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COMPUTER AIDED THERMAL DESIGN FOR A SOLAR DRYER
 

COMPUTER AIDED THERMAL DESIGN FOR A SOLAR DRYER

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Report for the project work carried out in the final year of B.Tech Agricultural Engineering

Report for the project work carried out in the final year of B.Tech Agricultural Engineering

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    COMPUTER AIDED THERMAL DESIGN FOR A SOLAR DRYER COMPUTER AIDED THERMAL DESIGN FOR A SOLAR DRYER Document Transcript

    • COMPUTER AIDED THERMAL DESIGN FOR A SOLAR DRYER PROJECT REPORT SUBMITTED BY: Achal Gupta (2005AE01BIV) B.TECH (AGRICULTURAL ENGINEERING) Project Advisor: Dr. Y. K. Yadav DEPARTMENT OF AGRICULTRAL, PROCESSING AND ENERGY COLLEGE OF AGRICULTURAL ENGG. & TECH. CCS HARYANA AGRICULTURAL UNIVERSITY HISAR-125004 2009
    • CERTIFICATE This is to certify that this project entitled, “Computer Aided Thermal Design of a Solar Dryer” submitted for Bachelor of Technology in Agricultural Engineering by Mr. Achal Gupta, Admission No. 2005AE01BIV, is based upon the project carried out by the student for the project course APE-482 and that no part of the project has been submitted for any other degree program. Date: Achal Gupta (2005AE01BIV) (DR. Y. K. YADAV ) (DR. Y. K. YADAV ) MAJOR ADVISOR HEAD DEPTT. OF AGRICULTURAL DEPTT. OF AGRICULTURAL PROCESSING & ENERGY PROCESSING & ENERGY COAE&T, CCS HAU COAE&T,CCS HAU HISAR-125004 HISAR-125004 (DR. M. K. GARG) DEAN COAE&T CCS HAU HISAR-125004 i
    • ABSTRACT Title of Project : Computer Aided Thermal Design for Solar Dryer Full Name : Achal Gupta Admission No. : 2005AE01BIV Title of Degree : Bachelor of Technology (Agricultural Engineering) Advisor : Dr. Y. K. Yadav Head, Department of Agricultural Processing and Energy ASHRAE provides the information for predicting of solar radiations at a particular place on the specified day for a clear sky. A Computer program was developed using the ASHRAE model on VISUAL BASIC platform. On clear days or cloudless skies, the predicted solar radiation by window based computer program using ASHRAE method were found in close agreement with the observed radiations. Knowing the drying properties of food products and the solar radiation data estimated by the model the computer program was extended for the design of solar dryer for a particular location. Graphs generated by the program for average daily solar radiations at a particular place for a day of the year can give a better insight of solar data geometry for that place and could predict the performance of solar dryer. Therefore, the developed mathematical model can be used to predict the dryer performance at different places by using the input data for that location. Advisor Signature of student Head of Department ii
    • A CK N O W L E D G E M E N T It is my privilege to express my sincere and deepest gratitude to my major advisor Dr. Y. K. Yadav Head Department of Agricultural Processing and Energy, for his learned counsel, proper guidance, continuous encouragement, constructive criticism and untiring enthusiasm in solving problems encountered during the work and preparation of this report. I sincerely wish to thank Dr. M. K. Garg, Dean College of Agricultural Engineering & Technology for providing all the necessary facilities. I am also thankful to Dr. D. K. Sharma and Er. Surjeet Jain and all the staff members of Department of Agricultural Processing and Energy for their co-operation and advice. I bow with reverence to my parents who made innumerable sacrifice for me. I also thank to all my friends and well wishers who from time to time showed great concern for my entire project and encouraged me. Last but not the least I am thankful to all those who helped me directly or indirectly but whose name do not find a mention in the endeavor. (Achal Gupta) iii
    • CONTENTS Chapter Description Page(s) 1 Introduction 1-3 2 Review of Literature 4-7 3 Materials and Methods 8-21 4 Results And Discussion 22-29 5 Summary And Conclusions 30 6 References 31-32 Symbols and Abbreviations 33-34 Appendices 35-58 iv
    • Chapter 1 INTRODUCTION Drying is a very important method in the processing of food items especially the preservation of fruits and vegetables. Use of proper drying techniques can significantly reduce the post-harvest losses of fruits and vegetables. Traditionally drying had been accomplished by the open sun drying. Then electricity had been used to accelerate the process of drying by use of tray dryers etc. Open sun drying is still the dominant one however; there exist many technical problems associated with open sun drying namely cloudiness and rain, insect infestation, high level of dirt and atmospheric pollution and intrusions from animals and men. Recently several solar drying techniques and equipments have been developed for drying various foods. In solar drying method, faster drying takes place which result a significant reduction in drying time. Product dried in solar dryer are superior in quality (colour and flavour). Though the same superior quality product can be obtained by using electricity or electric power, but the electric operations are expensive and are not within the reach of our rural and tribal population. India receives enormous amount of solar energy on an average of the order of 5 kWh/m2/day for about 300 days in a year. Therefore, there is abundant supply of sun’s energy which can be utilized. With the use of solar dryers there has been a good effort to save the world from energy crises at the same time being able to attain sustainable development. Solar dryer is a device for drying agricultural product under controlled conditions. The controlled drying means controlling the drying parameters like drying air temperature, humidity, drying rate and air flow rate. A solar dryer must be designed carefully keeping all the above drying parameters in mind. Since there are many options in the design of solar dryers, there is large variety of solar dryers. The dryers have been classified into several categories depending upon the mode of heating or the operational mode of heat derived from the solar radiations, and its subsequent use to remove the 1
    • moisture from the wet product. The solar dryers may be classified in the 3 categories: e.g. direct type dryer, indirect type solar Dryer and forced circulation type dryers or continues flow type dryers. In the direct type solar dryer the agricultural product is placed in shallow layer in an enclosure with a transparent cover. The solar radiations are directly absorbed by the product itself. The food product is heated up and the moisture from the product evaporates and goes out by the natural convection these kinds of dryers are popular in the developing countries. The various problems associated with these simple dryers are; slow drying, not much control on temperature and humidity, small quantities can be dried and some products due to direct exposure to the sun change colour and flavor. The example of these kinds of dryers is: rack or shelf type solar dryer, cabinet type solar dryers and green house type solar dryers. In indirect type solar dryer the product is not directly exposed to the solar radiations. These dryers use a drying chamber where food is placed. The air is heated in a solar air heater and then blown through the drying chamber. In some of the designs dryers receive direct solar radiations and also heated air from the solar air heater. In some other designs, the drying chamber receives hot air only from the air heater. These dryers are little superior then the direct type because here the drying temperature, humidity and the drying rates can be controlled to some extent. The considerable manipulation of the material feed is necessary because the temperature of air coming from the solar collector changes considerably with time. In forced circulation dryers hot air is continuously blown over the food product. The food product itself is loaded or unloaded continuously or periodically. This type of dryer is comparatively thermodynamically efficient, faster and can be used for drying large agricultural products. Information regarding solar energy availability at a particular location is essential in order to perform any activity regarding management, design and research of solar appliances. Since the solar radiations availability varies seasonally, daily and hourly as well as with the orientation, it is necessary to know the optimum orientation for a particular geographical location considering other climatic parameters that would receive the maximum solar radiations. In most of the agricultural applications simple flat plate 2
    • solar collectors are used and optimization of their orientations is important for achieving maximum effectiveness. Solar radiations, ambient conditions are different at different places on the earth. As these all factors affect the drying process in a solar dryer therefore there is a need to be able to make solar dryers as per the conditions at any particular place so as to get the maximum possible efficiency. The development of simulation model is a powerful tool for prediction of performance and can help designers to optimize the dryer geometry at various operating conditions without having to test experimentally the dryer performance at each condition. Therefore, the present study is undertaken with the following specific objectives: To develop a window based computer program for prediction of solar radiations. To develop a window based computer program for solar dryer design and its validation 3
    • Chapter 2 REVIEW OF LITERATURE The solar drying is the elaboration of the traditional methods of sun drying to enhance the effectiveness of drying. Development of simulation model of solar drying is a valuable tool for prediction of performance of solar drying systems. There has been continuous improvement in the model and efforts to perfect the drying time and its characteristics. Work done in the past has been reviewed and described in this chapter. Threlked and Jordan (1958) provided the values of constants A, B and C for different month during a year that was used for predicting of solar radiations. The American Society of Heating, Refrigeration and air-conditioning Engineers (ASHRAE) (1977) has given a method for estimating the hourly variation of global and diffuse solar radiation falling on a horizontal surface on a clear day. The equations are based on the exponential decay model in which the beam radiation decreases with increase in the distance traversed through the atmosphere. Pande (1980) developed an improved solar cabinet dryer made up of MS sheet provided with a glass roof. It was reported that the improved cabinet dryer with chimney is suitable for drying all types of fruits and vegetables within two to five days. Athwal and Neal (1981) developed a computer model to predict the solar radiation intensity at the ground level for a specific spectral region. The daily variations in the atmospheric water vapour and aerosol contents had introduced errors upto + 10% in the computed radiation levels. Mani and Rangarajan (1982) proposed a theoretical model to compute clear sky noon radiation. The accuracy of the model was found 1% to 2% and 3% to 5% at noon for direct and diffuse solar radiation respectively. Venkatesh and Prasad (1982) described the procedure to compute the spectral intensity of solar radiations using an atmospheric model. Malviya and Gupta (1987) designed and fabricated a cabinet dryer with chimney. They reported that drying of chilli from 80 to 6 per cent (wb) moisture content was achieved in four 4
    • days during the month of March as against six days in dryer without chimney. The organoleptic quality of product was found better. Virgnola and McDaniels (1989) described the relationship between direct radiations on horizontal and titled surfaces, examined on a daily and monthly average basis. The direct ratio factor, often called Rb. is shown to vary with beam intensity. A comparison is made between Rb calculated from hourly beam data from the Pacific Northwest, and Rb predicted using the atmospheric weighting model and other direct ration models. Davis and McKay (1989) evaluated selected models for estimation solar radiation on horizontal surfaces. Twelve models which simulate solar irradiance on horizontal surfaces were evaluated with data from seven countries. Simple , widely applicable models were considered which use standard meteorological observations. The principal components of a solar drying system are solar flat plate collector and drying unit. Solar flat plate collector (also called solar air heater) is used for heating the ambient air. Then the heated air from the solar collectors, passes to the drying unit. The drying takes place in a drying unit where air extracts moisture from the product to be dried.(Sodha and Chandra, 1994) Sharan and Kumar (1995) have developed fourier representation of ambient temperature and global radiation for several locations of the country. These may be useful for developing models for solar appliances, dryers, green houses, etc. When biological products, including cereal grains, are dried in a batch rather than as individual particles, they will initially display a constant rate drying period (Brooker et al., 1997). Because of the difference in drying behaviour of individual kernels and a bed of kernels, separate analysis is required for thin layer and deep bed drying. Drying with crop bed thickness less than 200 mm is termed as thin layer drying whereas, drying with crop bed thickenss more than 200 mm, it is called deep bed drying (Chakraverty, 1995). In convection drying, the constant drying rate of a biological product can be represented by the adiabatic evaporation of moisture from the surface of a wet bulb thermometre. The rate of drying during constant rate period is function of three external drying parameters: (i) Air velocity, (ii) air temperature and (iii) air humidity. (Henderson et al., 1997) A number of biological products, when dried as single particles or in thin layer under constant external conditions, exhibit a constant rate moisture loss during the initial drying period 5
    • followed by a falling rate drying period. Cereal grain kernels, however, usually dry entirely within the falling rate period, whereas high moisture products like fruits and vegetables dry under constant rate and falling rate period. Knowledge of drying principles is essential for simulation and optimal design of solar drying systems (Bala, 1998). Marion and George (2001) used METSTAT (meteorological/statistical) model to calculate hourly values of direct normal, diffuse horizontal, and global horizontal solar radiation for locations throughout the world. Opaque cloud cover, a key input parameter in METSTAT model, is derived from the DATSAV2 (database) layered cloud cover information. This model has got worldwide potential. Karim and Hawlader (2004) performed an experimental study of three types of solar air collector, namely flat plate, finned and v-corrugated towards achieving an efficient design of air collector suitable for a solar dryer. A series of experiments were conducted, based on the ASHRAE standard and concluded that v-corrugated collector was found to be most efficient collector and flat plate collector the least efficient. They also studied double pass operation of the collector led to further improvement of the efficiency compared to the single pass operation. The improvement in efficiency for the double pass mode was most significant in flat plate collector and least in the v-groove collector. Mohamed et al. (2005) conducted convective solar drying experiments in thin layers of Citrus aurantium leaves grown in Marrakech, morocco. The air temperature was varied from 50 to 60 °C; the relative humidity from 41% to 53%; and the drying air flow rate from 0.0277 to 0.0833 m3/s. A nonlinear regression analysis using a statistical computer program was used to evaluate the constants of the models. Janjai and Tung (2005) used roof integrated solar collectors for drying herbs and spices and its performance was tested. The dryer was a bin type with a rectangular perforated floor. The bin had a dimension of 1.0 m×2.0 m×0.7 m. Hot air was supplied to the dryer from fiberglass- covered solar collectors, which also functioned as the roof of a farmhouse. The dryer can be used to dry 200 kg of rosella flowers and lemon-grasses within 4 and 3 days, respectively. The solar air heater had an average daily efficiency of 35% and it performs well both as a solar collector and a roof of a farmhouse. 6
    • Shanmugam and Natarajan (2006) experimentally investigated the forced convection and desiccant integrated solar dryer under the hot and humid climatic conditions of Chennai. The system consisted of a flat plate solar air collector, drying chamber and a desiccant unit. The desiccant unit is designed to hold 75 kg of CaCl2-based solid desiccant consisting of 60% bentonite, 10% calcium chloride, 20% vermiculite and 10% cement. Drying experiments were performed for green peas at different air flow rate. The equilibrium moisture content Me was reached in 14 h at an air flow rate of 0.03 kg/m2 s. Sacilik, et al. (2006) performed experiments on thin layer solar drying of organic tomato using mathematical modelling on solar tunnel dryer under ecological conditions of Ankara, Turkey. During the experiments, organic tomatoes were dried to the final moisture content of 11.50 from 93.35% w.b. in four days of drying in the solar tunnel dryer. Experimental drying curves showed only a falling drying rate period. The approximation of diffusion model has shown a better fit to the experimental drying data as compared to other models. This system can be used for drying various agricultural products. Mwithiga and Kigo (2006) designed and tested a small solar dryer with limited sun tracking capabilities. The dryer had a mild steel absorber plate and a polyvinyl chloride (pvc) transparent cover and could be adjusted to track the sun in increments of 15°. The performance was tested by adjusting the angle the dryer made with the horizontal either once, three, five or nine times a day when either loaded with coffee beans or under no load conditions. The temperature inside the plenum chamber could reach a maximum of 70.4 °C and the dryer could lower the moisture content of coffee beans from 54.8% to below 13% (w.b.) in 2 days as opposed to the 5–7 days required in sun drying. Tracking the sun though allowing a faster rate of drying did not offer a significant advantage in terms of length of drying duration. 7
    • Chapter 3 MATERIALS AND METHODS Estimation of solar radiations The total irradiation on a surface is the sum of the direct solar radiation, ID, the diffuse sky radiation, Id and solar radiation reflected from surrounding surfaces, Ir. For the prediction of the solar radiations there is a need to understand the solar radiation geometry. In order to find the beam energy falling on a surface having any orientation, it is necessary to convert the value of the beam flux coming from the direction of the sun to an equivalent value corresponding to the normal direction to the surface. Relationship for making this conversion is as: …….(3.1) where: Ib is the equivalent flux falling normal to the surface Ibn is the Solar flux θ is angle between an incident beam of flux and the normal to a plane The angle θ can be related by a general equation to φ the latitude, δ the declination, γ the surface azimuth angle, ω the hour angle, and β the slope. Each of them is defined below: The Latitude φ of a location is the angle made by the radial line joining the location the location to the centre of the earth with the projection of the line on the equatorial plane. By convention, the latitude is measured as positive for the northern hemisphere. The Declination δ is the angle made by the line joining the centers of the sun and the eath with its projection on the equatorial plane. It arises by virtue of the fact that the earth rotates about an axis which makes an angle of approximately 66.5˚ with the plane of its rotation around the sun. the declination angle varies from a maximum value of +23.45˚ on June 21 to a maximum of - 8
    • 23.45 on Dec. 21. It is zero on the two equinox days of Mar. 21 and Sep. 22. The following simple relation prepared by Cooper (1969) was used for calculating of declination. ……. ( P. I. Cooper 1969)(3.2) Where, n is the day of the year. The Surface Azimuth Angle γ is the angle made in the horizontal plane between the line due south and the projection of the normal to the surface on the horizontal plane. By convention, the angle is taken to be positive if the normal is east of south and negative if west of south. The Hour Angle ω is an angular measure of time and is equivalent to 15˚ per hour. It is measured from noon based on local apparent time (LAT), being positive in the morning and negative in the afternoon. The Slope β is the angle made by the plane surface with the horizontal. It is taken to be positive for the surface sloping towards the south and negative for surface sloping towards the north. It can be shown that: …….(3.3) This equation can be simplified for the various particular conditions as: For Horizontal Surface β = 0˚ Therefore: …….(3.4) The angle in this case is called the Zenith angle and will be denoted by the symbol θz . 9
    • Local Apparent Time (LAT) The time used for the calculating the hour angle in the equations (3.3) to (3.5) is the local apparent time. This can be calculated by using the standard time observed on a clock by applying two corrections. The first correction arises because of the difference between the longitude of a location and the meridian of which the standard time is based. The correction has a magnitude of 4 minutes for every degree difference in longitude. The second correction called the equation of time correction is due to the fact that the earth’s orbit and rate of rotation are subject to small fluctuations. LAT = Standard time 4(standard time longitude – longitude of location) + Equation of time correction …….(3.5) The negative sign in the first correction is applicable for the eastern hemisphere, while the positive sign is applicable for the western hemisphere. Equation of time is given by: …….(3.6) Where B is given by equation: …….(3.7) Hourly global and diffuse radiation on clear days ASHRAE has given a method for estimating the hourly variation of global and diffuse solar radiation falling on a horizontal surface on a clear day. The equations are based on an exponential decay model in which the beam radiation decreases with increase in the distance traversed through atmosphere. The global radiation (Ig) reaching a horizontal surface on the earth is given by Ig = Ib + Id …….(3.8) Where: Ig = hourly global radiation Ib = hourly beam radiation 10
    • Id = hourly diffuse radiation Now, Ib = Ibn . cosθz Where Ibn = beam radiation in the direction of the rays θz = angle of incidence on a horizontal surface, i.e. the zenith angle. Thus, Ig = Ibn . cosθz + Id In the ASHRAE model, it is postulated that for a clear cloudless day Ibn = A exp[-B/cosθz] And Id = C. Ibn Where A,B and C are constants whose values were obtained from analysis given by Threlkeld and Jordan(1958). Values of the Constants A, B and C used for predicting hourly solar radiation on clear days are as follows: Month A (W/m2) B C January 21 1228 0.142 0.058 February 21 1213 0.144 0.060 March 21 1185 0.156 0.071 April 21 1134 0.180 0.097 May 21 1103 0.196 0.121 June 21 1087 0.205 0.134 July 21 1084 0.207 0.136 August 21 1106 0.201 0.122 September 21 1150 0.177 0.092 October 21 1191 0.160 0.073 November 21 1219 0.149 0.063 December 21 1232 0.142 0.057 The values have been determined for each month since they change during the year because of seasonal changes in the dust and water vapour content of the atmosphere, and also because of the changing earth-sun distance. 11
    • Solar radiations on tilted surfaces Most solar equipment (e.g. flat plate collectors) for absorbing radiation are tilted at an angle to the horizontal. It therefore becomes necessary to calculate the flux which falls on a tilted surface. This flux Is the sum of the beam and diffuse radiations falling directly on the surface and the radiation reflected on to the surface from the surroundings. IT = Ib.Rb + Id.Rd + (Ib + Id) .Rr …….(3.9) Beam radiation (Rb) The ratio of the beam radiation flux falling on a tilted surface to that falling on a horizontal surface is called the tilt factor for beam radiation. It is denoted by the symbol Rb. for the case of a tilted surface facing south (i.e. γ = 0˚) …….(3.10) While for a horizontal surface Hence …….(3.11) Similar expressions could be derived for other situation Diffuse Radiation (Rd) The tilt factor Rd for diffuse radiation is the ratio of the diffuse radiation flux falling on the tilted surface to that falling on a horizontal surface. The value of this tilt factor depends upon the distribution of diffuse radiation over the sky and on the portion of the sky dome seen by the titled surface. Assuming that that the sky is an isotropic source of diffuse radiation, we have …….(3.12) Since is the radiation shape factor for a tilted surface with respect to the sky. 12
    • Reflected Radiation (Rr) Since is the radiation shape factor for a tilted surface with respect to the sky, it follows that is the radiation shape factor for the surface with respect to the surrounding ground. Assuming that the reflection of the beam and diffuse radiations falling on the ground is diffuse and isotropic, and that the reflectivity is ρ, the tilt factor for reflected radiation is given by …….(3.13) Flux on a titled surface The flux IT falling on a tilted surface at any instant is thus given by: IT = Ib.Rb + Id.Rd + (Ib + Id) .Rr …….(3.14) It should be noted that this equation is valid for a south-facing surface. Ratio of flux falling on a tilted surface at any instant to that on a horizontal surface can be found out as: …….(3.15) Value of ρ is generally taken around 0.2 with surface of concrete or grass. Calculation of efficiency of solar flat plate collector (air heater) The useful heat gain rate for the collector is given by qu = FRAP [S-Ul (Tfi-Ta)] …….(3.16) where qu = useful heat gain rate (W) FR = Collector heat removal factor AP = Area of collect plate (m2) S = Solar flux(W/m2) 13
    • Ul = Overall heat loss coefficient (W/m2-k) Tfi = Temperature at collector inlet (ºC) Ta = Ambient air temperature (ºC) Instantaneous efficiency of collector is calculated as: Useful heat gain rate ηi = solar flux incident on collector face x collector plate area …….(3.17) Collector air temperature is obtained from the energy balance equation: qu = Ma . Cp (Tfo – Tfi) …….(3.18) where, Ma = Air mass flow rate (Kg/sec) Cp = Specific heat of the air(J/Kg-ºC) Tfi = Temperature at collector inlet (ºC) Tfo = Temperature at collector outlet (ºC) qu = The useful heat gain rate for the collector Design of Solar Dryer Calculation of amount of water removed from the product Mass of water to be removed from the product, Ww (kg) is calculated as: …….(3.19) Where, 14
    • Ww = Mass of water evaporated from a given quantity of product (kg) Wg = Initial mass of the product (kg) Mi = Initial moisture content (% wet basis) Mf = Final moisture content (% wet basis) Total heat required to evaporate water from the product in KJ …….(3.20) Where, L is latent heat of vaporization in KJ Calculation of quantity of air flow required for drying The quantity of air required for drying is calculated from energy-balance equation: WwL = Ma CP (To – Ti) …….(3.21) Where, Ma = Mass of drying air (kg) L = Latent heat of vapourization of water from the product (MJ/kg) = 2.8 (Exell, 1980) CP = Specific heat capacity of air at constant pressure (kJ/kg°C) = 1.02 Ti = Temperature of the drying air at the inlet of solar air heater (°C) To = Temperature of the drying air at the outlet of solar heater (°C) Air flow due to wind The effect of wind force in moving air through a building varies with velocity, prevailing direction, seasonal and daily variation in velocity and direction and local obstruction such as 15
    • nearby building, trees or hill. Wind velocity is usually lower in summer than in winter and varies in direction between summer and winter season. Thus, natural ventilation system may be designed for wind velocities of half the average seasonal velocity. The air exchange caused by wind velocity may be calculated by: Vw = E .A .v …….(3.22) Where, Vw = Air flow (m3/s) A = Free area of inlet opening (m2) v = Wind velocity (m/s) E = Effectiveness of openings = 0.5 to 0.6 for perpendicular to the opening wind and 0.25 to 0.35 for diagonal winds. Air flow due to thermal forces Thermal forces can be complementary to wind forces in providing air exchange through naturally ventilated structures. During times when there is effectively no wind force, thermal forces must be relied on entirely. The thermal (buoyancy) forces due to difference in air density at different temperature can cause air flow due to stack surfaces. It is estimated as: …….(3.23) Where, Vth = Air flow (m3/s) A = Free area of inlet or outlets (m2) g = Acceleration due to gravity (9.81 m2/s) h = Height from inlet to outlet (m) 16
    • θ = Ratio of flow with friction and other losses to frictionless flow = 0.3 to 0.5 Ti = Inlet absolute temperature (°K) To = Outlet absolute temperature (°K) Now Vt = volume of drying air(m3/Hr) is given by Vt = (Vth + Vw) *3600 …….(3.24) From Gas law PV = Ma RT Ma = PV/RT …….(3.25) Where, P = Atmospheric pressure(kPa) = 101.3 R = Gas constant (kPa/kg °K) = 0.291 T = Average temperature of the product (°K) V = Volume of air needed for drying of product (m3) Ma = Mass of drying air (kg) Calculation of drying time Collector area of the solar dryer is calculated as: …….(3.26) Where, A = Collector area of the solar dryer (m2) Qt = Total heat required to evaporate water from the product(kJ) 17
    • IT = Daily average of solar radiation intensity (W/m2) η = Efficiency of dryer (%) ddays = Drying time (days) Calculation of number of trays W = txdxA …….(3.27) Where, W = Total capacity of tray (kg) t = Thickness of material (m) d = Bulk density of the material (kg/m3) A = Area of the tray (m2) Assume Area of one tray (A1) = (0.95 X 0.45) m2 Number of trays (n) = Area of the tray / Area of one tray 18
    • Parameters used for design: Solar Radiation data Latitude of the place Longitude of the place Time of the day Day of the year Solar collector data Length of collector Breadth of collector Gap between cover and plate Average air velocity Ambient temperature Inside mean temperature Solar dryer data Length of the tray Breadth of tray Thickness of material to be kept in the tray Bulk density of the material to be dried Initial and final moisture content of the material to be dried Solar Collector parameters Type Flat Plate Type Gross Dimensions 200x100 cm2 Area of Absorbing Surface: 198x97 cm2 Absorbing Surface Black Painted G.I sheet Inlet Air gap Four no.(20 x 5 cm each) Transfer Fluid Air Collector Tilt Angle 30 Cover Plate plain glass Sheet 19
    • Instrumentation for experimental data Pyranometer for radiation measurement Multichannel temperature recorder for temperature measurement Hot wire Anemometer for air velocity measurement Vane Anemometer for wind velocity measurement Method used for the validation of the simulation model; Real time values of solar radiations were obtained by the use of Surya Mapi and were validated against the values predicted by the program using the Statistical methods: Two-Sample t-test for independent Samples Let X1, X2,X3, ……Xn1 and Y1, Y2, Y3,……Yn2 in be two independent random samples of sizes n1 and n2 from two normal populations N(µ1,σ12) and N(µ2,σ22) Assumptions: 1) Populations are normal 2) Samples are drawn independently and at randomly 3) Population variances σ12 and σ22 are unknown but equal. 4) Samples are small Null hypothesis Ho µ1 = µ2 Alternate hypothesis H1: µ1 ≠ µ2 (Two tailed test) H1: µ1 > µ2 (Right tailed test) H1: µ1 < µ2 (Left tailed test) 20
    • From the samples compute means , and the variances s12 and s22 and then find the pooled variance: Test statistic If , reject Ho , otherwise accept Ho 21
    • Chapter 4 RESULTS AND DISCUSSIONS For the design of the solar dryer first step was to record the solar radiation data. Readings for the insolation were recorded at the Renewable Energy Lab between the time period 8:30 to 4:30 at an interval of 1 hour. Readings were taken for two orientation i.e. horizontal and inclined surface: Insolation on horizontal surface Readings were taken on the horizontal surface and tabulated. Program developed in Visual Basic was used to predict the solar radiation data for the same period on horizontal surface, the detailed program with code is given in the APPENDIX A: Listing 2. Comparison was then made for the measured and predicted values so as to validate the developed model. Results of the study are presented in the Table 4.1 and Figure 4.1 In the observed values for horizontal insolation the maximum value was 953 W/m2 at 12:30 p.m. and minimum 313 W/m2 at 8:30 a.m. while the maximum value for the predicted insolation was 891 W/m2 at 12:30 a. m. and minimum 397 W/m2 at 4:30 p.m. T- test was applied on the predicted and observed values. The tabulated value for 16 degrees of freedom and 5% level of significance is 2.12. Calculated T- value is 0.48 which is in accordance to the tabulated values so it can be safely assumed that the predicted values by the model can be used to calculate insolation at any given place and time. Insolation on inclined surface (β = 30°) Readings were taken on the inclined surface (β = 30°) and tabulated. Program developed in Visual Basic was used to predict the solar radiation data for the same period on inclined surface, the detailed program with code is given in the APPENDIX A: Listing 2. Comparison was then made for the measured and predicted values so as to validate the developed model. Results of the study are presented in the Table 4.2 and Figure 4.2 22
    • In the observed values for inclined insolation the maximum value was 1040 W/m2 at 12:30 p.m. and minimum 353 W/m2 at 8:30 a.m. while the maximum value for the predicted insolation was 919 W/m2 at 12:30 a. m. and minimum 413 W/m2 at 4:30 p.m. T- test was applied on the predicted and observed values. The tabulated value for 16 degrees of freedom and 5% level of significance is 2.12. Calculated T- value is 0.64 which is in accordance to the tabulated values so it can be safely assumed that the predicted values by the model can be used to calculate insolation at any given place and time. Thermal performance testing of solar flat plate collector(air heater). For the calculation of the flat plate solar collector efficiency following parameters were recorded: Ambient Temperature Average surrounding air velocity Mean plate temperature Air flow rate through the chimney Standard formulas were used for the evaluation of the efficiency of the flat plate solar collector with the help of the program developed in the Visual Basic. The details of the program and code is given in the APPENDIX A: Listing 4. The results of the study are presented in the Table 4.3 and various graphs for the performance of the solar dryer are plotted in Figure 4.3(a), Figure 4.3(b) and Figure 4.3(c). The result show that mean plate temperature rises for a time and remains constant for some time even after the insolation has reached is maximum value at 12:30 after which it starts to decline. Max value of the mean plate temperature observed was 68 °C at 12:30 p.m. and minimum 33 °C at 8:30 a.m. ambient temperature follows the same trend. 23
    • Table 4.1 – Comparison of insolation on horizontal surface Horizontal Insolation Horizontal Insolation Time Observed Calculated 8.30 313 419 9.30 433 615 10.30 747 767 11.30 873 861 12.30 953 891 13.30 907 855 14.30 760 754 15.30 620 598 16.30 433 397 T value calculated 0.48 T tabulated = 2.12 Figure 4. 1 24
    • Table 4.2 – Comparison of insolation on inclined surface Time Inclined Insolation Observed Inclined Insolation Calculated 8.30 353 435 9.30 493 637 10.30 787 792 11.30 947 889 12.30 1040 919 13.30 973 882 14.30 827 779 15.30 673 618 16.30 467 413 T- value calculated 0.64 T tabulated = 2.12 Comparison of Inclined Insolation 1200 1000 800 Insolation in W/sq. mts. 600 400 200 0 8.30 9.30 10.30 11.30 12.30 13.30 14.30 15.30 16.30 Time of the day Observed Calculated Figure 4. 2 25
    • Table 4.3 – Solar performance data Time Insolation Temperature Thermal Horizontal Inclined Ambient Mean Air Wind efficiency 8.30 353 393 26 Plate 33 velocity 0.4 velocity 1.1 (%) 47 9.30 480 540 28 41 0.6 1.2 45 10.30 753 787 30 56 1.0 1.5 42 11.30 880 947 32 64 1.4 2.0 43 12.30 967 1053 33 68 1.4 2.2 43 13.30 927 987 33 67 1.5 3.1 43 14.30 787 853 35 65 1.1 3.1 46 15.30 613 673 35 60 1.1 2.9 45 16.30 380 413 35 53 0.7 2.1 46 Figure 4. 3(a) 26
    • Figure 4. 3(b) Figure 4. 3(c) 27
    • Computer aided thermal design of solar dryer Based on the insolation and collector plate efficiency a dryer was designed for the given place (latitude and longitude). The detailed program used for the calculation is given in the APPENDIX A: Listing 5 Factors which were taken into account were: • Weight of the material to be dried • Initial moisture content • Desired final moisture content • Time of drying Area of the collector plate required for drying the given quantity of the material form initial moisture content to the desired final moisture content in the given time was calculated. Following data were considered for the estimation of the drying area. • Drying time – 2 days • Initial moisture content 70% • Final moisture content 12% To determine the number of tray required to dry the given quantity of the material. The detailed program used for the calculation is given in the APPENDIX A: Listing 5. The factors which were considered were: • Tray size ◦ length – 95 cm ◦ breadth - 45 cm • Thickness of the material to be kept • Bulk density of the material Following data were assumed for the calculation of the no. trays required: • Thickness of material to be kept in the tray – 10 cm • Bulk density of the material – 650 kg/m3 28
    • Table 4.4 – Design of solar collector Weight of material(Kg) Area required (m2) 5 0.42 6 0.51 7 0.59 8 0.68 9 0.76 10 0.85 11 0.93 12 1.02 13 1.1 14 1.19 15 1.27 16 1.36 17 1.44 18 1.52 19 1.61 20 1.69 Table 4.5 – Design of trays in the drying chamber Weight of material (Kg) Number of trays 5 1 10 1 15 2 20 2 25 2 With the above data analysis it can be concluded that the program developed is a better tool using the Visual Basic user friendly model which is window based and easy to use for the estimation of solar radiations. The program can thus be used to determine the optimum drying area and number of trays required to be kept in the drying chamber for the dryer designed at any given place and given time of the year. And therefore various solar dryer with varying capacity can be designed with the help of this tool according to the user need, saving a lot of manual calculations, time, labour, resources and money. This tool can also help the industries working on the designing of the solar applications, after a little bit of modifications as the basic need of estimating the solar radiations at a place with accuracy is fulfilled and it adds a new dimension by window based user interaction to the previously hard to understand and labour intensive techniques of estimating the insolation and then designing the system based on it. 29
    • Chapter 5 SUMMARY AND CONCLUSION The development of simulation model is a powerful tool for prediction of performance and can help designers to optimize the dryer geometry at various operating conditions. Commercialization of any drying technology for agro-processing or industrial use needs thorough performance prediction and evaluation of system in techno-economic perspectives. Following are some of the conclusion drawn by this project. 1. Estimation of solar radiation at Hisar with the help of ASHRAE model has been in close agreement with the observed values taking 5% as level of significance. Thus the model can safely be used to predict isolation at Hisar. 2. The calculated efficiency of the solar plate collector using the readings at different point in the solar dryer during testing has been consistent and the efficiency of the solar collector has to be found out to be 44%. 30
    • Chapter 6 REFERENCES ASHRAE ,1972, Handbook of fundamentals pp.385-443. ASHRAE Transactions ,1958. Direct Solar radiation available on clear days,64,45, Atwall, P. S. and Neal,W.E.J. 1981. Measurements of spectral distribution of solar radiation and mathematical model validation. Proceedings of Solar World Forum, Vol. 3. International Solar Energy Society Congress; Brighton, England; Ed. Davis Hall and June Morton. New York. Pergamon Press. pp. 2439-2442. Bala, B.K. and Wood, J.L., 1994. Simulation of the indirect natural convection solar drying of rough rice. Solar Energy 53(3): 259-266. Brooker, D.B.; Bakker-Arkema, F.W. and Hall, C.W. 1997. Drying and storage of grains and cereals. CBS Publishers and Distributors, New Delhi (India). Chakraverty, A. 1995. Post harvest technology of cereals, pulses and oilseeds. III. Edition. Oxford & IBH Publishing Co. Pvt. Ltd., New Delhi (India). Davies, J. A. and Mckay D. C. 1989. Evaluation of selected models for estimation solar radiation on horizontal surfaces. Solar Energy 43(3):153-168. Henderson, S.M.; Perry, R.L. and Young, J.H. 1997. Principles of process engineering, IV edition. The Society for Engineering in Agricultural Food and Biological Systems (ASAE), USA. Exell, R.H.B. 1980. Basic design theory for simple solar rice dryer. Renewable Energy Review Journal 1(2): 1-12. Janjai, S. and Tung P. Performance of a solar dryer using hot air from roof-integrated solar collectors for drying herbs and spices. Renewable Energy 30(14): 2085-2095. P. I. Cooper, 1969. The Absorption of Solar Radiation in Solar Stills, Solar Energy, 12,3 Karim, M.A. and Hawlader, M.N.A. 2004. Development of solar air collectors for drying applications. Energy Conversion and Management 45(3): 329-344. Kaushik, L. S. 2003. Applied Statistical Methods. Dhanpat Rai & Co. (P) Ltd. pp 11.1-11.9 31
    • Malaviya, M.K. and Gupta, R.S.R. 1987. Cabinet type natural convection dryer with chimney. Agricultural Engineering Today 11(4): 37-39. Mani, Anna and Rangarajan, S., 1982. Solar Radiation over India. Allied Publishers Pvt. Ltd., New Delhi. Marion, W. and George, R. 2001. Calculation of Solar Radiation Using a methodology with Worldwide Potential. Solar Energy 71(4):273-283 Mathur,A. N.; Ali, Yusuf; Maheshwari, R. C., 1989. Solar Drying Mohamed, L. et al. Single layer solar drying behaviour of Citrus aurantium leaves under forced convection. Energy Conversion and Management. 46(9-10):1473-1483 Mwithiga, Gikuru and Kigo, Stephen Njoroge. Performance of a solar dryer with limited sun tracking capability. Journal of Food Engineering 74(2): 247-252 Sacilik, Kamil etal. Mathematical modelling of solar tunnel drying of thin layer organic tomato. Journal of Food Engineering 73(3):231-238 Sodha, M.S. and Chandra, R. 1994. Solar drying system and their testing procedures : A review. Energy Convers. Mgmt.35(3): 219-267. Sukhatme, S. P., 1988. Principles of Thermal Collection and Storage. pp 66-80,141-147 Shanmugam, V. and Natrajan, E., 2006. Experimental investigation of forced convection and desiccant integrated solar dryer. Renewable Energy 31(8):1239-1251 Sharan, G. and Kumar, M.K. 1995. Fourier representation of ambient temperature and solar radiation. Journal of SESI 5(2): 55-66. Threlkeld, J. L. and Jordan, R. C. 1958. Direct Solar Radiation Available on clear days. ASHRAE Transactions 64,45(1958) Venkatesh, P. and Prasad, C. R. 1982, Computation of solar spectral irradiance. Proceedings of National Solar Energy Convention, New Delhi, Allied Publishers, Pvt. Limited, pp. 5.030-5.033. Vignola, F. and McDaniels, D. K. 1989. Direct Radiation: Ratio between Horizontal and Tilted Surfaces. Solar Energy 43(3):183-190. 32
    • SYMBOLS AND ABBREVIATIONS °C : Degree celsius °K : Degree in kelvin % : Per cent ρ : Density of air µ : Viscosity of air σ : Stefen-Boltzman constant (5.67 x 10-8 W/m2 k4) η : Efficiency cm : Centimetre cu m : Cubic metre db : Dry basis et al. : And others exp : Exponential Fig. : Figure g : Acceleration due to gravity hc : Convective heat transfer coefficient Hr : Hour Id : Solar insolation K : Thermal conductivity of air kg : Kilogram L : length of collector Lv : Latent heat of vapourization m : Metre mc : Moisture content 33
    • P : Atmospheric pressure Pa : Water vapour pressure in the air rh, RH : Relative humidity s : Second sq. m. : Square metre t : Drying time t : Thickness of material Ta : Ambient temperature v : Wind velocity wb : Wet basis 34
    • APPENDIX A: Listing 1 Program to Load the Starting Screen of the Project and Introduce to the user about the Project. Purpose: The program called the Splash Screen Loads the Main Project and gives the user the information about the development work and team of the project. Usage: program uses Objects like Frame, Labels, Timer control for the GUI. The code consists of the Sub Procedures for Timer and form loading. Input Formats: nothing has to be provided by the user Output: Information about the Project Running: Following is the Run mode Screen of the Form1 of the Project. 35
    • Code for the Form Splash: Private Sub Timer1_Timer() Static count As Integer If count = 0 Then lblWarning.Caption = "Loading Project....." End If If count = 1 Then lblWarning.Caption = "Starting Processes....." End If If count = 2 Then lblWarning.Caption = "Welcome" End If If count = 3 Then Unload Me Form1.Show End If count = count + 1 End Sub 36
    • APPENDIX A: Listing 2 Program to estimate solar radiation falling on a surface : Purpose: The program estimates solar radiation falling on a surface (Horizontal and Tilted) corresponding to the given values of latitude and longitude of place in degrees and day of the year ( 1 to 365). Usage: program uses one Main Form and the Objects like List Boxes, Labels, Text Boxes, Combo Box, Option Buttons and Command Buttons for the GUI. The code consists of the Sub Procedures for various Command Buttons and the List Boxes. Input Formats: Selecting of Month, Day of the month, Latitude and Longitude, Time Period of the Day and Tilt of the Surface Output: Output consists of Global, Beam and Diffused radiation on a horizontal surface and Insolation on a tilted surface. Running: Following is the Run mode Screen of the Form1 of the Project 37
    • Code for the Form1 Private Sub Combo1_Click() If List1.ListIndex = -1 Then MsgBox ("Please select a Month before selecting a day") Combo1.Text = "" List1.SetFocus Else If Combo1.Text < 21 Then diff = 9 + Val(Combo1.Text) a.Text = Round(ac + (aa - ac) * diff / 30, 0) b.Text = Round(bc + (ba - bc) * diff / 30, 3) c.Text = Round(cc + (ca - cc) * diff / 30, 3) Inter = n + Val(Combo1.Text) - 21 ElseIf Combo1.Text > 21 Then diff = Val(Combo1.Text) - 21 a.Text = Round(aa + (ab - aa) * diff / 30, 0) b.Text = Round(ba + (bb - ba) * diff / 30, 3) c.Text = Round(ca + (cb - ca) * diff / 30, 3) Inter = n + Val(Combo1.Text) - 21 Else a.Text = aa b.Text = ba c.Text = ca End If End If End Sub Private Sub Command1_Click() If List1.ListIndex = -1 Then MsgBox ("Please Select a Month") List1.SetFocus ElseIf Combo1.Text = "" Then MsgBox ("Please Select a date and then continue") Combo1.SetFocus ElseIf List2.ListIndex = -1 And Option1.Value = True Then MsgBox ("Please Select the Place or Type the co-ordinated") List2.SetFocus ElseIf Option2.Value = True And (la.Text = "" Or lo.Text = "") Then MsgBox ("Please enter the co-ordinated of the place") la.SetFocus ElseIf List3.ListIndex = -1 Then MsgBox ("Please Select the time of the day") 38
    • List3.SetFocus ElseIf Text2.Text = "" Then MsgBox ("Please enter the tilt angle") Text2.SetFocus Else del = 23.45 * Sin(2 * 3.14 * (284 + Inter) / 365) sinla = Sin(Val(la.Text) * 2 * 3.14 / 360) sindel = Sin(del * 2 * 3.14 / 360) cosla = Cos(Val(la.Text) * 2 * 3.14 / 360) cosdel = Cos(del * 2 * 3.14 / 360) cosw = Cos(w * 2 * 3.14 / 360) cosz = sinla * sindel + cosla * cosdel * cosw expo = 0 - (Val(b.Text) / cosz) Ibn = (36 * Val(a.Text)) * Exp(expo) Id = Val(c.Text) * Ibn Ig = Ibn * cosz + Id Ib = Ibn * cosz globalRad.Text = Str(Int(Ig / 36)) diffuse.Text = Str(Int(Id / 36)) beam.Text = Str(Int(Ib / 36)) beta = Val(Text2.Text) * 2 * 3.14 / 360 ' now beta is in radians sinDiff = Sin(Val(la.Text) * 2 * 3.14 / 360 - beta) cosDiff = Cos(Val(la.Text) * 2 * 3.14 / 360 - beta) cosQ = sinla * sinDiff + cosla * cosw * cosDiff Rb = cosQ / cosz Rd = (1 + Cos(beta)) / 2 Rr = 0.2 * (1 - Cos(beta)) / 2 Sflux = (Ib * Rb + Id * Rd + (Ib + Id) * Rr) / 36 Text1.Text = Round(Sflux, 0) End If End Sub Private Sub Command2_Click() Form2.Show End Sub Private Sub Command3_Click() Form5.Show End Sub 39
    • Private Sub Command4_Click() Form4.Show End Sub Private Sub Command5_Click() Form3.Show End Sub Private Sub Command6_Click() End End Sub Private Sub Form_Load() For nt = 1 To 28 Combo1.AddItem nt Next nt End Sub Private Sub List1_MouseMove(Button As Integer, Shift As Integer, X As Single, Y As Single) If List1.ListIndex = 0 Then aa = 1228 ba = 0.142 ca = 0.058 ab = 1213 bb = 0.144 cb = 0.058 ac = 1232 bc = 0.142 cc = 0.057 n = 21 eqTime = -10 For nt = 0 To Combo1.ListCount - 1 Combo1.RemoveItem 0 Next nt For nt = 1 To 31 Combo1.AddItem nt Next nt End If If List1.ListIndex = 1 Then aa = 1213 ba = 0.144 ca = 0.06 ab = 1185 40
    • bb = 0.156 cb = 0.071 ac = 1228 bc = 0.142 cc = 0.058 n = 52 eqTime = -14 For nt = 0 To Combo1.ListCount - 1 Combo1.RemoveItem 0 Next nt For nt = 1 To 28 Combo1.AddItem nt Next nt End If If List1.ListIndex = 2 Then aa = 1185 ba = 0.156 ca = 0.071 ab = 1134 bb = 0.18 cb = 0.097 ac = 1213 bc = 0.144 cc = 0.06 n = 80 eqTime = -10 For nt = 0 To Combo1.ListCount - 1 Combo1.RemoveItem 0 Next nt For nt = 1 To 31 Combo1.AddItem nt Next nt End If If List1.ListIndex = 3 Then aa = 1134 ba = 0.18 ca = 0.097 ab = 1103 bb = 0.196 cb = 0.121 ac = 1185 bc = 0.156 cc = 0.071 n = 111 41
    • eqTime = 0 For nt = 0 To Combo1.ListCount - 1 Combo1.RemoveItem 0 Next nt For nt = 1 To 30 Combo1.AddItem nt Next nt End If If List1.ListIndex = 4 Then aa = 1103 ba = 0.196 ca = 0.121 ab = 1087 bb = 0.205 cb = 0.134 ac = 1134 bc = 0.18 cc = 0.097 n = 141 eqTime = 4 For nt = 0 To Combo1.ListCount - 1 Combo1.RemoveItem 0 Next nt For nt = 1 To 31 Combo1.AddItem nt Next nt End If If List1.ListIndex = 5 Then aa = 1087 ba = 0.205 ca = 0.134 ab = 1084 bb = 0.207 cb = 0.136 ac = 1103 bc = 0.196 cc = 0.121 n = 172 eqTime = 0 For nt = 0 To Combo1.ListCount - 1 Combo1.RemoveItem 0 Next nt For nt = 1 To 30 Combo1.AddItem nt 42
    • Next nt End If If List1.ListIndex = 6 Then aa = 1084 ba = 0.207 ca = 0.136 ab = 1106 bb = 0.201 cb = 0.122 ac = 1087 bc = 0.205 cc = 0.134 n = 202 eqTime = -5 For nt = 0 To Combo1.ListCount - 1 Combo1.RemoveItem 0 Next nt For nt = 1 To 31 Combo1.AddItem nt Next nt End If If List1.ListIndex = 7 Then aa = 1106 ba = 0.201 ca = 0.122 ab = 1150 bb = 0.177 cb = 0.092 ac = 1084 bc = 0.207 cc = 0.136 n = 232 eqTime = -5 For nt = 0 To Combo1.ListCount - 1 Combo1.RemoveItem 0 Next nt For nt = 1 To 31 Combo1.AddItem nt Next nt End If If List1.ListIndex = 8 Then aa = 1150 43
    • ba = 0.177 ca = 0.092 ab = 1191 bb = 0.16 cb = 0.073 ac = 1106 bc = 0.201 cc = 0.122 n = 263 eqTime = 5 For nt = 0 To Combo1.ListCount - 1 Combo1.RemoveItem 0 Next nt For nt = 1 To 30 Combo1.AddItem nt Next nt End If If List1.ListIndex = 9 Then aa = 1191 ba = 0.16 ca = 0.073 ab = 1219 bb = 0.149 cb = 0.063 ac = 1150 bc = 0.177 cc = 0.092 n = 293 eqTime = 15 For nt = 0 To Combo1.ListCount - 1 Combo1.RemoveItem 0 Next nt For nt = 1 To 31 Combo1.AddItem nt Next nt End If If List1.ListIndex = 10 Then aa = 1219 ba = 0.149 ca = 0.063 ab = 1232 bb = 0.142 cb = 0.057 ac = 1191 44
    • bc = 0.16 cc = 0.073 n = 324 eqTime = 15 For nt = 0 To Combo1.ListCount - 1 Combo1.RemoveItem 0 Next nt For nt = 1 To 30 Combo1.AddItem nt Next nt End If If List1.ListIndex = 11 Then aa = 1232 ba = 0.142 ca = 0.057 ab = 1228 bb = 0.142 cb = 0.058 ac = 1219 bc = 0.149 cc = 0.063 n = 354 eqTime = 5 For nt = 0 To Combo1.ListCount - 1 Combo1.RemoveItem 0 Next nt For nt = 1 To 31 Combo1.AddItem nt Next nt End If End Sub Private Sub List2_MouseMove(Button As Integer, Shift As Integer, X As Single, Y As Single) If List2.ListIndex = 0 Then la.Text = "28.55" lo.Text = "77.12" End If If List2.ListIndex = 1 Then la.Text = "19.11" lo.Text = "72.51" End If 45
    • If List2.ListIndex = 2 Then la.Text = "21.10" lo.Text = "79.05" End If If List2.ListIndex = 3 Then la.Text = "29.16" lo.Text = "75.75" End If If List2.ListIndex = 4 Then la.Text = "22.2" lo.Text = "88.45" End If If List2.ListIndex = 5 Then la.Text = "23.05" lo.Text = "73.02" End If If List2.ListIndex = 6 Then la.Text = "13.05" lo.Text = "80.18" End If If List2.ListIndex = 7 Then la.Text = "34.1" lo.Text = "74.85" End If End Sub Private Sub List3_MouseMove(Button As Integer, Shift As Integer, X As Single, Y As Single) If List3.ListIndex = 0 Then w = 52.5 End If If List3.ListIndex = 1 Then w = 37.5 End If If List3.ListIndex = 2 Then w = 22.5 End If 46
    • If List3.ListIndex = 3 Then w = 7.5 End If If List3.ListIndex = 4 Then w = -7.5 End If If List3.ListIndex = 5 Then w = -22.5 End If If List3.ListIndex = 6 Then w = -37.5 End If If List3.ListIndex = 7 Then w = -52.5 End If If List3.ListIndex = 8 Then w = -67.5 End If latDiff = (4 * (82.5 - Val(lo.Text))) + eqTime wDiff = latDiff / 4 w = w + wDiff End Sub Private Sub Option1_Click() If Option1.Value = True Then List2.Enabled = True la.Enabled = False lo.Enabled = False End If End Sub Private Sub Option2_Click() If Option2.Value = True Then List2.Enabled = False la.Enabled = True lo.Enabled = True End If End Sub 47
    • APPENDIX A: Listing 3 Program to draw the graph showing the global radiations falling on a horizontal surface and also to calculate the average Insolation falling for the whole day. Purpose: The program draws a graph for a particular place showing the global radiations falling for whole day a particular place Usage: program uses one Main Form and the Objects like Labels and Command Buttons for the GUI. The code consists of the Sub Procedures for various Command Buttons. Input Formats: program takes the input of the latitude, longitude and day of the year provided by the user in the previous form automatically. Output: Output consist of a graph showing the global radiations falling a the place and also the average Insolation for that place. Running: Following is the Run mode Screen of the Form1 of the Project 48
    • Code: Private Sub Command1_Click() Dim s As Double Dim ST As Double Label12.Caption = Form1.List2.Text Label16.Caption = Form1.List1.Text Line1.Visible = True Line2.Visible = True DrawWidth = 2 Line (0, 140)-(200, 140) Line (20, 0)-(20, 200) DrawWidth = 1 Line (80, 0)-(80, 140) Line (20, 40)-(200, 40) Line (20, 90)-(200, 90) DrawWidth = 2 For i = 52.5 To -67.5 Step -0.1 cosw = Cos((i + wDiff) * 2 * 3.14 / 360) cosz = sinla * sindel + cosla * cosdel * cosw expo = 0 - (Val(Form1.b.Text) / cosz) Ibn = (3.6 * Val(Form1.a.Text)) * Exp(expo) Id = Val(Form1.c.Text) * Ibn Ig = Ibn * cosz + Id Ib = Ibn * cosz beta = Val(Form1.Text2.Text) * 2 * 3.14 / 360 ' now beta is in radians sinDiff = Sin(Val(Form1.la.Text) * 2 * 3.14 / 360 - beta) cosDiff = Cos(Val(Form1.la.Text) * 2 * 3.14 / 360 - beta) cosQ = sinla * sinDiff + cosla * cosw * cosDiff Rb = cosQ / cosz Rd = (1 + Cos(beta)) / 2 Rr = 0.2 * (1 - Cos(beta)) / 2 Sflux = (Ib * Rb + Id * Rd + (Ib + Id) * Rr) / 36 ST = ST + Sflux Ig = Ig / 36 s = s + Ig t=t+1 PSet (j, Ig), QBColor(0) 49
    • Next i inso = Round(10 * s / t, 1) Savg = Round(10 * ST / t, 1) Label18.Caption = Str(inso) + " W/sq m" End Sub Private Sub Command2_Click() PrintForm End Sub Private Sub Command3_Click() Form4.Cls End Sub Private Sub Form_Load() ScaleMode = 6 End Sub 50
    • APPENDIX A: Listing 4 Programme to estimate solar collector efficiency: Purpose: The program estimates Solar Collector Efficiency Usage: program uses one Main Form and the Objects like Labels, Text Boxes and Command Buttons for the GUI. The code consists of the Sub Procedures for various Command Buttons. Input Formats: input of length of collector, width of collector, gap between cover and plate, average air velocity, inlet air temperature, ambient temperature and mean temperature. Output: gives the solar collector efficiency. Running: Following is the Run mode Screen of the Form1 of the Project. 51
    • Code: Private Sub Command1_Click() Dim l, w, b, a As Double Dim t, av, flow As Double Dim tInside As Double l = Val(Text1.Text) ' length of collector(m) w = Val(Text2.Text) ' width of collector(m) b = Val(Text3.Text) ' gap between cover and collector plate(m) a=l*w ' area of collector plate(m2) Text9.Text = Round(a, 2) t = 0.85 'Transmissivity av = Val(Text4.Text) * 5 / 18 ' average air velocity(m/s)for air ti = Val(Text5.Text) 'air inlet temperature ta = Val(Text6.Text) 'ambient temperature tInside = Val(Text7.Text) 'mean fluid temperature s = Val(Text8.Text) 'solar flux incident on collector face gp = Val(Text20.Text) p = 1.077 'density of air mfa = 4 * 0.08 * 0.06 * 0.6 * av * p * 3600 'air flow rate kg/hr If tInside > ta Then mfb = 3600 * p * 4 * 0.08 * 0.06 * 0.5 * ((2 * 9.8 * 2.1) / ((tInside - ta) / tInside)) ^ 0.5 Else MsgBox ("Please check the values of Inlet temperature ,Ambient temperature or Mean temperature and then continue") Exit Sub End If mf = mfa + mfb Text10.Text = Round(mf, 2) AvgFlow = mf / (p * gp * w * 3600) ' air flow speed through the collector ut = 6.2 'top loss coefficient ub = 0.8 'bottom loss coefficient u = ut + ub 'total loss coefficient ec = 0.95 'emmisivity of the cover ep = 0.95 'emmisivity of collector plate cp = 1.005 'specific heat of air v = 0.00001985 'viscosity of air k = 0.0287 'thermal conductivity of air de = 2 * (l * b) / (l + b) 'equivalent diameter 52
    • Text11.Text = Round(de, 2) re = (p * AvgFlow * de) / v 'reynold no Text12.Text = Round(re, 2) nu = 0.0158 * (re ^ 0.8) 'nusselt no hfc = nu * (k / de) 'convective heat transfer heat coefficient hfp = nu * (k / de) 'convective heat transfer heat coefficient sigma = 0.0000000567 'stefen boltzman constant hr = (4 * sigma * ((273.2 + tInside) ^ 3)) / (1 / ep + 1 / ec - 1) 'radiative heat transfer coefficient Text13.Text = Round(hr, 2) he = hfc + (hr * hfc / (hr + hfc)) 'effective heat transfer coefficient Text14.Text = Round(he, 2) f = 1 / (1 + ((ut + ub) / he)) 'collector efficiency factor Text15.Text = Round(f, 2) cons = (mf * cp * 1000) / (3600 * u * a) fr = cons * (1 - Exp(-f / cons)) 'collector heat removal factor Text16.Text = Round(fr, 2) qu = fr * a * (s * t - u * (ti - ta)) 'useful heat gain Text17.Text = Round(qu, 2) ef = qu / (s * a) 'efficiency of collector Text18.Text = Round(ef, 2) effi = Round(ef, 2) tfo = (3.6 * qu) / (1.005 * mf) + ti 'air outlet temperature Text19.Text = Round(tfo, 2) End Sub Private Sub Command2_Click() End End Sub Private Sub Command3_Click() PrintForm End Sub 53
    • APPENDIX A: Listing 5 Program to estimate solar collector Area and no. of trays required for the fixed capacity solar dryer in terms of quantity that can be loaded into it: Purpose: The program estimates Solar collector area required at a particular place for variable needs of drying needs. Usage: program uses one Main Form and the Objects like Labels, Text Boxes and Command Buttons for the GUI. The code consists of the Sub Procedures for various Command Buttons. Input Formats: giving input of the Quantity of Material, Initial moisture content(wb), Desired final moisture content(wb), drying time, efficiency of the dryer, thickness of material to be kept in the trays and the bulk density of the material. Output: Output consists Collector area required for proper drying of material and no. of trays required to dry the given quantity of material. Running: Following is the Run mode Screen of the Form1 of the Project 54
    • Code: Private Sub Command1_Click() moistx = Val(Text2.Text) - Val(Text3.Text) quant = Val(Text1.Text) mr = quant * moistx / (100 - Val(Text3.Text)) Text4.Text = Round(mr, 2) Text7.Text = Round(mr * 2800, 2) '(in Joules ) effi = Val(Text5.Text) / 100 dryday = Val(Text10.Text) area = Val(Text7.Text) * 1000 / (9 * 3600 * dryday * Savg * effi) Text6.Text = Round(area, 2) End Sub Private Sub Command2_Click() Dim captray As Double Dim thick As Double Dim bulk As Double Dim notray As Integer Dim q As Integer thick = Val(Text8.Text) bulk = Val(Text9.Text) q = Val(Text1.Text) captray = thick * bulk * 0.405 / 100 '( tray 90cm x 45 cm ) notray = q / captray Text12.Text = Round(notray, 0) + 1 End Sub Private Sub Command3_Click() Form5.Show End Sub Private Sub Command4_Click() PrintForm End Sub Private Sub Form_Load() Text5.Text = Str(effi * 100) End Sub 55
    • APPENDIX A: Listing 6 Program to estimate maximum drying capacity of the solar dryer installed at the college premises. Purpose: The program estimates maximum drying capacity of solar dryer in Kg of material. Usage: program uses one Main Form and the Objects like Labels, Text Boxes and Command Buttons for the GUI. The code consists of the Sub Procedures for various Command Buttons. Input Formats: giving input of the Initial moisture content(wb), Desired final moisture content(wb), drying time, efficiency of the dryer and area of the collector. Output: Output consists of maximum drying quantity in given time period. Running: Following is the Run mode Screen of the Form1 of the Project. 56
    • Code: Private Sub Command1_Click() moistx = Val(Text1.Text) - Val(Text2.Text) area = Val(Text4.Text) / 100 dryday = Val(Text3.Text) effi = Val(Text6.Text) qt = (area * 9 * 3600 * dryday * Savg * effi) mr = qt / 2800000 quant = mr * (100 - Val(Text2.Text)) / moistx Text5.Text = Round(quant, 1) End Sub Private Sub Form_Load() Text6.Text = Str(effi * 100) End Sub 57
    • APPENDIX A: Listing 7 Module consisting of all the variables used in the program Purpose: The module to declare all the variables used in the project in various forms. Usage: it has a declaration section with all the variables declared The declaration code is as follows: Option Explicit Dim d As Single Dim moistx As Double Dim moisty As Double Dim quant As Double Dim mr As Single Dim area As Double Dim dryday As Single Dim nt As Byte Dim diff As Integer Public n As Integer Public w As Double Public del, sinla, sindel, cosla, cosdel, cosw, cosz, expo, Ibn, Id, Ig, Ib As Double Public total As Double Public inso As Single Public latDiff As Single Public eqTime As Single Public wDiff As Single Public bd As Long Public effi As Double Public aa, ba, ca, ab, bb, cb, ac, bc, cc As Single Public Inter As Integer Public sinDiff, cosDiff, beta, cosQ, Rb, Rd, Rr, Sflux, Savg As Singl 58
    • RESUME ACHAL GUPTA Mob. No.: 9729635866 E-mail: achal4ever@gmail.com OBJECTIVE I am looking forward to spend some quality time at a good B-School enhancing my knowledge at graduation level and learning the nitty gritties and nuances at negotiations, networking etc. ACADEMIC QUALIFICATION • Pursuing Bachelor of Technology in Agril. Engg. from CCS HAU HISAR (H.R) with OGPA 7.43/10 in Jan, 2009. • Passed Senior Sec. Examination from CBSE with 87.0% in June, 2005. • Passed Matriculation examination from CBSE with 89.6% in June, 2003. FIELDS OF STUDY • Agricultural Processing & Energy • Soil & Water Conservation Engineering • Farm Power & Machinery PROFESSIONAL TRAINING • One month intensive training at Eicher Tractors a Unit of TMTL, Faridabad from 1st July to 31st July, 2008. • One month intensive training at the Central Farm Machinery Training and Testing Institute, Budni (M.P.) from 1st July to 31st July, 2007. COMPUTER AWARENESS • MS-Office, C++, Visual Basic and Oracle • Good working knowledge of Internet. 59
    • • Typing speed of 25 wpm HOBBIES • Listening to music • Playing Sudoku, Table Tennis • Reading novels HONORS/ACTIVITIES • ICAR (Indian Council of Agricultural Research) Scholarship Holder for the last 3 years of graduation. • President of the Hostel Co-operative mess for 2 Years. • Participated in 10 Days NSS Annual Camp at University level (Aug 2007). • NSS Volunteer for two years. • Participated in various cultural and sports activities at College level. PERSONAL PROFILE Name : Achal Gupta Father’s Name : Sh. Rajan Gupta Date of Birth : 28th Feb, 1987 Gender : Male Languages known : English & Hindi Correspondence Address : Room No. 69, Kailash Hostel No. 1, CCS HAU, Hisar-125004 (HR.). DECLARATION I hereby solemnly declare that all the statement made in the above resume is true and correct to the best of my knowledge & belief. Date: ___________ _______________ Place: ___________ (ACHAL GUPTA) 60