GUJARAT TECHNOLOGICAL UNIVERSITY Chandkheda, AhmadabadC.K. PITHAWALA COLLEGE OF ENGINEERING AND TECHNOLOGY A Project Report on Design and Fabrication of Solar drying System Under Subject of Final Year Project B.E. (7th semester) - Mechanical Branch Submitted By: Group No. : P18 Sr. NoNameEnrollment Number1Brijesh R. Patel1300901190692Jigar V. Patel1300901190793Pratik J. Patel1300901190854Vishal M. Patel1300901190925Kevin K. Patel110090119106 Faculty Guide : Prof. Shailesh Kanthariya.Head of Department : Dr. Sonal DesaiAcademic Year : 2016-2017 CERTIFICATEThis is to certify the project entitled “Design and Fabrication of Solar Drying System” submitted by Group No: 18 in partial Fulfillment for the degree of B.E (7th sem.) of the Gujarat Technological University is a record of their own work carried out under my Supervision and guidance.GuideProf. Shailesh Kanthariya. EXAMINER’S CERTIFICATE OF APPROVALThe project “Design and Fabrication of Solar Drying System” Submitted by Group No: P18 in partial fulfillment for the award of the degree of B.E. (7th sem.) of the Gujarat Technological University is here by approved.EXAMINERS: 1. 2. Mechanical Engineering Department CERTIFICATEThis is to certify that research work embodied in this entitles “Design and Fabrication of Solar Drying System” was carried out by Group No.: 18 under C.K. Pithawala College of Engineering and Technology for partial fulfillment of degree Bachelor of Engineering in Mechanical Engineering to be awarded by Gujarat Technological University. This Project work has been carried out under our supervision and is to our satisfaction. Date:Place:Guided By: Head of the DepartmentProf. Sailesh Kantharia Dr. Sonal DesaiInternal Examiner Sign: _______________ External ExaminerSign: ________________ ACKNOWLEDGEMENT I would like to articulate my profound gratitude and indebtedness to my thesis guide Prof. Sailesh kantharia who has always been a constant motivation and guiding factor throughout the thesis time in and out as well. It has been a great pleasure for me to get an opportunity to work under him complete the project successfully I wish to extend my sincere thanks to Dr. Sonal Desai, Head of our Department, for approving our project work with great interest. We express our profound gratitude to Dr. Anish Gandhi, Principal for his outstanding cooperation to provide all required facilities and proper guidance. My sincere thanks to C. K. Pithawala college of Engineering and Technology for providing us great environment for project work and also thankful to entire staff of Mechanical Department. Last but not the least, my sincere thanks to all of my friend who have patiently extended all sorts of help and motivate for accomplishing this undertaking.PATEL BRIJESH R. (130090119069)PATEL JIGAR V. (130090119079)` PATEL PRATIK J. (130090119085)PATEL VISHAL M. (130090119092)PATEL KEVIN K. (110090119106) TABLE OF CONTENTS Title page I Certificate II Acknowledgment III Table of Contents V List of Figures VI List of Tables VII Nomenclature X Abstract VIII Chapter 1 IntroductionSolar Power in IndiaWhat Is Drying?Advantages and Disadvantages of DryingNeeds of Solar dryingClassification Of Solar Dryer Direct Solar DryerIndirect Solar DryerForced Convection and Natural Convection solar DryerActive Solar Dryer and Passive Solar DryerDifferent Dryer Designs Chapter 2 Literature SurveyLiterature SurveyProblem Definition Research GapResearch objectives Chapter 3 Research methodology Chapter 4 Design and Analysis of solar Dryer SystemRadiation TerminologyCalculate the radiationDesign Equation for the solar dryer proposed experimental set-upReferencesAppendix-ILIST OF FIGURES FIG. NAME OF FIGURE PAGENO. NO.1.1 Installed solar Power Capacity in India 111.2 View of Classification 141.3 Direct solar drying (Natural convection type cabinet drier) 151.4 Indirect Solar Drier 16 1.5 Typical solar energy dryer designs 193.1 Proposed Research Methodology 24 4.1 Solar Angle 254.2 Solar Angle 264.3 Proposed Experimental Setup 29 Nomenclature ρ - Density of Air Ic- Insolation on the Collector ΔΤ - Temperature Cp - Specific Heat A - Effective Area L - Latent Heat of vaporization of water, M - Mass of the crop, T - Time of drying. q/A - Rate of Heat Transfer Per Unit Area, ha - Heat Transfer coefficient For the ambient, hd - Heat Transfer coefficient For the dryer chamber, Ta - Ambient Temperature, Td - Chamber Temperature, σ - Stefan-Boltzman constant, Δx - Thickness of the glass cover, A - Effective area of the collector L - Latent Heat of vaporization of water, Mw - Mass of crop before drying Ρ - Density of water, Ta - Ambient Temperature, Tb - Dryer Temperature. ABSTRACTDrying Crops by the solar energy is the great economic importance the world over, especially in countries where most of the crops and grain harvests are lost to fungal and microbial attacks. These wastages could be easily prevented by the proper drying, which enhance storage of crops and grains over long periods of time. This solar energy can be easily harnessed by a proper design of solar dryers for seed drying. This method of drying requires the transfer of both heat and water vapour. The objective of this work is to design and construct a modified portable forced circulated solar dryer, evaluate the performance over a climate conditions, and optimize the parameters needed for the thermal performance of the dryer. This experimental model have been used to predict product quality by achieving a compromise between drying rate, energy consumption, and grain quality. Such low-cost drying technologies can be readily introduced in rural areas to reduce spoilage, improve product quality and overall processing hygiene.KEY WORDSSolar Energy, Solar collector, Active Dryer, Design and Fabrication, Optimal Temperature, performance.Chapter 1 INTRODUCTIONSolar power in IndiaEnergy resources are getting depleted day by day at a very alarming rate. So continuous research is going on around the world to harness energy from other renewable sources. While we think of the word “Renewable” the very first thing that comes to our mind is “Solar”. With about 300 clear, sunny days in a year, India receives about 5 Petawatt-hours per year (PWh/year) (i.e.; 5 trillion KWH/day). The daily average solar energy incident over India varies from 4 to 7 kWh/m2 with about 1500-2000 sunshine hours per year), which is far more than current total energy consumption. For example, assuming if losses are minimized and processes optimized with better ideas and better technology, solar energy has enough potential to cater to the needs of modern man. Here state-wise distribution of solar power is given in fig.Fig 1.1 Installed solar Power Capacity in IndiaWhat is drying?Drying is a dual process of Heat transfer to the product from the heating source and Mass transfer of moisture from the interior of the product to its surface and from the surface to the surrounding air.The objective of a dryer:1. Supply the product with more heat than the available under ambient conditions2. Increasing sufficiently the vapor pressure of the moisture held within the crop3. Decreasing relative humidity of the drying air4. Ensuring a Sufficiently low equilibrium moisture content. Advantages: 1. Better quality of products are obtained.2. It reduces losses and better market price to the products. 3. Products are protected against flies, rain and dust; product can be left in the dryer Overnight during rain, since dryers are waterproof. 4. Prevent fuel dependence and reduces the environmental impact.5. It is more efficient and cheap.Disadvantages:1. Adequate solar radiation is required.2. It is more expensive3. Require more time for drying. Needs of Solar DryingSolar drying is the most common, economical and eco-friendly method of preservation of agricultural products in the topical and sub-Saharan African regions.Generally in African countries, agriculture represent the biggest part of the economy. 80-90% of the working population is employed in agriculture. Despite this large numbers, national food production still does not meet the needs of the population. The lack of appropriate preservation and storage systems caused considerable losses, thus reducing the food supply significantly.The dent in food production caused by crop failures as well as significant seasonal fluctuation in availability can be ironed out by food conservation, e.g., by drying.This method is most applicant where the solar radiation is very high for most of the year.In order to ensure continuous food supply to the growing population and to enable the farmers to produce high quality marketable products, efficient and at the same time affordable drying methods are necessary. There’s also some drawbacks of this method, but taking proper steps, it can be eliminated. Steps may include the technical upgradation so by improving required features, the solar drying system become the one of the widest using devise in reserved countries. Classification of Solar Dryer Following criteria are required for the classification of solar dryer:-1) Air movement mode2) Insulation exposure3) Air flow direction4) Dryer arrangement5) Solar contribution6) Type of fruit to be dried7429505003165Fig 1.2 View of ClassificationDirect Solar Dryer:Solar radiation is directly absorbed by the product to be dried. Direct solar dryers expose the substance to be dehydrated to direct sunlight. It is also called as “Natural Convection Cabinet Dryer”.The application of direct solar dryer is limited due to following reasons:Due to direct drying, the quality of food may decreased.Large in size compare to indirect solar dryer.Less efficient.9715504807585Fig 1.3 Direct solar drying (Natural convection type cabinet drier)Indirect Solar Dryer:The solar radiation gained by the system is utilized to heat the air which flows through the product to be dried quality of product improved though drying rate increased better control over drying is achieved.Indirect solar dryers are less compact compare to direct solar dryers.They are generally more efficient. Fig 1.4 Indirect Solar DrierNatural Convection Solar DryerNatural movement of air takes place thus called as passive dryers. The heated air flow is induced by thermal gradient.Forced Convection Solar DryerAir is forced through a solar collector and the product bed by a fan or a blower, normally referred to as active dryer.Active Solar DryerActive solar dryer is same referred as Natural Convection Solar Dryer. In such system, solar heated air is circulated through the product naturally. Due to natural convection, the application is limited or use only for small purposes.The process is time consuming.Passive Solar DryerPassive solar Dryer is same referred as Forced Convection Solar Dryer.In such system, solar heated air is circulated through the product by buoyancy forces or as a result of wind pressure, acting either singly or in combination.They are generally of a size appropriate for on farm use.They can be either direct (e.g. tent and box dryer) or indirect (e.g. cabinet dryer).Design arrangement of system components and the mode of utilisation of the solar heat are classified as-1. Integral type solar dryers Termed Direct Solar Dryers.Solar radiation impinges directly on the product. The heat extracts the moisture from the crop and lowers the relative humidity of the resident air, thereby increasing its moisture carrying capability.2. Distributed type solar dryersThese are often termed indirect passive solar dryers.Solar radiation is not incident directly on the crop, caramelization and localised heat damage do not occur.Higher operating temperatures than direct dryers.3. Mixed-mode type solar dryersThere are often turn to direct and indirect drying of third dryer. There are two types of flow occurs in the dryer.Different Dryer Designs:6096002250440Fig 1.5 Typical solar energy dryer designsChapter 2 Literature Survey2.1 Literature Survey1) Bukola O. Bolaji and Ayoola P. Olalusi Suggested that construction and performance evaluation of a mixed-mode solar dryer for food preservation. In the dryer, the heated air from a separate solar collector is passed through a grain bed, and at the same time, the drying cabinet absorbs solar energy directly through the transparent walls and roof. The results obtained during the test period revealed that the temperatures inside the dryer and solar collector were much higher than the ambient temperature during most hours of the day-light. The temperature rise inside the drying cabinet was up to 74% for about three hours immediately after12.00h (noon). The drying rate and system efficiency were 0.62 kg/h and 57.5% respectively. The rapid rate of drying in the dryer reveals its ability to dry food items reasonably rapidly to a safe moisture level.2) Ahmed Abed Gatea suggested that this paper presents the design, construction and performance evaluation of solar drying for maize, the solar drying system consists of V-groove collector of 2.04 m² area, drying chamber and blower. It was designed in such a way that solar radiation is not incident directly on the maize. K-type thermocouples were used for temperature measurement, while solar radiation was measured by solar meter m od.776. The thermal energy and heat losses from solar collector were calculated for each three tilt angles (30º, 45º, 60º). The results obtained during the test period denoted that the maximum gained energy occurred at 11 o\'clock hour and then gradually declined since the maximum solar radiation occurred at this time. The performance of the solar drying system was highly dependent on the solar radiation, tilt angle and ambient temperature. The total loss factor of the collector increases with the increase in the intensity of solar radiation intensity. The theoretical thermal energy, the experimental actual heats gain increase by increasing radiation intensity.3) M. MOHANRAJV, P. CHANDRASEKAR suggested that an indirect forced convection solar drier integrated with different sensible heat storage maternal has been developed and tested its performance for drying chili under the metrological conditions of Pollachi, India. The system consists of a flat plate solar air heater with heat storage unit, a drying chamber and a centrifugal blower. Drying experiments have been performed at an air flow rate of 0.25 kg/s. Drying of chili in a forced convection solar drier reduces the moisture content from around 72.8% (wet basis) to the final moisture content about 9.1% in 24 h. Average drier efficiency was estimated to be about21%. The specific moisture extraction rate was estimated to be about0.87 kg/kWh.4) F.K. Forson, M.A.ANazha, F.O. Akuffo, H.Rajakaruna suggested that A mixed-mode natural convection solar crop dryer (MNCSCD) designed and used for drying cassava and other crops in an enclosed structure is presented. A prototype of the dryer was constructed to specification and used in experimental drying tests. This paper outlines the systematic combination of the application of basic design concepts, and rules of thumb resulting from numerous and several years of experimental studies used and presents the results of calculations of the design parameters. A batch of cassava 160 kg by mass, having an initial moisture content of 67% wet basis from which 100 kg of water is required to be removed to have it dried to a desired moisture content of 17% wet basis, is used as the drying load in designing the dryer. A drying time of 30-36 h is assumed for the anticipated test location (Kumasi; 6.7°N,1.6°W) with an expected average solar irradiance of 400 W/m2 and ambient conditions of 25 °C and 77.8% relative humidity. A minimum of 42.4 m2 of solar collection area, according to the design, is required for an expected drying efficiency of 12.5%. Under average ambient conditions of 28.2 °C and 72.1% relative humidity with solar irradiance of 340.4 W/m2, a drying time of 35.5 h was realised and the drying efficiency was evaluated as 12.3% when tested under full designed load signifying that the design procedure proposed is sufficiently reliable.5) R. VidyaSagar Raju1, R. Meenakshi Reddy2, E. SivaReddy suggested that Sun drying is still the most common method used to preserve agricultural products in most tropical and subtropical countries. However, being unprotected from rain, wind-borne dirt and dust, infestation by insects, rodents and other animal, products may be seriously degraded to the extent that sometimes become inedible and the resulted loss of food quality in the dried Products may have adverse economic effects on domestics and international markets. Some of the problems associated with open-air sun drying can be solved through the use of a solar dryer which comprises of collector, a drying chamber and sometimes a chimney.The conditions in tropical countries make the use of solar energy for drying food practically attractive and environmentally sound. Dryers have been developed and used to dry agricultural products in order to improve shelf life. Most of these either use an expensive source of energy such as electricity or a combination of solar energy and some other form of energy. Most projects of these natures have not been adopted by the small farmers, either because the final design and data collection procedures are frequently inappropriate or the cost has remained inaccessible and the subsequent transfer of technology from researcher to the end user has been anything but effective. Drying may be an interesting method in order to prevent fresh fruit deterioration. There is spoilage of fruits and other fresh foods that could be preserved using drying techniques in India and other developing countries. Seasonal fruits like mangoes are not presently dried for export, or for local consumption during period of scarcity.Problem Definition:Through literature review problem is defined to get benefits of forced circulated solar drying which is effective as compared to natural circulation dryer (passive) type and design, and carried out the thermal analysis of the systemResearch Gap:Few researchers have done work on forced circulated drying with roughened absorber plate so finally decide to work on forced circulated drying system with roughened air collector to improve system performance and make faster return on investment.Research Objectives:Design and construct a modified portable solar grain dryer evaluate the performance over a low temperature and high relative humidity period Optimize the parameters needed for the optimal performance of the dryer.Chapter 3 Research Methodology11607802095500Fig 3.1 Proposed Research MethodologyChapter 4 Design and Analysis of Solar Drying SystemRadiation Terminology1. Beam radiationSolar radiation that has not been absorbed or scattered and reaches the ground directly from the sun is called “direct radiation ’’or beam radiation.2. Diffuse radiationDiffuse radiation is that solar radiation received from the sun after its direction has been changed by reflection and scattering by atmosphere.3. Global radiationSolar radiation on a horizontal surface due to both direct sun rays and diffuse sky radiation.Calculate the Radiation14079686134095 Fig 4.1 Solar angleDeclination angle (δ): δ = 23.45 sin (284 + n)Where n= number of dayLatitude angle (Ø): For Location Surat latitude angle is 21.170◦.Hour angle (ω):It is an angular measure of time and is equivalent to 15◦ per hour. It is also varies from - 180◦ to +180◦.18478503992245 Fig 4.2 Solar angleZenith angle (ӨZ):It is a vertical angle between the sun rays and line perpendicular to the horizontal plane through the point.ӨZ = (sin Ø sin δ + cos Ø cos δ cos ω)Solar azimuth angle (γs):It is angle made in the horizontal plane between due south and projection of the line of sight of the sun on the horizontal plane.cos γs = (cos Өz sin Ø - sin δ) / sin Өz cos ØAltitude angle (α): For Location Surat Altitude angle 72. Hourly beam radiation:Ibn = A exp Where, A – Apparent direct normal solar flux at the Outer edge of the earth’s atmosphere. B – Apparent atmospheric extinction coefficientHourly diffuse radiationId = C Ibn Where, C – dimensionless CoefficientHourly global radiation:Ig = Ibn cos Өz + IdDesign Equations for the solar dryer1. Collector efficiency:This is computed from, Ƞ= ρvCp∆TAIc ρ - Density of airIc - Insolation on the collector ΔΤ- temperatureCp - specific heat A - effective area2. Dryer efficiencyWhere,η=MLIcAtL -latent heat of vaporization of water, M- mass of the crop,T -time of drying.3. Rate of heat flow into the dryerThis is the sum of the convective heart (qc)Conductive heat (qk), and radiative heatq=qc+qk+qrTransfers (qr),q/A= rate of heat transfer per unit area,ha = heat transfer coefficient for the ambient,qA = Ta -Td 1ha+ Δxk+1hd+ εσ(Ta4-Td4) hd = heat transfer coefficient for the dryer chamber, Ta = ambient temperature, Td = chamber temperature, σ = Stefan-Boltzman constant, Δx = thickness of the glass cover, A = effective area of the collector4. Heat energy Q needed for crop drying at moderate temperatureWhere, L = latent heat of vaporization of water,Q=MwL= ρCp V(Ta-Tb) M = mass of crop before drying, ρw = density of water, Ta = ambient temperature, Tb = Dryer temperature.5. Moisture Content (M.C.):MC%=Mi-MfMi×100% Where Mi = mass of sample before drying and Mf = mass of sample after drying.6. Moisture loss (ML):ML=Mi-Mf(g)Where, Mi - mass of the sample before drying and Mf - mass of the sample after.Proposed experimental set up10096501842770 Fig 4.3 proposed experimental setup4.4.1 Solar dryer consists of1. Appropriately insulated ducting2. Drying chamber or drying tray3. Chimney.4. Collector box5. Roughness Geometry Absorber plate6. Glass cover7. Centrifugal blower or exhaust fan8. Manometer9. Valves10. Temperature sensor REFERENCES1. M. Mohanraj, P.Chandrasekar et al. “Performance of a Forced Convection Solar Drier Integrated With Gravel As Heat Storage Material For Chilli Drying” Journal of Engineering Science and Technology Vol. 4, No. 3 (2009) 305 - 314.2. Ahmed Abed Gatea.et al. “Design, construction and performance evaluation of solar maize dryer \"Journal of Agricultural Biotechnology and Sustainable Development Vol. 2(3), pp. 039- 046, March 20103. 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Arinze EA, Schoenau G, Bigsby FW. Solar-energy absorption properties of some agricultural products ASAE paper, no. 79-3071, 1979.16. Brooker DB, Bakker-Arkema FW, Hall CW. Drying cereal grains. Westport AVI, 1974.17. Hall CW. Drying and storage of agricultural crops. Westport AVI, 1980.18. Schirmer ETAL. . “Experimental Investigation of the Performance of the SolarTunnel Dryer for Dryin Bananas” Renewable Energy, Vol. 7, No. 2, pp: 119-129, 1996.
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