This document discusses the design of an air preheater for a solar dryer used to dry cereals. It describes the major components of a solar dryer, including the air preheater, air duct, and drying cabin. The air preheater is important as it concentrates solar energy to heat the air. Absorber plates made of materials like copper or aluminum are used to absorb solar radiation and heat the air flowing over them via convection. The heated air is then directed through ducts to the drying cabin where it removes moisture from cereals placed on trays. Empirical correlations are presented that can be used to model the performance of such a system and optimize the design of the air preheater.
Due to the current trends towards higher cost of fossil fuels and uncertainty regarding future cost
and availability, use of solar energy in food processing will probably increase and become more
economically feasible in the near future.The solar dryer is one of them which help to preserve our food and many eatable things like vegetable fruits and many more things
AN APPLICATION OF SOLAR DRYER IN ORDER TO REMOVE MOISTURE AND DIFFERENCIATING...Anugrah Soy
Due to the current trends towards higher cost of fossil fuels and uncertainty regarding future cost
and availability, use of solar energy in food processing will probably increase and become more
economically feasible in the near future.The solar dryer is one of them which help to preserve our food and many eatable things like vegetable fruits and many more things . In this experiment we find that how much moisture removed from the sample which is present in solar dryer and the sample which is present in ordinary air and we compare both of them by mathematical calculation. In this paper we took green chili, some of the chili we put inside the dryer and some in the ordinary air and then compare their moisture removed with respect to time and temperature.
DESIGN AND DEVELOPMENT OF HYBRID SOLAR DRYER FOR DOMESTIC APPLICATIONSsangeetkhule
Introduction
Role of The Sun
Importance of Renewable Energy Sources
Solar Drying
Basics of Solar Energy
Working of Solar Cell
Basics of Solar Thermal Conversions
Outline of Thesis
Solar Dryer
Basics of Solar Dryers
Need For Dryers
Various Methods of Drying
Basics of Solar Drying Technique
Difference Between OSD & Solar Drying
Various Types of Solar Dryers
Working Consist of Hybrid Solar Dryer
Advantages & Reasons For Limited Use In India
Applications of Solar Dryers
Literature Review
Direct Solar Dryer
Indirect Solar Dryer
Mixed Mode Solar Dryer
Hybrid Solar Dryer
Conclusions
The outcome of Literature Review
Selection of Food Products
Methodology And Design Criterion
Methodology
Design Criterion
Selection of Solar Dryer Type
Design of Solar Dryer
Working of Model
Design Calculations
The Fan/Blower Design
Computer-Aided Design of Hybrid Solar Dryer
Solar Collector
Drying Chamber
Trays
Stand
Computational Analysis
Pre-Processor
PostProcessor
Economic Analysis
Economic Analysis of Dried Food Products
Bill
Actual Components For Fabricating
Commercial Solar Dryers
Other Locations
Conclusion And Recommendations
Conclusion
Recommendations
References
Power Requirements
Optimum Angle of Inclination
Solar Collector Area Calculations
Calculation of Components
Solar radiation and it effects on human health . Sun is essential for life at the same time it is dangerous to humans . There are equal and opposite effects of sun on humans . Here are some of effects due to UV on humans .
Due to the current trends towards higher cost of fossil fuels and uncertainty regarding future cost
and availability, use of solar energy in food processing will probably increase and become more
economically feasible in the near future.The solar dryer is one of them which help to preserve our food and many eatable things like vegetable fruits and many more things
AN APPLICATION OF SOLAR DRYER IN ORDER TO REMOVE MOISTURE AND DIFFERENCIATING...Anugrah Soy
Due to the current trends towards higher cost of fossil fuels and uncertainty regarding future cost
and availability, use of solar energy in food processing will probably increase and become more
economically feasible in the near future.The solar dryer is one of them which help to preserve our food and many eatable things like vegetable fruits and many more things . In this experiment we find that how much moisture removed from the sample which is present in solar dryer and the sample which is present in ordinary air and we compare both of them by mathematical calculation. In this paper we took green chili, some of the chili we put inside the dryer and some in the ordinary air and then compare their moisture removed with respect to time and temperature.
DESIGN AND DEVELOPMENT OF HYBRID SOLAR DRYER FOR DOMESTIC APPLICATIONSsangeetkhule
Introduction
Role of The Sun
Importance of Renewable Energy Sources
Solar Drying
Basics of Solar Energy
Working of Solar Cell
Basics of Solar Thermal Conversions
Outline of Thesis
Solar Dryer
Basics of Solar Dryers
Need For Dryers
Various Methods of Drying
Basics of Solar Drying Technique
Difference Between OSD & Solar Drying
Various Types of Solar Dryers
Working Consist of Hybrid Solar Dryer
Advantages & Reasons For Limited Use In India
Applications of Solar Dryers
Literature Review
Direct Solar Dryer
Indirect Solar Dryer
Mixed Mode Solar Dryer
Hybrid Solar Dryer
Conclusions
The outcome of Literature Review
Selection of Food Products
Methodology And Design Criterion
Methodology
Design Criterion
Selection of Solar Dryer Type
Design of Solar Dryer
Working of Model
Design Calculations
The Fan/Blower Design
Computer-Aided Design of Hybrid Solar Dryer
Solar Collector
Drying Chamber
Trays
Stand
Computational Analysis
Pre-Processor
PostProcessor
Economic Analysis
Economic Analysis of Dried Food Products
Bill
Actual Components For Fabricating
Commercial Solar Dryers
Other Locations
Conclusion And Recommendations
Conclusion
Recommendations
References
Power Requirements
Optimum Angle of Inclination
Solar Collector Area Calculations
Calculation of Components
Solar radiation and it effects on human health . Sun is essential for life at the same time it is dangerous to humans . There are equal and opposite effects of sun on humans . Here are some of effects due to UV on humans .
A solar cooker is a device which is used to cook food by utilizing the heat energy radiated by the sun.
It utilizes the principle of reflection, concentration, absorption and greenhouse effect to convert sunlight to heat energy.
Most common, inexpensive and easier to build
A solar cooker consists of an insulated metal box or wooden box which is painted all black from inside.
Drying is an important unit operation in food processing which aids in preservationthrough the lowering of water activity of the product by evaporation of water. Using a solar dryer is comparatively cheaper and more efficient. Some solar dryersrun
without electrical grid power or fossil fuels. Various kinds of solar dryers that are widely used today. The indirect direct and mixed mode dryers that have shown potential in drying agricultural products in the tropical and subtropical countries are discussed. Aside from identifying the active and passive mode solar dryers, we also high light the environmental influence on solar energy (harnessing) that plays a vital role in the solar drying sector and related technologies that can help improve existingsolar dryers.
Solar drying is one of the application of solar energy. Drying means moisture removal from the product. Drying is helpful in preserving food product for long time; it prevent product from contamination. Direct solar drying, indirect solar drying, and mixed mode solar drying these are different solar drying methods. Primarily open to the sun or direct sun drying technique is used. However, it has some disadvantages. These disadvantages can be eliminated by indirect type of dryer which is used for drying products as application of solar energy. In this paper, we studied the different technique of drying and various modes of solar drying
Principles, Classification and Selection of Solar DryersiMentor Education
A comprehensive review of the fundamental principles governing the drying process with classification of the practically realized various designs and selection of solar
dryers for drying of agricultural and marine products has been presented. The classification clearly illustrates that the solar dryer designs can be grouped systematically according to their operating temperature ranges, heating
sources/modes and operational modes. It is difficult to have one single criteria for the selection of a solar dryer for a specific region or a product as solar insolation and other parameters change frequently with geographical location, however the general rules of thumb are mentioned to assist in making the final selection. The final selection is generally based on the available insolation rate, production
throughput, flexibility requirements, cost of fuel to run accessories as well as on the experience and judgment of the fabricator. As the solar dryer has a long life of about 20-40 years, the effect of a poor design can have a long-term impact on the economic health of the dryer.
Drying is the oldest preservation technique of agricultural products and it is an energy intensive process. High prices and shortages of fossil fuels have increased the emphasis on using alternative renewable energy resources. Drying of agricultural products using renewable energy such as solar energy is environmental friendly and has less environmental impact.
A solar cooker is a device which is used to cook food by utilizing the heat energy radiated by the sun.
It utilizes the principle of reflection, concentration, absorption and greenhouse effect to convert sunlight to heat energy.
Most common, inexpensive and easier to build
A solar cooker consists of an insulated metal box or wooden box which is painted all black from inside.
Drying is an important unit operation in food processing which aids in preservationthrough the lowering of water activity of the product by evaporation of water. Using a solar dryer is comparatively cheaper and more efficient. Some solar dryersrun
without electrical grid power or fossil fuels. Various kinds of solar dryers that are widely used today. The indirect direct and mixed mode dryers that have shown potential in drying agricultural products in the tropical and subtropical countries are discussed. Aside from identifying the active and passive mode solar dryers, we also high light the environmental influence on solar energy (harnessing) that plays a vital role in the solar drying sector and related technologies that can help improve existingsolar dryers.
Solar drying is one of the application of solar energy. Drying means moisture removal from the product. Drying is helpful in preserving food product for long time; it prevent product from contamination. Direct solar drying, indirect solar drying, and mixed mode solar drying these are different solar drying methods. Primarily open to the sun or direct sun drying technique is used. However, it has some disadvantages. These disadvantages can be eliminated by indirect type of dryer which is used for drying products as application of solar energy. In this paper, we studied the different technique of drying and various modes of solar drying
Principles, Classification and Selection of Solar DryersiMentor Education
A comprehensive review of the fundamental principles governing the drying process with classification of the practically realized various designs and selection of solar
dryers for drying of agricultural and marine products has been presented. The classification clearly illustrates that the solar dryer designs can be grouped systematically according to their operating temperature ranges, heating
sources/modes and operational modes. It is difficult to have one single criteria for the selection of a solar dryer for a specific region or a product as solar insolation and other parameters change frequently with geographical location, however the general rules of thumb are mentioned to assist in making the final selection. The final selection is generally based on the available insolation rate, production
throughput, flexibility requirements, cost of fuel to run accessories as well as on the experience and judgment of the fabricator. As the solar dryer has a long life of about 20-40 years, the effect of a poor design can have a long-term impact on the economic health of the dryer.
Drying is the oldest preservation technique of agricultural products and it is an energy intensive process. High prices and shortages of fossil fuels have increased the emphasis on using alternative renewable energy resources. Drying of agricultural products using renewable energy such as solar energy is environmental friendly and has less environmental impact.
Design and fabrication of Air Pre Heater for Diesel engineVIKAS SHARMA
In a diesel engine, the fuel-air mixture is introduced at room temperature and burned inside the cylinder. After the fuel is burned, the combustion products are discharged at atmospheric pressure and high temperature. The heat generated during the combustion of fuel is partially converted into work to drive the car (or any load) and remaining is wasted to the atmosphere through exhaust gas and coolant. The efficiency of the engines is between 20% and 30%. This project highlights provision for incorporating a heating vessel for preheating air before admitting in to the cylinder of a diesel engine. The heating vessel comprises heating elements for heating the air flowing past said heating element, and a body for mechanically holding and electrically contacting said heating element.
The presentation was made at the "Business Meet on Applications of solar drying systems in domestic, industrial and commercial applications", SPRERI, Anand, India.
It presents the advantages of CFD as a design tool to design better solar drying systems.
For my blogs kindly refer: https://www.learncax.com/knowledge-base/blog/by-author/ganesh-visavale
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
Among the most important components of solar energy systems, solar collectors are devices that receive solar energy and convert it into thermal energy, as most essential components of solar dryer. This review presents description and previous work performed on performances of solar air collector for agricultural produce. In addition, various solar collectors are classified and described. Solar air collectors for drying application of agricultural produce are presented and summarize. The energy and exergy efficiency of the solar air collector ranges from 28% to 62% and from 30% to 57%, respectively.
Three solar air heater having different absorber areas by er. vikas manushendraVikas Manushendra
In earlier years, the entire world has become completely dependent on relic energies such as natural gas, lubricant and coal. This type of resources are existing in limited amount. These resources has been created by natural processes across millions of years. The whole world is completely dependent upon energy. Energy is the basic part of our daily life. The utilization of energy in different purpose such as heating and cooling homes, schools and businesses. Energy is also used for lighting and appliances. In machinery purpose, energy perform different function such as running our vehicle, flying plane, boat sail and running machine. Energy is the player of new generation wealth and also it is significant component of economic development. In future consideration renewable energy is the main source of energy. The complete world is developing day by day and it requires more and more fuel so all the developing countries are focusing on shortage of fuels and necessity for other energy sources. Solar energy is the best alternative source of energy and also it is pollution free and unlimited energy. Nowadays world, the development of country is calculated by the energy utilization of country, the energy of utilization is completely connected with GDP of Country.
Energy being a crucial input in the process of social, economical and industrial development, plays a vital role
in our daily lives. The present trends show a continuous increase in the energy demands, with a
simultaneous reduction in the available conventional energy resources. Hence, there is an urgent need to
come up with energy efficient alternatives, such as developing devices that employ renewable energy
resources. Sol Aura is one such product that holds the potential to replace conventional heaters that employ
electrical energy. Sol Aura utilizes solar energy for the required energy conversion and thus, increase the
temperature of indoor areas. The paper presents the product design and the related mathematical computations.
Future scope and the advantages have also been covered within the scope of the paper.
DESIGN, SIMULATION AND ANALYSIS OF A HYBRID-TYPE (PV/T) SOLAR AIR HEATER FOR ...ijiert bestjournal
This paper deals with the numerical analysis of a H ybrid-Type (PV/T) Solar Air Heater and a study on t he effect of various design parameters that enhance th e performance of the system. The heat transfer improvement in general may be achieved by increasin g the heat transfer coefficient or by increasing th e surface area or by increasing both. The main object ive of the present work is to determine the optimum air mass flow rate at which PV/T systems are to be oper ated and to develop an optimal design of a hybrid t ype (PV/T) solar air heater that shows better performan ce at various heat fluxes due to solar radiation. T his study determines the set of design parameters which lead to the best annual yield of the system. In th is study of a hybrid type (PV/T) solar air heater ICEM CFD (ANSYS) is used to obtain the optimum results,there by increasing the efficiency of the system.
Selection procedure for air filter used in automobile enginesSumit Dharmarao
This paper concentrates idea about importance of air filter in automobile engines, its influence on engine performance. Paper also deals with general guidelines and procedure for selection of air filter in automobile. Air filter can be defined as fibrous material device used to remove unwanted subtended particles from air like dirt, dust, pollen & many other undesired things. Many times, it may contain chemical agents like Absorbent or catalysts to improve air quality eliminate odors and active gaseous.
Design of solar drier for rice at karjat, raigad, maharashtraSumit Dharmarao
This paper deals with current practices of drying
agricultural products in most of developing nations
like India. It also try to coin the concept of utilization
of Solar dryer at farm side. In a developing country like
India, having the second largest population and
agriculture as the source of income to nearly 60 % of
the total population, post-harvest and storage loss is a
major quandary, which needs to be addressed in due
diligence. Many food preservation techniques like cold
storage, drying, etc., have been evolved out over the
years to tackle the above losses. The major constraint
is that almost all the technologies are utilizing fossil
fuel resources, which are depleting very fast and wise
use of these precious resources are preferred for longterm
energy sustainability. Therefore, sustainable
methods for food preservation are the need of the
hour. Solar drying is one of the best choices in this
context. The effect of temperature to moisture
contents against time and rate of drying are studied &
discussed in this paper.
Experimental analysis of various pcs by spark testingSumit Dharmarao
Knowledge of material properties, production
methods and manufacturing processes are each
important subject in the material science discipline.
Material testing methods are standardized by several
organizations, such as ASTM, ISO, ASM and DIN etc.
Materials are tested and their mechanical properties
are tabulated in handbooks. This project will explain a
study conducted on how a certain number of carbon
steels might be identified through the observation of
the sparks projected when a specimen is held against a
grinding wheel. There are many factors that can
change the spark patterns that are projected, but the
main goal of this project is to attempt to standardize a
method of spark testing and how it is performed. The
study was conducted on six different grades of carbon
steels that are commonly used in manufacturing
processes. A reference manual was created from the
experimental data cataloguing the spark pictures. This
manual can be used by students and potentially by
machine shops to identify samples of the included
materials. This can lead to significant savings for
machine shops by using a relatively easy, user friendly
method, to identify unknown stock sitting around in
the shop
Design of concentric solar water distillator.Sumit Dharmarao
Distillation is one of many processes available for water purification, and sunlight has heat energy that can be used to power that process. Sunlight has advantage of zero fuel cost but it available in attuned format so requires larger collector areas i.e. absorber surfaces due to this it becomes costlier equipment. It is misnomer that for distillation we need to boil water actually simply elevating its temperature, short of boiling will adequately increase the evaporation rate. In fact, although vigorous boiling hastens the distillation process it also can force unwanted residue into the distillate, defeating purification. To boil water with sunlight requires more costly apparatus than is needed to distill it little more slowly without boiling. Different levels of purification can be achieved with this equipment which can be used for sterilized water for medical uses. Purification of heavy water in dissolved salts differs from purification of water that has been dirtied by other chemicals processes.
Water harvesting – a solution to drought & falling level of ground water ...Sumit Dharmarao
India is one of the growing economy in the world. Nearly 65% population of nation depends upon agriculture to fulfill their needs, eventually whole economy of nation depends on Agriculture. Agricultural production based on availability of water. Due to high industrialization and deforestation rain rate is decreasing in Indian subcontinent which results in frequent droughts. Due to drought there is sudden reduction in agricultural production and also increased pressure on ground water. Shortness of water is coped by ground water. Every ones thirst of water results in undeclared competition eventually water level below ground falls down. Water harvesting means saving & storing every drop of water is the only solution to frequent drought & maintaining ground water level.
An introduction to application of zebra pattern for dissipation of heat in el...Sumit Dharmarao
This paper helps to correlate unique characteristics of special animals with the science involved in it and applying the same principles to solve our technical problems for better performance of machines & that too at low cost. This paper focuses at stripes of zebra, scientific cause of it & checking the possibility for application of zebra pattern for better dissipation of heat generated within electronic equipments which results in satisfactory output of machines & equipments.
Development of low cost dust collector for textile industrySumit Dharmarao
Cotton dust in the work place is major problem in cotton textile industries. This problem is more
severe in spinning section. Dust consists of small and microscopic particles of various substances
which are present as suspended particles in air. These particles are harmful to human health.
Because of this various diseases are occurred like shortness of breath, cough, and lungs cancer.
Various aspects of health hazards in textile industries have been discussed and measure hazards
is lungs cancer to reduce this health hazards is lungs cancer our dust collector is helpful.
Solar assisted dryer for municipal solid wasteSumit Dharmarao
Urban India generates 188,500 tons per day (68.8 million tons per year) of municipal solid waste (MSW) at a per capita waste generation rate of 500 grams/person/day. Improper solid waste management deteriorates public health, degrades quality of life, and pollutes local air, water and land resources. It also causes global warming and climate change and impacts the entire planet. Improper waste management is also identified as a cause of 22 human diseases and results in numerous premature deaths every year. The composition of urban MSW in India is 51% organics, 17.5% recyclables (paper, plastic, metal, and glass) and 31 % of inerts. The moisture content of urban MSW is 47% and the average calorific value is 7.3 MJ/kg (1745 kcal/kg). The composition of MSW in the North, East, South and Western regions of the country varied between 50-57% of organics, 16-19% of recyclables, 28-31% of inerts and 45-51% of moisture. The calorific value of the waste varied between 6.8-9.8 MJ/kg (1,620-2,340 kcal/kg). Currently, there is no system or mechanism exists to dry the municipal solid waste. In this research work such system can be designed and developed which will dry the municipal solid waste and remove the odor from it. Dried municipal solid waste can be further used as fuel for boiler.
7 Alternatives to Bullet Points in PowerPointAlvis Oh
So you tried all the ways to beautify your bullet points on your pitch deck but it just got way uglier. These points are supposed to be memorable and leave a lasting impression on your audience. With these tips, you'll no longer have to spend so much time thinking how you should present your pointers.
You could be a professional graphic designer and still make mistakes. There is always the possibility of human error. On the other hand if you’re not a designer, the chances of making some common graphic design mistakes are even higher. Because you don’t know what you don’t know. That’s where this blog comes in. To make your job easier and help you create better designs, we have put together a list of common graphic design mistakes that you need to avoid.
Dive into the innovative world of smart garages with our insightful presentation, "Exploring the Future of Smart Garages." This comprehensive guide covers the latest advancements in garage technology, including automated systems, smart security features, energy efficiency solutions, and seamless integration with smart home ecosystems. Learn how these technologies are transforming traditional garages into high-tech, efficient spaces that enhance convenience, safety, and sustainability.
Ideal for homeowners, tech enthusiasts, and industry professionals, this presentation provides valuable insights into the trends, benefits, and future developments in smart garage technology. Stay ahead of the curve with our expert analysis and practical tips on implementing smart garage solutions.
Unleash Your Inner Demon with the "Let's Summon Demons" T-Shirt. Calling all fans of dark humor and edgy fashion! The "Let's Summon Demons" t-shirt is a unique way to express yourself and turn heads.
https://dribbble.com/shots/24253051-Let-s-Summon-Demons-Shirt
Book Formatting: Quality Control Checks for DesignersConfidence Ago
This presentation was made to help designers who work in publishing houses or format books for printing ensure quality.
Quality control is vital to every industry. This is why every department in a company need create a method they use in ensuring quality. This, perhaps, will not only improve the quality of products and bring errors to the barest minimum, but take it to a near perfect finish.
It is beyond a moot point that a good book will somewhat be judged by its cover, but the content of the book remains king. No matter how beautiful the cover, if the quality of writing or presentation is off, that will be a reason for readers not to come back to the book or recommend it.
So, this presentation points designers to some important things that may be missed by an editor that they could eventually discover and call the attention of the editor.
Design of air preheater for solar dryer for drying cereals
1. NOVATEUR PUBLICATIONS
INTERNATIONAL JOURNAL OF INNOVATIONS IN ENGINEERING RESEARCH AND TECHNOLOGY [IJIERT]
ISSN: 2394-3696
VOLUME 2, ISSUE 2 FEB.-2015
1 | P a g e
Design of Air Preheater for Solar Dryer for Drying Cereals
Sumit S.Dharmarao
Shailesh A. Nehatrao
Sagar S. Raje
Department of Mechanical Engineering, Bramhadevdada Mane Institute of Technology,
Solapur, India
Abstract
This paper explains about various factors which are to be considering while designing solar
dryer for agriculture products. It includes the major parts like air pre heater, air duct, and
cabin for keeping agricultural products. Out of these parts of air pre heater is important as
solar energy is available in attuned form & we have to concentrate it with help of solar
collectors. In collectors absorber plates are made up of good thermal conductor like copper,
aluminium so the plate is get heated due to solar radiation & hence air is heated by the
convection process by forcing the air to flow over absorber plate & this heated air is directed
towards the cabin through ducts. After that heated air is made to flow over agricultural
products specially cereals lying in the cabin which is a closed space having number of trays
placed in vertical shell with suitable distance & heated air takes away moisture present in it.
Introduction
There is one strong bond between humans & solar energy, in our Indian culture sun represents
basic source of energy and that is why people pray to the sun. Humans are using solar energy
since from ancient times; one of the traditional uses of solar energy is to dry agricultural
products. Basically drying requires as most of crops & food are grown & harvested in
particular period of year so we have to preserve it so that we can consume it throughout the
year. On of the best method to preserve food is to store it at specific temperature & humidity
which is easily & inexpensively obtained by solar energy known. Drying with help of solar
energy is known as sun drying but involves many disadvantages like contamination of the
products by dust, birds, animals and insects, spoiling due to rain, wind and moisture, and the
method totally depends on good weather conditions. Further, the process is labour intensive,
unhygienic, unreliable, time consuming, non-uniform drying, and requires a large area for
spreading the produce out to dry. There are many other modern methods are available for
preservation like heating with mechanical or electrical heaters or even store at subzero
temperatures but it requires electricity or other form of fuel which used as energy As we know
there is tremendous rise in costs of fossil fuels & uncertainty of availability world is leading
towards the use of solar energy in our day to day life. In case of developing nations like
INDIA the adoption of non conventional energy sources has become compulsion. As Indian
economy is based on agricultural produce per year so that we have to focus on reducing cost
of processing of agricultural outputs so that overall profit will increase & available to
consumer at cheaper rate. Due to the current trends towards higher cost of fossil fuels and
uncertainty regarding future cost and availability, use of solar energy in food processing will
probably increase and become more economically feasible in the near future.
2. NOVATEUR PUBLICATIONS
INTERNATIONAL JOURNAL OF INNOVATIONS IN ENGINEERING RESEARCH AND TECHNOLOGY [IJIERT]
ISSN: 2394-3696
VOLUME 2, ISSUE 2 FEB.-2015
2 | P a g e
Solar Dryer
Solar dryer is closed space which is used to dry products in better & hygienic way. Solar
dryers have more advantages over sun drying if it is correctly designed. They give faster
drying rates by heating the air to 10-30 0
C above surroundings, which causes the air to move
faster through the dryer, lowers its humidity also deters insects. The faster drying results into
reduced risk of spoilage, improves quality of the product and gives a higher output, so
reducing the drying area that is required. Solar dryers also protect foods form dust, insects,
birds & animals. They can be constructed from locally available materials at a relatively low
capital cost & there are no fuel costs. Thus, they can be useful in areas where fuel or
electricity are expensive, land for sun drying is in short supply or expensive, sunshine is
plentiful but the air humidity is high. Moreover, they may be useful as a means of heating air
for artificial dryers to reduce fuel costs. Solar food drying can be used in most areas but how
quickly the food dries is affected by many variables, especially the amount of sunlight and
relative humidity. Typical drying times in solar dryers range from 1 to 3 days depending on
sun, air movement, humidity and the type of food to be dried.
MATERIALS USED TO CONSTRUCT SOLAR DRYER
In any design procedure selection of material is having considerable wattage as all the
standard values we are referring from design data book are depends upon what material we
have selected. While selecting material one should consider its mechanical, physical &
chemical properties so BIS recommended following materials
Table 1. Materials for various parts of air pre heater
Sr.No. Part Material Used
1 Absorber Plate Copper or Aluminium
2 Transparent cover Toughened glass
3 Insulation Glass Wool or Rock Wool
4 Casing Aluminium with epoxy coating externally
Flat-Plate Solar Collector
A grain-drying solar-assisted system is composed of a solar collector, a fan, an additional
energy source for air heating, a plenum (for air distribution) and a bin batch drying system.
Flat-plate collectors are used in air and water heating systems. The incident solar energy is
partially absorbed by a dark and opaque surface, part of this energy is transferred to the fluid
and the remainder is lost to the environment. The collector plate is covered with a glass in
order to minimize convective losses and create a “green house” effect. Figure 1 shows the
outline of a flat-plate collector for air heating and the main parameters involved in heat
transfers: incident solar radiation (I), cover heat loss coefficient (Uc
), coefficient of convective
heat transfer between cover and air (hc-a
), coefficient of convective heat transfer between plate
and air (hp-a
),
coefficient of radiation heat transfer between plate and cover (hrp-c
), bottom heat
loss coefficient (Ubottom
), ambient temperature (Tamb
), cover temperature (Tc
), air temperature
(Ta
) and mean plate temperature (Tpm
).
3. NOVATEUR PUBLICATIONS
INTERNATIONAL JOURNAL OF INNOVATIONS IN ENGINEERING RESEARCH AND TECHNOLOGY [IJIERT]
ISSN: 2394-3696
VOLUME 2, ISSUE 2 FEB.-2015
3 | P a g e
Figure 1: Flat-Plate Solar Collector Heat Transfer Parameters.
According to Plate Efficiency Factor [4] presented an expression (equation (1)) to describe the
performance of a solar collector by an energy balance involving energy gain and thermal and
optic losses. Since this equation assumes the mean plate temperature to be equal to the
collector inlet air temperature (Ti
), a heat removal factor (FR
) is introduced:
q = AplateFR [I(ζα) - UL(Tin-Tamb)]……….(1)
(UL
is the collector heat loss coefficient)
The instantaneous efficiency of the flat-plate solar collector (η) is defined as the ratio of the
rate of useful energy supplied by the collector (q) to the rate of incident solar energy in its
Plate area Aplate:
η = q/IA = FR (ζα) - FR UL [(Tin-Tamb)/I]……...(2)
(τα is the absorptance-transmittance product).
The products FR
(τα) and FR
UL
are assumed to be constant terms. They can be experimentally
determined by plotting η versus (Ti
-Tamb
)/I as a independent variable and applying a linear
regression to the set of experimental points. Two characteristic parameters of solar collectors
are obtained: one is related to thermal losses and gains (FR
(τα)) and the other is related to
thermal losses (FR
UL
). The ASHRAE 93-77 standard gives the procedures to characterize a
flat-plate collector and to calculate its characteristic parameters.
Energy Storage Collectors
The main characteristic of energy storage collectors is the high thermal inertia, represented by
a high value for the collector time constant [5]. The advantage of this unit in the drying
process is the capacity to avoid temperature peaks during the day and to continue transferring
heat even when the incidence of solar radiation ends. However, due to their nature,
characterization of these collectors based on ASHRAE 93-77 standard Equation (2) does not
supply appropriate information about operation of this equipment. An alternative is to
consider the storage collector as a flat plate and to use the daily efficiency η (ratio of the heat
supplied by the solar collector to the total incident radiation in a whole
4. NOVATEUR PUBLICATIONS
INTERNATIONAL JOURNAL OF INNOVATIONS IN ENGINEERING RESEARCH AND TECHNOLOGY [IJIERT]
ISSN: 2394-3696
VOLUME 2, ISSUE 2 FEB.-2015
4 | P a g e
ń = ∫ q dt / ( Aplate ∫ I dt)…………(3)
despite their high thermal inertia, concrete collectors have linear behaviour similar to that in
the instantaneous efficiency model [6] :
ń = a – b [(Tin-Tamb) / HT ]………. (4)
Where Tin is the mean inlet air temperature, Tamb is the mean ambient temperature, HT
is the
daily incident radiation on a tilted surface and a and b are the daily characteristic parameters.
Empirical Correlations
Absorber plate present in the solar heater assembly is get heated due to solar radiation falling
on it. An air from environment will enter into the solar heater assembly where the absorber
plate is placed. As the air present over there is get heated due to convection . this heated air
will move forward as its density will drop and it enters into garbage box where the moist
garbage is placed. This type of circulation of heated air is called thermo siphon action. While
heated air flowing through the garbage will remove the moisture from it. Provision of
electrical heating coil will come into picture when drying is required to carry during nights &
cloudy days.
Klein et al. determined a correlation between the solar fraction f (ratio of the heat supplied by
a solar system Qs
to the energy demand of the process Qp
) and two dimensionless design
parameters (X and Y) for an air heating solar system [7]:
F = Qs / Qp ……..(5)
X = AplateFR [UL(100 - Tamb)] / Q……..(6)
Y = AplateFR [(ζα)m HT] /Q……….(7)
f 1.040Y – 0.064 X – 0.159Y2
+ 0.00187X2
– 0.0095Y3
…….(8)
The above correlation assumes a system with an air flow rate between 5 and 2l m3
/s, a slope
equal to the local latitude plus or minus 15° and thermal storage pebble diameters between 1
and 3 cm. The correlation of (Equations 9 and 10) uses only one design parameter (Y)
because when Ti
=Tamb
the heat losses term in Equation (1) becomes negligible.
f = Y; 0 < Y < 0.2……….(9)
f = -0.009 + 2.0251Y – 3.0482
Y2
= 1.5263Y3
; 0.25 < Y < 0.554 ……….(10)
Conclusions
By following above generalized design procedure one can determine the Area of plate by
considering overall radiation falls on it & various losses from the pre heater i.e. through
conduction & radiation.
References
[1]Fellows,P.(1997).Guidelines For Small-Scale Fruit and Vegetable Processor s, FAO
Agricultural Services Bulletin 127, FAO of the United Nations, Rome,
5. NOVATEUR PUBLICATIONS
INTERNATIONAL JOURNAL OF INNOVATIONS IN ENGINEERING RESEARCH AND TECHNOLOGY [IJIERT]
ISSN: 2394-3696
VOLUME 2, ISSUE 2 FEB.-2015
5 | P a g e
[2] Boiln, H. R., and Salunkhe, D. K. (1982) Food Dehydration by Solar Energy, CRC
Critical Reviews in Food Science and Nutrition, pp:327-354.
[3] IS 12933 part 2: 2003(2003)Solar Flat Plate Collector – Specifications, Bureau of Indian
Standard, New Delhi.
[4] Bliss, R.W. Jr., The Derivations of Several “Plate-Efficiency Factors” Useful in the
Design of Flat-Plate Solar Heat Collectors, Solar Energy, Vol. 3, no. 4, pp. 55-64,1959
[5] Duffie, J.A. and Beckman, W.A. (1991), Solar Engineering of Thermal Process, 2nd ed.,
New York, John Wiley.
[6] Nayak, J.K., Sukhatme, S.P., Limaye, R.G. and Bopshetty, S.V.(1989), “Performance
Studies on Solar Concrete Collectors”, Solar Energy, Vol. 42, no. 01, pp. 45-56.
[7] Klein, S.A., Beckman, W.A. and Duffie, J.A.(1976).,“A Design Procedure for Solar Air
Heating Systems”, Solar Energy, Vol. 19, pp. 509-512.