Solar collectors are the engines that drive all solar energy heating systems. Although solar heating collectors have settled upon a few basic designs, they are still manufactured in an array of configurations.Solar collectors are generally classified by the temperatures that can be produced under normal amounts of solar radiation. The collector’s end-use application can be determined by their temperature classification such as Low-temperature collectors, Medium-temperature collectors and High-temperature concentrators that track the sun and produces the highest temperatures.Reflectorsthat are axially symmetrical and shaped like a parabola, has the property of bringing parallel rays of light (such as sunlight) to a pointfocus and so any object that is located at its focus receives highly concentrated sunlight, and therefore becomes very hot. This is the basis for the use of this kind of reflector for high solar energy generation. Energy supply for domestic activities had been a major problem faced by both rural and city dwellers for a long time now in Africa. It was therefore desirable to design and construct a solar Fresnel reflector and a tracking stand that can be used to generate heat from the sun for cooking, baking and distillation purposes. The reflector and the tracking stand designed and constructed was able to concentrate solar energy within a regional diameter of 10cm and could be used to raise the temperature of any object placed at its focal region. It was discovered that the heat generated is directly proportional to both the perfection of the collector design, its construction, the quality of the reflectors e.g plain mirror, the area exposed to the sun and the solar intensity of the day.
Solar energy is most abundantly available on earth surface and it's a constant stream of energy, and is directly available as fuel for Generation of electrical power. Solar energy uses is increasing day to day in large quantity now a day, applications like solar based Lighting system, solar cooking applications, water heating etc. For STEAM GENERATION SYSTEM, which is new concept because with the use of Evacuated tube and Fresnel lens we adapt very High concentrated focused thermal heat which uses to produce superheated steam. Also there are no losses of solar rays.
This presentation contains Basic introduction of sun and solar power, Technical terminologies related to solar power, Electromagnetic Spectrum,Sun Earth relationships,Types of Solar Radiation,Principles of measurement of Solar Radiation,
Solar radiation measurement Instruments,
Solar Photo Voltaic System,P-N Junction,Solar Cell,Types of Solar Cells,SOLAR COLLECTORS and recent trades of solar power utilization
Solar energy is most abundantly available on earth surface and it's a constant stream of energy, and is directly available as fuel for Generation of electrical power. Solar energy uses is increasing day to day in large quantity now a day, applications like solar based Lighting system, solar cooking applications, water heating etc. For STEAM GENERATION SYSTEM, which is new concept because with the use of Evacuated tube and Fresnel lens we adapt very High concentrated focused thermal heat which uses to produce superheated steam. Also there are no losses of solar rays.
This presentation contains Basic introduction of sun and solar power, Technical terminologies related to solar power, Electromagnetic Spectrum,Sun Earth relationships,Types of Solar Radiation,Principles of measurement of Solar Radiation,
Solar radiation measurement Instruments,
Solar Photo Voltaic System,P-N Junction,Solar Cell,Types of Solar Cells,SOLAR COLLECTORS and recent trades of solar power utilization
Solar collector : A device designed to absorb incident solar radiation and to transfer the energy to a fluid passing in contact with it, usually liquid or air.
Flat – Plate Collector : A typical flat-plate collector is an insulated metal box with a glass or plastic cover (called the glazing) and a dark-colored absorber plate. These collectors heat liquid or air at temperatures less than 180°F.
Modeling Of Flat Plate Collector by Using Hybrid TechniqueIOSR Journals
(SWH) are becoming increasingly attractive in sustainable development. Hence the Efforts continuously made here is to reduce their costs to make them more affordable. Solar energy has experienced a remarkable development in recent years because of cost reduction due to technological development as well as renewable energy scheme supported by the government. The process of using sun’s energy to heat water is not a new technology. (SWH) technology has improved a lot during the past century. The primary method of energy transport in solar energy from sun is electromagnetic radiation .This type of radiation coming from the Sun also depends on temperature. The Sun generates electromagnetic radiation in extensive span of wavelengths. However, most of the radiation is being sent out in the observable range due to its surface temperature. The amount of solar energy received in a particular region depends on the time of the day, the season of the year, the sky’s cloudiness, and how closeness of Earth’s equator. For modeling we utilized Genetic algorithm and for prediction we employed hybrid ABC and PSO techniques. Genetic algorithm is utilized in order to optimize the modeling technique by using the dataset collected.
THERMAL PERFORMANCE OF EVACUATED TUBE AND FLAT PLATE SOLAR COLLECTORS IN NORD...IAEME Publication
In this paper the results of the experiments of measuring the performance of evacuated tube and flat plate type solar collectors in Nordic climate conditions are presented. The measurements of the collectors of a given and equal gross surface area were performed in the test installation
environment. While the azimuth of the collectors was preserved constantly by 180°, the vertical incline was varied in order to identify the most suitable value of the thermal performance
Concentrating collectors absorbs solar energy and convert it into heat for generating hot water, steam at required temperature, which can be further used for solar thermal applications. The developing countries like India where solar energy is abundantly available; there is need to develop technology for harnessing solar energy for power production, but the main problem associated with concentrating solar power technology is the high cost of installation and low output efficiency.
Employing of novel poly (amine-ester) with Pentaerithritol core as a new poly...IJERA Editor
A novel hyperbranched poly (amine-ester) (HBPAE) with a high number of hydroxyl end groups has been prepared and successfully applied as new polymeric admixture for ordinary Portland cement (OPC) after its complete characterization via GPC, IR, 1H-NMR, TGA and DSC. The effect of polymer addition on the cement paste was investigated by measuring the effect of 1, 3 and 5 wt. % HBPAE solutions on the properties of OPC. The results clarified that the addition of HBPAE to OPC pastes decreased the water of consistency while increased the compressive strength with no effect on the chemical composition of the cement phase. The SEM images indicated that the incorporation of HBPAE in cement phase affected the physical state, shape, size, morphology and microstructure of the formed hydrates. Generally, the addition of hyperbranched poly amine-ester (HBPAE) improved the physico-mechanical properties of cement.
Solar collector : A device designed to absorb incident solar radiation and to transfer the energy to a fluid passing in contact with it, usually liquid or air.
Flat – Plate Collector : A typical flat-plate collector is an insulated metal box with a glass or plastic cover (called the glazing) and a dark-colored absorber plate. These collectors heat liquid or air at temperatures less than 180°F.
Modeling Of Flat Plate Collector by Using Hybrid TechniqueIOSR Journals
(SWH) are becoming increasingly attractive in sustainable development. Hence the Efforts continuously made here is to reduce their costs to make them more affordable. Solar energy has experienced a remarkable development in recent years because of cost reduction due to technological development as well as renewable energy scheme supported by the government. The process of using sun’s energy to heat water is not a new technology. (SWH) technology has improved a lot during the past century. The primary method of energy transport in solar energy from sun is electromagnetic radiation .This type of radiation coming from the Sun also depends on temperature. The Sun generates electromagnetic radiation in extensive span of wavelengths. However, most of the radiation is being sent out in the observable range due to its surface temperature. The amount of solar energy received in a particular region depends on the time of the day, the season of the year, the sky’s cloudiness, and how closeness of Earth’s equator. For modeling we utilized Genetic algorithm and for prediction we employed hybrid ABC and PSO techniques. Genetic algorithm is utilized in order to optimize the modeling technique by using the dataset collected.
THERMAL PERFORMANCE OF EVACUATED TUBE AND FLAT PLATE SOLAR COLLECTORS IN NORD...IAEME Publication
In this paper the results of the experiments of measuring the performance of evacuated tube and flat plate type solar collectors in Nordic climate conditions are presented. The measurements of the collectors of a given and equal gross surface area were performed in the test installation
environment. While the azimuth of the collectors was preserved constantly by 180°, the vertical incline was varied in order to identify the most suitable value of the thermal performance
Concentrating collectors absorbs solar energy and convert it into heat for generating hot water, steam at required temperature, which can be further used for solar thermal applications. The developing countries like India where solar energy is abundantly available; there is need to develop technology for harnessing solar energy for power production, but the main problem associated with concentrating solar power technology is the high cost of installation and low output efficiency.
Employing of novel poly (amine-ester) with Pentaerithritol core as a new poly...IJERA Editor
A novel hyperbranched poly (amine-ester) (HBPAE) with a high number of hydroxyl end groups has been prepared and successfully applied as new polymeric admixture for ordinary Portland cement (OPC) after its complete characterization via GPC, IR, 1H-NMR, TGA and DSC. The effect of polymer addition on the cement paste was investigated by measuring the effect of 1, 3 and 5 wt. % HBPAE solutions on the properties of OPC. The results clarified that the addition of HBPAE to OPC pastes decreased the water of consistency while increased the compressive strength with no effect on the chemical composition of the cement phase. The SEM images indicated that the incorporation of HBPAE in cement phase affected the physical state, shape, size, morphology and microstructure of the formed hydrates. Generally, the addition of hyperbranched poly amine-ester (HBPAE) improved the physico-mechanical properties of cement.
Suomen Ympäristökeskuksen tutkimusprofessori ja ryhmäpäällikkö Pekka Leskisen ja
tutkija Anne Holman esitelmä "Biotalouden kestävyys" Säätytalolla 4.2.2015
Australian Trainers Investigated In Cobalt Doping Inquiryisteroidscom
The doping scandal of Australia has depended with the news that two more leading trainers have had horses test positive for the outlawed blood doping drug cobalt chloride.
Exhortacion Apostolica del Papa Francisco, invitando a los matrimonios a vivir su configuración con Cristo, Buen Pastor, y ver a la Iglesia como un lugar acogedor de su sacramento que han recibido.
Integrated ERT and Magnetic Surveys in a Mineralization Zone in Erkowit - Red...IJERA Editor
The present study focus on integrated geophysical surveys carried out in the mineralization zone in Erkowit region, Eastern Sudan to determine the extensions of the potential ore deposits on the topographically high hilly area and under the cover of alluvium along the nearby wadi and to locate other occurrences if any. The magnetic method (MAG) and the electrical resistivity tomography (ERT) were employed for the survey. Eleven traverses were aligned approximately at right angles to the general strike of the rock formations. The disseminated sulfides are located on the alteration shear zone which is composed of granitic and dioritic highly ferruginated rock occupying the southwestern and central parts of the area, this was confirmed using thin and polished sections mineralogical analysis. The magnetic data indicates low magnetic values for wadi sedimentary deposits in its southern part of the area, and high anomalies which are suspected as gossans due to magnetite formed during wall rock alteration consequent to mineralization. The significant ERT imagesdefinelow resistivity zone as traced as sheared zones which may associated with the main loci of ore deposition. The study designates that correlation of magnetic and ERT anomalies with lithology are extremely useful in mineral exploration due to variations in some specific physical properties of rocks.
Multiple Crop Classification Using Various Support Vector Machine Kernel Func...IJERA Editor
This study was carried out with techniques of Remote Sensing (RS) based crop discrimination and area estimation with single date approach. Several kernel functions are employed and compared in this study for mapping the input space with including linear, sigmoid, and polynomial and Radial Basis Function (RBF). The present study highlights the advantages of Remote Sensing (RS) and Geographic Information System (GIS) techniques for analyzing the land use/land cover mapping for Aurangabad region of Maharashtra, India. Single date, cloud free IRS-Resourcesat-1 LISS-III data was used for further classification on training set for supervised classification. ENVI 4.4 is used for image analysis and interpretation. The experimental tests show that system is achieved 94.82% using SVM with kernel functions including Polynomial kernel function compared with Radial Basis Function, Sigmoid and linear kernel. The Overall Accuracy (OA) to up to 5.17% in comparison to using sigmoid kernel function, and up to 3.45% in comparison to a 3rd degree polynomial kernel function and RBF with 200 as a penalty parameter.
Comparative Evaluation Of Reinforced Concrete, Steel And Composite Structures...IJERA Editor
Steel-concrete composite construction has gained wide acceptance all over the world as an alternative for pure steel and pure concrete construction. However this approach is a new concept for construction industry. R.C.C are no longer economical because of their increased dead load, hazardous formwork. The present study deals with comparison of reinforced concrete, steel and composite structures under the effect of static and dynamic loads. The results of this work show that composite structures are best suited for high rise buildings compared to that of steel and reinforced concrete structures. Response spectrum method is used for comparison of three structures with the help of ETABS software.
A New Approach for Design of Model Matching Controllers for Time Delay System...IJERA Editor
Modeling of physical systems usually results in complex high order dynamic representation. The simulation and design of controller for higher order system is a difficult problem. Normally the cost and complexity of the controller increases with the system order. Hence it is desirable to approximate these models to reduced order model such that these lower order models preserves all salient features of higher order model. Lower order models simplify the understanding of the original higher order system. Modern controller design methods such as Model Matching Technique, LQG produce controllers of order at least equal to that of the plant, usually higher order. These control laws are may be too complex with regards to practical implementation and simpler designs are then sought. For this purpose, one can either reduce the order the plant model prior to controller design, or reduce the controller in the final stage, or both. In the present work, a controller is designed such that the closed loop system which includes a delay response(s) matches with those of the chosen model with same time delay as close as possible. Based on desired model, a controller(of higher order) is designed using model matching method and is approximated to a lower order one using Approximate Generalized Time Moments (AGTM) / Approximate Generalized Markov Moments (AGMM) matching technique and Optimal Pade Approximation technique. Genetic Algorithm (GA) optimization technique is used to obtain the expansion points one which yields similar response as that of model, minimizing the error between the response of the model and that of designed closed loop system.
Comparative Analysis and Simulation of Diode Clamped & Cascaded H-Bridge Mult...IJERA Editor
Multilevel inverters have become more popular over the years in high power medium voltage applications without the use of a transformer and with promise of less disturbance & reduced harmonic distortion. In this paper, two types of multilevel converter in three phase configuration, cascaded H-Bridge multilevel inverter (CMLI) and diode clamped multilevel inverter (DCMLI) of 5 and 7-level are modelled and compared in the case of feeding of a three phase squirrel cage induction motor. Here, carrier based sinusoidal pulse width modulation (SPWM) technique is used as the modulation strategy. These modulation strategy include phase disposition technique (PD), phase opposition disposition technique (POD), and an alternative phase opposition disposition technique (APOD). A detailed study of the modulation technique has been carried out through MATLAB/SIMULINK for both multilevel converters and a comparative evaluation between DCMLI and CMLI using SPWM technique in terms of THD%.
Sebuah Bisnis yang real yang sudah dibuktikan manca negara. Telah berlangsung 4 tahun lebih mensukseskan banyak orang di 26 negara.
http://emgoldexindonesia.weebly.com
STUDY OF SOLAR THERMAL CAVITY RECEIVER FOR PARABOLIC CONCENTRATING COLLECTOR ijiert bestjournal
Energy is one of the building blocks of the country . The growth of the country has been fueled by chea p,abundant energy resources. Solar energy is a form of renewable ener gy which is available abundantly and collected unre servedly. The parabolic concentrator reflects the direct incident solar rad iation onto a receiver mounted above the dish at it s focal point. The conversion of concentrated solar radiation to heat takes place in receiver. The heat transfer characteristics of the receiver changes during the rotation of the receiver which affects thermal performance. The working temperature may also influence the ther mal performance and overall efficiency of the system. Thermal as well as optica l losses affect the performance of a solar paraboli c dish-cavity receiver system. The thermal losses of a solar cavity receiver include c onvective and radiative losses to the air in the ca vity and conductive heat loss through the insulation used behind the helical tube surface. Convective and radiative heat losses form the major constituents of the thermal losses. The convection heat loss from cavit y receiver in parabolic dish solar thermal power sy stem can significantly reduce the efficiency and consequently the cost effectiveness of the system. It is important to assess this heat loss and subsequently improve the thermal performance of the receiver.
MASTERS OF ENVIRONMENTAL ARCHITECTURE renewable energy systemsSamanth kumar
RENEWABLE ENERGY SYSTEMS,M.ARCH (ENVIRONMENTAL ARCHITECTURE) ANNA UNIVERSITY
UNIT I SOLAR ENERGY
➔ Solar radiation its measurements and prediction
➔ solar thermal flat plate collectors concentrating collectors –
applications - heating, cooling, desalination, power generation,drying, cooking etc
➔ principle of photovoltaic conversion of solar energy,
➔ types of solar cells and fabrication.
Photovoltaic applications:
➔ battery charger, domestic lighting, street lighting, and water pumping, power generation schemes.
UNIT II WIND ENERGY
➔ Atmospheric circulations and classification
➔ factors influencing wind , wind shear and turbulence
➔ wind speed monitoring
➔ Betz limit
➔ Aerodynamics of wind turbine rotor
➔ site selection
➔ Wind resource assessment
wind energy conversion devices
➔ classification,
➔ characteristics,
➔ applications.
➔ Hybrid systems - safety and environmental aspects.
UNIT III BIO-ENERGY
➔ Biomass resources and their classification
➔ chemical constituents
➔ physicochemical characteristics of biomass
➔ Biomass conversion processes
➔ Thermochemical conversion
➔ direct combustion,
➔ gasification,
➔ pyrolysis and liquefaction
➔ biochemical conversion
➔ Anaerobic digestion
➔ alcohol production from biomass
➔ chemical conversion process
➔ hydrolysis and hydrogenation
➔ Biogas - generation - types of biogas Plants- applications
UNIT IV HYDROGEN AND FUEL CELLS
➔ Thermodynamics and electrochemical principles
➔ asic design, types, and applications
➔ production methods
➔ Biophotolysis
➔ Hydrogen generation from algae biological pathways
➔ Storage gaseous
➔ cryogenic and metal hydride and transportation.
➔ Fuel cell
➔ principle of working
➔ various types
➔ construction and applications.
UNIT V OTHER TYPES OF ENERGY
➔ Ocean energy resources
➔ principles of ocean thermal energy conversion systems
➔ Ocean thermal power plants
➔ principles of ocean wave energy conversion
➔ tidal energy conversion
hydropower
➔ site selection, construction, environmental issues
Geothermal energy
➔ types of geothermal energy sites,
➔ site selection, and geothermal power plants.
Epistemic Interaction - tuning interfaces to provide information for AI supportAlan Dix
Paper presented at SYNERGY workshop at AVI 2024, Genoa, Italy. 3rd June 2024
https://alandix.com/academic/papers/synergy2024-epistemic/
As machine learning integrates deeper into human-computer interactions, the concept of epistemic interaction emerges, aiming to refine these interactions to enhance system adaptability. This approach encourages minor, intentional adjustments in user behaviour to enrich the data available for system learning. This paper introduces epistemic interaction within the context of human-system communication, illustrating how deliberate interaction design can improve system understanding and adaptation. Through concrete examples, we demonstrate the potential of epistemic interaction to significantly advance human-computer interaction by leveraging intuitive human communication strategies to inform system design and functionality, offering a novel pathway for enriching user-system engagements.
Neuro-symbolic is not enough, we need neuro-*semantic*Frank van Harmelen
Neuro-symbolic (NeSy) AI is on the rise. However, simply machine learning on just any symbolic structure is not sufficient to really harvest the gains of NeSy. These will only be gained when the symbolic structures have an actual semantics. I give an operational definition of semantics as “predictable inference”.
All of this illustrated with link prediction over knowledge graphs, but the argument is general.
PHP Frameworks: I want to break free (IPC Berlin 2024)Ralf Eggert
In this presentation, we examine the challenges and limitations of relying too heavily on PHP frameworks in web development. We discuss the history of PHP and its frameworks to understand how this dependence has evolved. The focus will be on providing concrete tips and strategies to reduce reliance on these frameworks, based on real-world examples and practical considerations. The goal is to equip developers with the skills and knowledge to create more flexible and future-proof web applications. We'll explore the importance of maintaining autonomy in a rapidly changing tech landscape and how to make informed decisions in PHP development.
This talk is aimed at encouraging a more independent approach to using PHP frameworks, moving towards a more flexible and future-proof approach to PHP development.
Smart TV Buyer Insights Survey 2024 by 91mobiles.pdf91mobiles
91mobiles recently conducted a Smart TV Buyer Insights Survey in which we asked over 3,000 respondents about the TV they own, aspects they look at on a new TV, and their TV buying preferences.
GDG Cloud Southlake #33: Boule & Rebala: Effective AppSec in SDLC using Deplo...James Anderson
Effective Application Security in Software Delivery lifecycle using Deployment Firewall and DBOM
The modern software delivery process (or the CI/CD process) includes many tools, distributed teams, open-source code, and cloud platforms. Constant focus on speed to release software to market, along with the traditional slow and manual security checks has caused gaps in continuous security as an important piece in the software supply chain. Today organizations feel more susceptible to external and internal cyber threats due to the vast attack surface in their applications supply chain and the lack of end-to-end governance and risk management.
The software team must secure its software delivery process to avoid vulnerability and security breaches. This needs to be achieved with existing tool chains and without extensive rework of the delivery processes. This talk will present strategies and techniques for providing visibility into the true risk of the existing vulnerabilities, preventing the introduction of security issues in the software, resolving vulnerabilities in production environments quickly, and capturing the deployment bill of materials (DBOM).
Speakers:
Bob Boule
Robert Boule is a technology enthusiast with PASSION for technology and making things work along with a knack for helping others understand how things work. He comes with around 20 years of solution engineering experience in application security, software continuous delivery, and SaaS platforms. He is known for his dynamic presentations in CI/CD and application security integrated in software delivery lifecycle.
Gopinath Rebala
Gopinath Rebala is the CTO of OpsMx, where he has overall responsibility for the machine learning and data processing architectures for Secure Software Delivery. Gopi also has a strong connection with our customers, leading design and architecture for strategic implementations. Gopi is a frequent speaker and well-known leader in continuous delivery and integrating security into software delivery.
Connector Corner: Automate dynamic content and events by pushing a buttonDianaGray10
Here is something new! In our next Connector Corner webinar, we will demonstrate how you can use a single workflow to:
Create a campaign using Mailchimp with merge tags/fields
Send an interactive Slack channel message (using buttons)
Have the message received by managers and peers along with a test email for review
But there’s more:
In a second workflow supporting the same use case, you’ll see:
Your campaign sent to target colleagues for approval
If the “Approve” button is clicked, a Jira/Zendesk ticket is created for the marketing design team
But—if the “Reject” button is pushed, colleagues will be alerted via Slack message
Join us to learn more about this new, human-in-the-loop capability, brought to you by Integration Service connectors.
And...
Speakers:
Akshay Agnihotri, Product Manager
Charlie Greenberg, Host
Essentials of Automations: Optimizing FME Workflows with ParametersSafe Software
Are you looking to streamline your workflows and boost your projects’ efficiency? Do you find yourself searching for ways to add flexibility and control over your FME workflows? If so, you’re in the right place.
Join us for an insightful dive into the world of FME parameters, a critical element in optimizing workflow efficiency. This webinar marks the beginning of our three-part “Essentials of Automation” series. This first webinar is designed to equip you with the knowledge and skills to utilize parameters effectively: enhancing the flexibility, maintainability, and user control of your FME projects.
Here’s what you’ll gain:
- Essentials of FME Parameters: Understand the pivotal role of parameters, including Reader/Writer, Transformer, User, and FME Flow categories. Discover how they are the key to unlocking automation and optimization within your workflows.
- Practical Applications in FME Form: Delve into key user parameter types including choice, connections, and file URLs. Allow users to control how a workflow runs, making your workflows more reusable. Learn to import values and deliver the best user experience for your workflows while enhancing accuracy.
- Optimization Strategies in FME Flow: Explore the creation and strategic deployment of parameters in FME Flow, including the use of deployment and geometry parameters, to maximize workflow efficiency.
- Pro Tips for Success: Gain insights on parameterizing connections and leveraging new features like Conditional Visibility for clarity and simplicity.
We’ll wrap up with a glimpse into future webinars, followed by a Q&A session to address your specific questions surrounding this topic.
Don’t miss this opportunity to elevate your FME expertise and drive your projects to new heights of efficiency.
Leading Change strategies and insights for effective change management pdf 1.pdf
Development of a Solar Fresnel Reflector and Its Tracking Stand Using Local Material
1. Manukaji John Int. Journal of Engineering Research and Applications www.ijera.com
ISSN : 2248-9622, Vol. 5, Issue 1( Part 5), January 2015, pp.22-30
www.ijera.com 22 |
P a g e
Development of a Solar Fresnel Reflector and Its Tracking Stand
Using Local Material
Manukaji John
Solar Energy Research Centre Federal Polytechnic, Bida Niger State Nigeria
ABSTRACT
Solar collectors are the engines that drive all solar energy heating systems. Although solar heating collectors
have settled upon a few basic designs, they are still manufactured in an array of configurations.Solar collectors
are generally classified by the temperatures that can be produced under normal amounts of solar radiation. The
collector’s end-use application can be determined by their temperature classification such as Low-temperature
collectors, Medium-temperature collectors and High-temperature concentrators that track the sun and produces
the highest temperatures.Reflectorsthat are axially symmetrical and shaped like a parabola, has the property of
bringing parallel rays of light (such as sunlight) to a pointfocus and so any object that is located at its focus
receives highly concentrated sunlight, and therefore becomes very hot. This is the basis for the use of this kind
of reflector for high solar energy generation. Energy supply for domestic activities had been a major problem
faced by both rural and city dwellers for a long time now in Africa. It was therefore desirable to design and
construct a solar Fresnel reflector and a tracking stand that can be used to generate heat from the sun for
cooking, baking and distillation purposes. The reflector and the tracking stand designed and constructed was
able to concentrate solar energy within a regional diameter of 10cm and could be used to raise the temperature
of any object placed at its focal region. It was discovered that the heat generated is directly proportional to both
the perfection of the collector design, its construction, the quality of the reflectors e.g plain mirror, the area
exposed to the sun and the solar intensity of the day.
I. INTRODUCTION
Solar collectors are either non-concentrating or
concentrating. In the non-concentrating type, the
collector area (i.e., the area that intercepts the solar
radiation) is the same as the absorber area (i.e., the
area absorbing the radiation). In these types the
whole solar panel absorbs light. Concentrating
collectors have a bigger interceptor than
absorber.Norton, Brian 2013
The classification of the collectors by their
effective end-use temperatures is a helpful method of
differentiation.
Flat plate solar collectors are the most common
for heating water and air in the home. The flat plate
solar collector is an insulated box with a plastic or
glass “lid” on top.
Solar collectors transform solar radiation into
heat and then transfer that heat to a medium (water,
solar fluid, or air). The term is applied to solar hot
water panels, but may also be used to denote more
complex installations such as solar parabolic, solar
trough and solar towers.
Concentrating solar collectors use mirrored
surfaces to concentrate the sun's energy on an
absorber called a receiver. Concentrating collectors
also achieve high temperatures, but unlike evacuated-
tube collectors, they can do so only when direct
sunlight is available.
Concentrating reflectors generate high
temperatures and cook quickly, but require frequent
adjustment. Reflectors that bring rays parallel to its
principal axis to point focus can be easily turned to
follow both the sun's daily motion and its seasonal
one. The cooking pot stays stationary at the focus. If
the paraboloidal reflector is axially symmetrical and
is made of material of uniform thickness, its centre of
mass coincides with its focus if the depth of the
reflector, measured along its axis of symmetry from
the vertex to the plane of the rim, is 1.8478 times its
focal length. The radius of the rim of the reflector is
2.7187 times the focal length. The angular radius of
the rim, as seen from the focal point, is 72.68
degrees.
If the reflector is aligned with its focal line
horizontal and east-west and is pointed so that its axis
of symmetry aims at the sun at noon, it will be tilted
up and down as the seasons progress. At the
equinoxes, no movement of the reflector is needed
during the day to track the sun.
Spherical reflectors operate much like
paraboloidal reflectors, such that the axis of
symmetry is pointed towards the sun so that light is
concentrated to a focus. However, the focus of a
spherical reflector will not be a point focus because it
suffers from a phenomenon known as spherical
aberration.
RESEARCH ARTICLE OPEN ACCESS
2. Manukaji John Int. Journal of Engineering Research and Applications www.ijera.com
ISSN : 2248-9622, Vol. 5, Issue 1( Part 5), January 2015, pp.22-30
www.ijera.com 23 |
P a g e
During the day the sun has different positions.
For low concentration systems tracking can be
avoided, butfor higher concentrations, however, if the
mirrors or lenses do not move, then the focus of the
mirrors or lenses changes and so tracking must be
carried out from time to time. The tracking system
increases the cost and complexity of a collector. With
this in mind, different designs can be distinguished in
how they concentrate the light and track the position
of the sun.
Solar reflectors and collectors use a renewable and
non- polluting type of energy source. They reflect and
collect an energy that is so decentralized that every
home can utilize it as desired. The techniques of
construction are simple. It involves only the initial
capital cost and does not attract any recurrent cost.
Under initial review, it was discovered that on an
average sunny day including the periods of cloud cover,
the reflectors and collectors, collect enough energy
from the sun that are equivalent to the energy supplied
by conventional energy sources. Finally, its use will
eventually reduce the family energy costs by reducing
the amount spent on purchase of conventional fuels.
Many solar reflectors have already been developed
world wide.
The performance of both types hadbeen reported in
the literature, but the results of these designs were not
based on comparative analysis. The performance of any
solar reflector improves if the collector efficiency is
increased. Therefore the efficiency of the collector
should be maximized if such a step does not
significantly increase the reflector and collector cost.
The variables affecting reflector and collector
efficiency fall into several groups.
1. Operating conditions (Insolation, tracking mode,
operating temperature, flow rate, wind speed and
other general weather conditions)
2. Properties of materials (reflectance, absorbtance,
and transmittance)
3. Receiver type (absorber shape, evacuated or non-
evacuated) and
4 Concentrator geometry (concentration ratio and
rim angle)
Because operating conditions may vary from
installation to installation, relative comparism between
existing reflectors may be difficult to achieve.
Comparatively, literature showed that the parabolic-
shaped-collectorgenerated the highest temperature than
any other reflector developed in modern times. This is
because it produces a point focus while others
generated a regional focus. However the production of
electroplated parabolic and Fresnel collectors requires a
sophisticated and costly fabrication process that is not
readily available in most developing countries. This
project therefore also aims at developing a collector
that has similar performance characteristics like the
conventional concentrating reflectors. It will be
constructed using local materials and constructional
techniques that are affordable by rural African dwellers.
II. DESIGN ANALYSIS
Many potential applications of solar heat require
higher temperature than those achievable by the best
flat plate collectors.
A concentrating collector comprises a receiver
where the radiation is absorbed and converted to some
other energy forms. A concentrator is the optical
system that directs beam radiation onto the receiver.
Therefore it is usually necessary to continually move
the concentrator so that it faces the solar beam.
The smooth optical surface of a reflector or lens
can be broken into segments, a trick invented by
Fresnel. Optically a Fresnel mirror can approximate a
focusing parabola. The effective aperture is obtained
by multiplying the total area of the Fresnel mirror by a
ground cover factor. Values of the factor between 0.3
and 0.6 are practical for Fresnel reflectorsDuffie and
Bechman, 1974.
The aperture of the system Aa is the projected area
of the concentrator, facing the beam. The concentration
ratio is the ratio of the area of aperture to the area of the
receiver.
CR = Aa/Ar
The individual plane or curved segments are each
designed to reflect radiation to the receiver. The
advantage of the system is in its lack of appreciable
dimension in the direction normal to the radiation
which may permit easy fabrication. A disadvantage
lies in the lost area between the segments near the rim
of the assembly.Duffie and Bechman, 1974
CONDUCTION: For the non-uniform flux
distribution of the radiation on the absorber’s surface,
substantial temperature gradients may exist across the
absorber’s surface and due to high surface temperature
of the absorber, the conduction losses through the
support structure may also be significant.
CONVECTION: Since the focal point of Fresnel
reflectors are located outside the reflectors, placing the
absorber in an open sunny location usually exposes it to
cooling breeze: This increases the convective losses
through forced convection by wind. The analysis of
this loss will be complex since the wind speed changes
from time to time. To reduce loss of heat from the
absorber by forced convection from wind which
severely limits the performance, the absorbermay be
sheltered on all sides except the top and bottom with a
wooden box. This will now reduce the analysis to free
convection by the air in the gap between the absorber
and casing.
RADIATION: Solar radiation arrives on the earth’s
surface at a maximum flux density of about 1 kW/m2
in
a wave length band between 0.3 and 2.5m. This is
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called short wave radiation and includes the visible
spectrum. Holman 1963.
Radiation losses are to the sky and or the
environmental. Solar collectors absorb radiation at
wavelengths around 0.5m and emit radiation at
wavelengths around 10mHolman1963.
The rate of radiation heat transfer between two
surfaces also depends upon their geometric
configuration and relationships. The influence of
geometry in radiation heat transfer can be expressed in
terms of the radiation shape factor between any two
surfaces 1 and 2.
III. DESIGN SPECIFICATION AND
CONSTRUCTIONAL DETAILS
MATERIAL SELECTION
The selection of materials for engineering design
and construction varies directly, with the type of
design, the aims and objectives of the design, the
function of each material and inversely with the cost
of the material, availability of the material,
processing of the material and maintenance.
Some of these factors have direct bearing with
the dimensions of the material, and the various ways
of joining the elements of the system. Others affect
the configuration of the total system and its usage.
The nature of the constructional problems, its
economics, the facilities and equipment available and
working methods play a key role in selection
exercises.
The solar Fresnel reflector being designed is
composed of two major parts
(1) The Fresnel reflector
(2) The tracking stand.
Table1: Materials Used For The Fresnel Reflector
S/No DESCRIPTION DIMENTION m QTY
1 Plywood 1.22x2.44x0.019 2
2 Plywood 1.22x2.44x0.0125 1
3 Galvanized iron sheet 1.22x2.44x.0.00055 2
4 Plain Mirror 0.42x1.22x0.003 4
5 Wood screws 0.04 1pkt
6 Nails 0.0125 0.5kg
7 Evostic 4litres
8 Oxblood paint 4litres
The construction of the Fresnel reflector was
made up of five stages.
STAGE 1 PRODUCTION OF THE
TEMPLATE
In constructing the Fresnel reflector, a template
was produced. The procedure used
in producing the Fresnel template was as follows.
1. A reference base line was drawn on a cardboard
paper.
2. A principal axis perpendicular to the base line
was drawn
3. A convenient focal distance was chosen along
the principal axis (45cm was chosen in this
Design)
4. A convenient focal width parallel to the base line
at the point of focus was marked A and B.
(10cm was chosen in this design)
5. It was assumed that the first direct ray from the
sun passed through the point B, parallel to the
principal axis and met the base line at C. That
incident ray was marked i1
6. At point C, a reflected ray r1 was drawn to pass
through the focal width at point A.
7. The angle BCA was bisected and the normal to
the incident and reflected rays was drawn to pass
it. The normal was n1.
8. At point C, a line p1 perpendicular to the normal
was drawn.
9. A line parallel to r1 was drawn to pass through
point B and meet the perpendicular line from C.
This line torched the base line at D.
10. Another assumed incident ray i2 parallel to the
first incident ray i1 was drawn to meet the base
line at D.
11. At D a reflected ray r2 was drawn to pass through
point A on the focal width. The ray r2 met the
perpendicular line from C at E. The point CE
was then the length of the mirror segment as well
as the slanting height of the Frustum that was to
be developed.
12. The angle between i2 and r2 was bisected and
normal n2 was drawn to pass through it.
13. A line perpendicular to n2 was drawn to produce
the second segment of the template.
14. Processes 9 to 11 were repeated each time until a
template equal in length to the radius of the
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circle derived from the collector area calculated
was achieved. In this case, the length was 47
cm. The ray diagram described in 1 to 14 above
is shown in figure 1 and the template in figure 2.
Figure 1 Ray diagram used for the development of template
Figure 2 the developed template.
The diagram in fig 2 was cut out from the
cardboard and transferred to the 21 mm thick
plywood. Twenty four of these shapes were
produced.
STAGE TWO: DEVELOPMENT AND
PRODUCTION OF THE FRUSTUM RINGS.
1. The vertical and horizontal components of each
template segment with reference to the base line
and the principal axis were determined. These
points were indicated as shown in fig 3.
Fig 3 Ray diagram for the development of the
Frustum ring.
VE was d2
Oc was a1
O1V was A1
O1C was b1
O1E was B1
CE was d1
The completed image of fig 3 is shown in fig 4
Fig 4. Complete image of Fig 3
Note that
d2 = radius of the big cone
a1 = radius of the small cone
B1 = Slant height of the big cone
b1 = slant height of the small cone
d1 = slant height of the Frustum
The Frustum ring was developed by performing the
following operation.
(1) Half of the drawing in fig 4 was produced
(2) With d2 as radius and V as centre, an arc was
constructed from point E to meet the extended line
O1V at F.
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(3) With F as centre and same radius, the previous
arc was cut at G.
(4) With E as centre and same radius the previous
arc was cut at H.
(5) With centre O1, and radius B1 an arc was
produced starting from E to point J
(6) With O1, as centre and b1 as radius another arc
was produced starting from C to point k
(7) With FG as length 13 points were marked off on
the EJ arc.
(8) The points O1L and O1J were joined.
The above construction was drawn to scale and
when it was exploded gave the first Frustum ring of the
first segment of the template. The diagrams produced
are in fig 4 and fig5. The other Frustum rings for the
other segments of the template were produced
following the same steps.
Fig 5 Frustum ring
Figure 5
The full scale dimension of the Frustum ring was now
cut out from the 0.55 mm thick
galvanized iron sheet.
STAGE THREE: PRODUCTION OF THE
TRAPEZOIDAL SHAPED MIRROR TABLETS.
The circumference of the outer edges of the first
Frustum is C1 = 2d2
The circumference of the inner edges of the first
Frustum is C2 = 2a1
C1 was divided into twenty four equal parts and C2
was divided into twenty four equal parts and the two
divisions formed the two parallel sides of the
trapezoidal mirror tablets. The height of the mirror
tablet was B1 - b1 each. The other Frustums were
also developed. The first two Frustums were divided
into 24 each to form the dimension of the mirror
tables while the other three Frustums were divided
into 48 each to form the dimensions of the mirror
tablets.
The mirror tablets are shown below in fig 6
Fig 6 mirror tablets
STAGE FOUR: PRODUCTION OF THE BASE
PLATE
A circular disc with a diameter equal to the
diameter of the circular area calculated was cut out
from the 21 mm thick plywood.
Figure 7
STAGE FIVE: ASSEMBLING
The twenty four templates were fixed round the
surface of the circular disc with the aid of the 40 mm
wood screws. Each Frustum ring was nailed into
position at the right template segment with the aid of
the 15 mm nails. The mirror tablets were glued onto
the surface of the Frustum rings with the aid of evostic
as shown below
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.
Figure 8
THE TRACKING STAND
Table .2 MATERIALS USED FOR THE TRACKING STAND
S/No DESCRIPTION DIMENTION M QTY
1 Galvanized hollow pipe 0 0.05x 3.66 1
2 Galvanized hollow pipe 0 0.45 x 3.66 1
3 Bolts and nuts 0 0.01 x 0.04 8
4 Mild steel flat bar 0.005 x 0.05 x 3.66 1
5 Mild steel angle iron 0.002 x 0.025 x 3.66 1
6 Welding electrode 1pkt
7 Wire mesh 0.35 x 0.35 x 0.002 1
The pipes and flat bars were cut into appropriate dimensions and were joined together to produce the structure
in fig 9.
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Figure 9
The assembly drawing of the FRESNEL collector with the tracking stand is in fig10.
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Figure 10
IV. PERFORMANCE TEST
The Fresnel reflector mounted on its tracking stand
was positioned outside in the north-south direction to
facilitate an east-west tracking of the sun: The reflector
was adjusted by changing the position of the chain at 15
minutes time intervals for altitudinal changes in the
sun’s position. The azimuthal changes were
compensated for by rotating the stand. A black painted
aluminumdisc15cm in diameter and 1cm thickness was
placed at the focal point. Thermocouple wires were
attached to the Aluminum disc.AComark digital
thermometer was used for the readout. The reflector
was able to raise the temperature of the aluminum disc
to an average of 300o
C
V. DISCUSSION
A critical analysis of the results derived with the
aluminum disc showed that the reflector was able to
raise the temperature of the disc to an average
temperature of 300o
C. It was also able to boil 3kg of
water within an average time of 30 minutes for tests
carried out between 10.00 am and 1.00 pm. For tests
carried out between 12 pm and 3 pm an average water
boiling time of 24-28 minutes were recorded. The
difference in the boiling time could be traced to the fact
that solar intensity is normally higher during the
afternoons than in the mornings. This therefore shows
that the temperature generated with the Fresnel
reflector is directly related to the weather condition of
the time and day of testing.
VI. RECOMMENDATION FOR
FURTHER WORKS
Since the performance of the reflector is strictly
connected to the weather more efficient reflectors that
can produce higher temperature should be developed
and used. The fragile mirrors used as reflectors should
be replaced with developed flat sheets electroplated
with shinning surfaces. Automatic tracking mechanism
should also be developed and incorporated to make the
tracking less labour intensive.
VII. CONCLUSION
From the results obtained when the reflector was
used, it performed satisfactorily and did not deviate
much from the initial assumption made during the
designing stage. The reflector uses an energy that has
been generally accepted as the most promising,
renewable and non-polluting type of energy. The
reflector can also be produced using local materials and
does not involve complex constructional techniques.
The energy it uses is so decentralized that any user can
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use it without having to transport it to the sight of use.
The energy it uses is also free. Since its performance
isfavourable, it should be used for cooking in Africa.
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