of input parameters. A sensitivity analysis of our thermal model has been performed for the most significant input parameters such as the incident solar irradiation, the inlet fluid temperature, the air mass flow rate, the depth of the fluid channel, the number and nature of the transparent covers in order to measure the impact of each of these parameters on our model. An important result which can be drawn from this study is that the heat transfer model developed is robust enough to be used for thermal design studies of most known flat plate solar air heaters, but also of flat plate solar water collectors and linear solar concentrators.
VERIFICATION OF HYBRID NUMERICAL SCHEME FOR THE CASE OF COMPRESSIBLE JET IMPINGIMENT ON FLAT PLATE
Directory of Open Access Journals (Sweden)
2016-01-01
Full Text Available The article deals with the questions of mathematical modeling of compressible jet outflow from model nozzle and jet impingiment on flat plate at various values of n. pisoCentralFoam solver which is based on the Kurganov-Tadmor hy- brid numerical scheme, PISO algorithm and finite volume method, is used for the solution of this problem. The model, based on unsteady Reynolds equation and K-omega SST turbulence model with boundary functions is used for compressi- ble jet calculation. The problem definition for calculation of jet impingiment on flat plate is given. The simulation domainwas selected as a rectangle. Only a half of the nozzle was considered for simplification. The mixed boundary condition for pressure setting in case of free jet was used on the outlet of simulation domain. The special condition for the pressure with table data, allowed to increase the value of pressure gradually, was used on the inlet of simulation domain. The value of the jet pressure degree was selected as n = 2.5 and n = 5.0. The results of distribution of the velocity magnitude, field pressure, upon symmetry axes were received. The simulations were done with grids 100 000-500 000 cells. The average value of y+ was equal to 270. The calculations were done for the end time Tend = 0.01 s. Comparison of the results of pressure distribution calculation based on nozzle length on different grids with the results of the experiment is carried out. The coin- cidence to engineering accuracy of 5 % is received.
Kegerise, Michael A.; Rufer, Shann J.
2016-08-01
In this paper, we report on the application of the atomic layer thermopile (ALTP) heat-flux sensor to the measurement of laminar-to-turbulent transition in a hypersonic flat-plate boundary layer. The centerline of the flat-plate model was instrumented with a streamwise array of ALTP sensors, and the flat-plate model was exposed to a Mach 6 freestream over a range of unit Reynolds numbers. Here, we observed an unstable band of frequencies that are associated with second-mode instability waves in the laminar boundary layer that forms on the flat-plate surface. The measured frequencies, group velocities, phase speeds, and wavelengths of these instability waves are consistent with data previously reported in the literature. Heat flux time series, and the Morlet wavelet transforms of them, revealed the wave-packet nature of the second-mode instability waves. In addition, a laser-based radiative heating system was used to measure the frequency response functions (FRF) of the ALTP sensors used in the wind tunnel test. These measurements were used to assess the stability of the sensor FRFs over time and to correct spectral estimates for any attenuation caused by the finite sensor bandwidth.
Film Condensation with and Without Body Force in Boundary-Layer Flow of Vapor Over a Flat Plate
Chung, Paul M.
1961-01-01
Laminar film condensation under the simultaneous influence of gas-liquid interface shear and body force (g force) is analyzed over a flat plate. Important parameters governing condensation and heat transfer of pure vapor are determined. Mixtures of condensable vapor and noncondensable gas are also analyzed. The conditions under which the body force has a significant influence on condensation are determined.
Johnson, S. M.
1976-01-01
Basic test results are reported for a flat plate solar collector whose performance was determined in a solar simulator. The collector was tested over ranges of inlet temperatures, fluxes and one coolant flow rate. Collector efficiency is correlated in terms of inlet temperature and flux level.
Lance, Blake W.
Simulations are becoming increasingly popular in science and engineering. One type of simulation is Computation Fluid Dynamics (CFD) that is used when closed forms solutions are impractical. The field of Verification & Validation emerged from the need to assess simulation accuracy as they often contain approximations and calibrations. Validation involves the comparison of experimental data with simulation outputs and is the focus of this work. Errors in simulation predictions may be assessed in this way. Validation requires highly-detailed data and description to accompany these data, and uncertainties are very important. The purpose of this work is to provide highly complete validation data to assess the accuracy of CFD simulations. This aim is fundamentally different from the typical discovery experiments common in research. The measurement of these physics was not necessarily original but performed with modern, high-fidelity methods. Data were tabulated through an online database for direct use in Reynolds-Averaged Navier-Stokes simulations. Detailed instrumentation and documentation were used to make the data more useful for validation. This work fills the validation data gap for steady and transient mixed convection. The physics in this study included mixed convection on a vertical flat plate. Mixed convection is a condition where both forced and natural convection influence fluid momentum and heat transfer phenomena. Flow was forced over a vertical flat plate in a facility built for validation experiments. Thermal and velocity data were acquired for steady and transient flow conditions. The steady case included both buoyancy-aided and buoyancy-opposed mixed convection while the transient case was for buoyancy-opposed flow. The transient was a ramp-down flow transient, and results were ensemble-averaged for improved statistics. Uncertainty quantification was performed on all results with bias and random sources. An independent method of measuring heat flux was
DEFF Research Database (Denmark)
Tian, Zhiyong; Perers, Bengt; Furbo, Simon
2017-01-01
in large solar heating plants for a district heating network, a hybrid solar collector field with 5960 m2 flat plate collectors and 4039 m2 parabolic trough collectors in series was constructed in Taars, Denmark. The design principle is that the flat plate collectors preheat the return water from...... for this type of hybrid solar district heating plants with flat plate collectors and parabolic trough collectors in the Nordic region, but also introduce a novel design concept of solar district heating plants to other high solar radiation areas.......Flat plate collectors have relatively low efficiency at the typical supply temperatures of district heating networks (70–95 °C). Parabolic trough collectors retain their high efficiency at these temperatures. To maximize the advantages of flat plate collectors and parabolic trough collectors...
Parametric Influence on Thermal Performance of Flat Plate Closed Loop Pulsating Heat Pipes
Institute of Scientific and Technical Information of China (English)
YANG Hong-hai; KHANDEKAR Sameer; GROLL Manfred
2006-01-01
This paper presents an experimental study on a flat plate closed loop pulsating heat pipes. It consisted of total 40 channels with square cross section (2 × 2 mm2, 165 mm long) machined directly on an aluminum plate(180× 120×3mm3 ), which was covered by a transparent plate. The working fluid employed was ethanol. As the results, the influence parameters of thermal performance were investigated, such as filling ratio, heat load and operational orientations etc. Filling ratio was found to be a critical parameter, and its effect was rather complicated. According to its values the PHP plate could have four distinct working zones with different operational characteristics and heat transfer performance. The effect of heat load on thermal performance was found to be positive, and in general,increasing the heat load would improve heat transfer performance. In order to analyze the effect of gravity on thermal performance, three different heat modes and total seven tilt angles were tested and compared. Successful operation at all orientations with respect to gravity was also achieved.
Vortex Formation, Shedding and Energy Harvesting from a Cyber-Physical Pitching Flat Plate
Onoue, Kyohei; Breuer, Kenneth
2014-11-01
We examine the dynamics and energy harvesting capabilities of an elastically mounted flat plate undergoing large amplitude limit cycle oscillations in a uniform flow. All experiments are performed using a cyber-physical system, wherein the structural inertia, stiffness and damping are numerically simulated using a position-following feedback algorithm. The cyber-physical system also allows for implementation of nonlinear spring and damping coefficients, which control the plate dynamics and subsequent energy harvesting characteristics. Analysis of the plate kinematics and the fluid flow over the plate and in the wake (measured using PIV) are used to understand the interplay between structural motion and vortex formation at the sharp leading and trailing edges of the plate. By varying the structural properties of the system we systematically analyze the formation, strength, stability and separation of the leading edge vortex, as well as the dependence on kinematic parameters and Reynolds number. Connections to previous results on vortex formation time and bluff body aerodynamics are discussed. This research is funded by the Air Force Office of Scientific Research (AFOSR).
A Dynamic Multinode Model for Component-Oriented Thermal Analysis of Flat-Plate Solar Collectors
Directory of Open Access Journals (Sweden)
Christoph N. Reiter
2015-01-01
Full Text Available A mathematical model of a flat-plate solar collector was developed on the basis of the physical principles of optics and heat transfer in order to determine collector’s component temperatures as well as collector efficiency. In contrast to many available models, the targeted use of this dynamic model is the detailed, theoretical investigation of the thermal behaviour of newly developed or adjusted collector designs on component level, for example, absorber, casing, or transparent cover. The defined model is based on a multinode network (absorber, fluid, glazing, and backside insulation containing the relevant physical equations to transfer the energy. The heat transfer network covers heat conduction, convection, and radiation. Furthermore, the collector optics is defined for the plane glazing and the absorber surface and also considers interactions between them. The model enables the variation of physical properties considering the geometric parameters and materials. Finally, the model was validated using measurement data and existing efficiency curve models. Both comparisons proved high accuracy of the developed model with deviation of up to 3% in collector efficiency and 1 K in component temperatures.
NUMERICAL INVESTIGATIONS INTO THE FRICTION REDUCTION BY MICROBUBBLES FOR FLAT PLATES
Institute of Scientific and Technical Information of China (English)
Zhan De-xin; Wang Jia-mei; Lin Li-ming
2003-01-01
The two-dimensional flow on the flat plate with injected microbubbles is simulated using the software, PHOENICS (V3.2), usually used in the CFD (Computational Fluid Dynamics).A set of formulas for K-ε turbulence model modified with the presence of microbubbles, is employed.With considering the effect of gravity, interfacial lift, interphase friction, virtual mass force and interfacial pressure on the flow with microbubbles, numerical calculations for the influence of variable air volume fracton as well as distribution, injecting speed, microbubble diameter and position of introducing microbubbles on the friction reduction are presented.Results show that the friction reduction increases with increasing volume fraction and microbubble diameter within the range of 100μm, and that the velocity in the boundary layer with microbubbles is greater than that without microbubbles.The order of magnitude and trends of the experimental skin-friction are reproduced well.The uniform free-stream speed in all cases is 4m/s, giving Reynolds number of up to 20 million.
Crust behavior in simultaneous melting and freezing on a submerged flat plate
Energy Technology Data Exchange (ETDEWEB)
Ganguli, A.; Bankoff, S.G.
1978-12-01
A theoretical and experimental investigation of the solidification of a flowing liquid onto a melting wall was carried out. In particular, the experimental work involved open channel laminar flow of water over a flat plate of n-decane. The point of interest is the dynamic behavior of the solidified crust, which forms a leading edge by melting. The motion of this leading edge was determined as a function of the water temperature, velocity, decane temperature and outlet weir height. This melting rate was found to be very sensitive to the water temperature and less dependent upon the other parameters. An approximate numerical method, using polynomial temperature profiles with time dependent coefficients, was used to solve the one-dimensional heat conduction model. From this, the dynamic behavior of the crust was predicted as a function of the experimental parameters and the local heat transfer coefficient on the freezing surface, which was later estimated. There is reasonable agreement between the predicted and experimentally observed motions of the leading edge.
A method for measuring skin friction drag on a flat plate in contaminated gas flows
Oetting, R. B.; Patterson, G. K.
1984-01-01
A technique for measuring friction drag in turbulent gas and gas/particle flows over flat plates is presented, and preliminary results are reported. A 0.25-in.-thick 72 x 6-in. Al plate is suspended by six horizontal support air bearings and four vertical alignment air bearings between fixed dummy plates and leading-edge and trailing-edge fairings in the 32-in.-high 48-in.-wide 11-ft-long test section of a closed-circuit atmospheric wind tunnel operating at 50-150 ft/sec. Particles of Fe and Al oxides of diameter 20-150 microns and density up to 0.3 lb particles per lb air are injected via a 6 x 0.167-in. nozzle; turbulence is induced by a roughened section of the leading-edge fairing; and friction drag is measured using a load-cell pressure transducer. Sample results are shown in a graph, demonstrating good agreement with theoretical drag calculations.
Production of Fatty Acids and Protein by Nannochloropsis in Flat-Plate Photobioreactors.
Hulatt, Chris J; Wijffels, René H; Bolla, Sylvie; Kiron, Viswanath
2017-01-01
Nannochloropsis is an industrially-promising microalga that may be cultivated for alternative sources of nutrition due to its high productivity, protein content and lipid composition. We studied the growth and biochemical profile of Nannochloropsis 211/78 (CCAP) in optimized flat-plate photobioreactors. Eighteen cultivations were performed at two nutrient concentrations. The fatty acid, protein content and calorific values were analyzed after 8, 12 and 16 days. Neutral lipids were separated and the changes in fatty acids in triglycerides (TAGs) during nutrient depletion were recorded. The maximum cell density reached 4.7 g∙L-1 and the maximum productivity was 0.51 g∙L-1∙d-1. During nutrient-replete conditions, eicosapentaneoic acid (EPA) and total protein concentrations measured 4.2-4.9% and 50-55% of the dry mass, respectively. Nutrient starvation induced the accumulation of fatty acids up to 28.3% of the cell dry weight, largely due to the incorporation of C16:0 and C16:1n-7 fatty acyl chains into neutral lipids. During nutrient starvation the total EPA content did not detectibly change, but up to 37% was transferred from polar membrane lipids to the neutral lipid fraction.
Lipid accumulation and growth of Chlorella zofingiensis in flat plate photobioreactors outdoors.
Feng, Pingzhong; Deng, Zhongyang; Hu, Zhengyu; Fan, Lu
2011-11-01
Culturing microalgae using natural sunlight is an effective way to reduce the cost of microalgae-based biodiesel production. In order to evaluate the feasibility of culturing Chlorella zofingiensis outdoors for biodiesel production, effects of nitrogen limitation and initial cell concentration on growth and lipid accumulation of this alga were investigated in 60 L flat plate photobioreactors outdoors. The highest μmax and biomass productivity obtained was 0.994 day(-1) and 58.4 mg L(-1)day(-1), respectively. The lipid content was much higher (54.5% of dry weight) under nitrogen limiting condition than under nitrogen sufficient condition (27.3%). With the increasing initial cell concentrations, the lipid contents declined, while lipid concentrations and productivities increased. The highest lipid content, lipid concentration, and lipid productivity obtained was 54.5%, 536 mg L(-1) and 22.3 mg L(-1)day(-1), respectively. This study demonstrated that it was possible to culture C. zofingiensis under outdoor conditions for producing biodiesel feedstock.
Directory of Open Access Journals (Sweden)
Md. Mamun Molla
2014-01-01
Full Text Available The purpose of this study is to investigate the natural convection laminar flow along an isothermal vertical flat plate immersed in a fluid with viscosity which is the exponential function of fluid temperature in presence of internal heat generation. The governing boundary layer equations are transformed into a nondimensional form and the resulting nonlinear system of partial differential equations is reduced to a convenient form which are solved numerically using an efficient marching order implicit finite difference method with double sweep technique. Numerical results are presented in terms of the velocity and temperature distribution of the fluid as well as the heat transfer characteristics, namely, the wall shear stress and the local and average rate of heat transfer in terms of the local skin-friction coefficient, the local and average Nusselt number for a wide range of the viscosity-variation parameter, heat generation parameter, and the Rayleigh number. Increasing viscosity variation parameter and Rayleigh number lead to increasing the local and average Nusselt number and decreasing the wall shear stress. Wall shear stress and the rate of heat transfer decreased due to the increase of heat generation.
Effect of Localized Heating on Three-Dimensional Flat-Plate Oscillating Heat Pipe
Directory of Open Access Journals (Sweden)
S. M. Thompson
2010-01-01
Full Text Available An experimental investigation was conducted, both thermally and visually, on a three-dimensional flat-plate oscillating heat pipe (3D FP-OHP to characterize its performance under localized heat fluxes while operating in the bottom heating mode and charged with acetone at a filling ratio of 0.73. The cooling area was held constant and three heating areas of 20.16 cm2, 11.29 cm2, and 1.00 cm2 were investigated, respectively. It was found that as the heating area was reduced and higher heat fluxes were imposed, the thermal resistance increased and the amplitude of thermal oscillations in the evaporator increased and became more chaotic. Using neutron radiography, it was observed that fluid oscillations did not occur in outer channels located away from the region of local heating. Although the thermal resistance increased during localized heating, a maximum heat flux of 180 W/cm2 was achieved with the average evaporator temperature not exceeding 90∘C.
Design, construction and testing of a liquid-heating flat-plate solar collector
Energy Technology Data Exchange (ETDEWEB)
Tuttle, R E
1980-02-01
The purpose of this study was to design, construct, and test a liquid-heating flat-plate solar collector. From the literature search, information was gathered concerning the basic components of the collector, the different processes and materials that can be used in the construction of these components, and their advantages and disadvantages. The literature search also revealed a method used to measure the performance of the collector in terms of efficiency and heat output. Design considerations were then listed for each of the major components as well as the collector as a single unit. Then, each component was designed, taking into consideration the final assembly of the completed unit. Detailed designs were required for the absorber plate and the box and frame assembly because of their complexity in construction and assembly. Once the components were designed, the construction details were arranged in a logical sequence, again considering the final assembly of the unit. The collector was then carefully constructed and assembled following the design details. After the solar collector was assembled completely, tests were made, data were obtained and recorded, and a collector performance curve was developed.
Design of a novel flat-plate photobioreactor system for green algal hydrogen production
Energy Technology Data Exchange (ETDEWEB)
Tamburic, B.; Zemichael, F.W.; Maitland, G.C.; Hellgardt, K. [Imperial College London (United Kingdom)
2010-07-01
Some unicellular green algae have the ability to photosynthetically produce molecular hydrogen using sunlight and water. This renewable, carbon-neutral process has the additional benefit of sequestering carbon dioxide during the algal growth phase. The main costs associated with this process result from building and operating a photobioreactor system. The challenge is to design an innovative and cost effective photobioreactor that meets the requirements of algal growth and sustainable hydrogen production. We document the details of a novel 1 litre vertical flat-plate photobioreactor that has been designed to accommodate green algal hydrogen production at the laboratory scale. Coherent, non-heating illumination is provided by a panel of cool white LEDs. The reactor body consists of two compartments constructed from transparent Perspex sheets. The primary compartment holds the algal culture, which is agitated by means of a recirculating gas flow. A secondary compartment is filled with water and used to control the temperature and wavelength of the system. The reactor is fitted with instruments that monitor the pH, pO{sub 2}, temperature and optical density of the culture. A membrane-inlet mass spectrometry system has been developed for hydrogen collection and in situ monitoring. The reactor is fully autoclaveable and the possibility of hydrogen leaks has been minimised. The modular nature of the reactor allows efficient cleaning and maintenance. (orig.)
Wavenumber resonance in nonlinear wave interactions in the wake of a flat plate
Davila, Jose Benigno
The spatial traits of nonlinear wave interactions in transitioning flow in the symmetric wake of a flat plate were studied. The study combines the use of hot wire anemometry and digital analysis techniques for extracting frequency and wavenumber information from velocity fluctuation time series measurements. The linear spatial coherence was computed from velocity fluctuation data in order to determine if the frequency modes behave as waves, that is, spatially coherent fluctuations with a well defined dispersion relation. A new method was used to compute the mode triad wavenumber mismatch. The results were used to determine to what extent wavenumber resonance is present among quadratically interacting frequency resonant modes, as predicted by resonant wave interaction theory. The results show that, in the early part of the transition, instability modes interact nonlinearity to generate spatially coherent modes at frequencies above the instability range. Quadratically interacting, frequency resonant mode triads involve the transfer of energy to the harmonics of the fundamental instability exhibit good wavenumber resonance, as predicted by resonant wave interaction theory.
Directory of Open Access Journals (Sweden)
Héctor L. Otálvaro-Marín
2014-01-01
Full Text Available This study provides information to design heterogeneous photocatalytic solar reactors with flat plate geometry used in treatment of effluents and conversion of biomass to hydrogen. The concept of boundary layer of photon absorption taking into account the efficient absorption of radiant energy was introduced; this concept can be understood as the reactor thickness measured from the irradiated surface where 99% of total energy is absorbed. Its thickness and the volumetric rate of photons absorption (VRPA were used as design parameters to determine (i reactor thickness, (ii maximum absorbed radiant energy, and (iii the optimal catalyst concentration. Six different commercial brands of titanium dioxide were studied: Evonik-Degussa P-25, Aldrich, Merck, Hombikat, Fluka, and Fisher. The local volumetric rate of photon absorption (LVRPA inside the reactor was described using six-flux absorption-scattering model (SFM applied to solar radiation. The radiation field and the boundary layer thickness of photon absorption were simulated with absorption and dispersion effects of catalysts in water at different catalyst loadings. The relationship between catalyst loading and reactor thickness that maximizes the absorption of radiant energy was obtained for each catalyst by apparent optical thickness. The optimum concentration of photocatalyst Degussa P-25 was 0.2 g/l in 0.86 cm of thickness, and for photocatalyst Aldrich it was 0.3 g/l in 0.80 cm of thickness.
A diagram for defined flat plate solar collector area for solar floor heating
Energy Technology Data Exchange (ETDEWEB)
Altuntop, N.; Tekin, Y. [Erciyes University, Dept. of Mechanical Engineering (Turkey); Cengel, Y.A. [Nevada Reno University, Dept. of Mechanical Engineering, NV (United States)
2000-07-01
In winters, one of the best ways to heat living areas by using the low- temperature - water obtained from flat-plate solar collectors is the floor heating. In floor heating, low temperature-water (30 + 60 deg C) can be used and heat can be stored in water when solar radiation is not possible. In this study, it is aimed to define collector surface needed to supply heat for floor heating. It is also aimed to define and explain the diagram developed for every heating months. The calculations about the sun geometry are used to define the amount of radiation coming in to the collectors. Formulations are made about the definition of solar radiation absorbed by the collectors, the total heat loss coefficient, and the collector plate surface temperature. These formulations are transformed in to the diagram. In addition, the studies, heat transfer calculations and design parameters about the floor of the heating areas are used. A combined collector floor heating diagram is obtained. This diagram is used to define collector surface area necessary to supply heat for floor heated places. In this diagram, the collector surface area is obtained by giving the heat capacity of the place area, floor surface temperature, approximate modulation distance of the floor, the elevation of city, collector slope angle, wind speed, sun shine lime and the amount of the solar radiation obtained from the solar radiation diagram. (authors)
Calculating forces on thin flat plates with incomplete vorticity-field data
Limacher, Eric; Morton, Chris; Wood, David
2016-11-01
Optical experimental techniques such as particle image velocimetry (PIV) permit detailed quantification of velocities in the wakes of bluff bodies. Patterns in the wake development are significant to force generation, but it is not trivial to quantitatively relate changes in the wake to changes in measured forces. Key difficulties in this regard include: (i) accurate quantification of velocities close to the body, and (ii) the effect of missing velocity or vorticity data in regions where optical access is obscured. In the present work, we consider force formulations based on the vorticity field, wherein mathematical manipulation eliminates the need for accurate near-body velocity information. Attention is restricted to nominally two dimensional problems, namely (i) a linearly accelerating flat plate, investigated using PIV in a water tunnel, and (ii) a pitching plate in a freestream flow, as investigated numerically by Wang & Eldredge (2013). The effect of missing vorticity data on the pressure side of the plate has a significant impact on the calculation of force for the pitching plate test case. Fortunately, if the vorticity on the pressure side remains confined to a thin boundary layer, simple corrections can be applied to recover a force estimate.
Changes in Flat Plate Wake Characteristics Obtained With Decreasing Plate Thickness
Rai, Man Mohan
2016-01-01
The near and very near wake of a flat plate with a circular trailing edge is investigated with data from direct numerical simulations. Computations were performed for four different Reynolds numbers based on plate thickness (D) and at constant plate length. The value of ?/D varies by a factor of approximately 20 in the computations (? being the boundary layer momentum thickness at the trailing edge). The separating boundary layers are turbulent in all the cases. One objective of the study is to understand the changes in wake characteristics as the plate thickness is reduced (increasing ?/D). Vortex shedding is vigorous in the low ?/D cases with a substantial decrease in shedding intensity in the largest ?/D case (for all practical purposes shedding becomes almost intermittent). Other characteristics that are significantly altered with increasing ?/D are the roll-up of the detached shear layers and the magnitude of fluctuations in shedding period. These effects are explored in depth. The effects of changing ?/D on the distributions of the time-averaged, near-wake velocity statistics are discussed.
Experimental investigation of a large aspect ratio flat plate encountering a steam-wise gust
Mulleners, Karen; Mancini, Peter; Jones, Anya
2015-11-01
While humans are capable of mimicking, and even outperform, the kinematic capabilities of natural flyers, birds and insects are still way ahead of us when it comes to anticipating and dealing with turbulent and gusty flow conditions. To tailor and improve flight control capabilities of low Reynolds number flyers in real weather, we need to bridge this gap of knowledge. As a first step, we experimentally studied the aerodynamic influence of a simplified stream-wise gust on a large aspect ratio flat plate. The experiments were conduction in the 7 × 1 . 5 × 1 m3 towing tank at UMD which was equipped with a 4-axis computer-controlled motion system. The effect of a stream-wise gust was simulated by accelerating or decelerating the wing to a new constant velocity after an initial constant surge. A high-speed camera and light sheet optics were attached to the tow carriage allowing for time-resolved particle image velocimetry along the entire motion in addition to direct force measurements. A proper orthogonal decomposition of the flow field was carried out to study the time scales related to changes induced by the sudden acceleration or deceleration in addition to analyzing the size, position and trajectory of prominent vortices and associated forces during the gust encounter.
Transient-forced convection film boiling on an isothermal flat plate.
Nagendra, H. R.
1972-01-01
Development of a new approach for the solution of transient-forced convection film boiling on an isothermal flat plate using the boundary layer model. The similarity variables are used to convert the governing partial differential equations to ordinary ones. The results of numerical solutions of these ordinary equations indicate that the transient process can be classified as one-dimensional conduction, intermediate, and the steady-state regions. The time required for the one-dimensional conduction and the time necessary to attain a steady-state condition are obtained. The use of local similarity approximations for the intermediate regime facilitates prediction of complete boundary layer growth. Using the ratio of time at any instant to the steady-state time as abscissa, the curves representing the boundary layer growth can be merged into a single mean curve within 5%. Further, the analysis shows that the average rate of heat transfer during transient is 50 to 100% higher than those at steady state. The average rate of vapor convected away is 10 to 15% lower than at steady state while the average rate of accumulation to form the vapor layer is 1 to 14 times larger.
Earth Reflected Solar Radiation Incident upon an Arbitrarily Oriented Spinning Flat Plate
Cunningham, Fred G.
1963-01-01
A general derivation is given for the earth reflected solar radiation input to a flat plate--a solar cell paddle, for example--which is spinning about an axis coincident with the axis of symmetry of the satellite to which it is affixed. The resulting equations are written for the general case so that arbitrary orientations of the spin axis with respect to the earth-satellite line and arbitrary orientations of the normal to the plate with respect to the spin axis can be treated. No attempt is made to perform the resulting integrations because of the complexity of the equations; nor is there any attempt to delineate the integration limits for the general case. However, the equations governing these limits are given. The appendixes contain: the results, in graphical form, of two representative examples; the general computer program for the calculation is given in Fortran notation; and the results of a calculation of the distribution of albedo energy on the proposed Echo II satellite. The value of the mean solar constant used is 1.395 times 10 (sup 4) ergs per centimeters-squared per second; the mean albedo of the earth is assumed to be 0.34; and the earth is assumed to be a diffuse reflector.
Design optimization of sinusoidal glass honeycomb for flat plate solar collectors
Mcmurrin, J. C.; Buchberg, H.
1980-01-01
The design of honeycomb made of sinusoidally corrugated glass strips was optimized for use in water-cooled, single-glazed flat plate solar collectors with non-selective black absorbers. Cell diameter (d), cell height (L), and pitch/diameter ratio (P/d) maximizing solar collector performance and cost effectiveness for given cell wall thickness (t sub w) and optical properties of glass were determined from radiative and convective honeycomb characteristics and collector performance all calculated with experimentally validated algorithms. Relative lifetime values were estimated from present materials costs and postulated production methods for corrugated glass honeycomb cover assemblies. A honeycomb with P/d = 1.05, d = 17.4 mm, L = 146 mm and t sub w = 0.15 mm would provide near-optimal performance over the range delta T sub C greater than or equal to 0 C and less than or equal to 80 C and be superior in performance and cost effectiveness to a non-honeycomb collector with a 0.92/0.12 selective black absorber.
Investigation into the causes of browning in EVA encapsulated flat plate PV modules
Energy Technology Data Exchange (ETDEWEB)
Holley, W.H. Jr.; Agro, S.C.; Galica, J.P.; Thoma, L.A.; Yorgensen, R.S. [Springborn Labs., Inc., Enfield, CT (United States); Ezrin, M.; Klemchuk, P.; Lavigne, G. [Univ. of Connecticut, Storrs, CT (United States). Inst of Materials Science; Thomas, H. [National Renewable Energy Lab., Golden, CO (United States)
1994-12-31
The problem of browning in a number of EVA encapsulated flat plate photovoltaic modules has led to the questioning of EVA as a suitable material for such applications. By isolating the variables that could possibly lead to EVA browning, such as module construction, types of glass superstrates, additives, and processing conditions, the authors have been able to determine those significant specific variables that seem to have the most influence on discoloration.When standard-cure EVA-based laminates were exposed to accelerated UV aging, measurable yellowing of those laminates was evident after only one to two weeks exposure, and visual discoloration was observed after four to six weeks. Some samples yellowed quickly and some not at all, and there were significant differences in the rates of discoloration between standard-cure and fast-cure EVA. This paper looks at the results of these studies, especially focusing on the effect of additives in the EVA on the rate of yellowing, and discusses how preliminary results can be used to reformulate EVA encapsulants.
Heat Transfer Analysis of a Flat-plate Solar Collector Running a Solid Adsorption Refrigerator
Directory of Open Access Journals (Sweden)
S. Thiao
2014-05-01
Full Text Available Adsorption solar cooling appears to have prospect in the tropical countries. The present study is a theoretical investigation of the performance of a solar adsorption refrigerator using a flat-plate solar collector. The values of glass cover and absorber plate temperatures obtained from numerical solutions of heat balance equations are used to predict the solar coefficient of performance of the solar refrigerator. The simulation technique takes into account the variations of ambient temperature and solar radiation along the day. The effects of optical parameters of the glass cover such as absorption and transmission coefficients on glass cover and absorber plate temperatures and consequently on the coefficient of performance are analyzed. As a result, it is found that the absorber plate temperature is less to the absorption coefficient than the cover glass temperature. Also the thermal radiation exchange has more effect on the cover glass temperature. The higher values of COP are obtained between 11 and 13 h during the morning when the temperatures of the absorber plate and the ambient temperatures increase. Moreover the COP increases with the coefficient of transmission of the glass cover but the main parameter acting on the variations of the COP remains the temperature of the evaporator.
Flowfield measurements in a separated and reattached flat plate turbulent boundary layer
Patrick, William P.
1987-03-01
The separation and reattachment of a large-scale, two-dimensional turbulent boundary layer at low subsonic speed on a flat plate has been studied experimentally. The separation bubble was 55 cm long and had a maximum bubble thickness, measured to the height of the mean dividing streamline, of 17 cm, which was twice the thickness of the inlet boundary layer. A combination of laser velocimetry, hot-wire anemometry, pneumatic probing techniques, and flow visualization were used as diagnostics. Principal findings were that an outer inviscid rotational flow was defined which essentially convected over the blockage associated with the inner, viscously dominated bubble recirculation region. A strong backflow region in which the flow moved upstream 100 percent of the time was measured near the test surface over the central 35 percent of the bubble. A laminar backflow boundary layer having pseudo-turbulent characteristics including a log-linear velocity profile was generated under the highly turbulent backflow. Velocity profile shapes in the reversed flow region matched a previously developed universal backflow profile at the upstream edge of the separation region but not in the steady backflow region downstream. A smoke flow visualization movie and hot-film measurements revealed low frequency nonperiodic flapping at reattachment. However, forward flow fraction data at reattachment and mean velocity profiles in the redeveloping boundary layer downstream of reattachment correlated with backward-facing step data when the axial dimension was scaled by the distance from the maximum bubble thickness to reattachment.
EVALUATION OF FLAT-PLATE PHOTOVOLTAIC THERMAL HYBRID SYSTEMS FOR SOLAR ENERGY UTILIZATION.
Energy Technology Data Exchange (ETDEWEB)
ANDREWS,J.W.
1981-06-01
The technical and economic attractiveness of combined photovoltaic/thermal (PV/T) solar energy collectors was evaluated. The study was limited to flat-plate collectors since concentrating photovoltaic collectors require active cooling and thus are inherently PV/T collectors, the only decision being whether to use the thermal energy or to dump it. it was also specified at the outset that reduction in required roof area was not to be used as an argument for combining the collection of thermal and electrical energy into one module. Three tests of economic viability were identified, all of which PV/T must pass if it is to be considered a promising alternative: PV/T must prove to be competitive with photovoltaic-only, thermal-only, and side-by-side photovoltaic-plus-thermal collectors and systems. These three tests were applied to systems using low-temperature (unglazed) collectors and to systems using medium-temperature (glazed) collectors in Los Angeles, New York, and Tampa. For photovoltaics, the 1986 DOE cost goals were assumed to have been realized, and for thermal energy collection two technologies were considered: a current technology based on metal and glass, and a future technology based on thin-film plastics. The study showed that for medium-temperature applications PV/T is not an attractive option in any of the locations studied. For low-temperature applications, PV/T appears to be marginally attractive.
Hydrogen production by Rhodobacter sphaeroides O.U.001 in a flat plate solar bioreactor
Energy Technology Data Exchange (ETDEWEB)
Eroglu, Inci; Tabanoglu, Altan; Eroglu, Ela [Department of Chemical Engineering, Middle East Technical University, 06531 Ankara (Turkey); Guenduez, Ufuk; Yuecel, Meral [Department of Biology, Middle East Technical University, 06531 Ankara (Turkey)
2008-01-15
Rhodobacter sphaeroides O.U.001 can produce hydrogen under anaerobic conditions and illumination. The objective of this study was to investigate the performance of an 8 l flat plate solar bioreactor operating in outdoor conditions. Different organic acids were used as carbon sources (malate, lactate and acetate) and olive mill waste water was used as a sole substrate source. The consumption and the production of the organic acids were determined by HPLC. The accumulation of by-products, such as poly-{beta}-hydroxybutyrate (PHB) and carotenoid, throughout the course of hydrogen production was determined. The hydrogen production rate was highest (0.01 l/l/h) when malate was the carbon source. Formate was observed as the fermentation end product. Acetate resulted in low hydrogen gas production and high PHB accumulation. When acetate was used as the carbon source, butyrate was produced as a result of fermentation. Promising amounts of PHB and caretenoid were accumulated during hydrogen production from diluted olive mill wastewater. (author)
Sun, Yahui; Huang, Yun; Liao, Qiang; Fu, Qian; Zhu, Xun
2016-05-01
To offset the adverse effects of light attenuation on microalgae growth, hollow polymethyl methacrylate (PMMA) tubes were embedded into a flat-plate photobioreactor (PBR) as light guides. In this way, a fraction of incident light could be transmitted and emitted to the interior of the PBR, providing a secondary light source for cells in light-deficient regions. The average light intensity of interior regions 3-6cm from surfaces with 70μmolm(-2)s(-1) incident light was enhanced 2-6.5 times after 3.5days cultivation, resulting in a 23.42% increase in biomass production to that cultivated in PBR without PMMA tubes. The photosynthetic efficiency of microalgae in the proposed PBR was increased to 12.52%. Moreover, the installation of hollow PMMA tubes induced turbulent flow in the microalgae suspension, promoting microalgae suspension mixing. However, the enhanced biomass production was mainly attributed to the optimized light distribution in the PBR. Copyright © 2016 Elsevier Ltd. All rights reserved.
Production of Fatty Acids and Protein by Nannochloropsis in Flat-Plate Photobioreactors
Wijffels, René H.; Bolla, Sylvie; Kiron, Viswanath
2017-01-01
Nannochloropsis is an industrially-promising microalga that may be cultivated for alternative sources of nutrition due to its high productivity, protein content and lipid composition. We studied the growth and biochemical profile of Nannochloropsis 211/78 (CCAP) in optimized flat-plate photobioreactors. Eighteen cultivations were performed at two nutrient concentrations. The fatty acid, protein content and calorific values were analyzed after 8, 12 and 16 days. Neutral lipids were separated and the changes in fatty acids in triglycerides (TAGs) during nutrient depletion were recorded. The maximum cell density reached 4.7 g∙L-1 and the maximum productivity was 0.51 g∙L-1∙d-1. During nutrient-replete conditions, eicosapentaneoic acid (EPA) and total protein concentrations measured 4.2–4.9% and 50–55% of the dry mass, respectively. Nutrient starvation induced the accumulation of fatty acids up to 28.3% of the cell dry weight, largely due to the incorporation of C16:0 and C16:1n-7 fatty acyl chains into neutral lipids. During nutrient starvation the total EPA content did not detectibly change, but up to 37% was transferred from polar membrane lipids to the neutral lipid fraction. PMID:28103296
Leading-edge vortex burst on a low-aspect-ratio rotating flat plate
Medina, Albert; Jones, Anya R.
2016-08-01
This study experimentally investigates the phenomenon of leading-edge-vortex burst on rotating flat plate wings. An aspect-ratio-2 wing was driven in pure rotation at a Reynolds number of Re=2500 . Of primary interest is the evolution of the leading-edge vortex along the wing span over a single-revolution wing stroke. Direct force measurements of the lift produced by the wing revealed a single global lift maximum relatively early in the wing stroke. Stereoscopic particle image velocimetry was applied to several chordwise planes to quantify the structure and strength of the leading-edge vortex and its effect on lift production. This analysis revealed opposite-sign vorticity entrainment into the core of the leading-edge vortex, originating from a layer of secondary vorticity along the wing surface. Coincident with the lift peak, there emerged both a concentration of opposite vorticity in the leading-edge-vortex core, as well as axial flow stagnation within the leading-edge-vortex core. Planar control volume analysis was performed at the midspan to quantify the contributions of vorticity transport mechanisms to the leading-edge-vortex circulation. The rate of circulation annihilation by opposite-signed vorticity entrainment was found to be minimal during peak lift production, where convection balanced the flux of vorticity resulting in stagnation and eventually reversal of axial flow. Finally, vortex burst was found to be correlated with swirl number, where bursting occurs at a swirl threshold of Sw<0.6 .
Experimental Study on Performance of a Box Solar Cooker with Flat Plate Collector to Boil Water
Sitepu, T.; Gunawan, S.; Nasution, D. M.; Ambarita, H.; Siregar, R. E. T.; Ronowikarto, A. D.
2017-03-01
In this study, a flat plate type solar cooker is tested by exposing in solar irradiation. The objective is to examine the performance of solar cooker in boiling water. The solar cooker is a box type with collector area and height are 100 × 100 cm and 40 cm, respectively. Vessel for water is made of aluminum plate with diameter and height of 22 cm and 15 cm. The experiments are performed by varying mass of the water. It is 2 kg and 4 kg, respectively. Every experiment starts from 10:00 AM until the boiling temperature is reached. The parameters measured are radiance intensity, ambient and solar box cooker temperatures, and wind speed. The results show that the duration of water heating up to 100°C with water mass 2 kg within 2 hours 45 minutes and water mass 4 kg within 3 hours 17 minutes. The maximum temperatur of solar box cooker is 117°C at 12:56 PM and maximum efficiency is 46.30%. The main conclusion can be drawn here is that a simple solar box cooker can be used to boil water.
EVALUATION OF FLAT-PLATE PHOTOVOLTAIC THERMAL HYBRID SYSTEMS FOR SOLAR ENERGY UTILIZATION.
Energy Technology Data Exchange (ETDEWEB)
ANDREWS,J.W.
1981-06-01
The technical and economic attractiveness of combined photovoltaic/thermal (PV/T) solar energy collectors was evaluated. The study was limited to flat-plate collectors since concentrating photovoltaic collectors require active cooling and thus are inherently PV/T collectors, the only decision being whether to use the thermal energy or to dump it. it was also specified at the outset that reduction in required roof area was not to be used as an argument for combining the collection of thermal and electrical energy into one module. Three tests of economic viability were identified, all of which PV/T must pass if it is to be considered a promising alternative: PV/T must prove to be competitive with photovoltaic-only, thermal-only, and side-by-side photovoltaic-plus-thermal collectors and systems. These three tests were applied to systems using low-temperature (unglazed) collectors and to systems using medium-temperature (glazed) collectors in Los Angeles, New York, and Tampa. For photovoltaics, the 1986 DOE cost goals were assumed to have been realized, and for thermal energy collection two technologies were considered: a current technology based on metal and glass, and a future technology based on thin-film plastics. The study showed that for medium-temperature applications PV/T is not an attractive option in any of the locations studied. For low-temperature applications, PV/T appears to be marginally attractive.
Heat transfer in a low latitude flat-plate solar collector
Directory of Open Access Journals (Sweden)
Oko C.O.C.
2012-01-01
Full Text Available Study of rate of heat transfer in a flat-plate solar collector is the main subject of this paper. Measurements of collector and working fluid temperatures were carried out for one year covering the harmattan and rainy seasons in Port Harcourt, Nigeria, which is situated at the latitude of 4.858oN and longitude of 8.372oE. Energy balance equations for heat exchanger were employed to develop a mathematical model which relates the working fluid temperature with the vital collector geometric and physical design parameters. The exit fluid temperature was used to compute the rate of heat transfer to the working fluid and the efficiency of the transfer. The optimum fluid temperatures obtained for the harmattan, rainy and yearly (or combined seasons were: 317.4, 314.9 and 316.2 [K], respectively. The corresponding insolation utilized were: 83.23, 76.61 and 79.92 [W/m2], respectively, with the corresponding mean collector efficiency of 0.190, 0.205 and 0.197 [-], respectively. The working fluid flowrate, the collector length and the range of time that gave rise to maximum results were: 0.0093 [kg/s], 2.0 [m] and 12PM - 13.00PM, respectively. There was good agreement between the computed and the measured working fluid temperatures. The results obtained are useful for the optimal design of the solar collector and its operations.
Directory of Open Access Journals (Sweden)
Rajendra Karwa
2014-01-01
Full Text Available The paper presents results of an analysis carried out using a mathematical model to find the effect of the uncertainties, variations, and tolerances in design and ambient parameters on the thermohydraulic performance of flat plate solar air heater. Analysis shows that, for the range of flow rates considered, a duct height of 10 mm is preferred from the thermohydraulic consideration. The thermal efficiency changes by about 2.6% on variation in the wind heat transfer coefficient, ±5 K variation in sky temperature affects the efficiency by about ±1.3%, and solar insolation variation from 500 to 1000 Wm−2 affects the efficiency by about −1.5 to 1.3% at the lowest flow rate of 0.01 kgs−1 m−2 of the absorber plate with black paint. In general, these effects reduce with increase in flow rate and are lower for collector with selective coating on the absorber plate surface. The tolerances in the duct height and absorber plate emissivity should be small while positive tolerance of 3° in the collector slope for winter operation and ±3° for year round operation, and a positive tolerance for the gap between the absorber plate and glass cover at nominal value of 40 mm are recommended.
Effect of Glass Thickness on Performance of Flat Plate Solar Collectors for Fruits Drying
Directory of Open Access Journals (Sweden)
Ramadhani Bakari
2014-01-01
Full Text Available This study aimed at investigating the effect of thickness of glazing material on the performance of flat plate solar collectors. Performance of solar collector is affected by glaze transmittance, absorptance, and reflectance which results into major heat losses in the system. Four solar collector models with different glass thicknesses were designed, constructed, and experimentally tested for their performances. Collectors were both oriented to northsouth direction and tilted to an angle of 10° with the ground toward north direction. The area of each collector model was 0.72 m2 with a depth of 0.15 m. Low iron (extra clear glass of thicknesses 3 mm, 4 mm, 5 mm, and 6 mm was used as glazing materials. As a control, all collector performances were analysed and compared using a glass of 5 mm thickness and then with glass of different thickness. The results showed that change in glass thickness results into variation in collector efficiency. Collector with 4 mm glass thick gave the best efficiency of 35.4% compared to 27.8% for 6 mm glass thick. However, the use of glass of 4 mm thick needs precautions in handling and during placement to the collector to avoid extra costs due to breakage.
Energy Technology Data Exchange (ETDEWEB)
Wissink, Jan G. [School of Engineering and Design, Howell Building, Brunel University, Uxbridge UB8 3PH (United Kingdom)], E-mail: jan.wissink@brunel.ac.uk; Rodi, Wolfgang [Institute for Hydromechanics, University of Karlsruhe, Kaiserstr. 12, D-76128 Karlsruhe (Germany)
2009-10-15
Direct numerical simulations (DNS) of flow over and heat transfer from a flat plate affected by free-stream fluctuations were performed. A contoured upper wall was employed to generate a favourable streamwise pressure gradient along a large portion of the flat plate. The free-stream fluctuations originated from a separate LES of isotropic turbulence in a box. In the laminar portions of the accelerating boundary layer flow the formation of streaks was observed to induce an increase in heat transfer by the exchange of hot fluid near the surface of the plate and cold fluid from the free-stream. In the regions where the streamwise pressure gradient was only mildly favourable, intermittent turbulent spots were detected which relaminarised downstream as the streamwise pressure gradient became stronger. The relaminarisation of the turbulent spots was reflected by a slight decrease in the friction coefficient, which converged to its laminar value in the region where the streamwise pressure gradient was strongest.
Institute of Scientific and Technical Information of China (English)
MIRZAEISEFAT Sina; FERNANDES Antonio Carlos
2013-01-01
This work describes investigations performed on the interaction of uniform current and freely rotating plate about a fixed vertical axis. Fluttering and autorotation are two different motions that may occur during the flow induced rotation. The dimensional analysis proves that the motion in flow induced rotation motion is governed essentially by the dimensionless moment of inertia and Reynolds number. Certain combinations define the stability boundaries between fluttering and autorotation. Fluttering is oscillation of body about a vertical axis and the autorotation is a name given to the case when the body turns continuously about the vertical axis. First, the loads and moment coefficients are calculated by experiments and streamline theory for different angles of attack for a fixed flat plate. Then for dynamic case, a bifurcation diagram is presented based on experiments to classify different motion states of flow induced rotation. Finally, a dynamical model is proposed for stability analysis of flow induced rotation of a flat plate.
American Society for Testing and Materials. Philadelphia
1986-01-01
1.1 This test method covers the determination of the resistance of flat plate solar collectors to water penetration when water is applied to their outer surfaces with a static air pressure at the outer surface higher than the pressure at the interior of the collector. 1.2 This test method is applicable to any flat plate solar collector. 1.3 The proper use of this test method requires a knowledge of the principles of pressure and deflection measurement. 1.4 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only. 1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Specific precautionary information is contained in Section 6.
Energy Technology Data Exchange (ETDEWEB)
Luna, N. [Direccion de Operacion Petrolera, Direccion General de Exploracion y Explotacion de Hidrocarburos, Secretaria de Energia, 03100 Mexico DF (Mexico); Mendez, F. [Facultad de Ingenieria, UNAM, 04510 Mexico DF (Mexico)
2005-07-01
The steady-state analysis of conjugated heat transfer process for the hydrodynamically developed forced convection flow on a heated flat plate embedded in a porous medium is studied. The governing equations for the fluid-saturated porous medium are solved analytically using the integral boundary layer approximation. This integral solution is coupled to the energy equation for the flat plate, where the longitudinal heat conduction effects are taken into account. The resulting equations are then reduced to an integro-differential equation which is solved by regular perturbation techniques and numerical methods. The analytical and numerical predictions for the temperature profile of the plate and appropriate local and average Nusselt numbers are plotted for finite values of the conduction parameter, {alpha}, which represents the presence of the longitudinal heat conduction effects. (authors)
Numerical analysis of flow and heat transfer behavior in fin-tube flat-plate solar collector
Institute of Scientific and Technical Information of China (English)
Namory Camara; LU Hui-lin
2007-01-01
Temperature distribution over the absorber plate of a parallel flow flat-plate solar collector is numerically analyzed. The governing differential equations with boundary conditions are solved numerically using fluent software. Effects of the inlet mass flux, inlet temperature and tube spacing on velocity and temperature distributions are discussed. Numerical results show that the distributions of velocity and temperature of fluid is unsymmetrical inside pipe.
Institute of Scientific and Technical Information of China (English)
孟显; 潘文霞; 张文宏; 吴承康
2001-01-01
By using steady and transient methods, the total heat fluxes and the distributions of the heat flux were measured experimentally for an argon DC laminar plasma jet impinging normally on a flat plate at atmospheric pressure. Results show that the total heat fluxes measured with a steady method are a little bit higher than those with a transient method. Numerical simulation work was executed to compare with the experimental results.
A. Malvandi; Faraz Hedayati; Ganji, D.D.
2015-01-01
The falling and settling of solid particles in gases and liquids is a natural phenomenon happens in many industrial processes. This phenomenon has altered pure forced convection to a combination of heat conduction and heat convection in a flow over a plate. In this paper, the coupling of conduction (inside the plate) and forced convection of a non-homogeneous nanofluid flow (over a flat plate) is investigated, which is classified in conjugate heat transfer problems. Two-component four-equatio...
Gallagher, B.; P. Alexander; D.Burger
1986-01-01
The Flat-Plate Solar Array (FSA) Project, funded by the U.S. Government and managed by the Jet Propulsion Laboratory, was formed in 1975 to develop the module/array technology needed to attain widespread terrestrial use of photovoltaics by 1985. To accomplish this, the FSA Project established and managed an Industry, University, and Federal Government Team to perform the needed research and development. The goal of the Process Development Area, as part of the FSA Project, was to develop ...
Effect of row-to-row shading on the output of flat-plate south-facing photovoltaic arrays
Energy Technology Data Exchange (ETDEWEB)
Goswami, D.Y.; Hassan, A.Y.; Collis, J. (North Carolina Agricultural and Technical State Univ., Greensboro, NC (USA)); Stefanakos, E.K. (University of South Florida, Tampa, FL (USA))
1989-08-01
When solar arrays (photovoltaic, thermal, etc.) are arranged in multiple rows of modules, all but the first row suffer reduction in (power) output, even when sufficient spacing between rows is provided. The reduction in output power occurs because the first row prevents some of the diffuse and reflected radiation from reaching the row directly behind it. This work presents estimates of the effect of shading on the amounts of solar radiation received by consecutive rows of flat-plate arrays.
Energy Technology Data Exchange (ETDEWEB)
Ferg, E.E.; Loyson, P. [Department of Chemistry, Nelson Mandela Metropolitan University, P.O. Box 77000, Port Elizabeth 6031 (South Africa); Poorun, A. [Willard Batteries, P.O. Box 1844, Port Elizabeth 6000 (South Africa)
2006-04-21
The study looked at the use of red lead in the manufacturing of valve regulated lead acid (VRLA) miners cap lamp (MCL) batteries that were made with either flat plate or tubular positive electrodes. A problem with using only grey oxide in the manufacture of thick flat plate or tubular electrodes is the poor conversion of the active material to the desired lead dioxide. The addition of red lead to the initial starting material improves the formation efficiency but is considerably more expensive thereby increasing the cost of manufacturing. The study showed that by carefully controlling the formation conditions in terms of the voltage and temperature of a battery, good capacity performance can be achieved for cells made with flat plate electrodes that contain up to 25% red lead. The small amount of red lead in the active cured material reduces the effect of electrode surface sulphate formation and allows the battery to achieve its rated capacity within the first few cycles. Batteries made with flat plate positive electrodes that contained more that 50% red lead showed good initial capacity but had poor structural active material bonding. The study showed that MCL batteries made with tubular positive electrodes that contained less than 75% red lead resulted in a poorly formed electrode with limited capacity utilization. Pickling and soaking times of the tubular electrodes should be kept at a minimum thereby allowing higher active material utilization during subsequent capacity cycling. The study further showed that it is beneficial to use higher formation rates in order to reduce manufacturing time and to improve the active material characteristics. (author)
Use of a rotating cylinder to induce laminar and turbulent separation over a flat plate
Afroz, F.; Lang, A.; Jones, E.
2017-06-01
An innovative and easy technique using a rotating cylinder system has been implemented in a water tunnel experiment to generate an adverse pressure gradient (APG). The strength of the APG was varied through adjustment in the rotation speed and location of the cylinder. Then the technique was used for inducing a laminar separation bubble (LSB) and turbulent boundary layer (TBL) separation over a flat plate. A theoretical model to predict the pressure variation induced on the plate consists of an inviscid flow over a reverse doublet-like configuration of two counter rotating cylinders. This model quantified the pressure distribution with changes of cylinder speed and location. The dimensionless velocity ratio (VR) of the cylinder rotation rate to the mainstream velocity and gap to diameter ratio \\tfrac{G}{D} were chosen as the two main ways of varying the strength of the APG, which affects the nature and extent of the LSB as well as TBL separation. The experimental parametric study, using time-resolved digital particle image velocimetry, was then conducted in a water tunnel. The variation in height (h), length (l), and the separation point (S) of the LSB was documented due to the variation in the APG. The similar type of experimental parametric study was used to explore the unsteady, turbulent separation bubble in a 2D plane aligned with the flow and perpendicular to the plate. The mean detachment locations of TBL separation are determined by two different definitions: (i) back-flow coefficient (χ) = 50%, and (ii) location of start of negative mean skin friction coefficient (C f). They are in good agreement and separation bubble characteristics agreed well with results obtained using different methods thus proving the validity of the technique.
Analysis of PV/T flat plate water collectors connected in series
Energy Technology Data Exchange (ETDEWEB)
Dubey, Swapnil; Tiwari, G.N. [Centre for Energy Studies, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016 (India)
2009-09-15
Photovoltaic-thermal (PV/T) technology refers to the integration of a PV and a conventional solar thermal collector in a single piece of equipment. In this paper we evaluate the performance of partially covered flat plate water collectors connected in series using theoretical modeling. PV is used to run the DC motor, which circulates the water in a forced mode. Analytical expressions for N collectors connected in series are derived by using basic energy balance equations and computer based thermal models. This paper shows the detailed analysis of thermal energy, exergy and electrical energy yield by varying the number of collectors by considering four weather conditions (a, b, c and d type) for five different cities (New Delhi, Bangalore, Mumbai, Srinagar, and Jodhpur) of India. Annual thermal and electrical energy yield is also evaluated for four different series and parallel combination of collectors for comparison purpose considering New Delhi conditions. This paper also gives the total carbon credit earned by the hybrid PV/T water heater investigated as per norms of Kyoto Protocol for New Delhi climatic conditions. Cost analysis has also been carried out. It is observed that the collectors partially covered by PV module combines the production of hot water and electricity generation and it is beneficial for the users whose primary requirement is hot water production and collectors fully covered by PV is beneficial for the users whose primary requirement is electricity generation. We have also found that if this type of system is installed only in 10% of the total residential houses in Delhi then the total carbon credit earned by PV/T water heaters in terms of thermal energy is USD $144.5 millions per annum and in terms of exergy is USD $14.3 millions per annum, respectively. (author)
A bubble column evaporator with basic flat-plate condenser for brackish and seawater desalination.
Schmack, Mario; Ho, Goen; Anda, Martin
2016-01-01
This paper describes the development and experimental evaluation of a novel bubble column-based humidification-dehumidification system, for small-scale desalination of saline groundwater or seawater in remote regions. A bubble evaporator prototype was built and matched with a simple flat-plate type condenser for concept assessment. Consistent bubble evaporation rates of between 80 and 88 ml per hour were demonstrated. Particular focus was on the performance of the simple condenser prototype, manufactured from rectangular polyvinylchlorid plastic pipe and copper sheet, a material with a high thermal conductivity that quickly allows for conduction of the heat energy. Under laboratory conditions, a long narrow condenser model of 1500 mm length and 100 mm width achieved condensate recovery rates of around 73%, without the need for external cooling. The condenser prototype was assessed under a range of different physical conditions, that is, external water cooling, partial insulation and aspects of air circulation, via implementing an internal honeycomb screen structure. Estimated by extrapolation, an up-scaled bubble desalination system with a 1 m2 condenser may produce around 19 l of distilled water per day. Sodium chloride salt removal was found to be highly effective with condensate salt concentrations between 70 and 135 µS. Based on findings and with the intent to reduce material cost of the system, a shorter condenser length of 750 mm for the non-cooled (passive) condenser and of 500 mm for the water-cooled condenser was considered to be equally efficient as the experimentally evaluated prototype of 1500 mm length.
1976-01-01
Basic test results of a flat-plate solar collector whose performance was determined in the NASA-Lewis solar simulator are given. The collector was tested over ranges of inlet temperature and flux level.
Min, Booki; Logan, Bruce E
2004-11-01
A microbial fuel cell (MFC) is a device that converts organic matter to electricity using microorganisms as the biocatalyst. Most MFCs contain two electrodes separated into one or two chambers that are operated as a completely mixed reactor. In this study, a flat plate MFC (FPMFC) was designed to operate as a plug flow reactor (no mixing) using a combined electrode/proton exchange membrane (PEM) system. The reactor consisted of a single channel formed between two nonconductive plates that were separated into two halves by the electrode/PEM assembly. Each electrode was placed on an opposite side of the PEM, with the anode facing the chamber containing the liquid phase and the cathode facing a chamber containing only air. Electricity generation using the FPMFC was examined by continuously feeding a solution containing wastewater, or a specific substrate, into the anode chamber. The system was initially acclimated for 1 month using domestic wastewater orwastewater enriched with a specific substrate such as acetate. Average power density using only domestic wastewater was 72+/-1 mW/m2 at a liquid flow rate of 0.39 mL/min [42% COD (chemical oxygen demand) removal, 1.1 h HRT (hydraulic retention time)]. At a longer HRT = 4.0 h, there was 79% COD removal and an average power density of 43+/-1 mW/m2. Power output was found to be a function of wastewater strength according to a Monod-type relationship, with a half-saturation constant of Ks = 461 or 719 mg COD/L. Power generation was sustained at high rates with several organic substrates (all at approximately 1000 mg COD/L), including glucose (212+/-2 mW/ m2), acetate (286+/-3 mW/m2), butyrate (220+/-1 mW/ m2), dextran (150+/-1 mW/m2), and starch (242+/-3 mW/ m2). These results demonstrate the versatility of power generation in a MFC with a variety of organic substrates and show that power can be generated at a high rate in a continuous flow reactor system.
Craft-Joule Project: Stagnation proof transparently insulated flat plate solar collector (static)
Energy Technology Data Exchange (ETDEWEB)
Oliva, A; Cadafalch, J; Perez-Segarra, C.D. [Universitat Politecnica de Catalunya, Barcelona (Spain)] (and others)
2000-07-01
The STATIC (STAgnation proof Transparently Insulated flat plate Solar Collector) project is a Craft-Joule Project within the framework of the Non Nuclear Energy Programme Joule III coordinated by the Centre Technologic de Transferencia de Calor (CTTC). The core group of SMEs involved in the project has its main economical activity in the field of solar thermal systems at low temperature level (domestic hot water, solar heating, etc.). Beyond this, a large application potential exists for solar heating at medium temperature level (from 80 to 160 Celsius degrees) : industrial process heat, solar cooling and air conditioning, solar drying , distillation and desalination. Three of the four SME proposers are located in Southern Europe and in the Caribean, where a continuos increase of the demand for air conditioning and cooling has been demonstrated in the last years. The recent development of flat plate solar collectors with honeycomb-type transparent insulation cover has shown that this type of collectors can become a low cost alternative to evacuated tube and high concentrating CPC collectors in the medium temperature range from 80 to 160 Celsius degrees. With the expected reduction of collector cost, that forms 30%-50% of total system cost, a decisive break-through of solar thermal systems using heat in the medium temperature range can be achieved. The feasibility and good performance of these solar collectors has been proved in several prototypes. Nevertheless, up to now no commercial products are available. In order to reach this, the following developments of new concepts are necessary and are being carried out within this project: solution of the problem of overheating: development of collector versions for different working temperatures: optimization of the design with the support of high level numerical simulation. Several prototypes of the new solar collectors are being tested. System tests will also be carried or for two test arrays of optimized collector
Influence of wire-coil inserts on the thermo-hydraulic performance of a flat-plate solar collector
Herrero Martín, R.; García, A.; Pérez-García, J.
2012-11-01
Enhancement techniques can be applied to flat-plate liquid solar collectors towards more compact and efficient designs. For the typical operating mass flow rates in flat-plate solar collectors, the most suitable technique is inserted devices. Based on previous studies from the authors, wire coils were selected for enhancing heat transfer. This type of inserted device provides better results in laminar, transitional and low turbulence fluid flow regimes. To test the enhanced solar collector and compare with a standard one, an experimental side-by-side solar collector test bed was designed and constructed. The testing set up was fully designed following the requirements of EN12975-2 and allow us to accomplish performance tests under the same operating conditions (mass flow rate, inlet fluid temperature and weather conditions). This work presents the thermal efficiency curves of a commercial and an enhanced solar collector, for the standardized mass flow rate per unit of absorber area of 0.02 kg/sm2 (in useful engineering units 144 kg/h for water as working fluid and 2 m2 flat-plate solar collector of absorber area). The enhanced collector was modified inserting spiral wire coils of dimensionless pitch p/D = 1 and wire-diameter e/D = 0.0717. The friction factor per tube has been computed from the overall pressure drop tests across the solar collectors. The thermal efficiency curves of both solar collectors, a standard and an enhanced collector, are presented. The enhanced solar collector increases the thermal efficiency by 15%. To account for the overall enhancement a modified performance evaluation criterion (R3m) is proposed. The maximum value encountered reaches 1.105 which represents an increase in useful power of 10.5% for the same pumping power consumption.
DEFF Research Database (Denmark)
Taherian, Hessam; Yazdanshenas, Eshagh
2006-01-01
Due to scarcity of literature on forced-convection heat transfer in a solar collector with rhombic cross-section absorbing tubes, a series of experiments was arranged and conducted to determine heat transfer coefficient. In this study, a typical rhombic cross-section finned tube of flat......-plate collectors used as the test section. Two correlations were proposed for the Nusselt number as a function of the Reynolds number and the Prandtl number based on hydraulic diameter for various heat fluxes. The temperature distribution along the finned tube for the fluid and the wall were also illustrated....
Christensen, Elmer
1985-01-01
The Flat-Plate Solar Array (FSA) Project, a Government-sponsored photovoltaics project, was initiated in January 1975 (previously named the Low-Cost Silicon Solar Array Project) to stimulate the development of PV systems for widespread use. Its goal then was to develop PV modules with 10% efficiency, a 20-year lifetime, and a selling price of $0.50 per peak watt of generating capacity (1975 dollars). It was recognized that cost reduction of PV solar-cell and module manufacturing was the key achievement needed if PV power systems were to be economically competitive for large-scale terrestrial use.
HEAT AND MASS TRANSFER FOR VISCO-ELASTIC MHD BOUNDARY LAYER FLOW PAST A VERTICAL FLAT PLATE
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Rita Choudhury
2012-07-01
Full Text Available The two-dimensional free convection flow of visco-elastic and electrically conducting fluid past a vertical impermeable flat plate is considered in presence of a uniform transverse magnetic field. The governing equations are reduced to ordinary differential equation by introducing appropriate co-ordinate transformation. The analytical expressions for the velocity, temperature and species concentration fields have been obtained. The corresponding expressions for the non-dimensional rates of heat transfer and mass transfer have beenobtained. The velocity profile and the shearing stress have been illustrated graphically, for various values of flow parameters involved in the solution to observe the effect of visco-elastic parameter.
Directory of Open Access Journals (Sweden)
Dr. G. Prabhakara Rao,
2015-04-01
Full Text Available We consider a two-dimensional MHD natural convection flow of an incompressible viscous and electrically conducting fluid through porous medium past a vertical impermeable flat plate is considered in presence of a uniform transverse magnetic field. The governing equations of velocity and temperature fields with appropriate boundary conditions are solved by the ordinary differential equations by introducing appropriate coordinate transformations. We solve that ordinary differential equations and find the velocity profiles, temperature profile, the skin friction and nusselt number. The effects of Grashof number (Gr, Hartmann number (M and Prandtl number (Pr, Darcy parameter (D-1 on velocity profiles and temperature profiles are shown graphically.
Reshetova, A. I.; Poplavskaya, T. V.
2016-10-01
The problem of disturbances evolution in a hypersonic viscous shock layer on a flat plate is considered. Numerical simulation was performed by solving 2D Navier-Stokes equations using the ANSYS Fluent software package within the model of thermally perfect gas. The change of vibrational energy was simulated by the Landau-Teller equation, in which the finite time of vibrational relaxation of CO2 molecules was taken into account. The quantitative data on the effect of vibrational relaxation of CO2 molecules on the evolution of acoustic disturbances in the shock layer on a plate is obtained.
Ayompe, Lacour; DUFFY Aidan
2013-01-01
The thermal performance of a solar water heating system with 4 m2 flat plate collectors in Dublin, Ireland is presented in this paper. The experimental setup consisted of a commercially available forced circulation domestic scale system fitted with an automated sub‐system that controlled hot water draw‐offs and the operation of an auxiliary immersion heater. The system was tested over a year and the maximum recorded collector outlet fluid temperature was 70.4 oC while the maximum water temper...
Bhuiyan, A. S.; Biswas, M. R.
2011-11-01
The effects of pressure stress work and viscous dissipation in mixed convection flow along a vertical flat plate have been investigated. The results are obtained numerically by transforming the governing system of boundary layer equations into a system of non-dimensional equations. Numerical results for different values of pressure stress work parameter, viscous dissipation parameter, and Prandtl number have been obtained. The velocity profiles, temperature distributions, skin friction coefficient, and the rate of heat transfer have been presented graphically for the effects of the aforementioned parameters. Results are compared with previous investigation.
PERFORMANCE DETERIORATION OF THERMOSIPHON SOLAR FLAT PLATE WATER HEATER DUE TO SCALING
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arunachala umesh chandavar
2011-12-01
Full Text Available 0 0 1 340 1943 International Islamic University 16 4 2279 14.0 Normal 0 false false false EN-US JA X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Times New Roman";} The performance of Flat plate Solar Water Heater deteriorates within five to twelve years of their installation due to factors related to manufacturing, operating conditions, lack of maintenance etc. Especially, problem due to scaling is significant as it is based on quality of water used. The remaining factors are system dependent and could be overcome by quality production. Software is developed by incorporating Hottel Whillier Bliss (H-W-B equation to ascertain the effect of scaling on system efficiency in case of thermosiphon system. In case of clean thermosiphon system, the instantaneous efficiency calculated at 1000 W/m2 radiation is 72 % and it drops to 46 % for 3.7 mm scale thickness. The mass flow rate is reduced by 90 % for 3.7 mm scale thickness. Whereas, the average temperature drop of water in the tank is not critical due to considerable heat content in water under severe scaled condition. But practically in case of major scale growth, some of the risers are likely to get blocked completely which leads to negligible temperature rise in the tank. ABSTRAK: Prestasi plat rata pemanas air suria merosot selepas lima hingga dua belas tahun pemasangannya disebabkan faktor-faktor yang berkaitan dengan pembuatannya, cara kendaliannya, kurangnya penyelenggaraan dan sebagainya. Terutama sekali, masalah disebabkan scaling (tembunan endapan mineral perlu diambil berat kerana ianya bergantung kepada kualiti air yang digunakan. Faktor-faktor selebihya bersandarkan sistem dan ia
Directory of Open Access Journals (Sweden)
Perović Bojan D.
2017-01-01
Full Text Available The main purpose of this paper is to show how the inclination angle affects natural convection from a flat-plate photovoltaic module which is mounted on the ground surface. In order to model this effect, novel correlations for natural convection from isothermal flat plates are developed by using the fundamental dimensionless number. On the basis of the available experimental and numerical results, it is shown that the natural convection correlations correspond well with the existing empirical correlations for vertical, inclined, and horizontal plates. Five additional correlations for the critical Grashof number are derived from the available data, three indicating the onset of transitional flow regime and two indicating the onset of flow separation. The proposed correlations cover the entire range of inclination angles and the entire range of Prandtl numbers. This paper also provides two worked examples, one for natural convection combined with radiation and one for natural convection combined with forced convection and radiation. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. TR33046
Energy Technology Data Exchange (ETDEWEB)
Borden, C.S.; Volkmer, K.; Cochrane, E.H.; Lawson, A.C.
1984-05-01
A simple methodology to estimate photovoltaic system size and life-cycle costs in stand-along applications is presented in this document. It is designed to assist engineers at government agencies in determining the feasibility of using small stand-alone photovoltaic systems to supply ac or dc power to the load. Photovoltaic system design considerations are presented as well as the equations for sizing the flat-plate array and the battery storage to meet the required load. Cost effectiveness of a candidate photovoltaic system is based on comparison with the life-cycle cost of alternative systems. Examples of alternative systems addressed herein are batteries, diesel generators, the utility grid, and other renewable energy systems. A companion document, Flat-Plate Photovoltaic Power Systems Handbook for Federal Agencies (Reference 10), is recommended for discussion of issues for evaluating the viability of potential photovoltaic applications; descriptions of present photovoltaic system applications; synthesis of lessons learned from photovoltaic system design, installation, and operation; and identification of procurement strategies for federal agencies.
Creager, Marcus O.
1959-01-01
An investigation of the effects of variation of leading-edge sweep and surface inclination on the flow over blunt flat plates was conducted at Mach numbers of 4 and 5.7 at free-stream Reynolds numbers per inch of 6,600 and 20,000, respectively. Surface pressures were measured on a flat plate blunted by a semicylindrical leading edge over a range of sweep angles from 0 deg to 60 deg and a range of surface inclinations from -10 deg to +10 deg. The surface pressures were predicted within an average error of +/- 8 percent by a combination of blast-wave and boundary-layer theory extended herein to include effects of sweep and surface inclination. This combination applied equally well to similar data of other investigations. The local Reynolds number per inch was found to be lower than the free-stream Reynolds number per inch. The reduction in local Reynolds number was mitigated by increasing the sweep of the leading edge. Boundary-layer thickness and shock-wave shape were changed little by the sweep of the leading edge.
Long, J.; New, T. H.
2016-07-01
Vortical structures and dynamics of a Re h = 2100 elliptic jet impinging upon a flat plate were studied at H/ d h = 1, 2 and 4 jet-to-plate separation distances. Flow investigations were conducted along both its major and minor planes using laser-induced fluorescence and digital particle image velocimetry techniques. Results show that the impingement process along the major plane largely consists of primary jet ring-vortex and wall-separated secondary vortex formations, where they subsequently separate from the flat plate at smaller H/ d h = 1 and 2 separation distances. Key vortex formation locations occur closer to the impingement point as the separation distance increases. Interestingly, braid vortices and rib structures begin to take part in the impingement process at H/ d h = 4 and wave instabilities dominate the flow field. In contrast, significantly more coherent primary and secondary vortices with physically larger vortex core sizes and higher vortex strengths are observed along the minor plane, with no signs of braid vortices and rib structures. Lastly, influences of these different flow dynamics on the major and minor plane instantaneous and mean skin friction coefficient levels are investigated to shed light on the effects of separation distance on the wall shear stress distributions.
Energy Technology Data Exchange (ETDEWEB)
Toyama, Y. [Mitsui Engineering and Shipbuilding Co. Ltd., Tokyo (Japan)
1996-12-31
A slamming load generated by interactive motions between a ship body and water face is an important load in ensuring safety of the ship. A flat plate approximation developed by Wagner is used as a two-dimensional slamming theory, but it has a drawback in handling edges of a flat plate. Therefore, an attempt was made to expand the two-dimensional Wagner`s theory to three dimensions. This paper first shows a method to calculate water face slamming of an arbitrary axisymmetric body by using circular plate approximation. The paper then proposes a method to calculate slamming pressure distribution and slamming force for the case when shape of the water contacting surface may be approximated by an elliptic shape. Expansion to the three dimensions made clear to some extent the characteristics of the three-dimensional slamming. In the case of two dimensions or a circular column for example, the water contacting area increases rapidly in the initial stage generating large slamming force. However, in the case of three dimensions, since the water contacting area expands longitudinally and laterally, the slamming force tends to increase gradually. Maximum slamming pressure was found proportional to square of moving velocity in a water contacting boundary in the case of three dimensions, and similar to stagnation pressure on a gliding plate. 12 refs., 17 figs., 1 tab.
Ambarita, Himsar; Kishinami, Koki; Daimaruya, Mashashi; Tokura, Ikuo; Kawai, Hideki; Suzuki, Jun; Kobiyama, Mashayosi; Ginting, Armansyah
The present paper is a study on the optimum plate to plate spacing for maximum heat transfer rate from a flat plate type heat exchanger. The heat exchanger consists of a number of parallel flat plates. The working fluids are flowed at the same operational conditions, either fixed pressure head or fixed fan power input. Parallel and counter flow directions of the working fluids were considered. While the volume of the heat exchanger is kept constant, plate number was varied. Hence, the spacing between plates as well as heat transfer rate will vary and there exists a maximum heat transfer rate. The objective of this paper is to seek the optimum plate to plate spacing for maximum heat transfer rate. In order to solve the problem, analytical and numerical solutions have been carried out. In the analytical solution, the correlations of the optimum plate to plate spacing as a function of the non-dimensional parameters were developed. Furthermore, the numerical simulation is carried out to evaluate the correlations. The results show that the optimum plate to plate spacing for a counter flow heat exchanger is smaller than parallel flow ones. On the other hand, the maximum heat transfer rate for a counter flow heat exchanger is bigger than parallel flow ones.
The flat-plate plant-microbial fuel cell: the effect of a new design on internal resistances
Directory of Open Access Journals (Sweden)
Helder Marjolein
2012-09-01
Full Text Available Abstract Due to a growing world population and increasing welfare, energy demand worldwide is increasing. To meet the increasing energy demand in a sustainable way, new technologies are needed. The Plant-Microbial Fuel Cell (P-MFC is a technology that could produce sustainable bio-electricity and help meeting the increasing energy demand. Power output of the P-MFC, however, needs to be increased to make it attractive as a renewable and sustainable energy source. To increase power output of the P-MFC internal resistances need to be reduced. With a flat-plate P-MFC design we tried to minimize internal resistances compared to the previously used tubular P-MFC design. With the flat-plate design current and power density per geometric planting area were increased (from 0.15 A/m2 to 1.6 A/m2 and from 0.22 W/m2 to and 0.44 W/m2as were current and power output per volume (from 7.5 A/m3 to 122 A/m3 and from 1.3 W/m3 to 5.8 W/m3. Internal resistances times volume were decreased, even though internal resistances times membrane surface area were not. Since the membrane in the flat-plate design is placed vertically, membrane surface area per geometric planting area is increased, which allows for lower internal resistances times volume while not decreasing internal resistances times membrane surface area. Anode was split into three different sections on different depths of the system, allowing to calculate internal resistances on different depths. Most electricity was produced where internal resistances were lowest and where most roots were present; in the top section of the system. By measuring electricity production on different depths in the system, electricity production could be linked to root growth. This link offers opportunities for material-reduction in new designs. Concurrent reduction in material use and increase in power output brings the P-MFC a step closer to usable energy density and economic feasibility.
Madavan, Nateri K.
1995-01-01
The work in this report was conducted at NASA Ames Research Center during the period from August 1993 to January 1995 deals with the direct numerical simulation of transitional and turbulent flow at low Mach numbers using high-order-accurate finite-difference techniques. A computation of transition to turbulence of the spatially-evolving boundary layer on a heated flat plate in the presence of relatively high freestream turbulence was performed. The geometry and flow conditions were chosen to match earlier experiments. The development of the momentum and thermal boundary layers was documented. Velocity and temperature profiles, as well as distributions of skin friction, surface heat transfer rate, Reynolds shear stress, and turbulent heat flux were shown to compare well with experiment. The numerical method used here can be applied to complex geometries in a straightforward manner.
Institute of Scientific and Technical Information of China (English)
R. TRˆIMBIT¸AS¸; T.GROSAN; I.POP
2015-01-01
An analysis is carried out to investigate the steady mixed convection bound-ary layer flow of a water based nanofluid past a vertical semi-infinite flat plate. Using an appropriate similarity transformation, the governing partial differential equations are transformed into the coupled, nonlinear ordinary (similar) differential equations, which are then solved numerically for the Prandtl number Pr = 6.2. The skin friction coeﬃ-cient, the local Nusselt number, and the velocity and temperature profiles are presented graphically and discussed. Effects of the solid volume fractionφand the mixed convection parameterλon the fluid flow and heat transfer characteristics are thoroughly examined. Different from an assisting flow, it is found that the solutions for an opposing flow are non-unique. In order to establish which solution branch is stable and physically realizable in practice, a stability analysis is performed.
Institute of Scientific and Technical Information of China (English)
SU CaiHong
2012-01-01
The transition criterion in the improved eN method is that transition would occur whenever the velocity amplitude of disturbance reaches 1％-2％ of the free stream velocity,while in the conventional eN method,the N factor is an empirical factor.In this paper the reliability of this key assumption in the improved eN method is checked by results of transition prediction by using the Parabolized Stability Equations (PSE).Transition locations of an incompressible boundary layer and a hypersonic boundary layer at Mach number 6 on a flat plate are predicted by both the improved eN method and the PSE method.Results from both methods agree fairly well with each other,implying that the transition criterion proposed in the improved eN method is reliable.
Phillips, M. J.
1986-01-01
Abstracts of final reports, or the latest quarterly or annual, of the Flat-Plate Solar Array (FSA) Project Contractor of Jet Propulsion Laboratory (JPL) in-house activities are presented. Also presented is a list of proceedings and publications, by author, of work connected with the project. The aim of the program has been to stimulate the development of technology that will enable the private sector to manufacture and widely use photovoltaic systems for the generation of electricity in residential, commercial, industrial, and Government applications at a cost per watt that is competitive with utility generated power. FSA Project activities have included the sponsoring of research and development efforts in silicon refinement processes, advanced silicon sheet growth techniques, higher efficiency solar cells, solar cell/module fabrication processes, encapsulation, module/array engineering and reliability, and economic analyses.
Rashidi, Mohammad M; Kavyani, Neda; Abelman, Shirley; Uddin, Mohammed J; Freidoonimehr, Navid
2014-01-01
In this study combined heat and mass transfer by mixed convective flow along a moving vertical flat plate with hydrodynamic slip and thermal convective boundary condition is investigated. Using similarity variables, the governing nonlinear partial differential equations are converted into a system of coupled nonlinear ordinary differential equations. The transformed equations are then solved using a semi-numerical/analytical method called the differential transform method and results are compared with numerical results. Close agreement is found between the present method and the numerical method. Effects of the controlling parameters, including convective heat transfer, magnetic field, buoyancy ratio, hydrodynamic slip, mixed convective, Prandtl number and Schmidt number are investigated on the dimensionless velocity, temperature and concentration profiles. In addition effects of different parameters on the skin friction factor, [Formula: see text], local Nusselt number, [Formula: see text], and local Sherwood number [Formula: see text] are shown and explained through tables.
Hasheminejad, S.M.
2017-04-03
Development of streamwise counter-rotating vortices induced by leading edge patterns with different pattern shape is investigated using hot-wire anemometry in the boundary layer of a flat plate. A triangular, sinusoidal and notched patterns with the same pattern wavelength λ of 15mm and the same pattern amplitude A of 7.5mm were examined for free-stream velocity of 3m/s. The results show a good agreement with earlier studies. The inflection point on the velocity profile downstream of the trough of the patterns at the beginning of the vortex formation indicates that the vortices non-linearly propagate downstream. An additional vortex structure was also observed between the troughs of the notched pattern.
Sforza, Eleonora; Calvaruso, Claudio; Meneghesso, Andrea; Morosinotto, Tomas; Bertucco, Alberto
2015-10-01
In this work, Nannochloropsis salina was cultivated in a continuous-flow flat-plate photobioreactor, working at different residence times and irradiations to study the effect of the specific light supply rate on biomass productivity and photosynthetic efficiency. Changes in residence times lead to different steady-state cell concentrations and specific growth rates. We observed that cultures at steady concentration were exposed to different values of light intensity per cell. This specific light supply rate was shown to affect the photosynthetic status of the cells, monitored by fluorescence measurements. High specific light supply rate can lead to saturation and photoinhibition phenomena if the biomass concentration is not optimized for the selected operating conditions. Energy balances were applied to quantify the biomass growth yield and maintenance requirements in N. salina cells.
On an ill-posed model of oscillations of a flat plate with a variety of mounts on opposite sides
Iskakova, Ulzada A.
2016-08-01
In this paper, we consider a model case of stationary vibrations of a thin flat plate, one side of which is embedded, the opposite side is free, and the sides are freely leaned. In mathematical modeling, there is a local boundary value problem for the biharmonic equation in a rectangular domain. Boundary conditions are given on all boundary of the domain. We show that the considered problem is self-adjoint. Herewith, the problem is ill-posed. We show that the stability of solution to the problem is disturbed. Necessary and sufficient conditions of existence of the problem solution are found. Spaces of the ill-posedness of the considered problem are constructed.
On a model of oscillations of a thin flat plate with a variety of mounts on opposite sides
Kal'menov, Tynysbek; Iskakova, Ulzada
2016-12-01
In this paper we consider a model case of stationary vibrations of a thin flat plate, one side of which is embedded, the opposite side is free, and the sides are freely leaned. In mathematical modeling there is a local boundary value problem for the biharmonic equation in a rectangular domain. Boundary conditions are given on all boundary of the domain. We show that the considered problem is self-adjoint. Herewith the problem is ill-posed. We show that the stability of solution to the problem is disturbed. Necessary and sufficient conditions of existence of the problem solution are found. Spaces of the ill-posedness of the considered problem are constructed.
Yokoyama, Tomoki; Takahashi, Kumiko; Seki, Daizaburou; Hasegawa, Akio
2002-05-01
The acoustic intensity distribution and radiation power of a flat-plate phased-array sound source consisting of Tonpilz-type transducers were measured. This study shows that the active acoustic intensity is skewed in the direction of wave propagation. In addition, it clarifies that if the measurement is carried out in the immediate vicinity of the sound source, the reactive acoustic intensity distribution is effective for identifying the positions of the individual sound source elements. Experimental values of active radiation power agree well with theoretical values. Conversely, experimental values of reactive radiation power do not agree with theoretical values; it is clear that they fluctuate significantly with distance from the radiating surface. The reason for this is explained in the case of a point sound source.
Directory of Open Access Journals (Sweden)
Norfifah Bachok
Full Text Available The steady boundary layer flow of a viscous and incompressible fluid over a moving vertical flat plate in an external moving fluid with viscous dissipation is theoretically investigated. Using appropriate similarity variables, the governing system of partial differential equations is transformed into a system of ordinary (similarity differential equations, which is then solved numerically using a Maple software. Results for the skin friction or shear stress coefficient, local Nusselt number, velocity and temperature profiles are presented for different values of the governing parameters. It is found that the set of the similarity equations has unique solutions, dual solutions or no solutions, depending on the values of the mixed convection parameter, the velocity ratio parameter and the Eckert number. The Eckert number significantly affects the surface shear stress as well as the heat transfer rate at the surface.
Directory of Open Access Journals (Sweden)
Park Dong-Woo
2015-01-01
Full Text Available Flat plate friction lines hare been used in the process to estimate speed performance of full-scale ships in model tests. The results of the previous studies showed considerable differences in determining form factors depending on changes in plate friction lines and Reynolds numbers. These differences had a great influence on estimation of speed performance of full-scale ships. This study- was conducted in two parts. In the first part, the scale effect of the form factor depending on change in the Reynolds number was studied based on CFD, in connection with three kinds of friction resistance curves: the ITTC-1957, the curve proposed by Grigson (1993; 1996, and the curve developed by Katsui et al (2005. In the second part, change in the form factor by three kinds of
An Explicit,Totally Analytic Solution of Laminar Viscous FLow over a Semi—Infinite Flat Plate
Institute of Scientific and Technical Information of China (English)
Shi－JunLIAO
1998-01-01
In this paper,a new kind of analytic technique for nonlinear problems,namely the Homotopy Analysis Method,is applied to give an explicit,totally analytic solution of the Blasius' flow.i.e.,the two dimensional (2D) laminar viscous flow over a semi-infinite flat plate.This analytic solution is valid in the whole region having physical meanings.To our knowledge,it is the first time in history that such a kind of explicit,totally analytic solution is given.This fact well verifies the great potential and validity of the Honmotopy Analysis Method as a kind of powerful analytic tool for nonlinear problems in science and engineering.
An experimental study of tip shape effects on the flutter of aft-swept, flat-plate wings
Dansberry, Bryan E.; Rivera, Jose A., Jr.; Farmer, Moses G.
1990-01-01
The effects of tip chord orientation on wing flutter are investigated experimentally using six cantilever-mounted, flat-plate wing models. Experimentally determined flutter characteristics of the six models are presented covering both the subsonic and transonic Mach number ranges. While all models have a 60 degree leading edge sweep, a 40.97 degree trailing edge sweep, and a root chord of 34.75 inches, they are subdivided into two series characterized by a higher aspect ratio and a lower aspect ratio. Each series is made up of three models with tip chord orientations which are parallel to the free-stream flow, perpendicular to the model mid-chord line, and perpendicular to the free-stream flow. Although planform characteristics within each series of models are held constant, structural characteristics such as mode shapes and natural frequencies are allowed to vary.
Borden, C. S.; Volkmer, K.; Cochrane, E. H.; Lawson, A. C.
1984-01-01
A simple methodology to estimate photovoltaic system size and life-cycle costs in stand-alone applications is presented. It is designed to assist engineers at Government agencies in determining the feasibility of using small stand-alone photovoltaic systems to supply ac or dc power to the load. Photovoltaic system design considerations are presented as well as the equations for sizing the flat-plate array and the battery storage to meet the required load. Cost effectiveness of a candidate photovoltaic system is based on comparison with the life-cycle cost of alternative systems. Examples of alternative systems addressed are batteries, diesel generators, the utility grid, and other renewable energy systems.
Directory of Open Access Journals (Sweden)
R. Venkata Rao
2015-12-01
Full Text Available This paper presents the performance of teaching–learning-based optimization (TLBO algorithm to obtain the optimum set of design and operating parameters for a smooth flat plate solar air heater (SFPSAH. The TLBO algorithm is a recently proposed population-based algorithm, which simulates the teaching–learning process of the classroom. Maximization of thermal efficiency is considered as an objective function for the thermal performance of SFPSAH. The number of glass plates, irradiance, and the Reynolds number are considered as the design parameters and wind velocity, tilt angle, ambient temperature, and emissivity of the plate are considered as the operating parameters to obtain the thermal performance of the SFPSAH using the TLBO algorithm. The computational results have shown that the TLBO algorithm is better or competitive to other optimization algorithms recently reported in the literature for the considered problem.
Institute of Scientific and Technical Information of China (English)
M.A.R.Akhanda
2000-01-01
Experimental study of natural convection heat transfer across air layers bounded by a lower hot rectangular and a square corrugated plates to an upper cold flat plate has been carried out.The surroundings of this space are adiabatic.The effect of the angle of inclination,the aspect ratio,the temperature potential and the Rayleigh number on average heat transfer coefficients are investigated within a range of 0°≤θ≤75°,2.33≤A≤6.33,10°≤ΔT≤35°，and 3.29×104≤RaL≤2.29×106,The developed correlation predicts well the experimental data within an error of ±15%.
Rashidi, Mohammad M.; Kavyani, Neda; Abelman, Shirley; Uddin, Mohammed J.; Freidoonimehr, Navid
2014-01-01
In this study combined heat and mass transfer by mixed convective flow along a moving vertical flat plate with hydrodynamic slip and thermal convective boundary condition is investigated. Using similarity variables, the governing nonlinear partial differential equations are converted into a system of coupled nonlinear ordinary differential equations. The transformed equations are then solved using a semi-numerical/analytical method called the differential transform method and results are compared with numerical results. Close agreement is found between the present method and the numerical method. Effects of the controlling parameters, including convective heat transfer, magnetic field, buoyancy ratio, hydrodynamic slip, mixed convective, Prandtl number and Schmidt number are investigated on the dimensionless velocity, temperature and concentration profiles. In addition effects of different parameters on the skin friction factor, , local Nusselt number, , and local Sherwood number are shown and explained through tables. PMID:25343360
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Hess, S.; Oliva, A.; Di Lauro, P.; Klemke, M.; Hermann, M.; Stryi-Hipp, G. [Fraunhofer-Institut fuer Solare Energiesysteme ISE, Freiburg (Germany); Kallwellis, V.; Kramp, G.; Eisenmann, W. [Wagner und Co. Solartechnik GmbH, Coelbe (Germany); Hanby, V. [DMU Leicester (United Kingdom). Inst. of Energy and Sustainable Development
2010-07-01
In cooperation with the Fraunhofer Institute for Solar Energy Systems (Freiburg, Federal Republic of Germany), the company Wagner and Co. Solar Technology (Coelbe, Federal Republic of Germany) developed a stationary concentrated, double-covered flat plate collector with an external reflector for generating process heat up to a temperature of 150 C. This prototype has a half-CPC reflector which is approximated by three flat segments. The reflectors use the distance between the collectors and serves simultaneously as a supporting structure. The collector is designed so that the aperture is not shaded. The authors of the contribution under consideration present the WKI curves and the IAM curves as a test pattern as well as a simulation of the annual energy yield. According to the simulation, the Reflec-collector has an annual energy yield which is greater by 64 % than that of the double-covered base-collector.
Huang, Jianke; Feng, Fei; Wan, Minxi; Ying, Jiangguo; Li, Yuanguang; Qu, Xiaoxing; Pan, Ronghua; Shen, Guomin; Li, Wei
2015-04-01
A novel mixer was developed to improve the performance of flat-plate photobioreactors (PBRs). The effects of mixer were theoretically evaluated using computational fluid dynamics (CFD) according to radial velocity of fluid and light/dark cycles within reactors. The structure parameters, including the riser width, top clearance, clearance between the baffles and walls, and number of the chambers were further optimized. The microalgae culture test aiming at validating the simulated results was conducted indoor. The results showed the maximum biomass concentrations in the optimized and archetype reactors were 32.8% (0.89 g L(-1)) and 19.4% (0.80 g L(-1)) higher than that in the control reactor (0.67 g L(-1)). Therefore, the novel mixer can significantly increase the fluid velocity along the light attenuation and light/dark cycles, thus further increased the maximum biomass concentration. The PBRs with novel mixers are greatly applicable for high-efficiency cultivation of microalgae.
DEFF Research Database (Denmark)
Kong, Weiqiang; Wang, Zhifeng; Fan, Jianhua;
2012-01-01
obtain fluid thermal capacitance in data processing. Then theoretical analysis and experimental verification are carried out to investigate influencing factors of obtaining accurate and stable second order term. A flat plate and ETC solar collector are compared using both the new dynamic method......A new dynamic test method is introduced. This so called improved transfer function method features on two new collector parameters. One is time term which can indicate solar collector's inner heat transfer ability and the other is a second order term of collector mean fluid temperature which can...... and a standard method. The results show that the improved function method can accurately and robustly estimate these two kinds of solar collectors....
Hollands, K. G. T.; Wright, J. L.
1983-01-01
This paper presents an efficient algorithm for solving the set of nonlinear equations governing the total heat transfer across an arbitrary number of parallel flat plate solar collector covers, each of which can be partly transparent to longwave thermal radiation. The governing equations are sufficiently general to permit each cover to have asymmetric radiative properties and to account for absorption of solar energy on the individual covers. This theory is shown to be in good agreement with the approximate equations of Whillier (provided certain interpretations are placed on his quantities) and with experiments using a plastic inner cover and bounding plates of various emissivities. Using this theory, it is demonstrated that if the absorber plate has a selective surface, an inner cover transparent to long wave radiation is to be preferred over one which is opaque.
Jakkareddy, Pradeep S.; Balaji, C.
2016-09-01
This paper employs the Bayesian based Metropolis Hasting - Markov Chain Monte Carlo algorithm to solve inverse heat transfer problem of determining the spatially varying heat transfer coefficient from a flat plate with flush mounted discrete heat sources with measured temperatures at the bottom of the plate. The Nusselt number is assumed to be of the form Nu = aReb(x/l)c . To input reasonable values of ’a’ and ‘b’ into the inverse problem, first limited two dimensional conjugate convection simulations were done with Comsol. Based on the guidance from this different values of ‘a’ and ‘b’ are input to a computationally less complex problem of conjugate conduction in the flat plate (15mm thickness) and temperature distributions at the bottom of the plate which is a more convenient location for measuring the temperatures without disturbing the flow were obtained. Since the goal of this work is to demonstrate the eficiacy of the Bayesian approach to accurately retrieve ‘a’ and ‘b’, numerically generated temperatures with known values of ‘a’ and ‘b’ are treated as ‘surrogate’ experimental data. The inverse problem is then solved by repeatedly using the forward solutions together with the MH-MCMC aprroach. To speed up the estimation, the forward model is replaced by an artificial neural network. The mean, maximum-a-posteriori and standard deviation of the estimated parameters ‘a’ and ‘b’ are reported. The robustness of the proposed method is examined, by synthetically adding noise to the temperatures.
Large-eddy simulation of separation and reattachment of a flat plate turbulent boundary layer
Cheng, W.
2015-11-11
© 2015 Cambridge University Press. We present large-eddy simulations (LES) of separation and reattachment of a flat-plate turbulent boundary-layer flow. Instead of resolving the near wall region, we develop a two-dimensional virtual wall model which can calculate the time- and space-dependent skin-friction vector field at the wall, at the resolved scale. By combining the virtual-wall model with the stretched-vortex subgrid-scale (SGS) model, we construct a self-consistent framework for the LES of separating and reattaching turbulent wall-bounded flows at large Reynolds numbers. The present LES methodology is applied to two different experimental flows designed to produce separation/reattachment of a flat-plate turbulent boundary layer at medium Reynolds number Reθ based on the momentum boundary-layer thickness θ. Comparison with data from the first case at demonstrates the present capability for accurate calculation of the variation, with the streamwise co-ordinate up to separation, of the skin friction coefficient, Reθ, the boundary-layer shape factor and a non-dimensional pressure-gradient parameter. Additionally the main large-scale features of the separation bubble, including the mean streamwise velocity profiles, show good agreement with experiment. At the larger Reθ = 11000 of the second case, the LES provides good postdiction of the measured skin-friction variation along the whole streamwise extent of the experiment, consisting of a very strong adverse pressure gradient leading to separation within the separation bubble itself, and in the recovering or reattachment region of strongly-favourable pressure gradient. Overall, the present two-dimensional wall model used in LES appears to be capable of capturing the quantitative features of a separation-reattachment turbulent boundary-layer flow at low to moderately large Reynolds numbers.
Stream-wise distribution of skin-friction drag reduction on a flat plate with bubble injection
Qin, Shijie; Chu, Ning; Yao, Yan; Liu, Jingting; Huang, Bin; Wu, Dazhuan
2017-03-01
To investigate the stream-wise distribution of skin-friction drag reduction on a flat plate with bubble injection, both experiments and simulations of bubble drag reduction (BDR) have been conducted in this paper. Drag reductions at various flow speeds and air injection rates have been tested in cavitation tunnel experiments. Visualization of bubble flow pattern is implemented synchronously. The computational fluid dynamics (CFD) method, in the framework of Eulerian-Eulerian two fluid modeling, coupled with population balance model (PBM) is used to simulate the bubbly flow along the flat plate. A wide range of bubble sizes considering bubble breakup and coalescence is modeled based on experimental bubble distribution images. Drag and lift forces are fully modeled based on applicable closure models. Both predicted drag reductions and bubble distributions are in reasonable concordance with experimental results. Stream-wise distribution of BDR is revealed based on CFD-PBM numerical results. In particular, four distinct regions with different BDR characteristics are first identified and discussed in this study. Thresholds between regions are extracted and discussed. And it is highly necessary to fully understand the stream-wise distribution of BDR in order to establish a universal scaling law. Moreover, mechanism of stream-wise distribution of BDR is analysed based on the near-wall flow parameters. The local drag reduction is a direct result of near-wall max void fraction. And the near-wall velocity gradient modified by the presence of bubbles is considered as another important factor for bubble drag reduction.
Design and Fabrication of a Two Axis Parabolic Solar Dish Collector
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Prof. Sonal C Yogi
2014-11-01
Full Text Available The work consists of the design of the chain drive system and the fabrication of the two axis parabolic solar dish. It is a model study of the two axis parabolic dish which worked by the automatic circuit that was developed. Ready made parabolic solar dish is taken and fabricated. The circular iron ring provides the two axis motion of the dish. A compound chain drive system was developed for the smooth movement of the dish. An electromechanical system which tracks the sun on both axes and which is controlled via a programmable logic control (PLC was designed and implemented. In this a theoretical study was done. A C program was made which gave the required result for the graphical representation of the recorded radiation. Programmable Logic Controls (PLC was used instead of photo sensors, which are widely used for tracking the sun. The azimuthal angle of the sun from sunrise to sunset times was calculated for each day of the year at 23.59 Lat & 72.38Longitude in the Northern hemisphere, the location of the city Mehsana. According to this azimuth angle, the required analog signal was taken from the PLC analog module and sent to the power window motor, which controlled the position of the panel to ensure that the rays fall vertically on the panel. After the mechanical control of the system was started, the performance measurements of the solar panel were carried out. The values obtained from the measurements were compared and the necessary evaluations were conducted.
Outdoor Performance Comparison of Concentrator Photovoltaic and Flat Plate Photovoltaic Systems
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Hidaka Yoshihide
2016-01-01
Full Text Available Output characteristics of tracking type concentrator photovoltaic (CPV system, multi-crystalline silicon (mc-Si PV system, CIGS PV system, and amorphous silicon (a-Si PV system were analyzed in the data period of a year from August 2013 to July 2014. In this study, we analyzed the influence of environmental factors using average photon energy (APE and temperature of solar cell (Tcell. The characteristics of 14 kW CPV system, 50 kW mc-Si PV system, 60 kW CIGS PV system, 1.35 kW a-Si PV system were evaluated and compared. As a result, the output performance of CPV was highest between the four systems at the most frequent conditions in the outdoor environment.
Munuswamy, Dinesh Babu; Madhavan, Venkata Ramanan; Mohan, Mukunthan
2015-12-01
To improve the efficiency of solar flat-plate collectors further, a study had been carried out wherein the conventional working fluid was replaced by nanofluids. A 25-L/day solar flat-plate water heater with collector area of 0.5 {m}^2 has been designed and fabricated. The thermosyphon system of the solar water heater was monitored at 15 locations using T-type thermocouples. Alumina and CuO nanoparticles were synthesized and characterized using Brunauer-Emmett-Teller and X-ray diffraction techniques and dispersed using ultrasonic mechanism. To stabilize the system at an optimum level, the collector is operated with volume fractions of 0.2% and 0.4% of synthesized Al2O3 and CuO nanoparticles mixed with distilled water and used in the solar flat-plate collector. The temperature profile was compared with different volume fractions of the nanoparticles in the flowing medium. Enhanced heat transfer was observed in the solar flat-plate collector using nanoparticles, and hence, it is inferred that addition of nanoparticles improves the efficiency of the solar water heaters. This paper details the temperature profile observed in the collectors, variation of insolation over the day, and change in efficiency both on the primary side (collector) and on the secondary side (storage tank) of the solar water heater.
Johnson, S.
1976-01-01
This preliminary data report gives basic test results of a flat-plate solar collector whose performance was determined in the NASA-Lewis solar simulator. The collector was tested over ranges of inlet temperatures, fluxes and coolant flow rates. Collector efficienty is correlated in terms of inlet temperature and flux level.
An Interval Type-2 Fuzzy Neural Network Control on Two-Axis Motion System
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Ye Xiaoting
2013-11-01
Full Text Available In this paper, an interval type-2 fuzzy neural network (IT2FNN control system is proposed to control a two-axis motion system, which is composed of two permanent magnet linear synchronous motors. The IT2FNN control system, which combines the merits of an interval type-2 fuzzy logic system and a neural network, is developed to approximate an unknown dynamic function. Moreover, adaptive learning algorithms that can train the parameters of the IT2FNN online are derived using the Lyapunov stability theorem. Furthermore, a robust compensator is proposed to confront the uncertainties. To relax the requirement for the value of the lumped uncertainty in the robust controller, an adaptive lumped uncertainty estimation law is also investigated. The proposed control algorithms are implemented. From the simulated and experimental results, the contour tracking performance of the two-axis motion control system is significantly improved and the robustness can be obtained as well using the proposed IT2FNN control system.
Adimurthy, M.; Katti, Vadiraj V.
2016-06-01
Local distribution of wall static pressure and heat transfer on a smooth flat plate impinged by a normal slot air jet is experimental investigated. Present study focuses on the influence of jet-to-plate spacing (Z/D h ) (0.5-10) and Reynolds number (2500-20,000) on the fluid flow and heat transfer distribution. A single slot jet with an aspect ratio (l/b) of about 22 is chosen for the current study. Infrared Thermal Imaging technique is used to capture the temperature data on the target surface. Local heat transfer coefficients are estimated from the thermal images using `SMART VIEW' software. Wall static pressure measurement is carried out for the specified range of Re and Z/D h . Wall static pressure coefficients are seen to be independent of Re in the range between 5000 and 15,000 for a given Z/D h . Nu values are higher at the stagnation point for all Z/D h and Re investigated. For lower Z/D h and higher Re, secondary peaks are observed in the heat transfer distributions. This may be attributed to fluid translating from laminar to turbulent flow on the target plate. Heat transfer characteristics are explained based on the simplified flow assumptions and the pressure data obtained using Differential pressure transducer and static pressure probe. Semi-empirical correlation for the Nusselt number in the stagnation region is proposed.
M, Adimurthy; Katti, Vadiraj V.
2017-02-01
Local distribution of wall static pressure and heat transfer on a smooth flat plate impinged by a normal slot air jet is experimental investigated. Present study focuses on the influence of jet-to-plate spacing ( Z/D h ) (0.5-10) and Reynolds number (2500-20,000) on the fluid flow and heat transfer distribution. A single slot jet with an aspect ratio ( l/b) of about 22 is chosen for the current study. Infrared Thermal Imaging technique is used to capture the temperature data on the target surface. Local heat transfer coefficients are estimated from the thermal images using `SMART VIEW' software. Wall static pressure measurement is carried out for the specified range of Re and Z/D h . Wall static pressure coefficients are seen to be independent of Re in the range between 5000 and 15,000 for a given Z/D h . Nu values are higher at the stagnation point for all Z/D h and Re investigated. For lower Z/D h and higher Re, secondary peaks are observed in the heat transfer distributions. This may be attributed to fluid translating from laminar to turbulent flow on the target plate. Heat transfer characteristics are explained based on the simplified flow assumptions and the pressure data obtained using Differential pressure transducer and static pressure probe. Semi-empirical correlation for the Nusselt number in the stagnation region is proposed.
Cai, Chunpei; He, Xin
2016-05-01
This paper presents two sets of analytical exact solutions for collisionless gas flows from a planar exit, impinging at an inclined flat plate. These analytical results are obtained by using gaskinetic theories. The first set of solutions are for a diffuse reflective plate surface, and the other set of solutions are for a specular reflective plate surface. A virtual nozzle exit is adopted to aid analyzing the specular reflective plate scenario. New formulas for plate surface properties, including velocity slips, pressure, shear stress, and heat flux distributions, are provided. For both problems, the flowfield exact solutions are investigated as well. Numerical simulations with the direct simulation Monte Carlo method are performed to validate these new analytical results, and good agreement is obtained for flows with high Knudsen numbers. The results consider effects from many factors, such as the plate inclination angle, geometry ratios, and exit gas and plate properties (such as exit gas bulk density, gas speed ratio, and exit gas and plate temperatures). Compared with past work, these new solutions are more comprehensive and practical. The results also illustrate that if the plate is quite close to the nozzle exit, it is improper to adopt the traditional treatments of a point source and a simple cosine function.
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Suozhu Wang
2015-02-01
Full Text Available Reducing friction resistance and aerodynamic heating has important engineering significance to improve the performances of super/hypersonic aircraft, so the purpose of transition control and turbulent drag reduction becomes one of the cutting edges in turbulence research. In order to investigate the influences of wall cooling and suction on the transition process and fully developed turbulence, the large eddy simulation of spatially evolving supersonic boundary layer transition over a flat-plate with freestream Mach number 4.5 at different wall temperature and suction intensity is performed in the present work. It is found that the wall cooling and suction are capable of changing the mean velocity profile within the boundary layer and improving the stability of the flow field, thus delaying the onset of the spatial transition process. The transition control will become more effective as the wall temperature decreases, while there is an optimal wall suction intensity under the given conditions. Moreover, the development of large-scale coherent structures can be suppressed effectively via wall cooling, but wall suction has no influence.
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Rhodes, R.O.; Chapman, N.J.; Chao, K.C.; Sorenson, K.F.
1980-01-01
This study investigated materials and processes for fundamental improvements in flat-plate solar collector cost and performance. The goal was to develop a process for direct conversion of inexpensive raw materials into a completed solar collector unit, without labor intensive assembly operations. It was thought that materials carefully matched to the process and end-use environment would substantially reduce collector costs, as compared to conventional industry practice. The project studied the feasibility of a cost-effective, glazed solar collector, with low labor input, utilizing a coaxial extrusion of compatible polymeric materials. This study evaluated all considered materials for the desired application. In addition, there was a trial extrusion of the leading candidate glazing and absorber materials, which resulted in successfully performing a coaxial extrusion of one cell. At the time the study was conducted, there were no materials available that met the necessary requirements for the specified utilization. It was recommended that, if potentially compatible materials become available, further investigation into the suitability of those materials be researched. Then, if a suitable material was found, proceeding into Phase II would be recommended.
Huang, Jianke; Li, Yuanguang; Wan, Minxi; Yan, Yi; Feng, Fei; Qu, Xiaoxing; Wang, Jun; Shen, Guomin; Li, Wei; Fan, Jianhua; Wang, Weiliang
2014-05-01
Novel flat-plate photobioreactors (PBRs) with special mixers (type-a, type-b, and type-c) were designed based on increased mixing degree along the light gradient. The hydrodynamic and light regime characteristic of the novel PBRs were investigated through computational fluid dynamics. Compared with the control reactor without mixer, the novel reactors can effectively increase liquid velocity along the light gradient, the frequency of light/dark (L/D) cycles, and the algal growth rates of Chlorella pyrenoidosa. The maximum biomass concentrations in type-a, type-b, and type-c reactors were 42.9% (1.3 g L(-1)), 31.9% (1.2 g L(-1)), and 20.9% (1.1 g L(-1)) higher than that in the control reactor (0.91 g L(-1)), respectively, at an aeration rate of 1.0 vvm. Correlation analysis of algal growth rate with the characteristics of mixing and light regime shows the key factors affecting algal photoautotrophic growth are liquid velocity along the light gradient and L/D cycles rather than the macro-mixing degree.
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ML CHOUGUI
2014-12-01
Full Text Available Adrar is a city in the Sahara desert, in southern Algeria known for its hot and dry climate, where a huge amount of energy is used for air conditioning. The aim of this research is to simulate a single effect lithium bromide–water absorption chiller coupled to a double-glazed flat plate collector to supply the cooling loads for a house of 200m2 in Adrar. The thermal energy is stored in an insulated thermal storage tank. The system was designed to cover a cooling load of 10.39KW for design day of July. Thermodynamic model was established to simulate the absorption cycle. The results have shown that the collector mass flow rate has a negligible effect on the minimum required collector area, but it has a significant effect on the optimum capacity of the storage tank. The minimum required collector area was about 65.3 m2, which could supply the cooling loads for the sunshine hours of the design day for July. The operation of the system has also been considered after sunset by saving solar energy.
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Lee, Handol; Yook, Sejin; Han, Seogyoung [Hanyang University, Seoul (Korea, Republic of)
2012-10-15
The deposition velocity is used to assess the degree of particulate contamination of wafers or photomasks. A numerical model was developed to predict the deposition velocity under the combined influences of thermophoresis and electrophoresis. The deposition velocity onto a face-up flat plate in parallel airflow was simulated by varying the temperature difference between the plate's surface and ambient air or by changing the strength of the electric field established above the plate. Both attraction and repulsion by thermophoresis or electrophoresis were considered. When the plate's surface was colder than ambient air, the surface of the face-up plate could be at risk of contamination by charged particles even with a repulsive applied electric force. When the temperature of the plate's surface was higher than the ambient temperature, the degree of particulate contamination on the surface of the face-up plate could be remarkably reduced in the presence of an electric field. The effect of repulsive thermophoresis, however, is expected to be reduced for very fine particles of high electric mobility or for micrometer-sized particles with large gravitational settling speed when the charged particles are influenced by an attractive electric force.
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S.K. Parida
2015-12-01
Full Text Available This work considers the two-dimensional steady MHD boundary layer flow of heat and mass transfer over a flat plate with partial slip at the surface subjected to the convective heat flux. The particular attraction lies in searching the effects of variable viscosity and variable thermal diffusivity on the behavior of the flow. In addition, non-linear thermal radiation effects and thermophoresis are taken into account. The governing nonlinear partial differential equations for the flow, heat and mass transfer are transformed into a set of coupled nonlinear ordinary differential equations by using similarity variable, which are solved numerically by applying Runge–Kutta fourth–fifth order integration scheme in association with quasilinear shooting technique. The novel results for the dimensionless velocity, temperature, concentration and ambient Prandtl number within the boundary layer are displayed graphically for various parameters that characterize the flow. The local skin friction, Nusselt number and Sherwood number are shown graphically. The numerical results obtained for the particular case are fairly in good agreement with the result of Rahman [6].
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A. Malvandi
2015-01-01
Full Text Available The falling and settling of solid particles in gases and liquids is a natural phenomenon happens in many industrial processes. This phenomenon has altered pure forced convection to a combination of heat conduction and heat convection in a flow over a plate. In this paper, the coupling of conduction (inside the plate and forced convection of a non-homogeneous nanofluid flow (over a flat plate is investigated, which is classified in conjugate heat transfer problems. Two-component four-equation non-homogeneous equilibrium model for convective transport in nanofluids (mixture of water with particles<100nm has been applied that incorporates the effects of the nanoparticles migration due to the thermophoresis and Brownian motion forces. Employing similarity variables, we have transformed the basic non-dimensional partial differential equations to ordinary differential ones and then solved numerically. Moreover, variation of the heat transfer and concentration rates with thermal resistance of the plate is studied in detail. Setting the lowest dependency of heat transfer rate to the thermal resistance of the plate as a goal, we have shown that for two nanofluids with similar heat transfer characteristics, the one with higher Brownian motion (lower nanoparticle diameter is desired.
On the correlation between force production and the flow field around a flapping flat-plate wing
Öz, Sören; Krishna, Swathi; Mulleners, Karen
2015-11-01
One of the several sophisticated flight skills that insects exhibit is hovering, which is accomplished largely by modulating the wing kinematics and thereby the flow field around the wings. Along with the prolonged attachment of the leading edge vortex, the wing reversal mechanisms form the basis by which insects regulate the magnitude and direction of forces produced. The duration and starting point of these directional flips are studied in the current experimental investigation. Particle image velocimetry is conducted to evaluate the flow features inherent to changes in wing reversal during the stroke of a flat plate, which is modelled based on hoverfly characteristics. The duration of rotation is one-third of the total time period. A +10% phase shift is used for delayed rotation, a -10% phase shift for advanced rotation. Phase-averaged data is analysed to understand the influence of a delayed or advanced rotation on the formation and evolution of large and small scale structures, their interactions with the wing, and disintegration. Additionally, force data is used to quantify the effects of phase-shift in terms of lift and drag variation and is correlated with the vortex dynamics.
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Andrew Y. A. Oyieke
2016-01-01
Full Text Available A flat-plate Vacuum Insulated Photovoltaic and Thermal (VIPV/T system has been thermodynamically simulated and experimentally evaluated to assess the thermal and electrical performance as well as energy conversion efficiencies under a subtropical climate. A simulation model made of specified components is developed in Transient Systems (TRNSYS environment into which numerical energy balance equations are implemented. The influence of vacuum insulation on the system’s electrical and thermal yields has been evaluated using temperatures, current, voltage, and power flows over daily and annual cycles under local meteorological conditions. The results from an experiment conducted under steady-state conditions in Durban, South Africa, are compared with the simulation based on the actual daily weather data. The VIPV/T has shown improved overall and thermal efficiencies of 9.5% and 16.8%, respectively, while electrical efficiency marginally reduced by 0.02% compared to the conventional PV/T. The simulated annual overall efficiency of 29% (i.e., 18% thermal and 11% electrical has been realised, in addition to the solar fraction, overall exergy, and primary energy saving efficiencies of 39%, 29%, and 27%, respectively.
Frankl, F.; Voishel, V.
1943-01-01
In the present report an investigation is made on a flat plate in a two-dimensional compressible flow of the effect of compressibility and heating on the turbulent frictional drag coefficient in the boundary layer of an airfoil or wing radiator. The analysis is based on the Prandtl-Karman theory of the turbulent boundary later and the Stodola-Crocco, theorem on the linear relation between the total energy of the flow and its velocity. Formulas are obtained for the velocity distribution and the frictional drag law in a turbulent boundary later with the compressibility effect and heat transfer taken into account. It is found that with increase of compressibility and temperature at full retardation of the flow (the temperature when the velocity of the flow at a given point is reduced to zero in case of an adiabatic process in the gas) at a constant R (sub x), the frictional drag coefficient C (sub f) decreased, both of these factors acting in the same sense.
The effect of aspect ratio on vortex rings within the wake of impulsively-started flat plates
Fernando, John; Rival, David
2014-11-01
Vortex pinch-off has been the focus of many studies since it was first observed for vortices produced via piston-cylinder arrangements. Minimal work has been performed on other vortex generation methods. The current study investigates vortex rings behind impulsively-started circular, square, and elliptical flat plates. Preliminary force and PIV measurements show temporal/spatial similarities between vortex growth in the wake of the circular and square plates. Forces and vortex evolution are also shown to be strongly coupled; the presence of stable wake vortex rings results in a reduction of plate drag. For all three plates, pinch-off is initiated by the formation of a positive pressure gradient on the leeward side of the plate, which terminates mass transport to the vortex. It is hypothesized that an increase in aspect ratio (AR) from unity results in isolated vortex lines with non-uniform vorticity along the leading edges. Strong spanwise velocity gradients and stretching near the plate tips facilities vortex detachment. Results from experiments on rectangular plates with varying ARs are discussed and the effect of stretching and tilting in the tip region is investigated. The United States Air Force Office of Scientific Research.
Feedback control of unstable steady states of flow past a flat plate using reduced-order estimators
Ahuja, Sunil
2009-01-01
We present an estimator-based control design procedure for flow control, using reduced-order models of the governing equations, linearized about a possibly unstable steady state. The reduced models are obtained using an approximate balanced truncation method that retains the most controllable and observable modes of the system. The original method is valid only for stable linear systems, and we present an extension to unstable linear systems. The dynamics on the unstable subspace are represented by projecting the original equations onto the global unstable eigenmodes, assumed to be small in number. A snapshot-based algorithm is developed, using approximate balanced truncation, for obtaining a reduced-order model of the dynamics on the stable subspace. The proposed algorithm is used to study feedback control of 2-D flow over a flat plate at a low Reynolds number and at large angles of attack, where the natural flow is vortex shedding, though there also exists an unstable steady state. For control design, we de...
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Flamm, H.; Lochau, R.; Maeiss, M.; Schiele, J.
1984-07-01
In a newly constructed south-west-facade 200 m/sup 2/ of flat plate collectors were integrated as construction elements to heat domestic water. The building needs 5-10 m/sup 3/ of hot water per day, i.e. 250-500 kWh/d. The solar circuit runs with a water-glycol-mixture with a specific volume flow rate of 20-40 l/m/sup 2/h. The storage capacity is 8 m/sup 3/, i.e. 40 l/m/sup 2/ collector area. The heating system is bivalent. The total cost was DM 220.000, excepting the cost of facade construction. The observation period was 2 years. The heat flow balance was measured daily using a microprocessor. As far as the construction was concerned, there were no defects during the observation period. The rooms behind solar collectors showed no additional thermal load. The most favourable season for running solar systems is from April to September. In this period the average efficiencies were 15 to 20%, the net energy yield was 76 kWh/m/sup 2/.
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Sona Kazemi
2016-01-01
Full Text Available The separator plays a key role on the performance of passive air-breathing flat-plate MFCs (FPMFC as it isolates the anaerobic anode from the air-breathing cathode. The goal of the present work was to study the separator characteristics and its effect on the performance of passive air-breathing FPMFCs. This was performed partially through characterization of structure, properties, and performance correlations of eight separators presented in Part 1. Current work (Part 2 presents a numerical model developed based on the mixed potential theory to investigate the sensitivity of the electrode potentials and the power output to the separator characteristics. According to this numerical model, the decreased peak power results from an increase in the mass transfer coefficients of oxygen and ethanol, but mainly increasing mixed potentials at the anode by oxygen crossover. The model also indicates that the peak power is affected by the proton transport number of the separator, which affects the cathode pH. Anode pH, on the other hand, remains constant due to application of phosphate buffer solution as the electrolyte. Also according to this model, the peak power is not sensitive to the resistivity of the separator because of the overshadowing effect of the oxygen crossover.
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Puvaneswari Puvaneswari
2016-01-01
Full Text Available The effect of conjugation on the enhancement of heat transfer in a liquid metal flow past a thermally conducting and sinusoidally oscillating infinite flat plate, when a constant temperature gradient is superimposed on the fluid, is investigated. The plate is made up of the materials compatible with the liquid metals used and is considered to be of finite thickness. Analytical solutions for the velocity and the temperature of the fluid and the solid are obtained. The effects of thermal conductivity and the thickness of the plate on the total time averaged heat flux transported and the thermal boundary layer thickness are investigated in detail. It is found that the effects of wall thickness and wall thermal conductivity on the heat flux transported depend on their effects on the transverse temperature gradient at any frequency. The optimum value of wall thickness at which the net heat flux transported attains the maximum value, for each fluid and for each wall material under consideration, is reported. A maximum increase of 46.14 % in the heat flux transported can be achieved by optimizing the wall thickness. A maximum convective heat flux of 1.87 × 108W/m2 is achieved using Na with AISI 316 wall. All the results obtained have been compared with the experimental and analytical results reported in the literature and are found to be in good agreement. It is believed that the new insights gained will be of significant use while designing liquid metal heat transfer systems.
Angle hybrid control for a two-axis piezo-positioning system and its application
Zhu, Wei; Zhou, Qinbo; Rui, Xiaoting
2016-09-01
The hysteresis characteristics of piezoelectric actuators and the residual vibration in the rapid positioning process will greatly affect the positioning accuracy and speed of a piezo-driven positioning system (PPS). In order to improve the positioning accuracy and to restrain the residual vibration of a two-axis PPS, a hybrid controller is proposed and explored based on a comprehensive model by combining the proposed feedforward linearization, the zero vibration and derivative shaping, and the linear-quadratic Gaussian feedback control for the PPS. The experimental results show that the proposed hybrid control significantly improves the positioning accuracy and suppresses the residual vibration of the PPS. Its application shows that the PPS proposed herein can effectively enhance the astronomical telescope’s star tracking and pointing performance.
A broadband two axis flux-gate magnetometer
Directory of Open Access Journals (Sweden)
P. Palangio
1998-06-01
Full Text Available A broadband two axis flux-gate magnetometer was developed to obtain high sensitivity in magnetotelluric measurements. In magnetotelluric sounding, natural low frequency electromagnetic fields are used to estimate the conductivity of the Earth's interior. Because variations in the natural magnetic field have small amplitude(10-100 pT in the frequency range 1 Hz to 100 Hz, highly sensitive magnetic sensors are required. In magnetotelluric measurements two long and heavy solenoids, which must be installed, in the field station, perpendicular to each other (north-south and east-west and levelled in the horizontal plane are used. The coil is a critical component in magnetotelluric measurements because very slight motions create noise voltages, particularly troublesome in wooded areas; generally the installation takes place in a shallow trench. Moreover the coil records the derivative of the variations rather than the magnetic field variations, consequently the transfer function (amplitude and phase of this sensor is not constant throughout the frequency range 0.001-100 Hz. The instrument, developed at L'Aquila Geomagnetic Observatory, has a flat response in both amplitude and phase in the frequency band DC-100 Hz, in addition it has low weight, low power, small volume and it is easier to install in the field than induction magnetometers. The sensivity of this magnetometer is 10 pT rms.
Propagation of angular errors in two-axis rotation systems
Torrington, Geoffrey K.
2003-10-01
Two-Axis Rotation Systems, or "goniometers," are used in diverse applications including telescope pointing, automotive headlamp testing, and display testing. There are three basic configurations in which a goniometer can be built depending on the orientation and order of the stages. Each configuration has a governing set of equations which convert motion between the system "native" coordinates to other base systems, such as direction cosines, optical field angles, or spherical-polar coordinates. In their simplest form, these equations neglect errors present in real systems. In this paper, a statistical treatment of error source propagation is developed which uses only tolerance data, such as can be obtained from the system mechanical drawings prior to fabrication. It is shown that certain error sources are fully correctable, partially correctable, or uncorrectable, depending upon the goniometer configuration and zeroing technique. The system error budget can be described by a root-sum-of-squares technique with weighting factors describing the sensitivity of each error source. This paper tabulates weighting factors at 67% (k=1) and 95% (k=2) confidence for various levels of maximum travel for each goniometer configuration. As a practical example, this paper works through an error budget used for the procurement of a system at Sandia National Laboratories.
Movement decoupling control for two-axis fast steering mirror
Wang, Rui; Qiao, Yongming; Lv, Tao
2017-02-01
Based on flexure hinge and piezoelectric actuator of two-axis fast steering mirror is a complex system with time varying, uncertain and strong coupling. It is extremely difficult to achieve high precision decoupling control with the traditional PID control method. The feedback error learning method was established an inverse hysteresis model which was based inner product dynamic neural network nonlinear and no-smooth for piezo-ceramic. In order to improve the actuator high precision, a method was proposed, which was based piezo-ceramic inverse model of two dynamic neural network adaptive control. The experiment result indicated that, compared with two neural network adaptive movement decoupling control algorithm, static relative error is reduced from 4.44% to 0.30% and coupling degree is reduced from 12.71% to 0.60%, while dynamic relative error is reduced from 13.92% to 2.85% and coupling degree is reduced from 2.63% to 1.17%.
Two Axis Pointing System (TAPS) attitude acquisition, determination, and control
Azzolini, John D.; McGlew, David E.
1990-12-01
The Two Axis Pointing System (TAPS) is a 2 axis gimbal system designed to provide fine pointing of Space Transportation System (STS) borne instruments. It features center-of-mass instrument mounting and will accommodate instruments of up to 1134 kg (2500 pounds) which fit within a 1.0 by 1.0 by 4.2 meter (40 by 40 by 166 inch) envelope. The TAPS system is controlled by a microcomputer based Control Electronics Assembly (CEA), a Power Distribution Unit (PDU), and a Servo Control Unit (SCU). A DRIRU-II inertial reference unit is used to provide incremental angles for attitude propagation. A Ball Brothers STRAP star tracker is used for attitude acquisition and update. The theory of the TAPS attitude determination and error computation for the Broad Band X-ray Telescope (BBXRT) are described. The attitude acquisition is based upon a 2 star geometric solution. The acquisition theory and quaternion algebra are presented. The attitude control combines classical position, integral and derivative (PID) control with techniques to compensate for coulomb friction (bias torque) and the cable harness crossing the gimbals (spring torque). Also presented is a technique for an adaptive bias torque compensation which adjusts to an ever changing frictional torque environment. The control stability margins are detailed, with the predicted pointing performance, based upon simulation studies. The TAPS user interface, which provides high level operations commands to facilitate science observations, is outlined.
Simon, F. F.
1975-01-01
A performance evaluation was made of two, black nickel coated, flat plate solar collectors. Collector performance was determined under a simulated sun for a wide range of inlet temperatures, including the temperature required for solar powered absorption air conditioning. For a basis of comparison a performance test was made on a traditional, two glass, nonselective, black paint coated, flat plate collector. Performance curves and performance parameters are presented to point out the importance of the design variables which determine an efficient collector. A black nickel coated collector was found to be a good performer at the conditions expected for solar powered absorption air conditioning. This collector attained a thermal efficiency of 50 percent at an inlet temperature of 366 K (200 F) and an incident flux of 946 watts/sq m (300 Btu/hr-sq ft).
Energy Technology Data Exchange (ETDEWEB)
Kovacs, Peter; Pettersson, Ulrik
2002-10-01
Two solar combisystems were mounted side by side in an outdoor test facility and continuously operated during one year. The whole year, all relevant temperatures, flow rates and environment variables were thoroughly measured. The systems were identical apart from the collectors which were a 9 m{sup 2} vacuum tube and a 12.2 m{sup 2} selective flat plate collector. A simulated space heating and tap water load of approx. 25 MWh/a was applied to each system and auxiliary heat was charged to the stores from emulated pellet boilers. Additionally, the two collectors and the store was tested separately and the systems simulated according to the CTSS principle described in ENV 12977. The aim of the project was to determine solar fractions in a solar combisystem from real measurements and to compare the two different collector types from different points of view. On the basis of the validated simulation model, the results from the long term measurements could be generalized and eight different loads were simulated. The results showed that the vacuum tubes performed 45-60% better than the flat plate per m{sup 2} depending on the load applied. The solar fractions (assuming no losses from the boiler) varied from 11% for the measured systems to approx. 30 % in a house with 25 % of the original space heating load. During the heating season, the vacuum tubes occasionally performed much worse than the flat plate due to the fact that snow and frost melted away much quicker from the flat plate. For the use of vacuum tubes in snowy regions, vertical mounting should therefore be strongly recommended.
Kaplanis, S.; Kaplani, E.
2012-01-01
This paper outlines and formulates a compact and effective simulation model, which predicts the performance of single and double glaze flat-plate collector. The model uses an elaborated iterative simulation algorithm and provides the collector top losses, the glass covers temperatures, the collector absorber temperature, the collector fluid outlet temperature, the system efficiency, and the thermal gain for any operational and environmental conditions. It is a numerical approach based on simu...
Institute of Scientific and Technical Information of China (English)
无
1996-01-01
The coupled heat and mass transfer problem of gas flow over a UHF flat plate with its wall coated with sublimable substance was been solved by local non-smimilarity method.Considerations have been given also to the effect of non-saturation of the sublimable substance in the oncoming flow and the normal injection velocity at the surface.Analytical results are given for local Noselt and Sherwood Numbers at the various locations.
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Palaniappan Chandramohan
2017-01-01
Full Text Available The aim of this work is to investigate experimentally the variation in temperature, heat transfer coefficient and Nusselt number of a hot plate subjected to multi-jet air impingement cooling to use the multi-objective optimization technique to arrive at optimum conditions. A flat plate of 15 cm x 10 cm is heated through a heating foil with a constant heat flux of 7667 W/m2. Air jets with and without swirling action are considered, fixing the distance of target surface from nozzle exit at 2D, 4D and 6D. Reynolds numbers 18000, 20000and 22000 and pipe diameters 8mm, 10mm and 12 mm have been considered for investigation. Experiments are designed and analyzed using Taguchi’s technique, coupled with principal component analysis for multi-variate optimization by calculating multi-response performance index (MRPI. Based on the observations made, it is concluded that lower H/D ratio and higher Reynolds number result in higher heat transfer coefficient, in accordance with the first principles. Heat transfer coefficient obtained for jets with swirl is compared with that of jet without swirling for the same Reynolds number and H/D ratio. Furthermore, it is concluded that introducing swirl results in increase of heat transfer coefficients for all the test conditions for 10mm and 12mm diameter jets. However for 8mm jet, introduction of swirl reduced the heat transfer rate for all the test conditions. From Analysis of Variance (ANOVA, it is found that significant contributions on outputs are due to the effect of H/D ratio and Reynolds number. Confirmation experiments with optimum condition result in improved heat transfer coefficient and Nusselt number. Numerical simulation has also been performed with the optimum condition. It is observed that the simulation results are in consistence with the experimental results.
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Orlando Montoya-Marquez
2017-01-01
Full Text Available In this experimental work, the effects of the inclination angle β and the (Ti − Ta/G on the efficiency and the UL-value were investigated on a medium-temperature flat plate solar collector. The experiments were based on steady-state energy balance, by heat flow calorimetry at indoor conditions and considering the standard American National Standard Institute/American Society of Heating Refrigerating and Air Conditioning Engineers (ANSI/ASHRAE 93-2010. The solar radiation was emulated by the Joule effect using a proportional integral derivative (PID control considering two conditions of the absorber temperature, Case 1: (To − Ti > 0, and Case 2: (To − Ti = 0. The inclination angles were 0°–90° and the (Ti − Ta/G were 0.044–0.083 m2·°C/W and 0.124–0.235 for Case 1 and Case 2, respectively. The variations of β and (Ti − Ta/G cause efficiency changes up to 0.37–0.45 (21.6% and 0.31–0.45 (45.0%, respectively, for Case 1. Also, the UL(β reached changes up to 10.1–12.0 W/m2·°C (19.2% and 8.4–12.0 W/m2·°C (41.7%, respectively, for Case 1. The most significant changes of UL(β/UL(90° vs. β were 8.0% at the horizontal position for Case 1, while for Case 2, the maximum change was 1.8% only. Therefore, the changes of the inclination angle cause significant variations of the convective flow patterns within the collector, which leads to considerable variation of the collector efficiency and its UL value.
Meda, Adimurthy; Katti, Vadiraj V.
2017-08-01
The present work experimentally investigates the local distribution of wall static pressure and the heat transfer coefficient on a rough flat plate impinged by a slot air jet. The experimental parameters include, nozzle-to-plate spacing (Z /D h = 0.5-10.0), axial distance from stagnation point ( x/D h ), size of detached rib ( b = 4-12 mm) and Reynolds number ( Re = 2500-20,000). The wall static pressure on the surface is recorded using a Pitot tube and a differential pressure transmitter. Infrared thermal imaging technique is used to capture the temperature distribution on the target surface. It is observed that, the maximum wall static pressure occurs at the stagnation point ( x/D h = 0) for all nozzle-to-plate spacing ( Z/D h ) and rib dimensions studied. Coefficient of wall static pressure ( C p ) decreases monotonically with x/D h . Sub atmospheric pressure is evident in the detached rib configurations for jet to plate spacing up to 6.0 for all ribs studied. Sub atmospheric region is stronger at Z/D h = 0.5 due to the fluid accelerating under the rib. As nozzle to plate spacing ( Z/D h ) increases, the sub-atmospheric region becomes weak and vanishes gradually. Reasonable enhancement in both C p as well as Nu is observed for the detached rib configuration. Enhancement is found to decrease with the increase in the rib width. The results of the study can be used in optimizing the cooling system design.
The flow of a power-law fluid in the near-wake of a flat plate
Zhou, Min; Ladeinde, Foluso; Bluestein, Danny
2006-08-01
The analysis of the near-wake flow downstream of a flat plate is reported in this paper for the case of a non-Newtonian (power-law) constitutive model. To our knowledge, the present paper is the first to address this problem, as previous work on near-wakes has been limited to the use of a Newtonian model. The motivation for this work comes from the biomedical engineering problem of blood flow around the bileaflet of a mechanical heart valve. In the present paper, the series method has been used to calculate the flow near the centerline of the wake, while an asymptotic method has been used for larger distances from the centerline. The effects of power-law inlet conditions on the wake flow are reported for various values of the power-law index n, within the range 0.7≤n ≤1.3. The present analysis has been successfully validated by comparing the results for n =1 to the near-wake results by Goldstein [Proc. Cambridge Philos. Soc. 26, 1 (1930)]. We generalized the equations for arbitrary values of n, without any special considerations for n =1. Therefore, the accurate results observed for n =1 validate our procedure as a whole. The first major finding is that a fluid with smaller n develops faster downstream, such that decreasing n leads to monotonically increasing velocities compared to fluids with large n values. Another finding is that the non-Newtonian effects become more significant as the downstream distance increases. Finally, these effects tend to be more pronounced in the vicinity of the wake centerline compared to larger y locations.
Diseño de un colector solar de placa plana; Design of a Solar Flat Plate Collector
Directory of Open Access Journals (Sweden)
Jeovany Rafael Rodríguez Mejía
2015-12-01
Full Text Available En el presente artículo se integra el uso de un software de diseño mecánico y un algoritmo de simulación de la operación de un colector solar de placa plana, con el objetivo de simplificar el proceso de diseño y manufactura de este último. Se exponen los resultados de la simulación de la operación del colector solar considerando diferentes combinaciones en los parámetros de los materiales utilizados, tales como sus propiedades y características físico químicas, además de la variación de las dimensiones del sistema adiseñar. Finalmente en el artículo se evalúa la operación de un colector solar para las condiciones climatológicas típicas de la irradiancia, velocidad de viento y temperatura ambiente a partir de una serie de curvas sinusoidales, típicas de Cuba, validándose la viabilidad del algoritmo como apoyo en la etapa de diseño y selección de materiales.In this article the use of mechanical design software and an algorithm for simulating the operation of a flat plate solar collector, with the objective of simplifying the process of design and manufacture of the latter isintegrated. The simulation results of the operation of the solar collector considering different combinations in the parameters of the materials used, such as its physicochemical properties and features in addition to thevariation of the dimensions of the system design are set. The article finally evaluates the operation of a solar collector for typical climatic conditions of irradiance, wind speed and ambient temperature from a series ofsinusoidal, typical Cuba curves is evaluated, validating the feasibility of the algorithm as support in step design and material selection.
Rates of solar angles for two-axis concentrators
Yung, C. S.; Lansing, F. L.
1982-01-01
The Sun's position by the azimuth and elevation angles and its rate of change at any time of day are determined to design 2 axis tracking mechanisms of solar concentrators. The Sun's angles and their rates for selected months of the year (March, June, September and December) and for seven selected atitudes (0, + or - 30, + or - 60, + or - 90) covering both the northern and southern hemispheres were studied. The development of the angle and angle rate analytical expressions for any month, hour of day, and latitude provides the solar concentrator designer with a quantitative determination of the limiting Sun's position and angle rates for an accurate automatic tracking mechanism.
Fedoul, Faical; Parras, Luis; Del Pino, Carlos; Fernandez-Feria, Ramon
2012-11-01
Wind tunnel experiments are conducted for the flow around both a single flat plate and a cascade of three parallel flat plates at different angles of incidence to compare their lift and drag coefficients in a range of Reynolds number about 105, and for two values of the aspect ratio of the flat plates. The selected cascade configuration is of interest for a particular type of tidal energy converter. The lift and drag characteristics of the central plate in the cascade are compared to those of the isolated plate, finding that there exist an angle of incidence, which depends on the Reynolds number and the aspect ratio, above which the effective lift of the plate in the cascade becomes larger than that of an isolated plate. These experimental results, which are also analyzed in the light of theoretical predictions, are used as a guide for the design of the optimum configuration of the cascade which extracts the maximum power from a tidal current for a given value of the Reynolds number. Supported by the Ministerio de Ciencia e Innovacion (Spain) Grant no. ENE2010-16851.
Rai, Man Mohan
2017-01-01
The near wake of a flat plate is investigated via direct numerical simulations (DNS). Many earlier experimental investigations have used thin plates with sharp trailing edges and turbulent boundary layers to create the wake. This results in large theta divided by D (sub TE) values (theta is the boundary layer momentum thickness towards the end of the plate and D (sub TE) is the trailing edge thickness). In the present study the emphasis is on relatively thick plates with circular trailing edges (CTE) resulting in theta divided by D values less than one (D is the plate thickness and the diameter of the CTE), and vigorous vortex shedding. The Reynolds numbers based on the plate length and D are 1.255 x 10 (sup 6) and 10,000, respectively. Two cases are computed; one with turbulent boundary layers on both the upper and lower surfaces of the plate (statistically the same, symmetric wake, Case TT) and, a second with turbulent and laminar boundary layers on the upper and lower surfaces, respectively (asymmetric case, Case TL). The data and understanding obtained is of considerable engineering interest, particularly in turbomachinery where the pressure side of an airfoil can remain laminar or transitional because of a favorable pressure gradient and the suction side is turbulent. Shed-vortex structure and phase-averaged velocity statistics obtained in the two cases are compared here. The upper negative shed vortices in Case TL (turbulent separating boundary layer) are weaker than the lower positive ones (laminar separating boundary layer) at inception (a factor 1.27 weaker in terms of peak phase-averaged spanwise vorticity at first appearance of a peak). The upper vortices weaken rapidly as they travel downstream. A second feature of interest in Case TL is a considerable increase in the peak phase-averaged, streamwise normal intensity (random component) with increasing streamwise distance (x divided by D) that occurs nears the positive vortex cores. This behavior is
Institute of Scientific and Technical Information of China (English)
司马文霞; 马高权; 杨庆
2008-01-01
The influence of sand dust on discharge of external insulation has caused widespread concern. At present, the research results show wind-sand electricity has a remarkable effect on the discharge characteristics of insulator and has little influence on the discharge characteristics of air gap. The flashover of insulator strings occurs along the insulator surface and air gaps, and the sand dust deposited on the insulator surface may affect the flashover characteristics of insulator strings. This paper studies the flashover characteristics of flat plate model under DC voltage in wind-sand condition. The experimental results show that under positive polarity voltage, the flashover voltage of the flat plate model has a maximum value, while under negative polarity voltage, the flashover voltage of the flat plate model has a minimum value with a certain degree of sand dust deposition. The wind or sand in sand-dust weather has an important effect on the flashover characteristics of the flat plate model. In certain variation range of electric charge, electric charge of sand dust has little effect on the flashover voltage of flat plate model under DC voltage. The deposition of sand has significant influence on the flashover process of flat plate model, which is related to the deposition density and moisture content of sand particle.
板式脉动热管强化传热方法研究%Research on Enhancing Heat Transfer of Flat Plate Loop Pulsating Heat Pipe
Institute of Scientific and Technical Information of China (English)
陈陶菲; 徐德好; 刘向东
2011-01-01
To research the method of enhancing heat transfer of flat plate loop pulsating heat pipe,the article compares the heat transfer character of the original heat pipe and the improved one by numerical simulation.Based on the VOF（volume of fluid） method,a three-dimensional unsteady mathematical model was developed to describe the vapor-liquid two-phase flow and phase change heat transfer in the flat plate loop pulsating heat pipe.The two-phase flow pattern transition and the temperature distribution in the flat plate loop pulsating heat pipe under different heat load conditions was numerically investigated using the developed model.The result shows that the heat transfer character of the improved heat pipe can be enhanced under high heat load condition.%为了研究板式脉动热管的传热性能强化的方法,对原型和改进型两种不同板式脉动热管传热特性进行数值分析比较。基于VOF方法建立板式脉动热管汽液两相流动及相变传热三维非稳态数学模型,仿真得到不同加热功率条件下热管内流型演化和温度分布。仿真结果表明,改进型脉动热管在高功率阶段,整体等效热阻小于原型。
NUMERICAL STUDIES OF AERODYNAMIC PERFORMANCE OF NORMAL FLAT PLATES WITH GAP%垂直开缝平板气动性能的数值研究
Institute of Scientific and Technical Information of China (English)
何伟; 田德; 王永; 汪宁渤
2013-01-01
为研究开缝对太阳能光电板承受风载的影响,采用雷诺应力模型分析二维不同间隙开缝平板的垂直绕流特性.基于Fluent模拟了高雷诺数下二维方柱绕流,所得阻力系数平均值及斯特劳哈尔数与文献提供的模拟及实验结果一致,验证了模型模拟高雷诺数下钝体绕流的有效性.通过高雷诺数下平板垂直绕流的阻力系数平均值与斯特劳哈尔数的对比,得出不同间隙尺寸对平板阻力系数的影响,计算结果为太阳能光电板的工程设计提供理论支撑.%The 2D flow characteristics of flat plates with different sizes gaps normal to the incoming flow were presented with Reynolds stress equation for studying the influence of wind loads on the solar PV panel with gap. The model was effective to simulate bluff bodies with high Reynolds numbers by consistency of time averaged mean drag coefficients and Strouhal numbers between this paper and other researchers' simulated and experimental results of 2D square cylinder with high Reynolds number. The time averaged mean drag coefficients and Strouhal numbers of normal flat plate flow with different sizes gaps were compared. The influences of gap sizes on the drag coefficients of flat plates were obtained. The simulated results can support the design of solar PV panel theoretically.
Christensen, Elmer
1985-01-01
The objectives were to develop the flat-plate photovoltaic (PV) array technologies required for large-scale terrestrial use late in the 1980s and in the 1990s; advance crystalline silicon PV technologies; develop the technologies required to convert thin-film PV research results into viable module and array technology; and to stimulate transfer of knowledge of advanced PV materials, solar cells, modules, and arrays to the PV community. Progress reached on attaining these goals, along with future recommendations are discussed.
MIRI, Mohadaseh
2015-01-01
Use solar energy to provide hot water consumption, space heating and cooling in recent decades is considered. In this article a model varies with time, a solar adsorption cooling system consists of a single effect lithium bromide absorption system, a flat plate collector and a storage tank or linear or parabolic simulated separately. The system for cooling an office building for hours of operation from 7 am to 18 pm is considered.About 7 kW peak cooling load occurs in July. Results obtained s...
Shu, Jian-Jun
2015-01-01
The paper presents a theoretical study using the Karman-Pohlhausen method for describing the transient heat exchange between the boundary-layer free convection and a vertical flat plate embedded in a porous medium. The unsteady behavior is developed after the generation of an impulsive heat flux step at the right-hand side of the plate. Two cases are considered according to whether the plate has a finite thickness or no thickness. The time and space evolution of the interface temperature is evidenced.
Lee, Dorothy B; Faget, Maxime A
1956-01-01
A modified method of Van Driest's flat-plate theory for turbulent boundary layer has been found to simplify the calculation of local skin-friction coefficients which, in turn, have made it possible to obtain through Reynolds analogy theoretical turbulent heat-transfer coefficients in the form of Stanton number. A general formula is given and charts are presented from which the modified method can be solved for Mach numbers 1.0 to 12.0, temperature ratios 0.2 to 6.0, and Reynolds numbers 0.2 times 10 to the 6th power to 200 times 10 to the 6th power.
Statistical analysis of the performance and simulation of a two-axis tracking PV system
Energy Technology Data Exchange (ETDEWEB)
Perpinan, O. [Grupo de Sistemas Fotovoltaicos, IES-UPM, UPM, Ciudad Universitaria s/n, 28040 Madrid (Spain)
2009-11-15
The energy produced by a photovoltaic system over a given period can be estimated from the incident radiation at the site where the Grid Connected PV System (GCPVS) is located, assuming knowledge of certain basic features of the system under study. Due to the inherently stochastic nature of solar radiation, the question ''How much energy will a GCPVS produce at this location over the next few years?'' involves an exercise of prediction inevitably subjected to a degree of uncertainty. Moreover, during the life cycle of the GCPVS, another question arises: ''Is the system working correctly?''. This paper proposes and examines several methods to cope with these questions. The daily performance of a PV system is simulated. This simulation and the interannual variability of both radiation and productivity are statistically analyzed. From the results several regression adjustments are obtained. This analysis is shown to be useful both for productivity prediction and performance checking exercises. Finally, a statistical analysis of the performance of a GCPVS is carried out as a detection method of malfunctioning parts of the system. (author)
Two-axis gimbal for air-to-air and air-to-ground laser communications
Talmor, Amnon G.; Harding, Harvard; Chen, Chien-Chung
2016-03-01
For bi-directional links between high-altitude-platforms (HAPs) and ground, and air-to-air communication between such platforms, a hemispherical +30°C field-of-regard and low-drag low-mass two-axis gimbal was designed and prototyped. The gimbal comprises two servo controlled non-orthogonal elevation over azimuth axis, and inner fast steering mirrors for fine field-of-regard adjustment. The design encompasses a 7.5cm diameter aperture refractive telescope in its elevation stage, folded between two flat mirrors with an exit lens leading to a two mirrors miniature Coude-path fixed to the azimuth stage. Multiple gimbal configurations were traded prior to finalizing a selection that met the requirements. The selected design was manifested onboard a carbon fiber and magnesium composite structure, motorized by custom-built servo motors, and commutated by optical encoders. The azimuth stage is electrically connected to the stationary base via slip ring while the elevation stage made of passive optics. Both axes are aligned by custom-built ceramic-on-steel angular contact duplex bearings, and controlled by embedded electronics featuring a rigid-flex PCB architecture. FEA analysis showed that the design is mechanically robust over a temperature range of +60°C to -80°C, and with first mode of natural frequencies above 400Hz. The total mass of the prototyped gimbal is 3.5kg, including the inner optical bench, which contains fast steering mirrors (FSMs) and tracking sensors. Future version of this gimbal, in prototyping stage, shall weigh less than 3.0kg.
Directory of Open Access Journals (Sweden)
Sandeep N
2015-03-01
Full Text Available In this study we analyzed the influence of radiation and aligned magneticfield on the flow of ferrofluids over a flat plate in presence of non-uniform heat source/sink and slip velocity. We considered Fe3O4 magnetic nano particles embedded within the two types of base fluids namely water and kerosene. The governing partial differential equations are transformed into nonlinear ordinary differential equations by using similarity transformation and solved numerically using bvp5c Matlab package. The effects of dimensionless quantities on the flow and temperature profiles along with the friction factor and Nusselt number is discussed and presented through graphs and tables. It is found that present results have an excellent agreement with the existed studies under some special assumptions. Results indicate that a raise in the aligned angle enhances the skin friction coefficient and heat transfer rate.
Energy Technology Data Exchange (ETDEWEB)
Srithar, K. [Department of Mechanical Engineering, Thiagarajar College of Engineering, Madurai 625 015 (India); Mani, A. [Department of Mechanical Engineering, Indian Institute of Technology, Madras, Chennai 600 036 (India)
2007-12-15
Presently, tanneries in Tamilnadu, India are required to segregate the effluent of soaking and pickling sections from other wastewater streams and send it to shallow solar pans for evaporation to avoid land pollution. A large area of solar pans is required for evaporating the water in the effluent at salt concentration in the range of 4-5%. An experimental study has been made by using fibre reinforced plastic flat plate collector (FRP-FPC) and spray system in a pilot plant with a capacity to handle 5000 l per day, which increases the evaporation rate. After increasing the salt concentration level to near saturation limit, the concentrated liquid was sent to conventional solar pans for its continued evaporation and recovery of salt. In this improved system, the rate of evaporation was found to be 30-40% more than that in the conventional solar pans. The performance is compared with the theoretically simulated performance. (author)
Edwards, D. K.; Rhee, S. J.
1984-05-01
An analysis is presented comparing Teflon film with glass for the inner glazing of a double-glazed selective-black, flat-plate solar collector. The effect of spacing between glazings and between the inner glazing and absorber plate is examined. It is shown that a 12.5-micron Teflon film is superior to glass for the inner glazing of a selective-black collector, because the advantage of its high solar transparency overwhelms the disadvantage of its infrared transparency. A too-small spacing between a selective-black absorber and its inner cover short-circuits the desirable thermal radiation resistance offered by a selective-black absorber plate. Account is taken of spectral variations in the radiation properties of glass, Teflon, and the absorber plate. Allowance is made for the fact that critical Rayleigh number is lower for a plastic film inner glazing than for a glass one.
Coumar, Sandra; Lago, Viviana
2017-06-01
This paper presents an experimental investigation, carried out at the Icare Laboratory by the FAST team, focusing on plasma flow control in supersonic and rarefied regime. The study analyzes how the Mach number as well as the ambient pressure modify the repercussions of the plasma actuator on the shock wave. It follows previous experiments performed in the MARHy (ex-SR3) wind tunnel with a Mach 2 flow interacting with a sharp flat plate, where modifications induced by a plasma actuator were observed. The flat plate was equipped with a plasma actuator composed of two aluminum electrodes. The upstream one was biased with a negative DC potential and thus, created a glow discharge type plasma. Experimental measurements showed that the boundary layer thickness and the shock wave angle increased when the discharge was ignited. The current work was performed with two nozzles generating Mach 4 flows but at two different static pressures: 8 and 71 Pa. These nozzles were chosen to study independently the impact of the Mach number and the impact of the pressure on the flow behavior. In the range of the discharge current considered in this experimental work, it was observed that the shock wave angle increased with the discharge current of +15% for the Mach 2 flow but the increase rate doubled to +28% for the Mach 4 flow at the same static pressure, showing that the discharge effect is even more significant when boosting the flow speed. When studying the effect of the discharge on the Mach 4 flow at higher static pressure, it was observed that the topology of the plasma changed drastically and the increase in the shock wave angle with the discharge current of +21 %.
1976-01-01
Basic test results are given of a flat-plate solar collector whose performance was determined in the NASA-Lewis solar simulator. The collector was tested over ranges of inlet temperatures, fluxes, and coolant flow rates. Collector efficiency is correlated in terms of inlet temperature and flux level.
1976-01-01
This preliminary data report gives basic test results of a flat-plate solar collector whose performance was determined in the NASA-Lewis solar simulator. The collector was tested over ranges of inlet temperatures, fluxes and coolant flow rates. Collector efficiency is correlated in terms of inlet temperature and flux level.
Bickler, Donald B.; Callaghan, W. T.
In 1986 during the flat-plate solar array project, silicon solar cells 4.0 sq cm in area were fabricated at the Jet Propulsion Laboratory (JPL) with a conversion efficiency of 20.1 percent (AM1.5-global). Sixteen cells were processed with efficiencies measuring 19.5 percent (AM1.5 global) or better. These cells were produced using refined versions of conventional processing methods, aside from certain advanced techniques that bring about a significant reduction in a major mechanism (surface recombination) that limits cell efficiency. Wacker Siltronic p-type float-zone 0.18-ohm-cm wafers were used. Conversion efficiencies in this range have previously been reported by other researchers, but generally on much smaller (0.5 vs. 4.0 cm) devices which have undergone sophisticated and costly processing steps. An economic analysis is presented of the potential payoffs for this approach, using the Solar Array Manufacturing Industry Costing Standards (SAMICS) methodology. The process sequence used and the assumptions made for capturing the economies of scale are presented.
Sayadi, Taraneh; Hamman, Curtis; Moin, Parviz
2011-11-01
Transition to turbulence via spatially evolving secondary instabilities in compressible, zero-pressure-gradient flat plate boundary layers is numerically simulated for both the Klebanoff K-type and Herbert H-type disturbances. The objective of this work is to evaluate the universality of the breakdown process between different routes through transition in wall-bounded shear flows. Each localized linear disturbance is amplified through weak non-linear instability that grows into lambda-vortices and then hairpin-shaped eddies with harmonic wavelength, which become less organized in the late-transitional regime once a fully populated spanwise turbulent energy spectrum is established. For the H-type transition, the computational domain extends from Rex =105 , where laminar blowing and suction excites the most unstable fundamental and a pair of oblique waves, to fully turbulent stage at Rex = 10 . 6 ×105 . The computational domain for the K-type transition extends to Rex = 9 . 6 ×105 . The computational algorithm employs fourth-order central differences with non-reflective numerical sponges along the external boundaries. For each case, the Mach number is 0.2. Supported by the PSAAP program of DoE, ANL and LLNL.
Peng, Di; Chen, Yujia; Wang, Shaofei; Liu, Yingzheng; Wang, Weizhe
2016-11-01
Previous studies have shown that it is possible to reconstruct the full flow field based on time-resolved measurements at discrete locations using linear stochastic estimation (LSE). The objective of this study is to develop and apply this technique to wall pressure fluctuation measurements in low speed flows. Time-resolved wall pressure fluctuations on a flat plate in the wake of a step cylinder at low speed (V PSP). The microphone arrays are arranged properly to capture the dominant features in the flow field at 10 kHz. The PSP is excited using a continuous UV-LED, and the luminescent signal is recorded by a high-speed camera at 2 kHz. The microphone data at discrete locations are used to reconstruct the full-field wall pressure fluctuations based on LSE. The PSP results serve as basis for improvement of the LSE scheme and also for validation of the reconstructed pressure field. Other data processing techniques including proper orthogonal decomposition (POD) and dynamic mode decomposition (DMD) are also used for analyzing the unsteady flow features. This LSE technique has great potential in real-time flow diagnostics and control.
Directory of Open Access Journals (Sweden)
E.Hemalatha
2015-09-01
Full Text Available This paper analyzes the radiation and chemical reaction effects on MHD steady two-dimensional laminar viscous incompressible radiating boundary layer flow over a flat plate in the presence of internal heat generation and convective boundary condition. It is assumed that lower surface of the plate is in contact with a hot fluid while a stream of cold fluid flows steadily over the upper surface with a heat source that decays exponentially. The Rosseland approximation is used to describe radiative heat transfer as we consider optically thick fluids. The governing boundary layer equations are transformed into a system of ordinary differential equations using similarity transformations, which are then solved numerically by employing fourth order Runge-Kutta method along with shooting technique. The effects of various material parameters on the velocity, temperature and concentration as well as the skin friction coefficient, the Nusselt number, the Sherwood number and the plate surface temperature are illustrated and interpreted in physical terms. A comparison of present results with previously published results shows an excellent agreement.
Directory of Open Access Journals (Sweden)
Sona Kazemi
2016-01-01
Full Text Available Passive air-breathing microbial fuel cells (MFCs are a promising technology for energy recovery from wastewater and their performance is highly dependent on characteristics of the separator that isolates the anaerobic anode from the air-breathing cathode. The goal of the present work is to systematically study the separator characteristics and its effect on the performance of passive air-breathing flat-plate MFCs (FPMFCs. This was performed through characterization of structure, properties, and performance correlations of eight separators in Part 1 of this work. Eight commercial separators were characterized, in non-inoculated and inoculated setups, and were examined in passive air-breathing FPMFCs with different electrode spacing. The results showed a decrease in the peak power density as the oxygen and ethanol mass transfer coefficients in the separators increased, due to the increase of mixed potentials especially at smaller electrode spacing. Increasing the electrode spacing was therefore desirable for the application of diaphragms. The highest peak power density was measured using Nafion®117 with minimal electrode spacing, whereas using Nafion®117 or Celgard® with larger electrode spacing resulted in similar peak powers. Part 2 of this work focuses on numerical modelling of the FPMFCs based on mixed potential theory, implementing the experimental data from Part 1.
Directory of Open Access Journals (Sweden)
Xavier Ortiz
2015-03-01
Full Text Available To improve knowledge of the wind loads on photovoltaic structures mounted on flat roofs at the high angles required in high latitudes, and to study starting flow on low aspect ratio wind turbine blades, a series of wind tunnel tests were undertaken. Thin flat plates of aspect ratios between 0.4 and 9.0 were mounted on a sensitive three-component instantaneous force and moment sensor. The Reynolds numbers varied from 6 × 104 to 2 × 105. Measurements were made for angles of attack between 0° and 90° both in the free stream and in wall proximity with increased turbulence and mean shear. The ratio of drag to lift closely follows the inverse tangent of the angle of incidence for virtually all measurements. This implies that the forces of interest are due largely to the instantaneous pressure distribution around the plate and are not significantly influenced by shear stresses. The instantaneous forces appear most complex for the smaller aspect ratios but the intensity of the normal force fluctuations is between 10% and 20% in the free-steam but can exceed 30% near the wall. As the wind tunnel floor is approached, the lift and drag reduce with increasing aspect ratio, and there is a reduction in the high frequency components of the forces. It is shown that the centre of pressure is closer to the centre of the plates than the quarter-chord position for nearly all cases.
Martinuzzi, Robert
2016-11-01
Quasi-periodic vortex shedding in the turbulent wake of a thin-flat plate placed normal to a uniform stream at Reynolds number of 6700 is investigated based on Particle Image Velocimetry experiments. The wake structure and vortex formation are characterized using a generalized phase average (GPA), a refinement of the triple decomposition of Reynolds and Hussain (1970) incorporating elements of mean-field theory (Stuart, 1958). The resulting analysis highlights the importance of cycle-to-cycle variations in characterizing vortex formation, wake topology and the residual turbulent Reynolds Stresses. For example, it is shown that during high-amplitude cycles vorticity is strongly concentrated within the well-organized shed vortices, whereas during low-amplitude cycles the shed vortices are highly distorted resulting in significant modulation of the shedding frequency. It is found that high-amplitude cycles contribute more to the coherent Reynolds stress field while the low-amplitude cycles contribute to the residual stress field. It is further shown that traditional phase-averaging techniques lead to an over-estimation of the residual stress field. Natural Sciences and Engineering Research Council of Canada.
Gao, Baoyan; Chen, Ailing; Zhang, Wenyuan; Li, Aifen; Zhang, Chengwu
2017-10-01
The marine diatom Phaeodactylum tricornutum is a polymorphological, ecologically significant, and well-studied model of unicellular microalga. This diatom can accumulate diverse important metabolites. Herein, we cultured P. tricornutum in an internally installed tie-piece flat-plate photobioreactor under 14.5 m mol L-1 (high nitrogen, HN) and 2.9 m mol L-1 (low nitrogen, LN) of KNO3 and assessed its time-resolved changes in biochemical compositions. The results showed that HN was inductive to accumulate high biomass (4.1 g L-1). However, the LN condition could accelerate lipid accumulation in P. tricornutum. The maximum total lipid (TL) content under LN was up to 42.5% of biomass on day 12. Finally, neutral lipids (NLs) were 63.8% and 75.7% of TLs under HN and LN, respectively. The content of EPA ranged from 2.3% to 1.5% of dry weight during the growth period under the two culture conditions. Peak volumetric lipid productivity of 128.4 mg L-1d-1 was achieved in the HN group (on day 9). The highest volumetric productivity values of EPA, chrysolaminarin, and fucoxanthin were obtained in the exponential phase (on day 6) under HN, which were 9.6, 93.6, and 4.7 mg L-1d-1, respectively. In conclusion, extractable amounts of lipids, EPA, fucoxanthin, and chrysolaminarin could be obtained from P. tricornutum by regulating the culture conditions.
EXPERIMENTAL RESEARCH ON A HIGH EFFICIENT FLAT PLATE SOLAR COLLECTOR%一种高效平板太阳能集热器试验研究
Institute of Scientific and Technical Information of China (English)
李戬洪; 江晴
2001-01-01
性能良好的太阳能集热器是太阳能空调的关键设备之一。广东省江门市太阳能空调系统采用了一种高效的平板集热器，其主要技术特征是增加了一块聚碳酸脂(PC)透明隔热板。本研究通过对比试验，确定了一种高效平板太阳能集热器的技术方案，并测定了瞬时效率曲线，其热损系数仅为2.90W/(m2*℃)。%Good performance of the solar collectors is one of the important elements for solar air-conditioning system.A novel type of high efficient flat plate solar collector was applied to the solar air-condition system in Jiangmen，Guangdong Province.Tests show that adding a transparent polycarbonate sheet in gap between glazing and absorber of the collector. The coefficient of the thermal loss is reduced to 2.90W/(m2℃) and the performance of the collector is improved.
Locke, Michael; Czarnomski, Mariusz; Qadir, Ashraf; Setness, Brock; Baer, Nicolai; Meyer, Jennifer; Semke, William H.
2011-03-01
A custom designed and manufactured gimbal with a wide field-of-view and fast response time is developed. This enhanced custom design is a 24 volt system with integrated motor controllers and drivers which offers a full 180o fieldof- view in both azimuth and elevation; this provides a more continuous tracking capability as well as increased velocities of up to 479° per second. The addition of active high-frequency vibration control, to complement the passive vibration isolation system, is also in development. The ultimate goal of this research is to achieve affordable, reliable, and secure air-to-air laser communications between two separate remotely piloted aircraft. As a proof-of-concept, the practical implementation of an air-to-ground laserbased video communications payload system flown by a small Unmanned Aerial Vehicle (UAV) will be demonstrated. A numerical tracking algorithm has been written, tested, and used to aim the airborne laser transmitter at a stationary ground-based receiver with known GPS coordinates; however, further refinement of the tracking capabilities is dependent on an improved gimbal design for precision pointing of the airborne laser transmitter. The current gimbal pointing system is a two-axis, commercial-off-the-shelf component, which is limited in both range and velocity. The current design is capable of 360o of pan and 78o of tilt at a velocity of 60o per second. The control algorithm used for aiming the gimbal is executed on a PC-104 format embedded computer onboard the payload to accurately track a stationary ground-based receiver. This algorithm autonomously calculates a line-of-sight vector in real-time by using the UAV autopilot's Differential Global Positioning System (DGPS) which provides latitude, longitude, and altitude and Inertial Measurement Unit (IMU) which provides the roll, pitch, and yaw data, along with the known Global Positioning System (GPS) location of the ground-based photodiode array receiver.
Direct calculation of acceleration field through homogeneous transformation for two-axis centrifuge
Institute of Scientific and Technical Information of China (English)
吴广玉; 任顺清; 陈希军
2003-01-01
A precision centrifuge is an inertial navigation test equipment used for calibrating the characteristicsof accelerometers with high overloading, and a two-axis centrifuge can be used to generate either constant accel-eration or harmonic acceleration. The moving trajectory equation about the origin of the accelerometer coordinatesystem in a two-axis centrifuge was directly deduced through homogeneous transformation. The acceleration vec-tor of the origin in accelerometer coordinate system was achieved by making the second derivative of this trajec-tory equation. The acceleration components were acquired by decomposing this acceleration vector along thethree axes of the accelerometer coordinate system. The correctness of the homogeneous transformation was veri-fied through vector analysis.
Use of two-axis joystick for control of externally powered shoulder disarticulation prostheses
Directory of Open Access Journals (Sweden)
Robert D. Lipschutz, BSME, CP
2011-07-01
Full Text Available We explored a new method for simple and accurate control of shoulder movement for externally powered shoulder disarticulation prostheses with a two-axis joystick. We tested 10 subjects with intact shoulders and arms to determine the average amount of shoulder motion and force available to control an electronic input device. We then applied this information to two different input strategies to examine their effectiveness: (1 a traditional rocker potentiometer and a pair of force-sensing resistors and (2 a two-axis joystick. Three nondisabled subjects and two subjects with shoulder disarticulation amputations attempted to control an experimental externally powered shoulder using both control strategies. Two powered arms were tested, one with powered flexion/extension and humeral rotation and one with powered flexion/extension and adduction/abduction. Overwhelmingly, the subjects preferred the joystick control, because it was more intuitively linked with their shoulder movement. Additionally, two motions (one in each axis could be controlled simultaneously. This pilot study provides valuable insight into an effective means of controlling high-level, externally powered prostheses with a two-axis joystick.
Use of a Two-Axis Joystick for Control of Externally Powered, Shoulder Disarticulation Prostheses
Lipschutz, Robert D.; Lock, Blair; Sensinger, Jonathon; Schultz, Aimee E.; Kuiken, Todd A.
2015-01-01
We explored a new method for simple and accurate control of shoulder movement for externally powered shoulder disarticulation prostheses using a two-axis joystick. Ten subjects with intact shoulders and arms were tested to determine the average amount of shoulder motion and force available for control of an electronic input device. This information was then applied to two different input strategies in order to examine their effectiveness: (1) a traditional strategy implemented with a rocker potentiometer and a pair of force-sensing resistors (FSRs), and (2) a strategy implemented with a two-axis joystick. Three able-bodied subjects and two subjects with shoulder disarticulation amputations attempted to control an experimental powered shoulder using both control strategies. Two powered arms were tested, one with powered flexion/extension and humeral rotation, and one with powered flexion/extension and adduction/abduction. Overwhelmingly, the subjects preferred the joystick control, as it was more intuitively linked with their shoulder movement. Additionally, two motions (one in each axis) could be controlled simultaneously. This pilot study provides valuable insight into an effective means of controlling high-level, externally powered prostheses via a two-axis joystick. PMID:21938653
Use of two-axis joystick for control of externally powered shoulder disarticulation prostheses.
Lipschutz, Robert D; Lock, Blair; Sensinger, Jonathon; Schultz, Aimee E; Kuiken, Todd A
2011-01-01
We explored a new method for simple and accurate control of shoulder movement for externally powered shoulder disarticulation prostheses with a two-axis joystick. We tested 10 subjects with intact shoulders and arms to determine the average amount of shoulder motion and force available to control an electronic input device. We then applied this information to two different input strategies to examine their effectiveness: (1) a traditional rocker potentiometer and a pair of force-sensing resistors and (2) a two-axis joystick. Three nondisabled subjects and two subjects with shoulder disarticulation amputations attempted to control an experimental externally powered shoulder using both control strategies. Two powered arms were tested, one with powered flexion/extension and humeral rotation and one with powered flexion/extension and adduction/abduction. Overwhelmingly, the subjects preferred the joystick control, because it was more intuitively linked with their shoulder movement. Additionally, two motions (one in each axis) could be controlled simultaneously. This pilot study provides valuable insight into an effective means of controlling high-level, externally powered prostheses with a two-axis joystick.
Energy Technology Data Exchange (ETDEWEB)
Hori, M.; Yata, J. [Kyoto Inst. of Technology, Kyoto (Japan); Minamiyama, T. [Fukuyama University, Hiroshima (Japan)
1996-04-25
The effects of free stream turbulence on turbulent boundary layer were calculated using a {kappa}-{epsilon} two-equation model. The calculations were performed with respect to velocity profiles on a flat plate wall shear stress turbulence energy integral length scales of turbulence and decay of free stream turbulence and the results were compared with experimental results. The energy of free stream turbulence and the dissipation values at the leading edge of flat plate were used, as the initial conditions for calculation. These initial values of dissipation were determined from the integral length scales of free stream turbulence at the leading edge. The calculated wall shear stress increased with the free stream turbulence and integral length scales of turbulence. The velocity profiles and turbulence energy agreed well with the experimental results and the effects of free stream turbulence on the wall shear stress agreed fairly well with those observed in experiments. 15 refs., 10 figs.
Energy Technology Data Exchange (ETDEWEB)
Tavakolpour, Ali Reza; Zomorodian, Ali [Department of Mechanics of Farm Machinery Engineering, Shiraz University, Shiraz (Iran); Akbar Golneshan, Ali [Department of Mechanical Engineering, Shiraz University, Shiraz (Iran)
2008-01-15
In this research, a gamma-type, low-temperature differential (LTD) solar Stirling engine with two cylinders was modeled, constructed and primarily tested. A flat-plate solar collector was employed as an in-built heat source, thus the system design was based on a temperature difference of 80{sup o}C. The principles of thermodynamics as well as Schmidt theory were adapted to use for modeling the engine. To simulate the system some computer programs were written to analyze the models and the optimized parameters of the engine design were determined. The optimized compression ratio was computed to be 12.5 for solar application according to the mean collector temperature of 100{sup o}C and sink temperature of 20{sup o}C. The corresponding theoretical efficiency of the engine for the mentioned designed parameters was calculated to be 0.012 for zero regenerator efficiency. Proposed engine dimensions are as follows: power piston stroke 0.044 m, power piston diameter 0.13 m, displacer stroke 0.055 m and the displacer diameter 0.41 m. Finally, the engine was tested. The results indicated that at mean collector temperature of 110{sup o}C and sink temperature of 25{sup o}C, the engine produced a maximum brake power of 0.27 W at 14 rpm. The mean engine speed was about 30 rpm at solar radiation intensity of 900 W/m{sup 2} and without load. The indicated power was computed to be 1.2 W at 30 rpm. (author)
Directory of Open Access Journals (Sweden)
Olek Małgorzata
2016-01-01
Full Text Available The popularity of solar collectors in Poland is still increasing. The correct location of the collectors and a relatively high density of solar radiation allow delivering heat even in spite of relatively low ambient temperature. Moreover, solar systems used for heating domestic heat water (DHW in summer allow nearly complete elimination of conventional energy sources (e.g. gas, coal. That is why more and more house owners in Poland decide to install solar system installations. In Poland the most common types of solar collectors are flat plate collectors (FPC and evacuated tube collectors with heat pipe (ETCHP; both were selected for the analysis. The heat demand related to the preparation of hot water, connected with the size of solar collectors’ area, has been determined. The analysis includes FPC and ETCHP and heat demand of less than 10 000 kWh/year. Simulations were performed with the Matlab software and using data from a typical meteorological year (TMY. In addition, a 126–year period of measurements of insolation for Krakow has been taken into account. The HDKR model (Hay, Davis, Klucher, Reindl was used for the calculation of solar radiation on the absorber surface. The monthly medium temperature of the absorber depends on the amount of solar system heat and on the heat demand. All the previously mentioned data were used to determine solar efficiency. Due to the fact that solar efficiency and solar system heat are connected, the calculations were made with the use of an iterative method. Additionally, the upper limit for monthly useful solar system heat is resulted from the heat demand and thus the authors prepared a model of statistical solar system heat deviations based on the Monte Carlo method. It has been found that an increase in the useful solar system heat in reference to the heat demand is associated with more than proportional increase in the sizes of the analyzed surfaces of solar collector types.
Batubara, Fatimah; Dina, Sari Farah; Klaudia Kathryn Y., M.; Turmuzi, M.; Siregar, Fitri; Panjaitan, Nora
2017-06-01
Research on the effect of openings solar collector and solar irradiance to thermal efficiency has been done. Solar collector by flat plate-finned type consists of 3 ply insulator namely wood, Styrofoam and Rockwool with thickness respectively are 10 mm, 25 mm and 50 mm. Absorber plate made of aluminum sheet with thickness of 0.30 mm, painted by black-doff. Installation of 19 units fins (length x height x thickness: 1000x20x10 mm) on the collector will increase surface area of absorber so it can receive much more solar energy. The solar collector cover is made of glass (thickness of 5 mm). During the research, the solar irradiance and temperature of collector are measured and recorded every five minutes. Temperature measurement performed on the surface of the absorber plate, inside of collector, surface cover and the outer side insulator (plywood). This data is used to calculate the heat loss due to conduction, convection and radiation on the collector. Openings of collectors vary as follows: 100%, 75%, 15% and 0% (total enclosed). The data collecting was conducted from 09.00 am to 17.00 pm and triplicates. The collector thermal efficiency calculated based on the ratio of the amount of heat received to the solar irradiance absorbed. The results show that each of openings solar collector has different solar irradiance (because it was done on a different day) which is in units of W/m2: 390 (100% open), 376 (75% open), 429 (15% open), and 359 (totally enclosed). The highest thermal efficiency is in openings variation of 15% opened. These results indicate that the efficiency of the collector is influenced by the solar irradiance received by the collector and the temperature on the collector plate. The highest thermal efficiency is in variation of openings 15%. These indicate that the efficiency of the collector was influenced by solar irradiance received by the collector and openings of the collector plate.
Einstein, Thomas H.
1961-01-01
Equations were derived representing heat transfer and pressure drop for a gas flowing in the passages of a heater composed of a series of parallel flat plates. The plates generated heat which was transferred to the flowing gas by convection. The relatively high temperature level of this system necessitated the consideration of heat transfer between the plates by radiation. The equations were solved on an IBM 704 computer, and results were obtained for hydrogen as the working fluid for a series of cases with a gas inlet temperature of 200 R, an exit temperature of 5000 0 R, and exit Mach numbers ranging from 0.2 to O.8. The length of the heater composed of the plates ranged from 2 to 4 feet, and the spacing between the plates was varied from 0.003 to 0.01 foot. Most of the results were for a five- plate heater, but results are also given for nine plates to show the effect of increasing the number of plates. The heat generation was assumed to be identical for each plate but was varied along the length of the plates. The axial variation of power used to obtain the results presented is the so-called "2/3-cosine variation." The boundaries surrounding the set of plates, and parallel to it, were assumed adiabatic, so that all the power generated in the plates went into heating the gas. The results are presented in plots of maximum plate and maximum adiabatic wall temperatures as functions of parameters proportional to f(L/D), for the case of both laminar and turbulent flow. Here f is the Fanning friction factor and (L/D) is the length to equivalent diameter ratio of the passages in the heater. The pressure drop through the heater is presented as a function of these same parameters, the exit Mach number, and the pressure at the exit of the heater.
Enhancing the Heat Transfer of Flat-plate Solar Collector%平板太阳能集热器强化传热应用研究进展∗
Institute of Scientific and Technical Information of China (English)
吉佳文; 王文志; 李金凯; 段广彬; 刘宗明
2016-01-01
As the key part of the flat-plate solar water heater,the heat transfer performance of the collector is determined by the heat collector efficiency.The flat-plate solar collector with typical structure and heat transfer mode are described.Meanwhile the present technologies for enhancing heat transfer of flat-plate solar collector and the fu-ture development trend are reviewed and discussed.%集热器作为平板太阳能热水器的关键部分，其传热性能决定着热水器集热效率的高低。介绍了平板太阳能集热器的典型结构以及传热方式，综述了平板太阳能集热器目前所采用的强化传热方式及今后强化传热技术的发展趋势。
Application of the Heat Pipe in Flat-Plate Solar Collectors%热管在平板式太阳能集热器中的应用研究
Institute of Scientific and Technical Information of China (English)
黄婷婷; 杜娜; 卿湛媛; 陈新; 牛宝联
2014-01-01
从集热器结构、传热效率、工艺、优缺点等方面详细介绍了3种常见的热管平板式太阳能集热器，它们包括蜂窝热管平板式、真空玻璃盖板热管平板式、CPC热管平板式太阳能集热器。与普通热管平板式集热器相比，3种改良方式均可降低集热器热损失，有效提高集热效率。通过对不同种类热管平板式太阳能集热器的热管种类、工作温度、结构参数等分析，发现随着温度升高，集热器集热效率下降，以及热管蒸发段长度普遍大于冷凝段长度等现象。%Three common heat pipe flat-plate solar collectors are introduced in details from the con-figuration of the collector such as heat transfer efficiency, crafts, merits, and so on, including the flat plate solar collector of honeycomb and heat pipe(HHCHP), flat plate solar collector of vacuum glass-cover board and heat pipe(HVGHP) and a compound parabolic concentrator heat pipe type solar collector(CPC). Com-pared with common heat pipe flat-plate solar collectors, these three improved programs can reduce heat loss, and effectively improve efficiency of the collector. From the analysis of different heat pipe types, oper-ating temperature, structure parameters, a phenomenon is discovered that whatever which type of heat pipe flat-plate solar collector is, as temperature goes up, the efficiency of the collectors drops and the length of evaporation is longer than the length of condensation.
Design and performance test of a two-axis fast steering mirror driven by piezoelectric actuators
Fang, Chu; Guo, Jin; Yang, Guo-qing; Jiang, Zhen-hua; Xu, Xin-hang; Wang, Ting-feng
2016-09-01
A novel design of a two-axis fast steering mirror (FSM) with piezoelectric actuators is proposed for incoherent laser beam combination. The mechanical performance of the FSM is tested. The results show that the tilting range of the mirror is about 4 mrad, and the 1st-order resonance frequency is about 250 Hz. A self-designed grating encoder is taken as the sensor, which ensures the optimal precision of 10 μrad. The novel mechanical design can meet the requirement of engineering in incoherent laser beam combination.
Development of Control System of Two - axis Solar Tracker%双轴式太阳跟踪装置控制系统的研究
Institute of Scientific and Technical Information of China (English)
耿其东; 李春燕
2011-01-01
介绍了双轴式太阳跟踪装置控制系统的原理及特点,设计了基于位置敏感探测器(PSD)的太阳跟踪器,实现对太阳的自动跟踪.控制系统同时采用太阳运动轨迹跟踪方法和传感器跟踪方法来完成1次跟踪,与以往2种模式相切换的控制系统相比,此系统的可靠性更好、跟踪精度更高、制造和运行成本低、性价比高,有广阔的应用前景.%This article describes the control theory and characteristic of two - axis solar track ing system, based on a position- sensitive detector a tracking device is designed and automatic track ing of sun. The control system use the methods of both program control and sensor track to complete a tracking mission, it has good reliability, high tracking accuracy, low manufacturing and operating cost, cost - effective and broad application prospects.
基于动网格方法的拍动平板升力分析%Lift performance analysis of flapping flat plate using dynamic mesh method
Institute of Scientific and Technical Information of China (English)
于宪钊; 苏玉民; 曹建; 闫岱峻
2012-01-01
Aim at micro air vehicles,two-dimensional and three-dimensional flapping flat plate lift performance of advanced,synchronized and delayed rotation were numerically investigated by dynamic mesh method.The vortices and lift changes versus kinematic motions were highlighted to analyze the relationship between lift performance and kinematic motions.Numerical results show that the lift coefficients of synchronized and advanced rotation model are larger than that of delayed rotation obviously;the lift coefficients of two-dimensional and three-dimensional flapping plate decrease with increasing of angular amplitude and increase with increasing phase lag,while the influence of plunging amplitude is less relatively.The lift coefficients of three-dimensional plate are larger than two-dimensional plate in advanced rotation model with higher angular amplitude,also in delayed rotation only when lower angular amplitude and shorter plunging amplitude.The lift coefficients of two-dimensional and three-dimensional flapping plate are not changed significantly in synchronized rotation with higher angular amplitude.%针对微型飞行器,采用动网格方法计算了旋转超前、同步、滞后3种拍动模式下的平板升力性能.通过比较分析二维、三维拍动平板的升力性能以及尾涡分布变化,探讨了拍动平板升力性能与其运动规律的关系.计算表明：旋转同步和超前模式下的平板升力系数明显高于旋转滞后模式下的平板升力系数;二维、三维平板升力系数均随角振幅的增大而减小,随相位差的增大而增大,拍动振幅的影响相对较小;角振幅较大时,旋转超前模式中三维平板升力系数均明显高于二维平板升力系数,旋转同步模式中二维、三维平板升力系数变化不明显,旋转滞后模式中仅当小角振幅且小平移振幅时,三维平板升力系数增加较大.
Installation of TVC Actuators in a Two Axis Inertial Load Simulator Test Stand
Dziubanek, Adam
2013-01-01
This paper is about the installation of Space Shuttle Main Engines (SSME) actuators in the new Two Axis Inertial Load Simulator (ILS) at MSFC. The new test stand will support the core stage of the Space Launch System (SLS). Because of the unique geometry of the new test stand standard actuator installation procedures will not work. I have been asked to develop a design on how to install the actuators into the new test stand. After speaking with the engineers and technicians I have created a possible design solution. Using Pro Engineer design software and running my own stress calculations I have proven my design is feasible. I have learned how to calculate the stresses my design will see from this task. From the calculations I have learned I have over built the apparatus. I have also expanded my knowledge of Pro Engineer and was able to create a model of my idea.
Wang, Donglin; Fu, Linlai; Wang, Xin; Gong, Zhongjian; Samuelson, Sean; Duan, Can; Jia, Hongzhi; Ma, Jun Shan; Xie, Huikai
2013-08-01
A microelectromechanical system (MEMS) mirror based endoscopic swept-source optical coherence tomography (SS-OCT) system that can perform three-dimensional (3-D) imaging at high speed is reported. The key component enabling 3-D endoscopic imaging is a two-axis MEMS scanning mirror which has a 0.8×0.8 mm2 mirror plate and a 1.6×1.4 mm2 device footprint. The diameter of the endoscopic probe is only 3.5 mm. The imaging rate of the SS-OCT system is 50 frames/s. OCT images of both human suspicious oral leukoplakia tissue and normal buccal mucosa were taken in vivo and compared. The OCT imaging result agrees well with the histopathological analysis.
Two-axis water-immersible microscanning mirror for scanning optics and acoustic microscopy
Xu, Song; Zou, Jun
2016-10-01
Fast multiaxis scanning is useful for not only optical but also acoustic microscopic imaging. Although they have been used for optical scanning, the application of (MEMS) scanning mirrors in acoustic microscopy is still very limited due to their small mirror plate size, and more importantly, inability to operate in liquids (as ultrasound coupling media). A microfabricated two-axis water-immersible scanning mirror for optical and acoustic microscopy is reported. It has an optical and acoustically reflective mirror plate (6 mm×4 mm) to provide numerical aperture for ultrasound beam steering. Electromagnetic and mechanical analysis and simulation were conducted to estimate the mechanical tilting angle and resonance frequency of both fast and slow axes, which matches well with the measurement results. The fast axis has a resonant frequency of 320 Hz in air and 220 Hz in water, which is more than 10 times higher than that of the slow axis (24 Hz in air and 14 Hz in water). Under a 100-mA driving current, the scanning angles of the fast axis reached ±9.5 deg in both air and water at the resonance frequency, respectively. The scanning angles of the slow axis reached ±15 deg in air and ±12.5 deg in water at resonant frequencies, respectively. Raster scanning of a collimated laser beam was achieved by driving both axes simultaneously close to their own resonance frequencies. The feasibility of using the two-axis water-immersible scanning mirror in scanning acoustic microscopy was also demonstrated.
Seguidor Solar de Dos Ejes para un Horno Solar Two-Axis Sun Tracking System for a Solar Furnace
Gabriel Villeda; Alejandro Castañeda; José T Vega; Jorge Pineda
2011-01-01
Se presenta el diseño y fabricación de un seguidor solar de dos ejes (rotación-elevación), el cual controla un helióstato de un horno solar para la cocción de tabiques de arcilla. El sistema trabaja con motores controlados desde una computadora personal. El algoritmo para el seguidor solar se desarrolló en un lenguaje de programación visual, calcula los ángulos de seguimiento primario y secundario del helióstato y los despliega en una pantalla. El microcontrolador está programado para control...
Low-Friction, Low-Profile, High-Moment Two-Axis Joint
Lewis, James L.; Le, Thang; Carroll, Monty B.
2010-01-01
The two-axis joint is a mechanical device that provides two-degrees-of-freedom motion between connected components. A compact, moment-resistant, two-axis joint is used to connect an electromechanical actuator to its driven structural members. Due to the requirements of the overall mechanism, the joint has a low profile to fit within the allowable space, low friction, and high moment-reacting capability. The mechanical arrangement of this joint can withstand high moments when loads are applied. These features allow the joint to be used in tight spaces where a high load capability is required, as well as in applications where penetrating the mounting surface is not an option or where surface mounting is required. The joint consists of one base, one clevis, one cap, two needle bearings, and a circular shim. The base of the joint is the housing (the base and the cap together), and is connected to the grounding structure via fasteners and a bolt pattern. Captive within the housing, between the base and the cap, are the rotating clevis and the needle bearings. The clevis is attached to the mechanical system (linear actuator) via a pin. This pin, and the rotational movement of the clevis with respect to the housing, provides two rotational degrees of freedom. The larger diameter flange of the clevis is sandwiched between a pair of needle bearings, one on each side of the flange. During the assembly of the two-axis joint, the circular shims are used to adjust the amount of preload that is applied to the needle bearings. The above arrangement enables the joint to handle high moments with minimal friction. To achieve the high-moment capability within a low-profile joint, the use of depth of engagement (like that of a conventional rotating shaft) to react moment is replaced with planar engagement parallel to the mounting surface. The needle bearings with the clevis flange provide the surface area to react the clevis loads/moments into the joint housing while providing minimal
Two-Axis Solar Heat Collection Tracker System for Solar Thermal Applications
Directory of Open Access Journals (Sweden)
Tsung-Chieh Cheng
2013-01-01
Full Text Available An experimental study was performed to investigate the effect of using a continuous operation two-axes tracking on the solar heat energy collected. This heat-collection sun tracking which LDR (light dependent resistor sensors installed on the Fersnel lens was used to control the tracking path of the sun with programming method of control with a closed loop system. The control hardware was connected to a computer through Zigbee wireless module and it also can monitor the whole tracking process information on a computer screen. An experimental study was performed to investigate the effect of using two-axes tracking on the solar heat energy collected. The results indicate that sun tracking systems are being increasingly employed to enhance the efficiency of heat collection by polar-axis tracking of the sun. Besides, the heating power was also measured by designed power measurement module at the different focal length of Fresnel lens, and the design of shadow mask of LDR sensors is an important factor for solar photothermal applications. Moreover, the results also indicated that the best time to obtain the largest solar irradiation power is during 11:00 –13:00 in Taiwan.
Institute of Scientific and Technical Information of China (English)
杜胜华; 苏海鹏
2014-01-01
介绍了平板热管的基本结构与原理，在分析乙二醇及其混合工质的热物理学特性的基础上，建立平板热管的物理与数学模型。采用数值计算模拟方法，分析了混合工质平板热管集热器的传热性能，研究了集热器的效率、温升和启动性能随工作时间的变化规律。研究表明，乙二醇水混合工质平板热管集热器适宜于低温寒冷地区，具有较高的集热性能。%The basic structure and principle of flat plate heat pipe were introduced based on thermal physics characteristics analysis of ethylene glycol and mixtures , physical and mathematical models of flat plate heat pipe were established.By the numerical simulation method , the heat transfer performance of the flat heat pipe heat collector with mixture working fluid was analyzed , and the efficiency , temperature collector up and starting performance by time were studied.It showed that flat heat pipe heat collector with ethylene glycol water mixture was suitable for cold area , and the heat collecting performance was high.
Kim, Sehui; Lee, Changho; Kim, Jin Young; Kim, Jeehyun; Lim, Geunbae; Kim, Chulhong
2016-10-01
Compact size and fast imaging abilities are key requirements for the clinical implementation of an optical coherence tomography (OCT) system. Among the various small-sized technology, a microelectromechanical system (MEMS) scanning mirror is widely used in a miniaturized OCT system. However, the complexities of conventional MEMS fabrication processes and relatively high costs have restricted fast clinical translation and commercialization of the OCT systems. To resolve these problems, we developed a two-axis polydimethylsiloxane (PDMS)-based MEMS (2A-PDMS-MEMS) scanning mirror through simple processes with low costs. It had a small size of 15×15×15 mm3, was fast, and had a wide scanning range at a low voltage. The AC/DC responses were measured to evaluate the performance of the 2A-PDMS-MEMS scanning mirror. The maximum scanning angles were measured as ±16.6 deg and ±11.6 deg along the X and Y axes, respectively, and the corresponding field of view was 29.8 mm×20.5 mm with an optical focal length of 50 mm. The resonance frequencies were 82 and 57 Hz along the X and Y axes, respectively. Finally, in vivo B-scan and volumetric OCT images of human fingertips and palms were successfully acquired using the developed SD-OCT system based on the 2A-PDMS-MEMS scanning mirror.
Spontaneous transfer of chirality in an atropisomerically enriched two-axis system.
Barrett, Kimberly T; Metrano, Anthony J; Rablen, Paul R; Miller, Scott J
2014-05-01
One of the most well-recognized stereogenic elements in a chiral molecule is an sp(3)-hybridized carbon atom that is connected to four different substituents. Axes of chirality can also exist about bonds with hindered barriers of rotation; molecules containing such axes are known as atropisomers. Understanding the dynamics of these systems can be useful, for example, in the design of single-atropisomer drugs or molecular switches and motors. For molecules that exhibit a single axis of chirality, rotation about that axis leads to racemization as the system reaches equilibrium. Here we report a two-axis system for which an enantioselective reaction produces four stereoisomers (two enantiomeric pairs): following a catalytic asymmetric transformation, we observe a kinetically controlled product distribution that is perturbed from the system's equilibrium position. As the system undergoes isomerization, one of the diastereomeric pairs drifts spontaneously to a higher enantiomeric ratio. In a compensatory manner, the enantiomeric ratio of the other diastereomeric pair decreases. These observations are made for a class of unsymmetrical amides that exhibits two asymmetric axes--one axis is defined through a benzamide substructure, and the other axis is associated with differentially N,N-disubstituted amides. The stereodynamics of these substrates provides an opportunity to observe a curious interplay of kinetics and thermodynamics intrinsic to a system of stereoisomers that is constrained to a situation of partial equilibrium.
Zhang, Jianbin; Lu, Kangkang; Chen, Weihai; Jiang, Jun; Chen, Wenjie
2015-02-01
Polarization maintaining optical fiber (PMOF) is a kind of special optical fiber that is designed to transmit the linearly polarized light. Unlike the general optical fiber, it is critical to conduct the rotational alignment between two PMOFs to guarantee the efficiency of light transmission. Until now, this alignment task still cannot be addressed with an efficient and economical way. Hence, we propose a monolithically integrated two-axis flexure-based microgripper that has the grasping and rubbing functions. To achieve a compact structure, the microgripper is designed with an asymmetric architecture. In this paper, the pseudo-rigid body model approach and finite element analysis are conducted to provide the essential guideline to accomplish the theoretical design. The prototype is fabricated by wire electrical discharge machining, with which two experiments are conducted to validate the performance of the microgripper. The experimental results demonstrate that the proposed microgripper can firmly grasp the optical fiber with the diameter of 250 μm and meanwhile can rub it more than 90° accurately and effectively, which indicate that it can satisfy the operating requirements well in the PMOF assembly.
Investigation on coaxial stability of nano-bearing under two axis-deviation perturbations
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
A spatial cylindrical model on nano-bearing constructed by double-walled carbon nano-tube (DWCNT) is established. Two motion equations are advanced to characterize the eccentric and deflective mode of the nano-bearing, respectively. On the basis of these equations, the coaxial stability of the nano-bearing under two axis-deviation perturbations is investigated. A characteristic parameter λ * governing the coaxial stability of the nano-bearing is determined. The influences of the angular velocity, interlayer spacing and axial length of the nano-bearing on the characteristic parameter λ * are analyzed and discussed in detail. It is found that when the angular velocity or interlayer spacing is smaller than a certain critical value, the parameter λ * keeps negative, and the coaxial stability of the nano-bearing is maintained. However, the axial length has very insignificant influence on λ * . In addition, for the two non-coaxial modes, the eccentric mode occurs more easily than the deflective one. The results of this paper provide a further insight into the coaxial stability of nano-bearing via the spatial model.
Directory of Open Access Journals (Sweden)
F Nadi
2017-05-01
back propagation learning rule was used to simulate the output temperature of a solar collector. The number of neurons within the hidden layer varied from 1 to 20. The hyperbolic tan- sigmoid and pure-line were used as the transfer function in the hidden layer and output layer, respectively. Minimization of error was achieved using the Levenberg-Marquardt algorithm. To carry out the aforementioned steps, the dataset (105 observations was split into training (70 observations, and test (35 observations data. Training sets used to develop models included air velocity, solar radiation, time of the day, ambient moisture and temperature values as inputs with an associated temperature of the collector as outputs. The aim of every training algorithm is to reduce this global error by adjusting the weights and biases. Results and Discussion Compare experimental results with ANN The performance of the three-layer ANN for the prediction of output temperature of flat-plate solar collector by the Levenberg–Marquardt training algorithm was illustrated in Fig. 4. ANN predicted output temperatures with R2 and RMSE of 0.92 and 1.23, respectively. Furthermore, the maximum error in prediction of output temperature of solar collector was 3.3 K. These results are in agreement with Tripathy and Kumar, (2009 those who have predicted the output temperatures of food product in the solar drier using ANN with and RMSE of 0.95 and 0.77, respectively. Compare experimental results with CFD simulation Fig. 6 shows that over the starting length of the absorber plate, there is a variation of the velocity profile which is caused by sharp geometry and it leads to some recirculation of the air in this part of absorber plate. After this part of boundary layers, flow is fully developed and velocity profile becomes smoother and constant. Fig. 8 shows that the predicted temperature was within the experimentally measured temperature. The highest differences between simulated and experimental temperatures
Sound propagation in two-axis underwater channel based on beam-displacement ray-mode theory
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
Sound propagation in a deep ocean two-axis underwater channel is often complex and difficult to simulate between surface channel and sound fixing and ranging (SOFAR) channel. The beam-displacement ray-mode (BDRM) theory is a normal mode method for propagation modeling in horizontally stratified shallow water. An improved method for computing the upper boundary reflection coefficient in the BDRM is proposed and applied to calculate the acoustic fields of a two-axis underwater channel. Transmission losses in the two-axis underwater channel are calculated in the new BDRM. The corresponding results are in good agreement with those from the Kraken code, and furthermore the computed speed of the new BDRM excels the other methods.
Institute of Scientific and Technical Information of China (English)
邓月超; 全贞花; 赵耀华; 王林成; 叶三宝
2013-01-01
为了检验一种新型平板太阳能热水器的性能,该文对其核心部件—基于微热管阵列的集热器及其组成的热水器进行了热性能试验.集热器热性能测试结果表明,微热管阵列平板太阳能集热器瞬时效率的斜率为4.7,截距为0.80,分别优于国家标准要求值11.0%和22.3%.在满足测试要求的天气情况下,对微热管阵列平板太阳能热水器进行的多次热性能测试结果表明,热水器的日有效得热量均高于国家标准要求值,日平均集热效率均高于60%.同时,该热水器具有承压能力强、无炸裂、轻巧、成本低、无需焊接、抗冻性能好、易于建筑一体化等优势.基于微热管阵列的平板太阳能热水器由于性能优异,并能克服现有太阳能热水器的缺点,具有广阔的应用前景.%A novel flat plate solar water heater based on the micro heat pipe array (MHPA) was invented, and the experiments were carried out on the MHPA heat collector and water heater to test their thermal performance. Owing to its distinctive structure, the MHPA has good heat transfer ability, high reliability, high compressive strength and low cost. The structure and character of the novel collector with MHPA as the high-efficiency heat transfer element are as follows. First, the contact surface between the absorber and the MHPA is so large that the heat resistance is smaller than the traditional one, thus its thermal transfer capability is greatly improved. Second, the condenser section of the MHPA is connected closely to the heat exchanger with dry type. The heat pipes do not contact with water, which precludes scaling and leakage in the collector. Third, the MHPA uses low freezing points of the refrigerants, which makes the collector more suitable for extremely cold areas. Fourth, the MHPA is made of aluminum instead of copper, which could reduce the fabrication cost significantly. Fifth, the unique heat exchanger could exclude water easily
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
利用平板式光生物反应器对一种新分离的微藻 Parietochloris incisa 进行了室外放大培养研究.在最适培养条件下, 实现了对该微藻的超高密度培养,使单位培养体积和单位培养面积的细胞生物量分别达到了 7.35 g/(L·d)和 96.12 g/(m2·d).%One kind of new microalgae Parietochloris incisa is cultured in outdoor in flat plate photobioreactors. Under optimal culture conditions, the highest volumetric cell biomass output rate of 7.35 g/(L·d) and the areal cell biomass output rate of 96.12 g/(m2·d) are obtained in the photobioreactor.
Institute of Scientific and Technical Information of China (English)
倪贝; 丁昀; 杨庆
2011-01-01
As it is difficult to solve the problem of unsteady - state heat transfer in theory, study of flat plate solar collectors in series -connected system with intermittent output is conducted by numerical simulation.Under the unsteady - state heat transfer condition, the impact of the diameter and center distance of solar collectors on the instantaneous collector efficiency and water production rate per square meter are discussed respectively.The results show that flat cartridge collector performed high effeciency.And under the same conditions, the larger the diameter of collector is, the higher efficiency will be.These can be used for optimizing design parameters of flat plate solar collectors.%由于非稳态传热问题通过理论计算得到解析解较困难,本文运用数值模拟方法研究定温放水型直流式系统中平板型太阳能集热器的工作状况,讨论了集热器的管径和管中心距在非稳态传热条件下对集热器的效率和每平方米产水量的影响.可得到结论扁盒式集热器具有较高效率;相同条件下,管径越大集热器效率越高.该结果有利于优化直流式平板集热器的设计参数.
Institute of Scientific and Technical Information of China (English)
李世平; 向开根; 李雯; 罗会龙; 王霜
2015-01-01
Heat pipe has many advantages, such as higher heat transfer coefficient, lower transfer temperature-difference and a one-way heat transfer. A new flat plate heat pipe solar air collector was designed and built based on a reasonable construction. The test results indicated that the instantaneous efficiency of collector is 15.3%~74.5% under the climatic conditions of daily solar radiation being about 14.4 to19.8MJ/m2·day. Its daily average thermal efficiency is about 32.6%~53.5%with heat loss coefficient being 3.6~8.4W/(m2·K). The maximum outlet air temperature can reach 79.1℃. Compared with conventional air collectors, the new flat plate heat pipe solar air collector has higher thermal efficiency and outlet air.%热管具有传热系数高、传热温差小及单向传热等诸多优良特性。以热管为集热部件，试制了一种平板式热管太阳能空气集热器。测试结果表明，在日总太阳辐射为14.4MJ/m2～19.8MJ/m2的气候条件下，平板式热管太阳能空气集热器的瞬时集热效率在15.3%～74.5%之间，集热器出口空气温度可达79.1℃，其日平均集热效率约为32.6%～53.5%，其热损失系数约为3.6～8.4W/(m2·K)。与常规的太阳能空气集热器相比，平板式热管太阳能空气集热器具有较高的集热效率和较低的热损失系数，并且供热温度较高。
Kishan, N.; Jagadha, S.
2016-01-01
The paper presents an investigation of the influence of thermophoresis on MHD mixed convective heat and mass transfer of a viscous, incompressible and electrically conducting fluid along a vertical flat plate with radiation effects. The plate is permeable and embedded in a porous medium. To describe the deviation from the Darcy model the Forchheimer flow model is used. The Rosseland approximation is used to describe the radiative heat flux in the energy equation. The governing partial differential equations are transformed into a system of ordinary differential equations using similarity transformation. The nonlinear ordinary differential equations are linearized by using quasilinearization technique and then solved numerically by using implicit finite difference scheme. The numerical results are analyzed for the effects of various physical parameters such as magnetic parameter Ha, mixed convection parameter Ra d /Pe d , Reynolds number Red, radiation parameter R, thermophoretic parameter τ, Prandtl number Pr, and Schmidt number Sc. The heat transfer coefficient is also tabulated for different values of physical parameters.
Institute of Scientific and Technical Information of China (English)
姜孝均; 李良荣
2016-01-01
本文针对平板便携式卫星通信终端的伺服控制系统展开研究，本文提出一种根据终端设备所在位置的经纬度信息和目标卫星的经度信息，通过对终端设备的平板天线俯仰和方位的伺服控制，自动调整天线的方位和俯仰姿态，使天线指向目标卫星，并进一步对极化角进行调整，从而快速建立起稳定的卫星通信链路的算法设计方案。%The purpose of this paper is to study servosystem for Flat Plate Portable Satellite Communication Terminal. In this paper,we propose a longitude information of the latitude and longitude information and the target satellite,which is located at the location of the terminal equipment.Through the servo control of the antenna's elevation and azimuth of the terminal device to set up fast algorithm design stability of the satellite communication link. The azimuth and elevation of the antenna are adjusted automatically to make the antenna point to the target satellite,and the polarization angle is adjusted further.
Study on a Flat Plate Solar Air Collector with Baffles%扰流板型太阳能平板空气集热器集热性能
Institute of Scientific and Technical Information of China (English)
夏佰林; 赵东亮; 代彦军; 李勇
2011-01-01
对一种扰流板型太阳能平板空气集热器的集热性能进行了研究,并对各种影响集热器热性能的因素进行了分析,揭示了总热损失系数、扰流板肋片效率、流道内空气流速和扰流板的间距对效率因子和热迁移因子的影响机理.获得了扰流板型太阳能平板空气集热器的集热效率理论表达式,为此类太阳能空气集热器的设计及应用提供了参考.%A flat plate solar air collector with baffles was studied. Several factors that have influence on the thermal performance of the solar collectors were analyzed. The paper investigated the relations between the efficiency factor, the heat-removal factor of the solar air collector and the total heat loss coefficient, baffles fin efficiency, air velocity inside the flow channel, the space between baffles, and the height of baffles. Also, the time constant of the collectors was studied. The theoretical formula of the collector's thermal efficiency was obtained, which can be used for design and application of such kind of collectors.
Institute of Scientific and Technical Information of China (English)
卢郁; 于洪文; 丁海成; 张艳丽; 刘宗明
2013-01-01
以平板太阳能集热器作为研究对象,通过对平板太阳能集热器热性能进行理论推导,引入效率因子,构建更为准确、便捷的平板集热器的数学模型,进行计算机程序模拟.根据模拟数据得出吸热体板芯几何结构、板芯用材对平板太阳能集热器性能的影响.在不降低集热器效率因子的情况下,使翅片的单位面积质量降低45.8％；在材料消耗相同的情况下,集热器效率因子提高了0.03.%Taking a flat-plate solar collector as research object and introducing an efficiency factor, we establish a mathematical model for the collector after theoretically deriving out the thermal properties of it, and numerically simulate it according to this model. Simulation results show that the mass per unit area of the collector drops 45. 8% with the same efficiency factor and the efficiency factor increasesby 0.03 with the same material consumption.
Energy Technology Data Exchange (ETDEWEB)
Bracamonte-Baran, Johane Hans; Baritto-Loreto, Miguel Leonardo [Universidad Central de Venezuela (Venezuela)]. E-mails: johanehb@gmail.com; johane.bracamonte@ucv.ve; miguel.baritto@ucv.ve
2013-04-15
The dimensionless model developed and validated by Baritto and Bracamonte (2012) for the thermal behavior of flat plate solar collector without glass cover is improved by adding the entropy balance equation in a dimensionless form. The model is solved for a wide range of aspect ratios and mass flow numbers. A parametric study is developed and the distribution of internal irreversibilities along the collector is analyzed. The influence of the design parameters on the entropy generation by fluid friction and heat transfer is analyzed and it is found that for certain combinations of these parameters optimal thermodynamic operation can be achieved. [Spanish] En el presente trabajo, el modelo adimensional desarrollado y validado por Baritto y Bracamonte (2012) para describir el comportamiento termico de colectores solares de placas planas sin cubierta transparente, se complementa con la ecuacion adimensional de balance de entropia para un elemento diferencial de colector solar. El modelo se resuelve para un amplio rango de valores de relaciones de aspecto y numero de flujo de masa. A partir de los resultados del modelo se desarrolla un analisis detallado de la influencia de estos parametros sobre la distribucion de irreversibilidades internas a lo largo del colector. Adicionalmente se estudia la influencia de estos parametros sobre los numeros de generacion de entropia por friccion viscosa, por transferencia de calor y total. Se encuentra que existen combinaciones de los parametros antes mencionados, para los cuales, la operacion del colector es termodinamicamente optima para numeros de flujo de masa elevados.
An automatic registration system of multi-view 3D measurement data using two-axis turntables
He, Dong; Liu, Xiaoli; Cai, Zewei; Chen, Hailong; Peng, Xiang
2016-09-01
Automatic registration is a key researcher issue in 3D measurement field. In this work, we developed the automatic registration system, which is composed of a stereo system with structured light and two axis turntables. To realize the fully automatically 3D point registration, the novel method is proposed for calibration the stereo system and the two turntable direction vector simultaneously. The plane calibration rig with marked points was placed on the turntable and was captured by the left and right cameras of the stereo system with different rotation angles of the two axis turntable. By the shot images, a stereo system (intrinsically and extrinsically) was calibrated with classics camera model, and reconstruction 3D coordinates of the marked points with different angle of the two turntable. The marked point in different angle posted the specific circle, and the normal line of the circle around the turntable axis direction vector. For the each turntable, different points have different circle and normal line, and the turntable axis direction vector is calculated by averaging the different normal line. And the result show that, the proposed registration system can precisely register point cloud under the different scanning angles. In addition, there are no the ICP iterative procedures, and that make it can be used in registration of the point cloud without the obvious features like sphere, cylinder comes and the other rotator.
Rogers, Loranzie S; Van Wert, Jacey C; Mensinger, Allen F
2017-08-15
Chronically implanted electrodes allow monitoring neural activity from free moving animals. While a wide variety of implanted headstages, microdrives and electrodes exist for terrestrial animals, few have been developed for use with aquatic animals. A two axis micromanipulator was fabricated with a Formlabs 3D printer for implanting electrodes into free-swimming oyster toadfish (Opsanus tau). The five piece manipulator consisted of a base, body, electrode holder, manual screw drive and locking nut. The manipulator measured approximately 25×20×30mm (l×w×h) and weighed 5.28g after hand assembly. Microwire electrodes were inserted successfully with the manipulator to record high fidelity signals from the anterior lateral line nerve of the toadfish. The micromanipulator allowed the chronically implanted electrodes to be repositioned numerous times to record from multiple sites and extended successful recording time in the toadfish by several days. Three dimensional printing allowed an inexpensive (<$US 5 material), two axis micromanipulator to be printed relatively rapidly (<2h) to successfully record from multiple sites in the anterior lateral line nerve of free-swimming toadfish. Copyright © 2017 Elsevier B.V. All rights reserved.
Institute of Scientific and Technical Information of China (English)
张玉敏; 苏幼坡; 苏经宇
2013-01-01
The new beam-column and concrete-filled steel tubular column-flat plate composite structure is characterized by the joint with dedicated connection device ( hinged connection) between steel columns and concrete slab. The nodes bear only vertical loads while the horizontal loads are born by the shear wall and beam-column frame, and the unbalanced moment in the joint should be very small even naught to avoid the punching damage of slab when an earthquake occurs. The new structure is different from the general frame-shear wall or slab-column structure, therefore the experiment should be implemented to study the performance of the floor system. Through a model test of concrete filled steel tubular (CFST) column-flat plate structure (inter-cross with less than 3) with 1/2-scale, the mechanical performance should be studied under vertical uniform and horizontal loads. Results show that the bearing capacity of the floor system with high security reserves is 2 times higher than the vertical design load; the relative displacement of the joint can achieve 2. 25 % of storey height that is two times more of a frame structure's story drift limit in Code for Seismic Design of Building Structure before the specimens were destroyed even in high ratio of shearing force from the weight of superstructure and punching shear capacity of slabs (gravity shear ratio, GSR >0. 8) . The seismic behavior exceeds ordinary flat floor slab.%新型梁柱-钢管混凝土板柱混合结构的特点是钢管混凝土柱-板节点处只承担竖向荷载,不出现或者出现较小的不平衡弯矩,同时提高节点抗侧移能力,避免地震时楼板发生冲切破坏,水平荷载则全部由抗震墙和梁柱框架承担.通过1个1/2比例钢筋混凝土梁柱-钢管混凝土柱无梁楼盖异型板(跨数少于3跨)结构模型试验,研究其在受竖向均布荷载和水平荷载作用下结构的受力性能.试验结果表明,楼盖系统的竖向承载力超出设计荷载的2倍以上,
Effects of Key Parameters on Thermal Performance of Solar Flat-Plate Collector%太阳能平板集热器关键参数对其热性能的影响
Institute of Scientific and Technical Information of China (English)
车永毅; 厚彩琴
2016-01-01
为了提升太阳能在建筑能源供给体系中的比重，形式多样的太阳能集热设备及其系统在建筑领域得到了广泛应用。基于机理分析法，建立了具有单层玻璃盖板的管板式太阳能平板集热器的稳态传热模型。并且针对集热管间距、集热管内径、工质入口温度和工质质量流量等关键参数对集热器集热效率的影响特性进行了数值模拟与分析。结果表明，建立的该稳态传热模型是可行的；此外，在其余参数值保持不变的情况下，减小集热管间距或增加集热管内径均可使集热器瞬时效率增大；增大工质入口温度会导致集热器瞬时效率下降；而增大工质质量流量会提升集热器瞬时效率。这些结论对于太阳能平板集热器在太阳能建筑一体化的实际应用中，具有一定的参考作用。%In order to improve the proportion of solar energy in building energy supply system, various forms of solar heat collection equipment and systems in the construction field has been widely used. Based on the mechanism analysis method, one steady-state heat transfer model of the single glass cover flat-plate collector is built. The numerical simulation and analysis of the effect of the key parameters including col-lector tube spacing, collector tube diameter, and inlet temperature and inlet mass flow rate of the working fluid on heat collection efficiency of the collector is carried out. The results show that the steady-state heat transfer model is feasible;and in the case of the same parameters, either reducing the collector tube spacing or increasing the collector tube diameter can increase the instantaneous efficiency of the collector; the instantaneous efficiency of the collector decline with the increase of inlet temperature of the working fluid. However, increasing the mass flow rate at the entrance can improve the instantaneous efficiency of the collector. These conclusions have a certain
Institute of Scientific and Technical Information of China (English)
徐国宾; 王永鹏; 高仕赵; 刘昉
2011-01-01
Based on the basic principle of smoothed particle hydrodynamics ( SPH ) method, the paper gave 2 - D SPH Fortran program to make numerical simulations for Poiseuille flow and Couette flow which are Laminar Flow between two parallel flat plates after a comprehensive consideration of several kinds of settings on solution conditions. Compared SPH with theoretical analysis solution and simulation results which use Flow-3D numerical simulation software, this paper discovers that they are very anastomosis. The results realized a verification for the SPH mathematical model and 2 - D SPH Fortran program, supplied theoretical support and laid a good foundation for the use and development of SPH in the future.%基于SPH方法的基本原理,综合考虑了对各种定解条件的设置,用Fortran语言独立编写了一套用于模拟两平行平板间层流的SPH二维计算程序,并应用于泊肃叶流和库埃特流的数值模拟之中,将模拟结果与理论解析解和通过Flow -3D软件数值模拟得到的数值结果进行对比,分析表明三种方法得到的计算结果非常吻合,从而实现了对SPH数学模型和SPH计算程序的验证,为SPH方法的进一步发展和广泛应用奠定了一定的基础.
Experimental Analysis of Serpentine-flow Flat-plate Solar Collector%蛇形管平板式太阳能集热器的试验研究
Institute of Scientific and Technical Information of China (English)
李俊贤; 王辉涛; 王华; 包桂蓉
2011-01-01
A serpentine-flow flat-plate solar collector of small volume and large temperature difference is designed and developed in order to explore the fiat-plate solar collector used in high temperature situation. And experiment of stagnation and instantaneous efficiency is carried out. The results shown that stagnation temperature can reach 170.2 ℃ and heat loss coefficient is 5. 239 W/( m2 · ℃ ). Efficiency of solar collector between 52％ —55％ when inlet temperature of working fluid is 70 ℃. By comparison the temperature trend of various parts of the collector the corrective measure is proposed to improve performance of serpentine-flow fiat-plate solar collector in high temperature conditions.%为了探寻一种在中高温场合使用的平板式太阳能集热器,设计和开发了小流量、大温差的蛇形管平板式太阳能集热器,并进行了空晒试验和瞬时效率试验.试验结果表明:集热器的空晒温度可达170.2℃,热损系数为5.239 W/(m2·℃),载热工质进口温度70℃时效率52%-55%.通过对集热器各部分温度变化趋势的比较,提出改进措施,以提高蛇形管平板式集热器在中高温工况下的集热性能.
High temperature flat plate solar collector
Energy Technology Data Exchange (ETDEWEB)
Hozumi, S.; Aso, S.; Ebisu, K.; Uchino, H.
1981-04-01
Improvements in the efficiency of collectors are of great importance for extending the utilization of solar energy for heating and cooling in homes. A highly efficient collector makes the system size small and decreases the system cost effectively. From the view of the amount of energy collected, the efficient collector has a multiple effect, not only because of the high increase in instantaneous efficiency, but also because of the large usable intensity range of the insolation. On the basis of a functional analysis for a flat collector, the materials and parameters were selected and optimized, and a new high temperature flat collector was designed. The collector has 2 panes. The first pane is low iron glass and the second pane is a thin film of fluorinated ethylene-propylene copolymer. The overall solar transmittance for the two panes is 0.89. The collecting panel and its water paths were formed by means of welding and hydraulic expansion. The selective absorbing surface consists of colored stainless steel whose absorption characteristic is 0.89 and emission characteristic is 0.16. The thermal insulator preventing backward heatloss consists of double layers of urethane foam and glass wool. Furthermore, the sustained method for the second pane is contrived so as to prevent water condensation on the panes and excessive elevation of the absorber temperature during no load heating.
Operational success - Flat-plate photovoltaic systems
Risser, V. V.; Zwibel, H. S.
The performance-to-date of 20 and 100 kW peak DOE photovoltaic array demonstration projects in New Mexico and Texas are reported. An El Paso 20 kW unit feeds power to an uninterruptible power supply for a computer controlling a 197 MW generator. System availability has been 97 percent after over 800 days of operation, and has reached monthly efficiencies of 5.3-6.2 percent. The Lovington, NM 100 kW unit has operated at an average 6.7 percent efficiency, furnishing over 15.8 MWh/mo for a 2 yr period. System availability has been 99 percent, although at increased costs due to regular maintenance.
Liu, Lin; Wu, Lei; Sun, Jingjing; Lin, Elaine; Xie, Huikai
2011-02-01
We present the design and experimental results of a new MEMS-based endoscopic optical coherence tomography (OCT) probe. The uniqueness of this miniature OCT imaging probe is a two-axis MEMS mirror with through-silicon vias (TSVs) for interconnecting. The TSV interconnection enables ultracompact probe design, successfully reducing the probe size to only 2.6 mm in diameter. The MEMS mirror is actuated by an electrothermal actuator that is capable of scanning ± 16° at only 3.6 V DC. Two-dimensional and three-dimensional OCT images of microspheres embedded in PDMS and acute rat brain tissue have been obtained with this miniature probe in a time-domain OCT system.
Jeong, Jae-Woong; Park, Bryan; Keum, Hohyun; Kim, Seok; Rogers, John A; Solgaard, Olav
2013-06-03
We present a two-axis electrostatic MEMS scanner with high-reflectivity monolithic single-crystal-silicon photonic crystal (PC) mirrors suitable for applications in harsh environments. The reflective surfaces of the MEMS scanner are transfer-printed PC mirrors with low polarization dependence, low angular dependence, and reflectivity over 85% in the wavelength range of 1490nm~1505nm and above 90% over the wavelength band of 1550~1570nm. In static mode, the scanner has total scan range of 10.2° on one rotation axis and 7.8° on the other. Dynamic operation on resonance increase the scan range to 21° at 608Hz around the outer rotation axis and 9.5° at 1.73kHz about the inner rotation axis.
Institute of Scientific and Technical Information of China (English)
朱婷婷; 刁彦华; 赵耀华; 马骋; 李凤飞
2016-01-01
In common types of flat-plate solar air heaters, the uneven flow and heat exchange between air and an absorber plate poses a problem. To resolve this problem, this paper proposed a novel type of flat-plate solar air heater based on micro-heat pipe arrays (MHPA). An investigation was carried out on the design, thermal performance and flow resistance characteristic of the novel heater based on micro-heat pipe arrays. The new air collector consists of 15 MHPAs with V-shaped fins attached to the heat release (condenser) section, absorber film, insulation board, bottom plate, and air ventilation and heat exchange section. The components of the heater include the toughened glass cover, air layer (35 mm), MHPA-absorber plate, thermal insulation layer, and the back board. Solar energy is absorbed by the MHPA evaporator section with the organic combination of high efficiency absorber film, which formed a heat pipe effect within each micro heat pipe arrays. The heat has been released to the air in the ventilation and heat exchange section of the heater, whereas the air was eventually warmed. Simultaneously, the working medium in MHPA proceeds continuous phase transition cycle and continuously passes solar radiation heat to air in the air duct with high efficiency. The MHPA heat-absorbing plate core can realize the whole area of heat absorption, high efficient heat transmission, and large surface of heat release. The total solar energy is received by the heater, and some energy is transferred to the air flow in the air duct as useful energy; the remaining energy is lost mainly through the glass cover, frames, bottom plate, and air duct. The heat loss through the frames and the air duct can be ignored because of good heat preservation condition. So the glass cover becomes the main source of heat loss. Thermal analysis shows that heat loss through the glass cover occupies the largest proportion of the total heat loss of the heater.To test the new heater thermal efficiency and
Zheng, Minyi; Zhang, Bangji; Zhang, Jie; Zhang, Nong
2016-07-01
Physical parameters are very important for vehicle dynamic modeling and analysis. However, most of physical parameter identification methods are assuming some physical parameters of vehicle are known, and the other unknown parameters can be identified. In order to identify physical parameters of vehicle in the case that all physical parameters are unknown, a methodology based on the State Variable Method(SVM) for physical parameter identification of two-axis on-road vehicle is presented. The modal parameters of the vehicle are identified by the SVM, furthermore, the physical parameters of the vehicle are estimated by least squares method. In numerical simulations, physical parameters of Ford Granada are chosen as parameters of vehicle model, and half-sine bump function is chosen to simulate tire stimulated by impulse excitation. The first numerical simulation shows that the present method can identify all of the physical parameters and the largest absolute value of percentage error of the identified physical parameter is 0.205%; and the effect of the errors of additional mass, structural parameter and measurement noise are discussed in the following simulations, the results shows that when signal contains 30 dB noise, the largest absolute value of percentage error of the identification is 3.78%. These simulations verify that the presented method is effective and accurate for physical parameter identification of two-axis on-road vehicles. The proposed methodology can identify all physical parameters of 7-DOF vehicle model by using free-decay responses of vehicle without need to assume some physical parameters are known.
Energy Technology Data Exchange (ETDEWEB)
Haneda, Y.; Kurasawa, H. (Nagano National College of Technology, Nagano (Japan)); Tsuchiya, Y. (Shinshu Univ., Nagano (Japan). Faculty of Engineering); Suzuki, K. (Kyoto Univ., Kyoto (Japan). Faculty of Engineering)
1994-04-25
The flow field and heat transfer around a circular cylinder is investigated experimentally when two dimensional jet is impinged on a circular cylinder mounted near two flat plates which are set at a fixed inclination against the axis of jet. Flow field varies markedly depending on whether the minimum channel width is the minimum space B between the flat plates or the space C between the cylinder and the plates. The local Nusselt number of the cylinder strongly depends on the value of space C between the cylinder and the plates. The minimum and maximum locations correspond to the locations of separation and reattachment, respectively, of the flow around the cylinder. When the ratio between the nozzle-to-cylinder distance L and the short side h of the nozzle is 3 (L/h=3), the mean Nusselt number around the cylinder becomes the maximum when C/D is 0.1 where D is the diameter of the cylinder, and increases by about 9 to 12% as compared with the case where no plate is provided. For L/h=7 and L/h=10, the mean Nusselt number does not increase distinctly as compared with the case where no flat plate is provided. 16 refs., 15 figs.
Institute of Scientific and Technical Information of China (English)
郑土逢; 李明; 魏生贤; 罗熙; 王炳灿
2011-01-01
The device of natural circulation flat plate solar water heater has been built.In accordance with the national testing standard methods, the efficiency of the system was tested.The transient model of NFSWH has been developed by using the TRNSYS simulation program.The effect of installation height between the bottom of the tank and the outlet of the collector on efficiency of the solar collector has been investigated both theoretically and experimentally.The data show the theoretical results are highly consistent with the experimental ones.Results indicate that the optimum value of installation height is 0.74m with the maximum efficiency of 67.5％ for the system with a total area of 1.5m2 and a storage water tank capacity of 120L.When the installation height is between 0.44 and 1.04 m, the change of thermal efficiency of the solar system is at a range of 3％.%搭建了自然循环平板式太阳能热水器(NFSWH)的实验平台,根据太阳能热水器国家测试标准方法对系统的热效率进行测试.用TRNSYS软件建立了NFSWH的瞬态模型.模拟和实际测量了水箱放置高度对热水器热效率的影响.结果显示,实验与模拟吻合较好.对于集热面积为1.5m2水箱容积为120L的系统,水箱底到集热器出口的高度(Hr)为0.74m时,系统的热效率最大(67.7%).放置高度为0.44-1.04m时,系统集热效率变化不大,在3%以内.
Edwards, C. L.; Boone, B. G.; Levine, W. S.; Davis, C. C.
2007-04-01
The availability of recently developed MEMS micro-mirror technology provides an opportunity to replace macro-scale actuators for free-space laser beamsteering in lidar and communication systems. Such an approach is under investigation at the Johns Hopkins University Applied Physics Laboratory for use on space-based platforms. Precision modeling of mirror pointing and its dynamics are critical to optimal design and control of MEMS beamsteerers. Beginning with Hornbeck's torque approach, this paper presents a first-principle, analytically closed-form torque model for an electro-statically actuated two-axis (tip-tilt) MEMS structure. An Euler dynamic equation formulation describes the gimbaled motion as a coupled pair of damped harmonic oscillators with a common forcing function. Static physical parameters such as MEMS mirror dimensions, facet mass, and height are inputs to the model as well as dynamic harmonic oscillator parameters such as damping and restoring constants fitted from measurements. A Taylor series expansion of the torque function provides valuable insights into basic one dimensional as well as two dimensional MEMS behavior, including operational sensitivities near "pull-in." The model also permits the natural inclusion and analysis of pointing noise sources such as electrical drive noise, platform vibration, and molecular Brownian motion. MATLAB and SIMULINK simulations illustrate performance sensitivities, controllability, and physical limitations, important considerations in the design of optimal pointing systems.
Edwards, C. L.; Edwards, M. L.
2009-05-01
MEMS micro-mirror technology offers the opportunity to replace larger optical actuators with smaller, faster ones for lidar, network switching, and other beam steering applications. Recent developments in modeling and simulation of MEMS two-axis (tip-tilt) mirrors have resulted in closed-form solutions that are expressed in terms of physical, electrical and environmental parameters related to the MEMS device. The closed-form analytical expressions enable dynamic time-domain simulations without excessive computational overhead and are referred to as the Micro-mirror Pointing Model (MPM). Additionally, these first-principle models have been experimentally validated with in-situ static, dynamic, and stochastic measurements illustrating their reliability. These models have assumed that the mirror has a rectangular shape. Because the corners can limit the dynamic operation of a rectangular mirror, it is desirable to shape the mirror, e.g., mitering the corners. Presented in this paper is the formulation of a generalized electrostatic micromirror (GEM) model with an arbitrary convex piecewise linear shape that is readily implemented in MATLAB and SIMULINK for steady-state and dynamic simulations. Additionally, such a model permits an arbitrary shaped mirror to be approximated as a series of linearly tapered segments. Previously, "effective area" arguments were used to model a non-rectangular shaped mirror with an equivalent rectangular one. The GEM model shows the limitations of this approach and provides a pre-fabrication tool for designing mirror shapes.
Johnson, Michael R.; Gehling, Russ; Head, Ray
2006-01-01
The Mars Reconnaissance Orbiter (MRO) spacecraft has three two-axis gimbal assemblies that support and move the High Gain Antenna and two solar array wings. The gimbal assemblies are required to move almost continuously throughout the mission's seven-year lifetime, requiring a large number of output revolutions for each actuator in the gimbal assemblies. The actuator for each of the six axes consists of a two-phase brushless dc motor with a direct drive to the wave generator of a size-32 cup-type harmonic gear. During life testing of an actuator assembly, the harmonic gear teeth failed completely, leaving the size-32 harmonic gear with a maximum output torque capability less than 10% of its design capability. The investigation that followed the failure revealed limitations of the heritage material choices that were made for the harmonic gear components that had passed similar life requirements on several previous programs. Additionally, the methods used to increase the stiffness of a standard harmonic gear component set, while accepted practice for harmonic gears, is limited in its range. The stiffness of harmonic gear assemblies can be increased up to a maximum stiffness point that, if exceeded, compromises the reliability of the gear components for long life applications.
Directory of Open Access Journals (Sweden)
Minyi Zheng
2015-01-01
Full Text Available A new physical parameter identification method for two-axis on-road vehicle is presented. The modal parameters of vehicle are identified by using the State Variable Method. To make it possible to determine the matrices M, C, and K of the vehicle, a known mass matrix ΔM is designed to add into the vehicle in order to increase the number of equations ensuring that the number of equations is more than the one of unknowns. Therefore, the physical parameters of vehicle can be estimated by using the least square method. To validate the presented method, a numerical simulation example and an experiment example are given in this paper. The numerical simulation example shows that the largest of absolute value of percentage error is 1.493%. In the experiment example, a school bus is employed in study for the parameter identification. The simulation result from full-car model with the estimated physical parameters is compared with the test result. The agreement between the simulation and the test proves the effectiveness of the proposed estimation method.
Ye, Liangchen; Zhang, Gaofei; You, Zheng
2017-03-05
The MEMS (Micro-Electronical Mechanical System) scanning mirror is an optical MEMS device that can scan laser beams across one or two dimensions. MEMS scanning mirrors can be applied in a variety of applications, such as laser display, bio-medical imaging and Light Detection and Ranging (LiDAR). These commercial applications have recently created a great demand for low-driving-voltage and low-power MEMS mirrors. However, no reported two-axis MEMS scanning mirror is available for usage in a universal supplying voltage such as 5 V. In this paper, we present an ultra-low voltage driven two-axis MEMS scanning mirror which is 5 V compatible. In order to realize low voltage and low power, a two-axis MEMS scanning mirror with mechanical leverage driven by PZT (Lead zirconate titanate) ceramic is designed, modeled, fabricated and characterized. To further decrease the power of the MEMS scanning mirror, a new method of impedance matching for PZT ceramic driven by a two-frequency mixed signal is established. As experimental results show, this MEMS scanning mirror reaches a two-axis scanning angle of 41.9° × 40.3° at a total driving voltage of 4.2 Vpp and total power of 16 mW. The effective diameter of reflection of the mirror is 2 mm and the operating frequencies of two-axis scanning are 947.51 Hz and 1464.66 Hz, respectively.
Institute of Scientific and Technical Information of China (English)
宋瞡毅
2015-01-01
Gypsum embedded filler flat plate floor,which uses precast gypsum embedded fillers as permanent formworks, is a monolithic cast-in-situ hollow concrete floor system.There are five kinds of structures.They are waffle slab,composite open-web floor,composite cross-beam and open-web floor,cross-beam floor,and nine-rectangle-grid floor.According to topology optimization of solid floor structure of two or three spans by ANSYS,72 false density distributions have been ob-tained.On the basis of the above results,a new structural model with composite hidden-prop-cap and cantilever-three-rib floor can be designed.Through the static analysis under vertical load by ANSYS,deflection and stress distribution of com-posite hidden-prop-cap and cantilever-three-rib floor are studied in detail.The results show that the stress of composite hid-den-prop-cap and cantilever-three-rib floor does not take on obvious characteristics of solid floor.So its strength of concrete and reinforcement does not been fully used and its reinforcement design will be complex.However,the composite hidden-prop-cap and cantilever-three-rib floor is suitable for those buildings which large span and whose floors under big loads be-cause of the less consumptions of concrete,good vertical rigidity and small peak tensile stress.%石膏空腔模无梁楼盖是以预制石膏空腔模为永久性施工内模的整体现浇空心楼盖，有密肋式、空腹板架式、井字－空腹板架组合式、井式、9区格式五种结构。用 ANSYS 对不同情况下的双跨、三跨楼盖做拓扑优化，得到72张单元伪密度云图并归纳伪密度分布规律，在此基础上设计一种新型结构———暗柱帽－悬挑三肋楼盖。用 AN-SYS 对暗柱帽－悬挑三肋楼盖做竖向荷载作用下的静力特性理论分析，详细研究其挠度和正应力分布。研究表明：暗柱帽－悬挑三肋楼盖的正应力分布不呈实体板特征，不利于发挥材料强度和配筋设计；
Institute of Scientific and Technical Information of China (English)
王淋淋; 尤学一
2012-01-01
The computational fluid dynamics was applied to simulate the flow field of a flat plate photobioreactor (PBR) with waved baffle panel. After the reliability of model was validated, the effects of two structural parameters of waved baffles, i.e. the ratio of waved baffles height to wave length (L/λX) and ratio of wave amplitude to wave length (A/λ) on the mass transfer and mixing performance were systematically analyzed. The results showed that when L/λ=12, better mass transfer and mixing performance were obtained and those related parameters such as the liquid volumetric mass transfer coefficient (kLa), ratio of cycle time of the downcomer to that of PBR (ff) and averaged turbulence kinetic energy (Em) were higher. Besides, the obtained liquid velocity was close to the optimum value being most favorable to microalgal growth. When L/λ12 and A/λ=0.8, the mass transfer performance was the best and the value of kLa was increased by about 10% compared with that of bioreactor with flat baffles. As L//b=l2 and A/λ0.4, the mixing performance of the reactor was the best and the value of Em was increased by 14.7% compared with that of bioreactor with flat baffles.%对带波纹隔板的平板式生物反应器,利用计算流体动力学进行流场模拟,验证模型可靠性后,系统分析波纹隔板高/波长(L/λ)和波幅/波长(A/λ)两个波纹隔板结构参数对反应器传质及流动混合特性的影响.结果表明,当L/λ=12时,传质及流动混合性能较好,液相体积传质系数(kLa)、平均湍动能(Em)、下降区停留时间占循环一周时间之比(θ)等表征传质及混合的参数值均较大,得到的液体流速在微藻生长的最佳流速附近.当A/λ=0.8时,反应器的传质性能最优,kLa比采用平直隔板时增加了约10％;当A/λ=0.4时,反应器的混合效果最佳,Em比采用平直隔板时增加14.7％.
Thermal advantage of tracking solar collectors under Danish weather conditions
DEFF Research Database (Denmark)
Andersen, Elsa; Dragsted, Janne; Furbo, Simon
2010-01-01
Theoretical investigations have been carried out with the aim to elucidate the thermal advantage of tracking solar collectors for different weather conditions in Kgs. Lyngby, Denmark (55.8°N), and for the weather conditions in Sisimiut, Greenland (66.9°N), just north of the arctic circle....... The investigations are based on calculations with a newly developed program. Measured weather data from a solar radiation measurement station at Technical University of Denmark in Kgs. Lyngby Denmark in the period 1990 to 2002 and the Danish Design Reference Year, DRY data file are used in the investigations....... The weather data used for Sisimiut are based on a Test Reference Year, TRY weather data file. The thermal advantages of different tracking strategies is investigated for two flat plate solar collectors with different efficiencies, operated at different temperature levels. The investigations show...
Thermal advantage of tracking solar collectors under Danish weather conditions
DEFF Research Database (Denmark)
Andersen, Elsa; Dragsted, Janne; Furbo, Simon
2010-01-01
. The investigations are based on calculations with a newly developed program. Measured weather data from a solar radiation measurement station at Technical University of Denmark in Kgs. Lyngby Denmark in the period 1990 to 2002 and the Danish Design Reference Year, DRY data file are used in the investigations....... The weather data used for Sisimiut are based on a Test Reference Year, TRY weather data file. The thermal advantages of different tracking strategies is investigated for two flat plate solar collectors with different efficiencies, operated at different temperature levels. The investigations show......Theoretical investigations have been carried out with the aim to elucidate the thermal advantage of tracking solar collectors for different weather conditions in Kgs. Lyngby, Denmark (55.8°N), and for the weather conditions in Sisimiut, Greenland (66.9°N), just north of the arctic circle...
Energy Technology Data Exchange (ETDEWEB)
Morales Castorena, Armando
2003-06-15
The results of parameter sensitivity studies performed on two axis equivalent circuits (TAECs) of synchronous machines are presented in this thesis. The circuits consist of inductive and resistive elements. Their connectivity represents the magnetic and electric coupling inside the machine as well as its energy losses. Two equivalent circuits are needed to represent the machine, one for the direct axis (d) and another for the quadrature axis (q), because it is modeled under the two-axis reaction theory of Park. Parameter values have been identified in advance, using standstill frequency response tests (SSFR). This response was calculated using a finite element model of a turbine generator. The parameter identification is achieved by applying an optimization process based on a hybrid algorithm (stochastic-deterministic). The fitness function is defined as the square of the differences between magnitudes and phase angles of the frequency response functions of the TAECs and of the turbogenerator. This procedure yields the TAECs that better fit the frequency response of the machine. Thus, the circuits identified are considered good models of the machine and they can be applied for digital simulation of dynamic behavior. The identified TAECs are the basis of the parameter sensitivity studies reported here. These studies consist of doing very small variations to parameter values, and to calculate the new value of the fitness function. The ratio between the change of the fitness function to the change in parameter value is called sensitivity of the fitness function, or simply, sensitivity function. Its magnitude indicates which parameter has a greater or lesser influence on the fitness function. If the fitness function is very sensitive to a particular parameter, then the rightness of the identified value of that parameter may be in doubt. With this information it is possible to establish the reliability of the identification process and to exert corrective actions. It is
Institute of Scientific and Technical Information of China (English)
邓月超; 赵耀华; 全贞花; 刘中良
2015-01-01
In this paper, a three-dimensional CFD numerical model of heat transfer and fluid flow was developed to simulate the thermal performance of the novel flat plate solar collector based on a micro heat pipe array to provide a theoretical basis for the structure improvement and optimization of the collector. The simulation of the novel collector with water flow included the CFD modeling of solar irradiation and the modes of mixed convection and radiation heat transfer between the absorber plate and glass cover, as well as the heat transfer in the circulating water inside the heat exchanger and conduction of the insulation. The fluid flow and heat transfer in the computational domain satisfied the continuity equation, the momentum equation, and the energy equation. The standardk-ε two-equation turbulence model was used in this paper. In order to predict the direct illumination energy source that results from incident solar radiation and the radiation field inside the collector, the discrete ordinate radiation model with a solar ray-tracing model was used. A commercial computational fluid dynamics program (Fluent 6.3 CFD software) was used to solve the coupled fluid flow, heat transfer, and the radiation equation. The solver used is the segregated solver. Body Force Weighted was selected as the discretization method for pressure, and the SIMPLE algorithm was used to resolve the coupling between pressure and velocity. The discretization methods for the solving of momentum, energy, radiation, and turbulence were second order upwind. The thermal performance could be achieved by simulation results under different conditions. Then, the experimental and numerical results were compared to validate the prediction of the CFD model. The results showed that the numerical results of the thermal efficiency of the novel collector were in reasonable agreement with the experimental data. The validated CFD model was used to analyze the properties of the insulation layer. First, the
Directory of Open Access Journals (Sweden)
Xiangyang Zhou
2015-08-01
Full Text Available This paper presents a method based on co-simulation of a mechatronic system to optimize the control parameters of a two-axis inertially stabilized platform system (ISP applied in an unmanned airship (UA, by which high control performance and reliability of the ISP system are achieved. First, a three-dimensional structural model of the ISP is built by using the three-dimensional parametric CAD software SOLIDWORKS®; then, to analyze the system’s kinematic and dynamic characteristics under operating conditions, dynamics modeling is conducted by using the multi-body dynamics software ADAMS™, thus the main dynamic parameters such as displacement, velocity, acceleration and reaction curve are obtained, respectively, through simulation analysis. Then, those dynamic parameters were input into the established MATLAB® SIMULINK® controller to simulate and test the performance of the control system. By these means, the ISP control parameters are optimized. To verify the methods, experiments were carried out by applying the optimized parameters to the control system of a two-axis ISP. The results show that the co-simulation by using virtual prototyping (VP is effective to obtain optimized ISP control parameters, eventually leading to high ISP control performance.
Zhou, Xiangyang; Zhao, Beilei; Gong, Guohao
2015-08-14
This paper presents a method based on co-simulation of a mechatronic system to optimize the control parameters of a two-axis inertially stabilized platform system (ISP) applied in an unmanned airship (UA), by which high control performance and reliability of the ISP system are achieved. First, a three-dimensional structural model of the ISP is built by using the three-dimensional parametric CAD software SOLIDWORKS(®); then, to analyze the system's kinematic and dynamic characteristics under operating conditions, dynamics modeling is conducted by using the multi-body dynamics software ADAMS™, thus the main dynamic parameters such as displacement, velocity, acceleration and reaction curve are obtained, respectively, through simulation analysis. Then, those dynamic parameters were input into the established MATLAB(®) SIMULINK(®) controller to simulate and test the performance of the control system. By these means, the ISP control parameters are optimized. To verify the methods, experiments were carried out by applying the optimized parameters to the control system of a two-axis ISP. The results show that the co-simulation by using virtual prototyping (VP) is effective to obtain optimized ISP control parameters, eventually leading to high ISP control performance.
Bainum, P. M.; Sellappan, R.
1977-01-01
The problem of optimal control with a minimum time criterion as applied to a single boom system for achieving two axis control is discussed. The special case where the initial conditions are such that the system can be driven to the equilibrium state with only a single switching maneuver in the bang-bang optimal sequence is analyzed. The system responses are presented. Application of the linear regulator problem for the optimal control of the telescoping system is extended to consider the effects of measurement and plant noises. The noise uncertainties are included with an application of the estimator - Kalman filter problem. Different schemes for measuring the components of the angular velocity are considered. Analytical results are obtained for special cases, and numerical results are presented for the general case.
New Low Cost Structure for Dual Axis Mount Solar Tracking System Using Adaptive Solar Sensor
DEFF Research Database (Denmark)
Argeseanu, Alin; Ritchie, Ewen; Leban, Krisztina Monika
2010-01-01
A solar tracking system is designed to optimize the operation of solar energy receivers. The objective of this paper is proposing a new tracking system structure with two axis. The success strategy of this new project focuses on the economical analysis of solar energy. Therefore it is important...... to determine the most cost effective design, to consider the costs of production and maintenance, and operating. The proposed tracking system uses a new solar sensor position with an adaptive feature....
Lei, Xusheng; Zou, Ying; Dong, Fei
2015-11-01
Due to the nonlinearity and time variation of a two-axis inertially stabilized platform (ISP) system, the conventional feedback control cannot be utilized directly. To realize the control performance with fast dynamic response and high stabilization precision, the dynamic model of the ISP system is expected to match the ideal model which satisfies the desired control performance. Therefore, a composite control method based on the adaptive radial basis function neural network (RBFNN) feedback control and the extended state observer (ESO), is proposed for ISP. The adaptive RBFNN is proposed to generate the feedback control parameters online. Based on the state error information in the working process, the adaptive RBFNN can be constructed and optimized directly. Therefore, no priori training data is needed for the construction of the RBFNN. Furthermore, a linear second-order ESO is constructed to compensate for the composite disturbance. The asymptotic stability of the proposed control method has been proven by the Lyapunov stability theory. The applicability of the proposed method is validated by a series of simulations and flight tests.
Gueymard, Christian A.
2008-08-01
The Solar Resource Enhancement Factor (SREF) method is proposed here to help solar system designers optimize their installations and decrease their risk. The method is based on solar radiation data from 239 sites in the United States to evaluate the variance in collected irradiation when using flat-plate and concentrating solar collectors (thermal or PV) mounted on fixed or tracking structures of various geometries. SREF can be predicted from readily available solar resource indicators and latitude for winter, summer or annual usage. An estimate of the year-to-year variability of the annual collected energy is also provided. The method should be accurate enough for use in most areas of the world.
Energy Technology Data Exchange (ETDEWEB)
Collares-Pereira, M.; Rabl, A.
1978-06-01
The Liu and Jordan method of calculating long term average energy collection of flat plate collectors is simplified (by about a factor of 4), and generalized to all collectors, concentration and nonconcentrating. The only meteorological input needed are the long term average daily total hemispherical insolation H/sub h/ on a horizontal surface and, for thermal collectors the average ambient temperature. The collector is characterized by optical efficiency, heat loss (or U-value), heat extraction efficiency, concentration ratio and tracking mode. An average operating temperature is assumed. Interaction with storage can be included by combining the present model with the f-chart method of Beckman, Klein and Duffie. Formulas and examples are presented for five collector types: flat plate, compound parabolic concentrator, concentrator with E.-W. tracking axis, concentrator with polar tracking axis, and concentrator with two axis tracking. The examples show that even for relatively low temperature applications and cloudy climates (50/sup 0/C in New York in February), concentrating collectors can outperform the flat plate. The method has been validated against hourly weather data (with measurements of hemispherical and beam insolation), and has been found to have an average accuracy better than 3% for the long term average radiation available to solar collectors. The suitability of this method for comparison studies is illustrated by comparing in a location independent manner the radiation availability for several collector types or operating conditions: two axis tracking versus one axis tracking; polar tracking axis versus east-west tracking axis; fixed versus tracking flat plate; effect of ground reflectance; and acceptance for diffuse radiation as function of concentration ratio.
Institute of Scientific and Technical Information of China (English)
魏生贤; 胡粉娥; 晏翠琼
2016-01-01
thermal performance of the flat-plate type solar energy water heater has been studied globally. In order to ensure the efficient operation of the solar water heater and user's demand to the terminal temperature of a tank, the countries all over the world with different climate have given different recommended value for water-mass-to-collector-area ratio (the ratio is abbreviated as MAR) of the flat-plate solar water heater. However, China has a vast territory and its climate is complex. The value range of recommended value from literatures is too large to be used to practical application. The main residential buildings in large and medium-sized cities are mostly high-rise buildings. The solar water heater installed on roof can only meet hot water use for the top six to eight floors. The application of the balcony wall-mounted solar water heater is one of the effective ways to solve hot water needs for the rest of users in high-rise buildings. Based on the typical meteorological data of nine cities in mild region of China, the values of MAR of the balcony wall-mounted flat-plate solar water heater have been calculated by using the established mathematical model. The water tank terminal temperature of 60℃, the collector angle of 60°-90° and the azimuth angle of 0-90° were used in model analysis. Calculation results for south-facing balcony wall-mounted solar water heater in mild region showed that the appropriate MAR of spring, summer, autumn, winter and the whole year was 28-51, 21-41, 31-53, 37-57 and 31-47 kg/m2, respectively. For convenience of practical application, the linear regression relation between seasonal and annual average MAR and the tilt angle for south-facing balcony wall-mounted solar water heater. The correlation coefficients between them were greater than 0.99. In this paper, we introduced a new concept “azimuth factor of MAR” which was easy to calculate MAR for the collector with different azimuth angle. For the non-south-facing balcony wall
Guarded Flat Plate Cryogenic Test Apparatus and Calorimeter
Fesmire, James E. (Inventor); Johnson, Wesley L. (Inventor)
2017-01-01
A test apparatus for thermal energy measurement of disk-shaped test specimens has a cold mass assembly locatable within a sealable chamber with a guard vessel having a guard chamber to receive a liquid fluid and a bottom surface to contact a cold side of a test specimen, and a test vessel having a test chamber to receive a liquid fluid and encompassed on one side by a center portion of the bottom surface shared with the guard vessel. A lateral wall assembly of the test vessel is closed by a vessel top, the lateral wall assembly comprising an outer wall and an inner wall having opposing surfaces that define a thermal break including a condensable vapor pocket to inhibit heat transfer through the lateral wall from the guard vessel to the test vessel. A warm boundary temperature surface is in thermal communication with a lower surface of the test specimen.
Numerical study of viscous starting flow past a flat plate
Xu, Ling
2014-01-01
Viscous flow past a finite plate which is impulsively started in direction normal to itself is studied numerically using a high order mixed finite difference and semi-Lagrangian scheme. The goal is to resolve details of the vorticity generation at early times, and to determine the effect of viscosity on flow quantities such as the core trajectory and vorticity, and the shed circulation. Vorticity contours, streaklines and streamlines are presented for a range of Reynolds numbers $Re \\in [250, 2000]$ and a range of times $t \\in[0. 0002, 5]$. At early times, most of the vorticity is attached to the plate. The paper proposes a definition for the shed circulation at early as well as late times, and shows that it indeed represents vorticity that separates from the plate without reattaching. The contribution of viscous diffusion to the circulation shedding rate is found to be significant, but, interestingly, to depend only slightly on the value of the Reynolds number. The shed circulation and the vortex core trajec...
COMPARATIVE FIELD EXPERIMENTAL INVESTIGATIONS OF DIFFERENT FLAT PLATE SOLAR COLLECTORS
Directory of Open Access Journals (Sweden)
Guangming Chen
2015-12-01
Full Text Available Full-scale traditional metal solar collectors and solar collector specimens fabricated from polymeric materials were investigated in the present study. A polymeric collector is 67.8% lighter than a traditional metal solar collector, and a metal solar collector with transparent plastic covering is 40.3% lighter than a traditional metal solar collector. Honeycomb multichannel plates made from polycarbonate were chosen to create a polymeric solar collector. A test rig for the natural circulation of the working fluid in a solar collector was built for a comparative experimental investigation of various solar collectors operating at ambient conditions. It was shown experimentally that the efficiency of a polymeric collector is 8–15% lower than the efficiency of a traditional collector.
Flat plate solar air heater with latent heat storage
Touati, B.; Kerroumi, N.; Virgone, J.
2017-02-01
Our work contains two parts, first is an experimental study of the solar air heater with a simple flow and forced convection, we can use thatlaste oneit in many engineering's sectors as solardrying, space heating in particular. The second part is a numerical study with ansys fluent 15 of the storage of part of this solar thermal energy produced,using latent heat by using phase change materials (PCM). In the experimental parts, we realize and tested our solar air heater in URER.MS ADRAR, locate in southwest Algeria. Where we measured the solarradiation, ambient temperature, air flow, thetemperature of the absorber, glasses and the outlet temperature of the solar air heater from the Sunrise to the sunset. In the second part, we added a PCM at outlet part of the solar air heater. This PCM store a part of the energy produced in the day to be used in peak period at evening by using the latent heat where the PCMs present a grateful storagesystem.A numerical study of the fusion or also named the charging of the PCM using ANSYS Fluent 15, this code use the method of enthalpies to solve the fusion and solidification formulations. Furthermore, to improve the conjugate heat transfer between the heat transfer fluid (Air heated in solar plate air heater) and the PCM, we simulate the effect of adding fins to our geometry. Also, four user define are write in C code to describe the thermophysicalpropriety of the PCM, and the inlet temperature of our geometry which is the temperature at the outflow of the solar heater.
Improvement of flat plate collectors for solar energy conversion
Boeck, H.; Hallermayer, R.; Schoelkopf, W.; Sizman, R.
1984-03-01
Selective absorption for thermal conversion of radiative energy was investigated. Improvement and operation of various measuring devices for absorption and emission are presented. Selective coatings were produced by vapor deposition and galvanic treatment. Calculations of the transmittance of turbular collector fields are presented. Operational Characteristics of Collector were examined. A collector test field with simultaneous recording of data from 24 collectors or uncovered absorbers was built and connected to a high performance microprocessor system. The transient behavior of collectors by variation of the irradiation and the collector inlet temperature were investigated. A mechanism for stratification of hot water of fluctuating inlet temperature in a storage tank was studied. The operating conditions of a heat pump installed in the collector test plant are investigated. A large domestic hot water system is equipped with temperature sensors and flowmeters for computer recording.
Step tracking program for concentrator solar collectors
Ciobanu, D.; Jaliu, C.
2016-08-01
The increasing living standards in developed countries lead to increased energy consumption. The fossil fuel consumption and greenhouse gas effect that accompany the energy production can be reduced by using renewable energy. For instance, the solar thermal systems can be used in temperate climates to provide heating during the transient period or cooling during the warmer months. Most used solar thermal systems contain flat plate solar collectors. In order to provide the necessary energy for the house cooling system, the cooling machine uses a working fluid with a high temperature, which can be supplied by dish concentrator collectors. These collectors are continuously rotated towards sun by biaxial tracking systems, process that increases the consumed power. An algorithm for a step tracking program to be used in the orientation of parabolic dish concentrator collectors is proposed in the paper to reduce the consumed power due to actuation. The algorithm is exemplified on a case study: a dish concentrator collector to be implemented in Brasov, Romania, a location with the turbidity factor TR equal to 3. The size of the system is imposed by the environment, the diameter of the dish reflector being of 3 meters. By applying the proposed algorithm, 60 sub-programs are obtained for the step orientation of the parabolic dish collector over the year. Based on the results of the numerical simulations for the step orientation, the efficiency of the direct solar radiation capture on the receptor is up to 99%, while the energy consumption is reduced by almost 80% compared to the continuous actuation of the concentrator solar collector.
Institute of Scientific and Technical Information of China (English)
丁刚; 左然; 张旭鹏; 王坤
2011-01-01
对传统平板式太阳能空气集热器的流道进行了改进,把对角型进出口流道改为多进出口式流道.对改进的集热器的性能进行了试验测试.新的进出口流道消除了吸热板和空气换热不均的现象,出口温度提升明显.在相同条件下,集热器的瞬时效率增加约20%.用CFD方法对集热器内部的流场结构和传热进行的数值模拟对比表明,传统集热器内部存在流动死区,中心截面温度分布不均匀,吸热板上有局部的高温区域,改进后的集热器流场和温度场分布得较均匀.%The flow channels of traditional flat-plate solar air collector were changed from diagonal inlet/outlet to multi-inlet/outlet. Experimental investigation on characteristics of solar air collectors after the improvement of flow channels was reported. The inlet and outlet channels of the conventional air collector were improved. The new flow channel eliminates the ununiformity of heat transfer between air and absorber plate, so there is a distinct temperature increasing at the outlet. The instantaneous efficiency is improved by about 20％ at the same condition. An analysis of flow characteristics and heat transfer in the collectors had been carried out by using Computation Fluid Dynamic (CFD). There is the dead zone in flow field of traditional collector. The temperature distribution of center section is different and there is local high-temperature region on the heat-absorbing plate in the traditional collector, while the flow field and temperature distribution are uniform in the improved collector.
Institute of Scientific and Technical Information of China (English)
朱海威; 高文峰; 林文贤; 刘滔; 李泽东
2014-01-01
In this paper,the domestic solar water heater with a vertical storage tank and a flat-plat collector,which is commercially available and popular in the market,was experimentally in-vestigated.Firstly, natural circulation experiment platform of flat plate domestic solar water heater was set up.The effect of two different positions of upper connecting pipe on temperature variation in the water tank during the heating stage in the daytime and thermal performances was measured.Through the analysis of test data,The difference of temperature stratification in the water tank with upper connecting pipe at high position and at low position were studied re-spectively.Also the instantaneous efficiency in 10 minutes was defined and compared.The results showed that there was better temperature stratification in the water tank when it’s upper con-necting pipe at high position during heating stage.In addition,the instantaneous efficiency of so-lar water heater,which water tank with upper connecting pipe at high location under the natural circulation condition was superior to the water tank with upper circulation pipe at low position.%对一种常见的平板型立式储热水箱家用太阳能热水器进行试验分析。搭建了自然循环平板型家用太阳能热水器的实验平台。测量了两种不同位置的上循环管对白天加热阶段储热水箱温度变化及对热性能的影响，通过测试数据分析对比了高、低位上循环管循环时，水箱内温度变化、分层状况，定义了十分钟内的平均效率，并进行了比较。结果表明：储热水箱升温阶段采用高位上循环管的水箱内部出现较好的水温分层；高位上循环管热水器的自然循环瞬时效率比低位上循环管热水器的瞬时效率高。
2016-01-01
A compound control scheme is proposed to achieve high control performance for a two-axis inertially stabilized platform (ISP) with multi-sensors applied to an unmanned helicopter (UH)-based airborne power line inspection (APLI) system. Compared with the traditional two closed-loop control scheme that is composed of a high-bandwidth rate loop and a lower bandwidth position loop, a new current loop inside rate loop is particularly designed to suppress the influences of voltage fluctuation from ...
Energy Technology Data Exchange (ETDEWEB)
Furaus, J P; Gruchalla, M E; Sower, G D
1980-01-01
Problems were surveyed and evaluated with respect to solar tracking mechanisms and rotary joints for coolant piping. An analytical development of celestial mechanics, one- and two-axis tracking configurations and the effect of tracking accuracy versus collector efficiency are reported. Daily operational requirements and tracking modes were defined and evaluated. A literature and patent search on solar tracking technology was performed. Tracking system and control system performance specifications were determined. Alternative conceptual tracking approaches were defined and a cost and performance evaluation of a mechanical tracking concept was performed. Fluid coupling service specifications were determined. The cost and performance of several types of actuators and error detectors were evaluated with respect to solar tracking mechanisms.
基于双轴磁强计及GPS的滚转角测量方法%Method to measure roll angle by two-axis magnetometer and GPS
Institute of Scientific and Technical Information of China (English)
李冰; 霍鹏飞; 祁克玉
2012-01-01
In order to measure the roll angle of high-speed rolling projectile in a high-dynamic ballistic trajectory, a method based on GPS and two-axis magnetometer is proposed. With the speed information measurement of GPS and two-axis magnetometer, the roll angel of the projectile in flight is solved in real time with the good vector properties of geomagnetic field. Simulation results show that the method of roll angle measurement has a high accuracy.and can be applied to the roll angel measurement of high-speed rolling projectiles in a high-dynamic ballistic trajectory.%针对高速旋转弹丸在高动态弹道环境下的滚转角测量难度大,精度低等问题,提出了基于双轴磁强计及GPS的滚转角测量方法.该方法利用地磁场良好的矢量特性,利用双轴磁强计和GPS速度信息的量测,实时解算弹丸飞行过程中的滚转角.仿真结果表明,该滚转角测量方法精度较高,能应用于弹丸在高动态、高过载弹道环境下的滚转角测量.
Optimization Controller for Mechatronic Sun Tracking System to Improve Performance
Directory of Open Access Journals (Sweden)
Mustafa Engin
2013-01-01
Full Text Available An embedded system that contains hardware and software was developed for two-axis solar tracking system to improve photovoltaic panel utilization. The hardware section of the embedded system consists of a 32-bit ARM core microcontroller, motor driver circuits, a motion control unit, pyranometer, GPS receiver, and an anemometer. The real-time control algorithm enables the solar tracker to operate automatically without external control as a stand-alone system, combining the advantages of the open-loop and the closed-loop control methods. The pyranometer is employed to continuously send radiation data to the controller if the measured radiation is above the lower radiation limit the photovoltaic panel can generate power, guaranteeing the solar tracking process to be highly efficient. The anemometer is utilized in the system to ensure that the solar tracking procedure halts under high wind speed conditions to protect the entire system. Latitude, longitude, altitude, date, and real-time clock data are provided by GPS receiver. The algorithm calculates solar time using astronomical equations with GPS data and converts it to pulse-width modulated motor control signal. The overall objective of this study is to develop a control algorithm that improves performance and reliability of the two-axis solar tracker, focusing on optimization of the controller board, drive hardware, and software.
Miniature Two-Axis Joystick Controller
Hollow, R.
1983-01-01
Novel movable-button-actuated self-centering controller uses optoelectronics to produce X and Y signals for aircraft control. In addition to be extremely compact, device puts our voltages having high signal-to-noise ratio, especially at critical center position where in many controllers this ratio is poorest. Combination of new saddle-shaped button and positive centering gives "feel" and "breakout" met with pilot approval.
Two-axis magnetic field sensor
Jander, Albrecht (Inventor); Nordman, Catherine A. (Inventor); Qian, Zhenghong (Inventor); Smith, Carl H. (Inventor)
2006-01-01
A ferromagnetic thin-film based magnetic field sensor with first and second sensitive direction sensing structures each having a nonmagnetic intermediate layer with two major surfaces on opposite sides thereof having a magnetization reference layer on one and an anisotropic ferromagnetic material sensing layer on the other having a length in a selected length direction and a smaller width perpendicular thereto and parallel to the relatively fixed magnetization direction. The relatively fixed magnetization direction of said magnetization reference layer in each is oriented in substantially parallel to the substrate but substantially perpendicular to that of the other. An annealing process is used to form the desired magnetization directions.
DEFF Research Database (Denmark)
Bruun, Maja Hojer; Krause-Jensen, Jakob; Saltofte, Margit
2015-01-01
Anthropology attempts to gain insight into people's experiential life-worlds through long-term fieldwork. The quality of anthropological knowledge production, however, does not depend solely on the duration of the stay in the field, but also on a particular way of seeing social situations. The an...... the students followed the work of a group of porters. Drawing on anthropological concepts and research strategies the students gained crucial insights about the potential effects of using tracking technologies in the hospital....
Energy Technology Data Exchange (ETDEWEB)
Stastny, P.
2007-03-15
Many employees are now choosing to work from home using laptops and telephones. Employers in the oil and gas industry are now reaping a number of benefits from their telecommuting employees, including increased productivity; higher levels of employee satisfaction, and less absenteeism. Providing a telecommunication option can prove to be advantageous for employers wishing to hire or retain employees. Telecommuting may also help to reduce greenhouse gas (GHG) emissions. This article provided details of Teletrips Inc., a company that aids in the production of corporate social responsibility reports. Teletrips provides reports that document employee savings in time, vehicle depreciation maintenance, and gasoline costs. Teletrips currently tracks 12 companies in Calgary, and plans to grow through the development of key technology partnerships. The company is also working with the federal government to provide their clients with emission trading credits, and has forged a memorandum of understanding with the British Columbia government for tracking emissions. Calgary now openly supports telecommuting and is encouraging businesses in the city to adopt telecommuting on a larger scale. It was concluded that the expanding needs for road infrastructure and the energy used by cars to move workers in and out of the city are a massive burden to the city's tax base. 1 fig.
P. Sharp
The CMS Inner Tracking Detector continues to make good progress. The Objective for 2006 was to complete all of the CMS Tracker sub-detectors and to start the integration of the sub-detectors into the Tracker Support Tube (TST). The Objective for 2007 is to deliver to CMS a completed, installed, commissioned and calibrated Tracking System (Silicon Strip and Pixels) aligned to < 100µ in April 2008 ready for the first physics collisions at LHC. In November 2006 all of the sub-detectors had been delivered to the Tracker Integration facility (TIF) at CERN and the tests and QA procedures to be carried out on each sub-detector before integration had been established. In December 2006, TIB/TID+ was integrated into TOB+, TIB/TID- was being prepared for integration, and TEC+ was undergoing tests at the final tracker operating temperature (-100 C) in the Lyon cold room. In February 2007, TIB/TID- has been integrated into TOB-, and the installation of the pixel support tube and the services for TI...
Directory of Open Access Journals (Sweden)
Xiangyang Zhou
2016-03-01
Full Text Available A compound control scheme is proposed to achieve high control performance for a two-axis inertially stabilized platform (ISP with multi-sensors applied to an unmanned helicopter (UH-based airborne power line inspection (APLI system. Compared with the traditional two closed-loop control scheme that is composed of a high-bandwidth rate loop and a lower bandwidth position loop, a new current loop inside rate loop is particularly designed to suppress the influences of voltage fluctuation from power supply and motor back electromotive force (BEMF on control precision. In this way, the stabilization accuracy of the ISP is greatly improved. The rate loop, which is the middle one, is used to improve sensor’s stability precision through compensating for various disturbances. To ensure the pointing accuracy of the line of sight (LOS of multi-sensors, the position loop is designed to be the outer one and acts as the main feedback path, by which the accurate pointing angular position is achieved. To validate the scheme, a series of experiments were carried out. The results show that the proposed compound control scheme can achieve reliable control precision and satisfy the requirements of real APLI tasks.
Design of a solar tracking interactive kiosk
Greene, Nathaniel R.; Brunskill, Jeffrey C.
2017-01-01
A two-axis solar tracker and its interactive kiosk were designed by an interdisciplinary team of students and faculty. The objective was to develop a publicly accessible kiosk that would facilitate the study of energy usage and production on campus. Tracking is accomplished by an open-loop algorithm, microcontroller, and ham radio rotator. Solar panel output is monitored in real time and displayed to the public with lights and digits that can be read by the casual passersby. While maximum power point tracking is the most accurate means of quantifying the output power of a photovoltaic panel, simplicity and design constraints dictated the use of short-circuit current as a proxy for power. A touchscreen display allows kiosk visitors to compare two solar panels, an automatic tracker that faces the sun, and an identical panel whose elevation and azimuth can be controlled with a virtual joystick. This project was a capstone experience for students in physics/engineering, computer science, and instructional technology. We discuss technical challenges and design choices, as well as the educational goals of the kiosk.
P. Sharp
The CMS Inner Tracking Detector continues to make good progress. The successful commissioning of ~ 25% of the Silicon Strip Tracker was completed in the Tracker Integration Facility (TIF) at CERN in July 2007 and the Tracker has since been prepared for moving and installation into CMS at P5. The Tracker was ready to move on schedule in September 2007. The Installation of the Tracker cooling pipes and LV cables between Patch Panel 1 (PP1) on the inside the CMS magnet cryostat, and the cooling plants and power system racks on the balconies has been completed. The optical fibres from PP1 to the readout FEDs in the USC have been installed, together with the Tracker cable channels, in parallel with the installation of the EB/HB services. All of the Tracker Safety, Power, DCS and the VME Readout Systems have been installed at P5 and are being tested and commissioned with CMS. It is planned to install the Tracker into CMS before Christmas. The Tracker will then be connected to the pre-installed services on Y...
P. Sharp
The CMS Inner Tracking Detector continues to make good progress. The successful commissioning of ~ 25% of the Silicon Strip Tracker was completed in the Tracker Integration Facility (TIF) at CERN on 18 July 2007 and the Tracker has since been prepared for moving and installation into CMS at P5. The Tracker will be ready to move on schedule in September 2007. The Installation of the Tracker cooling pipes and LV cables between Patch Panel 1 (PP1) on the inside the CMS magnet cryostat, and the cooling plants and power system racks on the balconies has been completed. The optical fibres from PP1 to the readout FEDs in the USC will be installed in parallel with the installation of the EB/HB services, and will be completed in October. It is planned to install the Tracker into CMS at the end of October, after the completion of the installation of the EB/HB services. The Tracker will then be connected to the pre-installed services on YB0 and commissioned with CMS in December. The FPix and BPix continue to make ...
Patient Treatment Tracking Chart
... ZIP code here Hepatitis C Treatment Tracking Chart Patient Treatment Tracking Chart Patient Treatment Tracking Chart Sample Chart This chart is ... this website Submit Share this page Related Resource Patient Treatment Tutorial return to top CONNECT Veterans Crisis ...
Characterization of the New GBT Azimuth Track and Pointing Model
Hunter, T. R.; Constantikes, K. T.; Ghigo, F.; Brandt, J.; Grider, R.
2008-01-01
Following the completion of the mechanical aspect of the azimuth track refurbishment project (described in the October 2007 Newsletter), it was necessary to character- ize the performance of the new track and implement a new pointing model prior to the resumption of scheduled operations. The Precision Telescope Control System (PTCS) team was responsible for this effort, which required significant planning and development beginning a year ago in January 2007. Although there was high confidence that the refurbishment would yield a flatter and more resilient track, the possibility of remaining low-level features spurred the team to develop a robust technique for measuring track features prior to the April 30 shutdown. To characterize the track, the centerpiece instrument is a pair of two-axis gas-damped capacitive-readout inclinometers mounted on the ends of the elevation axle. With the new track, both the large scale (tens of degrees) and small scale structure has been greatly reduced, with an rms of 0.94 arcseconds (equivalent to 5.7 thousandths of an inch at the track radius). A repeated measurement of the new track over the timescale of a week has shown the remaining features to be stable, but it will be monitored occasionally during the coming year. The nighttime blind pointing performance now shows a standard deviation of 3.4" in cross-elevation, 3.7" in elevation, and 2.0 mm in focus. These rms values are improved by about 1" in elevation and 1 mm in focus over the previous model when compared under the same conditions in fall 2006 and spring 2007.
Energy Technology Data Exchange (ETDEWEB)
Okandan, Murat; Nielson, Gregory N.
2016-07-12
Solar tracking systems, as well as methods of using such solar tracking systems, are disclosed. More particularly, embodiments of the solar tracking systems include lateral supports horizontally positioned between uprights to support photovoltaic modules. The lateral supports may be raised and lowered along the uprights or translated to cause the photovoltaic modules to track the moving sun.
A comparison between the solar energy collection by fix and tracking collectors
Energy Technology Data Exchange (ETDEWEB)
Garrison, John D [San Diego State University, San Diego (United States)
2000-07-01
A realistic mathematical simulation of solar thermal energy collection for an air flat plate collector, six designs of fixed evacuated collectors and two designs of tracking evacuated collectors at port Hardy, British Columbia and Edmonton, Alberta, in Canada and Daggett, California in the United States has been calculated. Differences in solar energy collection by the different collector designs arise only from differences in collector geometry, since the same collector orientations, selective absorber and solar radiation data are used in the simulations for all collector designs. It is found that solar energy collection in Canada by an air flat plate collector is significantly lower than that of the fixed evacuated and the tracking evacuated collectors at the lowest operating temperatures. This occurs because of the high thermal losses for the air flat plate collector, and the low solar insolation and low winter ambient temperatures in Canada. Highly concentrating tracking collectors which collect no diffuse radiation do not collect as much solar energy at lower temperatures as all of the fixed evacuated collectors at Port Hardy in Canada where there are a limited number of clear days. The fixed, vacuum tubular (dewar type) collector collects the most solar energy at low temperatures. At higher temperatures it collects the least amount of energy of all of the evacuated collectors. This is because of its low concentration and thus larger radiation losses. The vacuum vertical fin and higher concentration shaped glass evacuated collectors at high temperatures. Solar energy collection at Daggett is much higher than that at the two Canadian stations because of the high solar insolation and moderate to warm ambient temperatures. By rotating of the more highly concentrating CPC evacuated collectors about their axes placed parallel to the polar axis so as to track the sun, significantly higher energy collection is obtained, particularly for sites with higher annual
Renewable Energy Tracking Systems
Renewable energy generation ownership can be accounted through tracking systems. Tracking systems are highly automated, contain specific information about each MWh, and are accessible over the internet to market participants.
Indian Academy of Sciences (India)
Klaus Mönig
2007-11-01
Forward tracking is an essential part of a detector at the international linear collider (ILC). The requirements for forward tracking are explained and the proposed solutions in the detector concepts are shown.
Roe, Shaun; The ATLAS collaboration
2017-01-01
Run-2 of the Large Hadron Collider (LHC) has provided new challenges to track and vertex reconstruction with higher centre-of-mass energies and luminosity leading to increasingly high-multiplicity envi-ronments. This talk provides an overview of the tracking performance, highlighting tracking improvements due to the Insertable B-Layer (IBL) and the introduction of time-dependent alignment.
Energy Technology Data Exchange (ETDEWEB)
Allmendinger, T.; Bhuyan, B.; Brown, D. N.; Choi, H.; Christ, S.; Covarelli, R.; Davier, M.; Denig, A. G.; Fritsch, M.; Hafner, A.; Kowalewski, R.; Long, O.; Lutz, A. M.; Martinelli, M.; Muller, D. R.; Nugent, I. M.; Lopes Pegna, D.; Purohit, M. V.; Prencipe, E.; Roney, J. M.; Simi, G.; Solodov, E. P.; Telnov, A. V.; Varnes, E.; Waldi, R.; Wang, W. F.; White, R. M.
2012-12-10
We describe several studies to measure the charged track reconstruction efficiency and asymmetry of the BaBar detector. The first two studies measure the tracking efficiency of a charged particle using τ and initial state radiation decays. The third uses the τ decays to study the asymmetry in tracking, the fourth measures the tracking efficiency for low momentum tracks, and the last measures the reconstruction efficiency of K$0\\atop{S}$ particles. The first section also examines the stability of the measurements vs. BaBar running periods.
Hypersonic Laminar Boundary Layer Velocimetry with Discrete Roughness on a Flat Plate
Bathel, Brett; Danehy, Paul M.; Inman, Jennifer A.; Watkins, A. Neal; Jones, Stephen B.; Lipford, William E.; Goodman, Kyle Z.; Ivey, Christopher B.; Goyne, Christopher P.
2010-01-01
Laminar boundary layer velocity measurements are made on a 10-degree half-angle wedge in a Mach 10 flow. Two types of discrete boundary layer trips were used to perturb the boundary layer gas. The first was a 2-mm tall, 4-mm diameter cylindrical trip. The second was a scaled version of the Orbiter Boundary Layer Transition (BLT) Detailed Test Objective (DTO) trip. Both 1-mm and 2.5-mm tall BLT DTO trips were tested. Additionally, side-view and plan-view axial boundary layer velocity measurements were made in the absence of these tripping devices. The free-stream unit Reynolds numbers tested for the cylindrical trips were 1.7x10(exp 6)/m and 3.3x10(exp 6)/m. The free-stream unit Reynolds number tested for the BLT DTO trips was 1.7x10(exp 6)/m. The angle of attack was kept at approximately 5-degrees for most of the tests resulting in a Mach number of approximately 8.3. These combinations of unit Reynolds numbers and angle of attack resulted in laminar flowfields. To study the precision of the measurement technique, the angle of attack was varied during one run. Nitric-oxide (NO) molecular tagging velocimetry (MTV) was used to obtain averaged axial velocity values and associated uncertainties. These uncertainties are as low as 20 m/s. An interline, progressive scan CCD camera was used to obtain separate images of the initial reference and shifted NO molecules that had been tagged by the laser. The CCD configuration allowed for sub-microsecond sequential acquisition of both images. The maximum planar spatial resolution achieved for the side-view velocity measurements was 0.07-mm in the wall-normal direction by 1.45-mm in the streamwise direction with a spatial depth of 0.5-mm. For the plan-view measurements, the maximum planar spatial resolution in the spanwise and streamwise directions was 0.69-mm by 1.28-mm, respectively, with a spatial depth of 0.5-mm. Temperature sensitive paint (TSP) measurements are provided to compliment the velocity data and to provide further insight into the behavior of the boundary layers. The experiments were performed at the NASA Langley Research Center 31-Inch Mach 10 Air tunnel.
Numerical-perturbation technique for stability of flat-plate boundary layers with suction
Reed, H. L.; Nayfeh, A. H.
1986-01-01
A numerical-perturbation scheme is proposed for determining the stability of flows over plates with suction through a finite number of porous suction strips. The basic flow is calculated as the sum of the Blasius flow and closed-form linearized triple-deck solutions of the flow due to the strips. A perturbation technique is used to determine the increment a(ij) in the complex wavenumber at a given location x(j) due to the presence of a strip centered at x(i). The end result is a set of influence coefficients that can be used to determine the growth rates and amplification factors for any suction levels without repeating the calculations. The numerical-perturbation results are verified by comparison with interacting boundary layers for the case of six strips and the experimental data of Reynolds and Saric for single- and multiple-strip configurations. The influence coefficient form of the solution suggests a scheme for optimizing the strip configuration. The results show that one should concentrate the suction near branch I of the neutral stability curve, a conclusion verified by the experiments.
Energy Technology Data Exchange (ETDEWEB)
Smith, J.L.; Gates, W.R.; Lee, T.
1978-04-01
The results of a literature search on the diffusion of new industrial production processes and the determinants of success of previous federally-funded demonstration projects are presented. The industrialization goal of the LSSA project is analyzed. The conclusions of that analysis are used to develop recommendations with respect to pilot, demonstration, and commercial scale production plants, as well as the disposition of the LSSA annual output goal. (MHR)
Validation of Multiple Tools for Flat Plate Photovoltaic Modeling Against Measured Data
Energy Technology Data Exchange (ETDEWEB)
Freeman, J.; Whitmore, J.; Blair, N.; Dobos, A. P.
2014-08-01
This report expands upon a previous work by the same authors, published in the 40th IEEE Photovoltaic Specialists conference. In this validation study, comprehensive analysis is performed on nine photovoltaic systems for which NREL could obtain detailed performance data and specifications, including three utility-scale systems and six commercial scale systems. Multiple photovoltaic performance modeling tools were used to model these nine systems, and the error of each tool was analyzed compared to quality-controlled measured performance data. This study shows that, excluding identified outliers, all tools achieve annual errors within +/-8% and hourly root mean squared errors less than 7% for all systems. It is further shown using SAM that module model and irradiance input choices can change the annual error with respect to measured data by as much as 6.6% for these nine systems, although all combinations examined still fall within an annual error range of +/-8.5%. Additionally, a seasonal variation in monthly error is shown for all tools. Finally, the effects of irradiance data uncertainty and the use of default loss assumptions on annual error are explored, and two approaches to reduce the error inherent in photovoltaic modeling are proposed.
Convective Heat Transfer Enhancement of a Rectangular Flat Plate by an Impinging Jet in Cross Flow
Institute of Scientific and Technical Information of China (English)
李国能; 郑友取; 胡桂林; 张治国
2014-01-01
Experiments were carried out to study the heat transfer performance of an impinging jet in a cross flow. Several parameters including the jet-to-cross-flow mass ratio (X=2%-8%), the Reynolds number (Red=1434-5735) and the jet diameter (d=2-4 mm) were explored. The heat transfer enhancement factor was found to increase with the jet-to-cross-flow mass ratio and the Reynolds number, but decrease with the jet diameter when other parameters maintain fixed. The presence of a cross flow was observed to degrade the heat transfer performance in respect to the effect of impinging jet to the target surface only. In addition, an impinging jet was confirmed to be capable of en-hancing the heat transfer process in considerable amplitude even though the jet was not designed to impinge on the target surface.
Institute of Scientific and Technical Information of China (English)
Antar M.M.Abdala; Qun Zheng; Fifi N.M.Elwekeel; Ping Dong
2013-01-01
In the present work,computational simulations was made using ANSYS CFX to predict the improvements in film cooling performance with dual trench.Dual-trench configuration consists of two trenches together,one wider trench and the other is narrow trench that extruded from the wider one.Several blowing ratios in the range (0.5∶5) were investigated.The pitch-to-diameter ratio of 2.775 is used.By using the dual trench configuration,the coolant jet impacted the trench wall two times allowing increasing the spreading of coolant laterally in the trench,reducing jet velocity and jet completely covered on the surface.The results indicate that this configuration increased adiabatic effectiveness as blowing ratio increased.The spatially averaged adiabatic effectiveness reached 57.6％ for at M=2.No observed film blow-offat all blowing ratios.The adiabatic film effectiveness of dual trench case outperformed the narrow trench case,laidback fan-shaped hole,fan-shaped hole and cylinder hole at different blowing ratios.
Computational Fluid Dynamics Uncertainty Analysis Applied to Heat Transfer over a Flat Plate
Groves, Curtis Edward; Ilie, Marcel; Schallhorn, Paul A.
2013-01-01
There have been few discussions on using Computational Fluid Dynamics (CFD) without experimental validation. Pairing experimental data, uncertainty analysis, and analytical predictions provides a comprehensive approach to verification and is the current state of the art. With pressed budgets, collecting experimental data is rare or non-existent. This paper investigates and proposes a method to perform CFD uncertainty analysis only from computational data. The method uses current CFD uncertainty techniques coupled with the Student-T distribution to predict the heat transfer coefficient over a at plate. The inputs to the CFD model are varied from a specified tolerance or bias error and the difference in the results are used to estimate the uncertainty. The variation in each input is ranked from least to greatest to determine the order of importance. The results are compared to heat transfer correlations and conclusions drawn about the feasibility of using CFD without experimental data. The results provide a tactic to analytically estimate the uncertainty in a CFD model when experimental data is unavailable
Scale-Up of flat plate photobioreactors considering diffuse and direct light characteristics.
Quinn, Jason C; Turner, Chris W; Bradley, Thomas H
2012-02-01
This study investigates the scaling of photobioreactor productivity based on the growth of Nannochloropsis salina incorporating the effects of direct and diffuse light. The scaling and optimization of photobioreactor geometry was analyzed by determining the growth response of a small-scale system designed to represent a core sample of a large-scale photobioreactor. The small-scale test apparatus was operated at a variety of light intensities on a batch time scale to generate a photosynthetic irradiance (PI) growth dataset, ultimately used to inform a PI growth model. The validation of the scalability of the PI growth model to predict productivity in large-scale systems was done by comparison with experimental growth data collected from two geometrically different large-scale photobioreactors operated at a variety of light intensities. For direct comparison, the small-scale and large-scale experimental systems presented were operated similarly and in such a way to incorporate cultivation relevant time scales, light intensities, mixing, and nutrient loads. Validation of the scalability of the PI growth model enables the critical evaluation of different photobioreactor geometries and design optimization incorporating growth effects from diffuse and direct light. Discussion focuses on the application of the PI growth model to assess the effect of diffuse light growth compared to direct light growth for the evaluation of photobioreactors followed by the use of the model for photobioreactor geometry optimization on the metric of areal productivity.
Heat Transfer to Vertical Flat Plates in a Rectangular Gas-Fluidized Bed.
1984-06-01
it. These taps were connected by flexible plastic tubing to a manifold 6 29 61 which permitted selective connection of the taps to a Meriam Model...Spencer Turbine 550 SCFM Turbo Compressor Rotometer Fisher & Porter 34 SCFM 30-Inch Meriam 33KA35 A69513 Water Manometer Computer Hewlett-Packard HP 85
Some tests of flat plate photovoltaic module cell temperatures in simulated field conditions
Griffith, J. S.; Rathod, M. S.; Paslaski, J.
1981-01-01
The nominal operating cell temperature (NOCT) of solar photovoltaic (PV) modules is an important characteristic. Typically, the power output of a PV module decreases 0.5% per deg C rise in cell temperature. Several tests were run with artificial sun and wind to study the parametric dependencies of cell temperature on wind speed and direction and ambient temperature. It was found that the cell temperature is extremely sensitive to wind speed, moderately so to wind direction and rather insensitive to ambient temperature. Several suggestions are made to obtain data more typical of field conditions.
Design of a photovoltaic central power station: flat-plate array
Energy Technology Data Exchange (ETDEWEB)
1984-02-01
A design for a photovoltaic central power station using fixed flat-panel arrays has been developed. The 100 MW plant is assumed to be located adjacent to the Saguaro Power Station of Arizona Public Service. The design assumes high-efficiency photovoltaic modules using dendritic web cells. The modules are arranged in 5 MW subfields, each with its own power conditioning unit. The photovoltaic output is connected to the existing 115 kV utility switchyard. The site specific design allows detailed cost estimates for engineering, site preparation, and installation. Collector and power conditioning costs have been treated parametrically.
On the Estimation of Spanwise Pressure Coherence of a Turbulent Boundary Layer over a Flat Plate
Van der Velden, W.C.P.; Van Zuijlen, A.H.; De Jong, A.T.; Bijl, H.
2014-01-01
A Large Eddy Simulation (LES) with four different closure models are analyzed in OpenFOAM, an open source Computional Fluid Dynamics (CFD) package and validated for the determination of the streamwise and spanwise coherence length of the pressure field below a turbulent boundary layer at low
Thin flat plate with linear spring as mechanical stop. Final report
Energy Technology Data Exchange (ETDEWEB)
Johnson, B.H.
1997-06-01
A mechanical device has been developed which dissipates mechanical energy simply and reliably, without generating debris. The device basically consists of a stack of thin flat metal layers, forming a flexible plate, and a mechanical spring to buffer the impact of the moving object. Equations have been developed which allow the design of such devices for particular applications.
Overview - Flat-plate technology. [review of Low Cost Solar Array Project
Callaghan, W. T.
1981-01-01
Progress and continuing plans for the joint NASA/DoE program at the JPL to develop the technologies and industrial processes necessary for mass production of low-cost solar arrays (LSA) which produce electricity from solar cells at a cost of less than $0.70/W are reviewed. Attention is given to plans for a demonstration Si refinement plant capable of yielding 1000 MT/yr, and to a CVD process with chlorosilane, which will yield material at a cost of $21/kg. Ingot and shaped-sheet technologies, using either Czochralski growth and film fed growth methods have yielded AM1 15% efficient cells in an automated process. Encapsulation procedures have been lowered to $14/sq m, and robotics have permitted assembled cell production at a rate of 10 sec/cell. Standards are being defined for module safety features. It is noted that construction of a pilot Si purification plant is essential to achieving the 1986 $0.70/W cost goals.
Climate specific thermomechanical fatigue of flat plate photovoltaic module solder joints
Energy Technology Data Exchange (ETDEWEB)
Bosco, Nick; Silverman, Timothy J.; Kurtz, Sarah
2016-07-01
FEM simulations of PbSn solder fatigue damage are used to evaluate seven cities that represent a variety of climatic zones. It is shown that the rate of solder fatigue damage is not ranked with the cities' climate designations. For an accurate ranking, the mean maximum daily temperature, daily temperature change and a characteristic of clouding events are all required. A physics-based empirical equation is presented that accurately calculates solder fatigue damage according to these three factors. An FEM comparison of solder damage accumulated through service and thermal cycling demonstrates the number of cycles required for an equivalent exposure. For an equivalent 25-year exposure, the number of thermal cycles (-40 degrees C to 85 degrees C) required ranged from roughly 100 to 630 for the cities examined. It is demonstrated that increasing the maximum cycle temperature may significantly reduce the number of thermal cycles required for an equivalent exposure.
Directory of Open Access Journals (Sweden)
Baritto-Loreto Miguel Leonardo
2013-04-01
Full Text Available En el presente trabajo, el modelo adimensional desarrollado y validado por Baritto y Bracamonte (2012 para describir el comportamiento térmico de colectores solares de placas planas sin cubierta transparente, se complementa con la ecuación adimensional de balance de entropía para un elemento diferencial de colector solar. El modelo se resuelve para un amplio rango de valores de relaciones de aspecto y número de flujo de masa. A partir de los resultados del modelo se desarrolla un análisis detallado de la influencia de estos parámetros sobre la distribución de irreversibilidades internas a lo largo del colector. Adicionalmente se estudia la influencia de estos parámetros sobre los números de generación de entropía por fricción viscosa, por transferencia de calor y total. Se encuentra que existen combinaciones de los parámetros antes mencionados, para los cuales, la operación del colector es termodinámicamente óptima para números de flujo de masa elevados.
Parametric Study of the Device Angle Dependency of a Single Vortex Generator on a Flat Plate
DEFF Research Database (Denmark)
Fernandez, U.; Réthoré, Pierre-Elouan; Sørensen, Niels N.
. The computational fluid dynamic (CFD) simulations have been com-pared with a wind tunnel experiment, where the corresponding parametric study was per-formed over a single vane mounted on the test section wall in low-speed wind tunnel. In this experiment the flow was recorded using Stereoscopic Particle Image...
Development of flat-plate solar thermal collectors equipped with aerogel sandwiched absorber
Energy Technology Data Exchange (ETDEWEB)
Goto, Yusuke; Izumi, Hiroaki; Aizawa, Mamoru [Dynax Corp. (Japan); Yugami, Hiroo [Graduate School of Engineering, Tohoku Univ. (Japan)
2004-07-01
It is important to utilize the solar energy efficiently. However, conventional solar thermal collectors have some drawbacks of high cost, heavy weight and low temperature output. These drawbacks prevent from spreading of the market of solar thermal collectors, especially in Japan. To find a solution to the problems, we propose an absorber / aerogel one-piece structure for high temperature solar thermal collectors. TiOxNy and silica aerogel were employed as a selectively solar-absorbing coating of absorber and as an optically transparent thermal insulator, respectively. Selectively solar-absorbing coatings must show lower reflectance and lower emittance. We have developed selectively solar-absorbing coatings of which optical property was {alpha} = 98.5, {epsilon} = 3 %. Wet coating of newly designed TiOxNy precursor enabled fabricating selectively solar-absorbing coatings, easily. Shrinkage of silica aerogel had to be minimized to produce an absorber / aerogel one-piece structure. Selectively solar-absorbing coatings and silica aerogel were prepared via sol-gel processing. (orig.)
Study of bioadhesion on a flat plate with a yeast/glass model system.
Mercier-Bonin, M; Ouazzani, K; Schmitz, P; Lorthois, S
2004-03-15
The attachment of microorganisms to a surface is a critical first step of biofilm fouling in membrane processes. The shear-induced detachment of baker's yeast in adhesive contact with a plane glass surface was thus experimentally studied, using a specially designed shear stress flow chamber. The yeast was marketed either as rod-shaped pellets (type I yeast) or as spherical pellets (type II yeast). A complete series of experiments for measuring the shear stress necessary to detach a given proportion of individual yeast cells of type I or II was performed under different environmental conditions (ionic strength, contact time). In parallel, the surface physicochemical properties of the cells (surface charge, hydrophobicity, and electron donor and electron acceptor components) were determined. For the first type of yeast cells, which were rather hydrophilic, adhesion to the glass plate was weak. This was due to both electrostatic effects and hydrophilic repulsion. Furthermore, adhesion was not sensitive to any variation of the ionic strength. For yeast of the second type, adhesion was drastically increased. This could be explained by their physicochemical surface properties and especially their hydrophobic and electron acceptor components, which caused strong attractive van der Waals and Lewis acid-base interactions, counterbalancing the electrostatic repulsion. For increasing ionic strengths, adhesion was greater, due to lower electrostatic repulsion. The results were quantified through the definition of a critical wall shear stress ( tau w 50% ) required to detach 50% of the yeast cells initially deposited on the glass surface. The influence of the contact time was also evaluated and it was shown that, whatever the type of yeast, macromolecules such as proteins were released into the extracellular medium due to cell lysis and could contribute to the formation of a conditioning film. As a result, the cells were more strongly stuck to the glass plate.
Tests and Evaluation of Upgraded Flat-Plate and Waffle-Slab Floor Systems
1983-12-01
tested in the LBLG. The LBLG (Figure 2.J9) is a large, three-dimensional device designed pri- marily to test underground protective structures...34 Report AIWL-TR-74-102, Octo- ber 1974, Air Force Weapons Laboratory, Kirtland Air Force Base, N. Mex . 9. M. E. Criswell; "Strength and Behavior of...35th St. Commander, Air Force Weapons Laboratory, AFSC Chicago, Ill. 60616 ATTN: SUL, Technical Library Kirtland Air Force Base, N. Mex . 87117 Director
A summary report on the Flat-Plate Solar Array Project Workshop on Transparent Conducting Polymers
Kachare, R.; Moacanin, J.
1985-01-01
The proceedings and technical discussions of a workshop on Transparent Conducting Polymers (TCP) for solar cell applications are reported. This is in support of the Device Research Task of the Flat-Flate Solar Array Project. The workshop took place on January 11 and 12, 1985, in Santa Barbara, California. Participants included university and industry researchers. The discussions focused on the electronic and optical properties of TCP, and on experimental issues and problems that should be addressed for high-efficiency solar cell application.
Development and life cycle analysis of double slope active solar still with flat plate collector
Directory of Open Access Journals (Sweden)
A.K. Sethi
2014-02-01
Full Text Available Potable water is an essential ingredient of socio-economic development and economic growth. Often water sources are brackish (i.e. contain dissolved salts and/or contain harmful bacteria and therefore cannot be used for drinking. In addition, there are many coastal locations where seawater is abundant but potable water is not available. This study is focused on a development of solar still with flat plat collector for water desalination considered for small scale applications at remote locations where only saline water is available. In this paper the cost of distilled water per kg has been calculated by using the concept of life cycle cost analysis. The pay back periods for different conditions of the distribution of distilled water, namely at the cost it is produced and at the selling price on market rate have been evaluated. The cost of water per kg is minimum Rs. 0.59, when the interest rate and the lifetime of solar still are taken as 4% and 50 years respectively. The lowest payback time 1.23 years is obtained when the selling price of water Rs. 10 per kg.
Ochrymiuk, Tomasz
2016-06-01
Numerical simulations were performed to predict the film cooling effectiveness on the fiat plate with a three- dimensional discrete-hole film cooling arrangement. The effects of basic geometrical characteristics of the holes, i.e. diameter D, length L and pitch S/D were studied. Different turbulent heat transfer models based on constant and variable turbulent Prandtl number approaches were considered. The variability of the turbulent Prandtl number Pr t in the energy equation was assumed using an algebraic relation proposed by Kays and Crawford, or employing the Abe, Kondoh and Nagano eddy heat diffusivity closure with two differential transport equations for the temperature variance k θ and its destruction rate ɛ θ . The obtained numerical results were directly compared with the data that came from an experiment based on Transient Liquid Crystal methodology. All implemented models for turbulent heat transfer performed sufficiently well for the considered case. It was confirmed, however, that the two- equation closure can give a detailed look into film cooling problems without using any time-consuming and inherently unsteady models.
Laboratory Test for Measurement of Adhesion Strength of Spray Ice to Coated Flat Plates
1990-05-01
became trapped within the ice. After the by test group 612 during icing due to nozzle freezeup sprayer was turned off, the unfrozen water became and the...indicated if and when nozzle freezeup occurred. Short and the push block increased as the block moved for- duration peaks in the nozzle temperature occurred...either nozzle freezeup and conse- bond strength of each sample. Notice, in Figure 2 1. the quent efforts to thaw, the application of more insulation
Smith, J. L.; Gates, W. R.; Lee, T.
1978-01-01
Problems which may arise as the low cost silicon solar array (LSSA) project attempts to industrialize the production technologies are defined. The charge to insure an annual production capability of 500 MW peak for the photovoltaic supply industry by 1986 was critically examined, and focused on one of the motivations behind this goal-concern over the timely development of industrial capacity to supply anticipated demand. Conclusions from the analysis are utilized in a discussion of LSSA's industrialization plans, particularly the plans for pilot, demonstration and commercial scale production plants. Specific recommendations for the implementation of an industrialization task and the disposition of the project quantity goal were derived.
Experimental study of flat plate cooling using draft induced by a submerged radial jet
Directory of Open Access Journals (Sweden)
Argemiro Palencia-Diaz
2017-01-01
Full Text Available Una investigación experimental se ha llevado a cabo para evaluar la transferencia de calor en una configuración modificada de un chorro radial sumergido, por medio del cual se puede extraer el fluido directamente debajo de la boquilla, en busca de una mejora en la velocidad de transferencia de calor. Los experimentos se llevaron a cabo para las siguientes gamas de parámetros que rigen el fenómeno: boquilla de 16 mm de diámetro, distancia entre boquilla y placa entre 10 mm a 20 mm, número de Reynolds que oscila entre 10.000 y 20.000, y calor de 10,2 – 13,6 kW/m2. La transferencia de calor se estima a través de la distribución de temperatura obtenida por medio de un dispositivo de adquisición de datos y un apropiado post-procesamiento, lo que hace posible determinar el coeficiente de transferencia de calor y el número de Nusselt para las diferentes condiciones en estudio. El uso de la extracción de fluido a través de tiro inducido genera un aumento significativo en la transferencia de calor en el área debajo de la boquilla, obteniendo valores desde 290 hasta 1500 W/m2.°C.
The measurement of thermal stress distributions along the flow path in injection-molded flat plates
Hastenberg, C.H.V.; Wildervanck, P.C.; Leenen, A.J.H.; Schennink, G.G.J.
1992-01-01
Internal stresses in injection-molded parts are the result of thermal, flow, and pressure histories. Internal stresses can be roughly divided into thermal and flow-induced stresses. In this paper, a modified layer-removal method is presented to determine thermal stress distributions in injection-mol
Energy Technology Data Exchange (ETDEWEB)
Janke, S.H.; Boehm, R.F.
1977-01-01
A determination is made regarding the energy density and flux available after passage of direct solar radiation through single and double glass covers, for panels inclined at various angles and oriented with varying azimuths, several latitudes are also considered. Results of a computer program which for any latitude, date, time of day and arbitrary pannel orientation allows for atmospheric attenuation and glass transmission are displayed in several graphical formats. Orientizations other than south facing are found to give greater availability of energy for a period of roughly 90 days centered about the summer solstice, and to give higher flux values early or late in the day for winter dates, but are inferior to south facing pannels in other respects.
Flat Plate and Turbine Vane Cascade Heat Transfer Investigation Using a Shock Tube.
1985-12-01
piece of -. work would not have been possible without the superior and talented AFIT Shop personnel lead by Mr. Carl Shortt. I would also like to...tube. Curves were presented showing the time required to reach steady state for a given flow condition and model size. Davies and Berstein (1969...inverse of Davies’ and Bersteins ’ I alpha as the transition requirement. Dunn and Stoddard (1977) .. * .conducted heat transfer experiments in a shock
A Study on hypersonic flow over a flat plate with narrow channels
Omichi, Yuya; Suzuki, Kojiro; 大道, 勇哉; 鈴木, 宏二郎
2011-01-01
At the development of hypersonic vehicles, it is quite important to estimate the aerodynamic heating with high accuracy, because hypersonic vehicles are exposed to high temperature and/or high pressure flow behind a strong shock wave formed over the body. A hypersonic vehicle often has small irregularities on its body surface. For example, the gaps between the tiles for the thermal protection may work as the surface roughness. Such irregularity on the body surface causes local peaks of aerody...
Direct numerical simulation methods of hypersonic flat-plate boundary layer in thermally perfect gas
Jia, WenLi; Cao, Wei
2014-01-01
High-temperature effects alter the physical and transport properties of air such as vibrational excitation in a thermally perfect gas, and this factor should be considered in order to compute the flow field correctly. Herein, for the thermally perfect gas, a simple method of direct numerical simulation on flat-plat boundary layer is put forward, using the equivalent specific heat ratio instead of constant specific heat ratio in the N-S equations and flux splitting form of a calorically perfect gas. The results calculated by the new method are consistent with that by solving the N-S equations of a thermally perfect gas directly. The mean flow has the similarity, and consistent to the corresponding Blasius solution, which confirms that satisfactory results can be obtained basing on the Blasius solution as the mean flow directly in stability analysis. The amplitude growth curve of small disturbance is introduced at the inlet by using direct numerical simulation, which is consistent with that obtained by linear stability theory. It verified that the equation established and the simulation method is correct.
Computer program for Thin Wire Antennas Mounted on a Satellite Body Modeled by Flat Plates.
1978-12-01
S \\ l I ’ ( ’ ) + t ’ p ’ )~~~ T f.~~~’ l * \\ , ]~~~ - - ( , ’ ) - 4 - lf r , , . I , t . ~~) 4 i5~ ‘~Tt ;t ~) Il5 ’-~ t~) i-~c- = L~ 1I’ .~ 4
BUOYANCY INSTABILITY IN THE NATURAL CONVECTION BOUNDARY LAYER AROUND A VERTICAL HEATED FLAT PLATE
Institute of Scientific and Technical Information of China (English)
颜大椿; 张汉勋
2002-01-01
A systematic research on the buoyancy instability in the natural convection boundary layer was conducted, including the basic characteristics such as its spectral components, wave length and velocity, the location of its critical layer,and amplitude distributions of the triple independent eigenmodes with the linear instability theory, the growth rates of its temperature and velocity fluctuations and the corresponding neutral curves for the buoyancy eigenmode were also obtained.Results indicated that the neutral curve of the velocity fluctuation had a nose shape consistent with that obtained in the numerical calculation, but for the temperature fluctuation, a ring-like region could be measured at a lower Grashof number before the nose-shaped main portion of the neutral curve.
Boundary Layer Stability Measurements over a Flat Plate at Mach 3.
1985-11-01
ADDRESS0i/ different 1om (-7ntrollnl1 Office) 1S SECURITY CLASS. (of this re ort) ’ ISa . DECLASSIFICATION DOWNGRADING SCHEDULE 16. DISTRIBUTION...7.7 777777117a-F77-Ir - - 7-7-7 i .3 r. ca. . (n ~o . ..... M! a ~ I g rtU 0 cD q icw ix " 4(D -’-4 z Cz A ~ <. in c o U) 00 a-a 132 @3 S ml- 0I -0- o
Comparative performance of twenty-three types of flat plate solar energy collectors
Simon, F. F.
1975-01-01
Report compares efficiencies of 23 solar collectors for four different purposes: operating a Rankine-cycle engine, heating or absorption air conditioning, heating hot water, and heating a swimming pool.
Status of the NASA-Lewis flat-plate collector tests with a solar simulator
Simon, F. F.
1974-01-01
Simulator test results of 15 collector types are reported. Collectors are given performance ratings according to their use for pool heating, hot water, absorption A/C or heating and solar Rankine machines. Collectors found to be good performers in the above categories, except for pool heating, were a black nickel coated, 2 glass collector, and a black paint 2 glass collector containing a mylar honeycomb. For pool heating, a black paint, one glass collector was found to be the best performer. Collector performance parameters of 5 collector types were determined to aid in explaining the factors that govern performance. The two factors that had the greatest effect on collector performance were the collector heat loss and the coating absorptivity.
2007-11-02
the former preferred for high-temperature collectors since it is opaque in the longer wavelength region and hence improves the efficiency by reducing re...different temperature regions . The analyses show that collectors equipped with Lexan honeycomb are more cost ef- fective than comparable nonhoneycomb...Contract E(04-3)- 1081. " REFERENCES 1. Francia , G., "A New Collector of Solar Energy -- Theory and Experimental Verification -- Calculation of the
Incompressible viscous flow near the leading edge of a flat plate admitting slip
Vooren, A.I. van de; Veldman, A.E.P.
1975-01-01
The shear stress at the leading edge, calculated on basis of the Navier-Stokes equations and the no-slip boundary condition, approaches infinity. However, taking into account the mean free path of the molecules, which implies admitting a certain slip, the shear stress becomes inversely proportional
Review of Consensus Standard Spectra for Flat Plate and Concentrating Photovoltaic Performance
Energy Technology Data Exchange (ETDEWEB)
Myers, D.
2011-09-01
Consensus standard reference terrestrial solar spectra are used to establish nameplate ratings for photovoltaic device performance at standard reporting conditions. This report describes reference solar spectra developed in the United States and international consensus standards community which are widely accepted as of this writing (June 2011).
Heat transfer performance of silver/water nanofluid in a solar flat-plate collector
Lazarus, Godson; Roy, Siddharth; Kunhappan, Deepak; Cephas, Enoch; Wongwises, Somchai
2015-01-01
An experimental study is carried out to investigate the heat transfer characteristics of silver/water nanofluid in a solar flatplate collector. The solar radiation heat flux varies between 800 W/m2and 1000W/m2, and the particle concentration varies between 0.01%, 0.03%, and 0.04%. The fluid Reynolds number varies from 5000 to 25000. The influence of radiation heat flux, mass flow rate of nanofluid, inlet temperature into the solar collector, and volume concentration of the particle on the con...
Evaluation of flat-plate collector efficiency under controlled conditions in a solar simulator
Johnson, S. M.; Simon, F. F.
1976-01-01
The measured thermal efficiencies of 35 collectors tested with a solar simulator, along with the correlation equations used to generalize the data, are presented in this report. The single correlation used is shown to apply to all the different types of collectors tested, including one with black paint and one cover, one with a selective surface coating and two covers, and an evacuated-tube collector. The test and correlation technique is also modified by using a shield so that collectors larger than the simulator test area can also be tested. This technique was verified experimentally for a shielded collector for which the collector shielded area was 31% of the solar simulator radiation area. A table lists all the collectors tested, the collector areas, and the experimental constants used to correlate the data for each collector.
Buoyancy effects on thermal behavior of a flat-plate solar collector
DEFF Research Database (Denmark)
Fan, Jianhua; Furbo, Simon
2008-01-01
Theoretical and experimental investigations of the flow and temperature distribution in a 12.53 m(2) solar collector panel with an absorber consisting of two vertical manifolds interconnected by 16 parallel horizontal fins have been carried out. The investigations are focused on overheating and b...
Investigation of Heat Transfer to a Flat Plate in a Shock Tube.
1987-12-01
as the driven gas whose properties are identified by region 1. The gases of both regions initially have no velocity. When the diaphragm is ruptured... inSe CIc E m ’! i M oV I’)c Ci *C’ C4 P1 *s2ijns o L~EOL191 E L 0 J ILi cu cu ESC. an CI: c.I- S 9 5K * 0 C~ * 6. c i CDT 5~4 I ’- LLJ I: U _ T I 0uC
A simulation modeling for optimization of flat plate collector design in Riyadh, Saudi Arabia
Energy Technology Data Exchange (ETDEWEB)
Al Ajlan, S.A.; Al Faris, H.; Khonkar, H. [King Abdulaziz City for Science and Technology, Riyadh (Saudi Arabia). Energy Research Inst.
2003-07-01
A simulation of forced convection solar heated water system is presented. A computer program is developed consisting of independent subroutines, capable of handling the variation of the collector tube diameter, tube spacing, ambient conditions, material thermal properties, collector and system design optimization. The meteorological data of Riyadh were used as the input in the program to simulate the performance of the collector system. The output of the program is analyzed to optimize the system design in the Riyadh region. The results of the simulations are compared with experimental data. There is a good agreement between the predicted and measured values.(author)
A Comparison of the Thermodynamic Efficiency of Vacuum Tube and Flat Plate Solar Collector Systems
Directory of Open Access Journals (Sweden)
Juozas Bielskus
2013-12-01
Full Text Available The article presents simulation based exergy analysis used for comparing solar thermal systems applied for preparing domestic hot water. The simulation of flat and vacuum tube solar collector systems was performed in TRNSYS simulation environment. A period of one year under Lithuanian climate conditions was chosen. Simulation was performed on 6 min time step resolution by calculating energy and exergy flows and creating balance calculation. Assessment results at system and element levels have been presented as monthly variation in efficiency. The conducted analysis has revealed that the systems designed to cover equal heat energy demand operates in different exergetic efficiencies.Article in Lithuanian
The effect of contact spacing on the efficiency of flat plate solar collector plates
Schneider, G. E.; Crha, S.
1984-01-01
Rather than use a continuous weld or solder for thermal contact in the attachment of an extended surface to an energy removal tube, attention is given to the use of discontinuous attachment through the uniform distribution of finite regions of contact. This scheme is applied to a solar energy collection system in which it was thought capable of yielding fabrication and reliability improvements. A nondimensional formulation and numerical solution of FEM modeling yields the sensitivity of collector thermal performance to weld-solder joint dimensions. The discontinuous weld is found to significantly degrade system performance in proportion to the fin surface Biot modulus, with the controlling parameter (with respect to weld dimensions) being the perimeter length at the weld location of contact.
Heat transfer in flow past a continuously moving porous flat plate with heat flux
Digital Repository Service at National Institute of Oceanography (India)
Murty, T.V.R.; Sarma, Y.V.B.
The analysis of the heat transfer in flow past a continuously moving semi-infinite plate in the presence of suction/ injection with heat flux has been presented. Similarity solutions have been derived and the resulting equations are integrated...
Most-Critical Transient Disturbances in an Incompressible Flat-Plate Boundary Layer
Monschke, Jason; White, Edward
2015-11-01
Transient growth is a linear disturbance growth mechanism that plays a key role in roughness-induced boundary-layer transition. It occurs when superposed stable, non-orthogonal continuous spectrum modes experience algebraic disturbance growth followed by exponential decay. Algebraic disturbance growth can modify the basic state making it susceptible to secondary instabilities rapidly leading to transition. Optimal disturbance theory was developed to model the most-dangerous disturbances. However, evidence suggests roughness-induced transient growth is sub-optimal yet leads to transition earlier than optimal theory suggests. This research computes initial disturbances most unstable to secondary instabilities to further develop the applicability of transient growth theory to surface roughness. The main approach is using nonlinear adjoint optimization with solutions of the parabolized Navier-Stokes and BiGlobal stability equations. Two objective functions were considered: disturbance kinetic energy growth and sinuous instability growth rate. The first objective function was used as validation of the optimization method. Counter-rotating streamwise vortices located low in the boundary layer maximize the sinuous instability growth rate. The authors would like to acknowledge NASA and the AFOSR for funding this work through AFOSR Grant FA9550-09-1-0341.
Directory of Open Access Journals (Sweden)
Acosta-Flores José Jesús
2013-04-01
Full Text Available En ingeniería nos enfrentamos con problemas tan diversos como la elección del sitio donde debe construirse una carretera, una presa, un puente o un aeropuerto. Las consecuencias de tomar decisiones equivocadas son tan grandes que es conveniente contar con un método eficiente para enfrentar dichas situaciones, ya que siempre existe incertidumbre sobre lo que puede acontecer. En este artículo se presenta dicho método a través de un ejemplo sobre un sistema de protección de huracanes en el que dos actores serán fundamentales: el decisor y el analista. Se ha elegido este ejemplo porque permitiría tomar decisiones que disminuyan los daños que ocasionan los huracanes en nuestro país.
DEFF Research Database (Denmark)
Jensen, Christian Søndergaard; Li, K.-J.; Pakalnis, Stardas
2005-01-01
With the continued advances in wireless communications, geo-location technologies, and consumer electronics, it is becoming possible to accurately track the time-varying location of each vehicle in a population of vehicles. This paper reports on ongoing research that has as it objective to develop...... efficient tracking techniques. More specifically, while almost all commercially available tracking solutions simply offer time-based sampling of positions, this paper's techniques aim to offer a guaranteed tracking accuracy for each vehicle at the lowest possible costs, in terms of network traffic...... and server-side updates. This is achieved by designing, prototyping, and testing novel tracking techniques that exploit knowledge of the road network and past movement. These resulting tracking techniques are to support mobile services that rely on the existence of a central server that continuously tracks...
Tracks: Nurses and the Tracking Network
Centers for Disease Control (CDC) Podcasts
2012-06-06
This podcast highlights the utility of the National Environmental Public Health Tracking Network for nurses in a variety of work settings. It features commentary from the American Nurses Association and includes stories from a public health nurse in Massachusetts. Created: 6/6/2012 by National Center for Environmental Health (NCEH)/Division of Environmental Hazards and Health Effects (DEHHE)/Environmental Health Tracking Branch (EHTB). Date Released: 6/6/2012.
Lateral translation micro-tracking of planar micro-optic solar concentrator
Hallas, Justin M.; Karp, Jason H.; Tremblay, Eric J.; Ford, Joseph E.
2010-08-01
High-concentration photo-voltaic systems focus incident sunlight by hundreds of times by combining focusing lenses with accurate, dual-axis solar tracking. Conventional systems mount large optical arrays on expensive tracking pedestals to maintain normal incidence throughout the day. A recently proposed micro-optic solar concentrator utilizes a twodimensional lens array focusing into a planar slab waveguide. Localized mirrors fabricated on the waveguide surface reflect focused sunlight into guided modes which propagate towards an edge-mounted photovoltaic cell. This geometry enables a new method of solar tracking by laterally translating the waveguide with respect to the lens array to capture off-axis illumination. Using short focal length lenses, translations on the order of millimeters can efficiently collect 70° full-angle incident fields. This allows for either one or two-axis tracking systems where the small physical motion is contained within the physical footprint of a fixed solar panel. Here, we experimentally demonstrate lateral micro tracking for off-axis light collection using table-mounted components. We also present a novel tracking frame based on de-centered cams and describe a lens configuration optimized for off-axis coupling.
Reactive self-tracking solar concentrators: concept, design, and initial materials characterization.
Baker, Katherine A; Karp, Jason H; Tremblay, Eric J; Hallas, Justin M; Ford, Joseph E
2012-03-10
Étendue limits angular acceptance of high-concentration photovoltaic systems and imposes precise two-axis mechanical tracking. We show how a planar micro-optic solar concentrator incorporating a waveguide cladding with a nonlinear optical response to sunlight can reduce mechanical tracking requirements. Optical system designs quantify the required response: a large, slow, and localized increase in index of refraction. We describe one candidate materials system: a suspension of high-index particles in a low-index fluid combined with a localized space-charge field to increase particle density and average index. Preliminary experiments demonstrate an index change of aqueous polystyrene nanoparticles in response to a low voltage signal and imply larger responses with optimized nanofluidic materials.
Washburn, A.R.
1990-01-01
IEEE Transactions on Automatic Control, Vol. 35, 1990, pp. 852-855. This paper uses tracking time as an explicit objective in designing tracking algorithms that function in clutter. Implications of using "time to the first mistake" as a measure of tracking time are explored. An optimal tracker is derived for a special circukstance where there is clutter, but no measurement error, and is compared to a tracker based on the Maximum Likelihood principle.
Social Security Administration — DCS Budget Tracking System database contains budget information for the Information Technology budget and the 'Other Objects' budget. This data allows for monitoring...
CWI at TREC 2012, KBA track and Session Track
Araújo, S.; Boscarino, C.; Gebremeskel, G.G.; He, J.; Vries, A.P. de; Voorhees, E.M.; Buckland, L. P.
2013-01-01
We participated in two tracks: Knowledge Base Acceleration (KBA) Track and Session Track. In the KBA track, we focused on experi- menting with different approaches as it is the first time the track is launched. We experimented with supervised and unsupervised re- trieval models. Our supervised appro
CWI at TREC 2012, KBA track and Session Track
S. Araújo (Samur); C. Boscarino (Corrado); G.G. Gebremeskel (Gebre); J. He (Jiyin); A.P. de Vries (Arjen)
2013-01-01
htmlabstractWe participated in two tracks: Knowledge Base Acceleration (KBA) Track and Session Track. In the KBA track, we focused on experi- menting with different approaches as it is the first time the track is launched. We experimented with supervised and unsupervised re- trieval models. Our supe
Gursky, Daniel
1990-01-01
Discusses problems with student tracking. Although supporters consider tracking the best way for teachers to handle classroom diversity, many minorities say that it condemns their children to an inferior education. Studies show that heterogeneous classes benefit all students if the teachers adopt flexible instructional methods to handle the…
Can Tracking Improve Learning?
Duflo, Esther; Dupas, Pascaline; Kremer, Michael
2009-01-01
Tracking students into different classrooms according to their prior academic performance is controversial among both scholars and policymakers. If teachers find it easier to teach a homogeneous group of students, tracking could enhance school effectiveness and raise test scores of both low- and high-ability students. If students benefit from…
Can Tracking Improve Learning?
Duflo, Esther; Dupas, Pascaline; Kremer, Michael
2009-01-01
Tracking students into different classrooms according to their prior academic performance is controversial among both scholars and policymakers. If teachers find it easier to teach a homogeneous group of students, tracking could enhance school effectiveness and raise test scores of both low- and high-ability students. If students benefit from…
Large scale tracking algorithms
Energy Technology Data Exchange (ETDEWEB)
Hansen, Ross L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Love, Joshua Alan [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Melgaard, David Kennett [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Karelitz, David B. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Pitts, Todd Alan [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Zollweg, Joshua David [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Anderson, Dylan Z. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Nandy, Prabal [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Whitlow, Gary L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Bender, Daniel A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Byrne, Raymond Harry [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2015-01-01
Low signal-to-noise data processing algorithms for improved detection, tracking, discrimination and situational threat assessment are a key research challenge. As sensor technologies progress, the number of pixels will increase signi cantly. This will result in increased resolution, which could improve object discrimination, but unfortunately, will also result in a significant increase in the number of potential targets to track. Many tracking techniques, like multi-hypothesis trackers, suffer from a combinatorial explosion as the number of potential targets increase. As the resolution increases, the phenomenology applied towards detection algorithms also changes. For low resolution sensors, "blob" tracking is the norm. For higher resolution data, additional information may be employed in the detection and classfication steps. The most challenging scenarios are those where the targets cannot be fully resolved, yet must be tracked and distinguished for neighboring closely spaced objects. Tracking vehicles in an urban environment is an example of such a challenging scenario. This report evaluates several potential tracking algorithms for large-scale tracking in an urban environment.
Incentives from Curriculum Tracking
Koerselman, Kristian
2013-01-01
Curriculum tracking creates incentives in the years before its start, and we should therefore expect test scores to be higher during those years. I find robust evidence for incentive effects of tracking in the UK based on the UK comprehensive school reform. Results from the Swedish comprehensive school reform are inconclusive. Internationally, I…
Bewegingsvolgsysteem = Monitor tracking system
Slycke, Per Johan; Veltink, Petrus Hermanus; Roetenberg, Daniel
2006-01-01
A motion tracking system for tracking an object composed of object parts in a three-dimensional space. The system comprises a number of magnetic field transmitters; a number of field receivers for receiving the magnetic fields of the field transmitters; a number of inertial measurement units for rec
Bewegingsvolgsysteem = Monitor tracking system
Slycke, Per Johan; Veltink, Petrus Hermanus; Roetenberg, Daniel
2007-01-01
A motion tracking system for tracking an object composed of object parts in a three-dimensional space. The system comprises a number of magnetic field transmitters; a number of field receivers for receiving the magnetic fields of the field transmitters; a number of inertial measurement units for rec
Directory of Open Access Journals (Sweden)
Gabriela GROSSECK
2006-01-01
Full Text Available Eye-tracking: one of the newest and most efficient methods of improving on-line marketing communication is called eye-tracking. Marketers have borrowed this technique, usually used in psychological and medical research, in order to study web users with the help of a video camera incorporated in the monitor.
Large scale tracking algorithms.
Energy Technology Data Exchange (ETDEWEB)
Hansen, Ross L.; Love, Joshua Alan; Melgaard, David Kennett; Karelitz, David B.; Pitts, Todd Alan; Zollweg, Joshua David; Anderson, Dylan Z.; Nandy, Prabal; Whitlow, Gary L.; Bender, Daniel A.; Byrne, Raymond Harry
2015-01-01
Low signal-to-noise data processing algorithms for improved detection, tracking, discrimination and situational threat assessment are a key research challenge. As sensor technologies progress, the number of pixels will increase signi cantly. This will result in increased resolution, which could improve object discrimination, but unfortunately, will also result in a significant increase in the number of potential targets to track. Many tracking techniques, like multi-hypothesis trackers, suffer from a combinatorial explosion as the number of potential targets increase. As the resolution increases, the phenomenology applied towards detection algorithms also changes. For low resolution sensors, "blob" tracking is the norm. For higher resolution data, additional information may be employed in the detection and classfication steps. The most challenging scenarios are those where the targets cannot be fully resolved, yet must be tracked and distinguished for neighboring closely spaced objects. Tracking vehicles in an urban environment is an example of such a challenging scenario. This report evaluates several potential tracking algorithms for large-scale tracking in an urban environment.
Zhang, Lihe; Lu, Huchuan; Du, Dandan; Liu, Luning
2016-02-01
In this paper, we propose a novel tracking framework based on a sparse and discriminative hashing method. Different from the previous work, we treat object tracking as an approximate nearest neighbor searching process in a binary space. Using the hash functions, the target templates and the candidates can be projected into the Hamming space, facilitating the distance calculation and tracking efficiency. First, we integrate both the inter-class and intra-class information to train multiple hash functions for better classification, while most classifiers in previous tracking methods usually neglect the inter-class correlation, which may cause the inaccuracy. Then, we introduce sparsity into the hash coefficient vectors for dynamic feature selection, which is crucial to select the discriminative and stable features to adapt to visual variations during the tracking process. Extensive experiments on various challenging sequences show that the proposed algorithm performs favorably against the state-of-the-art methods.
Energy Technology Data Exchange (ETDEWEB)
2007-05-08
Revision 75 of the Tracked Vehicle software is a soft real-time simulation of a differentially steered, tracked mobile robot, which, because of the track flippers, resembles the iRobot PackBot (http://www.irobot.com/). Open source libraries are used for the physics engine (http://www.ode.org/), the display and user interface (http://www.mathies.com/cpw/), and the program command line and configuration file parameters (http://www.boost.org/). The simulation can be controlled by a USB joystick or the keyboard. The configuration file contains demonstration model parameters of no particular vehicle. This simulation can be used as a starting point for those doing tracked vehicle simulations. This simulation software is essentially a research tool which can be modified and adapted for certain types of tracked vehicle research. An open source license allows an individual researchers to tailor the code to their specific research needs.
Mueller, Matthias
2016-04-13
In this thesis, we propose a new aerial video dataset and benchmark for low altitude UAV target tracking, as well as, a photo-realistic UAV simulator that can be coupled with tracking methods. Our benchmark provides the rst evaluation of many state of-the-art and popular trackers on 123 new and fully annotated HD video sequences captured from a low-altitude aerial perspective. Among the compared trackers, we determine which ones are the most suitable for UAV tracking both in terms of tracking accuracy and run-time. We also present a simulator that can be used to evaluate tracking algorithms in real-time scenarios before they are deployed on a UAV "in the field", as well as, generate synthetic but photo-realistic tracking datasets with free ground truth annotations to easily extend existing real-world datasets. Both the benchmark and simulator will be made publicly available to the vision community to further research in the area of object tracking from UAVs. Additionally, we propose a persistent, robust and autonomous object tracking system for unmanned aerial vehicles (UAVs) called Persistent Aerial Tracking (PAT). A computer vision and control strategy is applied to a diverse set of moving objects (e.g. humans, animals, cars, boats, etc.) integrating multiple UAVs with a stabilized RGB camera. A novel strategy is employed to successfully track objects over a long period, by \\'handing over the camera\\' from one UAV to another. We integrate the complete system into an off-the-shelf UAV, and obtain promising results showing the robustness of our solution in real-world aerial scenarios.
Department of Transportation — AVS is now required to collect, track, and report on data from the following Flight, Business and Workforce Plan. The Human Resource Management’s Performance Target...
Federal Laboratory Consortium — The TLV is designed to apply forces close to the strength limits of the rails and other track structure components, such as ties, rail fasteners, and ballast, while...
US Fish and Wildlife Service, Department of the Interior — The goal of St. Vincent National Wildlife Refuge's Track Count Protocol is to provide an index to the population size of game animals inhabiting St. Vincent Island.
National Archives and Records Administration — CATS tracks Public and Federal Agency Reference Requests for OPF (Official Personnel Folder) , EMF (Employee Medical Folder), and eOPF (electronic Official Personnel...
Financial Disclosure Tracking System
US Agency for International Development — USAID's FDTS identifies personal service contractors and local employees who should file disclosure reports. It tracks late filers and identifies those who must take...
Matter Tracking Information System -
Department of Transportation — The Matter Tracking Information System (MTIS) principle function is to streamline and integrate the workload and work activity generated or addressed by our 300 plus...
National Oceanic and Atmospheric Administration, Department of Commerce — The objectives of this project are to use novel satellite tracking methods to provide improved estimation of threats at foraging areas and along migration routes for...
2006-01-01
On 7 and 8 June 2006, the last large component of the LHCb experiment was lowered into the cavern. This 10-tonne, 18-metre long metal structure known as 'the bridge' will support the LHCb tracking system.
Patient Treatment Tracking Chart
... Treatment Tracking Chart Viral Hepatitis Menu Menu Viral Hepatitis Viral Hepatitis Home For Veterans and the Public Veterans ... can record dates of blood work, laboratory values, hepatitis C viral load levels, medication dosages, and side effects. You ...
Energy Tracking Software Platform
Energy Technology Data Exchange (ETDEWEB)
Ryan Davis; Nathan Bird; Rebecca Birx; Hal Knowles
2011-04-04
Acceleration has created an interactive energy tracking and visualization platform that supports decreasing electric, water, and gas usage. Homeowners have access to tools that allow them to gauge their use and track progress toward a smaller energy footprint. Real estate agents have access to consumption data, allowing for sharing a comparison with potential home buyers. Home builders have the opportunity to compare their neighborhood's energy efficiency with competitors. Home energy raters have a tool for gauging the progress of their clients after efficiency changes. And, social groups are able to help encourage members to reduce their energy bills and help their environment. EnergyIT.com is the business umbrella for all energy tracking solutions and is designed to provide information about our energy tracking software and promote sales. CompareAndConserve.com (Gainesville-Green.com) helps homeowners conserve energy through education and competition. ToolsForTenants.com helps renters factor energy usage into their housing decisions.
Wandernoth, S
2010-01-01
We present the tracking performance at LHCb by showing the mass resolution, impact parameter resolution and proper time resolution of the first data taken at LHCb. Furthermore several methods to estimate the tagging efficiency on data are presented.
Procurement Tracking System (PTS)
Office of Personnel Management — The Procurement Tracking System (PTS) is used solely by the procurement staff of the Office of the Inspector General (OIG) at the U.S. Office of Personnel Management...
LHCb VELO Tracking Resolutions
Alexander, Michael
2011-01-01
The excellent tracking performance of the Vertex Locator (VELO) at LHCb is presented. The resolutions it achieves on single hits, impact parameters, and primary vertex positions are shown, with particular attention paid to measurement of impact parameters.
Jarodzka, Halszka
2011-01-01
Jarodzka, H. (2010, 12 November). Applied eye tracking research. Presentation and Labtour for Vereniging Gewone Leden in oprichting (VGL i.o.), Heerlen, The Netherlands: Open University of the Netherlands.
Federal Laboratory Consortium — Located in Lakehurst, New Jersey, the Jet Car Track Site supports jet cars with J57 engines and has a maximum jet car thrust of 42,000 pounds with a maximum speed of...