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ThesisItem Open Access Development of Solar Energy Based Inclined Plate Honey Moisture Reduction System(Punjab Agricultural University, Ludhiana, 2019) Iqbal Singh; Sukhmeet SinghHoney is delicious, nutritious and has high medicinal value in comparison to other sweeteners. Honey is usually extracted from comb as immature product which results in high moisture which makes it more liable to be fermented by osmophilic yeasts. So, it needs to be processed for moisture reduction, to delay crystallization and to overcome the problem of fermentation. The present study was undertaken to develop honey moisture reduction system based on solar energy with auxiliary electric heating. The system consists of a flat plate inclined at an angle. The plate is heated from the underside and honey for moisture reduction is re-circulated over it until desired moisture content is achieved. During testing, the moisture content of honey was reduced from 21.5% (w.b.) to 17% (w.b.). The moisture reduction system requires energy input for honey pumping, water pumping and water heating. The drying behavior and honey quality parameters affected by heating viz. HMF (Hydroxymethylfurfural content), diastase activity and colour difference from raw honey were investigated. The process parameters, water temperature and plate inclination were investigated in the range 40 to 70oC and 30 to 60o using four level full factorial design. The process parameters were optimized under simulated indoor conditions based on quality parameters and minimum energy input. The optimum water temperature and plate inclination have been found as 60oC and 60o. The solar energy based honey moisture reduction system has been validated at optimized conditions for quality parameters. The benefit cost ratio of the system considering the cost of raw and processed honey has been determined to be 3.90, thereby indicating that the developed system can be used profitably to reduce the moisture content of honey.ThesisItem Open Access Recovery of sensible heat from air leaving drying chamber of conventional forced circulation solar dryer(Punjab Agricultural University, Ludhiana, 2017) Simranjeet Singh; Sukhmeet SinghAir leaving drying chamber of conventional solar crop dryers is at higher temperature than ambient which leads to wastage of energy. Therefore it is proposed to use thermal storage at exit of the drying chamber of solar dryers to extract heat from leaving air, which can later on be utilised. In this research work, the proposed method is tested for conventional forced circulation solar dryer. The setup consists of multi-tray drying chamber, air heating unit, electric air blower and sensible heat storage unit. Crushed rocks were used for sensible heat storage. Electric heaters were used instead of solar air heaters to have control over drying air temperature. Heat recovery was tested for extending drying operation in two scenerios, namely, with thermal storage only and thermal storage along with auxiliary heating. Evaluation was done at constant inlet air temperatures of 55, 60, 65 and 70oC and fixed air mass flow rate of 0.025 kg/s. 5.850 kg fresh carrots were loaded in each experiment. It was found that thermal storage at exit of drying chamber is beneficial in both cases. During testing, 1.08-9.41% energy savings were achieved along with extended drying operation. Further, heat recovery supplemented by auxiliary heating proved to be more effective. For drying at 60oC, recovered energy was 1.53 MJ and 1.7 MJ with and without auxiliary heating. Computer model has also been developed to predict drying rate for the same setup using air from solar air heater.ThesisItem Restricted Effect of angle of attack on heat transfer and friction characteristics of inclined rib roughened solar air heater duct(Punjab Agricultural University, Ludhiana, 2017) Gurpreet Singh; Hans, V.S.Thermal performance of solar air heaters is very low due to formation of laminar sublayer over the heat transferring surface. By use of artificial roughness in the form of wires, thermal performance of solar air heaters can be increased considerably. This study represents an experimental investigation carried out to examine the effect of angle of attack on heat transfer and friction characteristics of inclined rib roughened solar air heater duct. The various parameters related to roughness geometry and flow were Reynolds number in the range of 2000 to 16000, relative roughness height (e/D) in the range of 0.02 to 0.043, relative roughness pitch (P/e) in the range to 6 to 14 and angle of attack (α) in the range of 45o to 75o: The results obtained from this experimental investigation suggested that ribs inclined at 67o, having relative roughness pitch and relative roughness height value of 10 and 0.043 respectively outperformed the other rib configuration in terms of thermal and thermo-hydraulic performance. Correlations for Nusselt number and friction factor in terms of roughness geometry parameters and flow parameters have also been developed from experimental data.ThesisItem Open Access Thermal modeling of asymmetric overlap roof greenhouse for year round microclimate control(Punjab Agricultural University, Ludhiana, 2017) Amanpreet Singh; Sethi, V. P.In this study global solar radiation availability and thermal model for newly developed asymmetric overlap roof shape of greenhouse was developed. A mathematical model for global solar radiation availability was utilized to compute monthly average daily solar radiation, hourly solar radiation and instantaneous solar radiation; the computed values of solar radiation were utilized in dynamic thermal model to ascertain hourly plant and inside air temperature. Newly developed shape was also compared with previously developed two best shapes of greenhouse viz. even-span and modified arch in terms of solar radiation capture and for inside plant and air temperature buildup. Experimental validation of both the models is carried out for the measured instantaneous solar radiation, plant and inside air temperature for an east-west orientation, asymmetric overlap roof greenhouse (for a typical day in summer) at Ludhiana (310N and 770E) Punjab, India. The per cent difference between predicted inside air temperature and the average of measured values ranged from 0.49 to 24.58 with root mean square error of 5.69. The difference between the measured and predicted values of plant temperature varies from 3.96 to 26.99 per cent with root mean square error of 3.7. During the experimentation, tomato crop is grown inside the greenhouse and modified fan-fogger evaporative cooling system was installed and operated in sequence with different combinations of back side screen net (40×40 mesh size) and assorted sequential timings of on/off operations of fan-fogger. In this study, three different combinations of back side screen net with operational timings of fan-foggers combinations were employed and in order to optimize the operation time of fans and foggers, different combinations of operational time at fixed back side screen opening were also tested. By using modified fan-fogger evaporative cooling system, inside air temperature (Tai) drop was 120 C in twelve minutes during peak hours of solar load. During summer months of May and June, modified fan-fogger evaporative cooling system extracts heat at the rate of 9-10 kW to maintain inside air temperature lower by 8-90 C as compared to ambient air. Optimum value of cooling efficiency of modified fan-fogger evaporative cooling system comes out to be at 6 feet back side screen net slot and at 25 seconds of total operational time of MFFECS.ThesisItem Open Access Performance Evaluation and Thermal Modelling of Box Type Multi-Shelf Inclined Solar-Cooker-cum-Dryer(Punjab Agricultural University, Ludhiana, 2017) Manpreet SinghIn this study, a multi-shelf box type inclined solar cooker-cum-dryer (ISCCD) was developed and experimentally tested. The global solar radiation availability as well as thermal model has been developed for selected latitudes. For calculating monthly average daily solar insolation, hourly solar insolation and instantaneous solar intensity captured by ISCCD, a mathematical program using FREEMAT was developed. The model validation was carried out for different ISCCD parameters such as; upper and lower glass cover temperature, chamber air temperature, absorber plate temperature and temperature of water in the cooking vessel. The heat transfer analysis of parallelepiped cooking vessel was also performed. The top, side and bottom loss coefficients of ISCCD were calculated to find out overall heat loss coefficient which further used in evaluation of thermal efficiency. The cooking performance of ISCCD was tested as per BIS standards (IS Code – 14329) and observed that F1, F2 and tboil were 0.13, 0.45 and 194 minutes respectively. It was also concluded that inclined surface of ISCCD captures maximum incident solar radiation as compared to horizontal surface. Drying performance of ISCCD was evaluated by drying amla (gooseberry) with natural and forced convection drying (with medium (1.8 m s-1) and high speed (3.6 m s-1) of fan). For each case, the experiment was carried out with and without using north facing booster mirror to calculate moisture content, drying rate and drying time. Forced convection with medium speed of fan (1.8 m s-1) using booster mirror took less time (10.5 hrs) to reach equilibrium moisture content (1.66 % db). The Logarithmic model was found best by obtaining the determination of coefficient (R2) and standard error estimate (SEE).ThesisItem Open Access Computational Fluid Dynamics Analysis on Heat and Fluid Flow of Square Wave Profile Transverse Rib Roughened Solar Air Heater Duct(Punjab Agricultural University, Ludhiana, 2017) Inderjeet Singh; Sukhmeet SinghIn this investigation, the thermal and hydraulic performance of solar air heater duct roughened with non-uniform cross-section square wave profiled transverse rib is carried out using Computational Fluid Dynamics software ANSYS Academic Research CFD 15.0. The 3-D investigation considered parameters as relative roughness pitch from 4-30, relative roughness width from 10-310, relative roughness height from 0.015-0.043 and Reynolds number from 3000-15000. The turbulence model RNG k-ε with enhanced wall treatment and one periodic length was selected for analysis. The CFD methodology has been validated with the experimental results available in literature. The maximum enhancement in Nusselt number and friction factor over smooth duct was found to be 2.22 times and 3.40 times respectively at relative roughness pitch of 10, relative roughness width of 85, relative roughness height of 0.043 and Reynolds number of 15000. The maximum thermohydraulic performance parameter was found to be 1.49 at relative roughness pitch of 10, relative roughness width from 85, relative roughness height from 0.043 and Reynolds number of 12000.ThesisItem Open Access Osmo-mechanical dehydration of Fig (Ficus carica L.) and its value addition.(PAU Ludhiana, 2012) Rajneesh Kant; Jarnail SinghThe fresh fully matured fig fruits were procured from markets, orchard of PAU Ludhiana and Dera Baba Jaimal Singh, Beas, Punjab. The detailed nutritional, mechanical, physical and colour analysis of fresh fig fruit were carried out before undergoing osmo-mechanical drying. Osmotic dehydration followed by hot air drying and only hot air drying were carried out under different process parameters. The independent process variable was temperature for hot air drying. Concentration of osmotic agent, temperature of osmotic agent and fruit to solution ratio were independent variables for osmotic dehydration. Levels of temperature for hot air drying were 60, 70, and 80OC. Levels of concentration and temperature of osmotic agent (sucrose solution) were 50, 60, and 70OBx and 60, 70 and 80OC respectively. Similarly levels of fruit to solution ratio were 1:4, 1:5 and 1:6 (w/w basis). Process variables were standardized by carrying out experimental observations and score rating of hedonic scale. Response surface methodology was also adopted for optimization of these process variables. Water loss, solute gain and overall acceptability were response variables under central composite face centered design. The selected process conditions viz. concentration, temperature and fruit to solution ratio for desired product were 60OBx, 70OC and 1:5 respectively. Kinetics of hot air drying and osmotic dehydration were studied. Variations in drying rates and moisture content were investigated. The desired product was observed to be in the range of 18-20% moisture content. Sensory, nutritional and colour analysis of the osmo-mechanically dried fig slices was carried out during storage of six months under ambient conditions. The fig slices were found acceptable. The microbial count, water activity and color was comparable to market product and safe for human consumption. Protein, carbohydrates, and total fat were observed as 3.4g, 65.2 g, 1.2 g per 100g respectively. These remained intact as for fresh fig fruit these values were 1.50g,18.50g and 0.20g respectively. Vitamin A was observed as 180 IU and150 IU for dried and fresh fig respectively.ThesisItem Open Access Heat and fluid flow analysis of solar air heater duct roughened with saw-tooth shaped transverse rib(Punjab Agricultural University, Ludhiana, 2017) Amritpal Singh; Sukhmeet SinghIn this investigation, the Nusselt number and friction factor characteristics have been numerically studied for solar air heater duct roughened artificially with non-uniform crosssection saw tooth rib. The investigation has been carried in 3-D using software ANSYS Academic Research CFD. The parameters, relative roughness pitch, angle of saw-tooth rib, relative roughness height and Reynolds number were varied from 4 to 30, 15° to 75°, 0.015 to 0.043 and 3000 to 15000 respectively . The turbulence model renormalization group (RNG) k-ε was selected for analysis of roughened duct. Both, the Nusselt number and friction factor have been found to be maximum at relative roughness pitch of 16, relative roughness height of 0.043 and angle of saw-tooth of 45° and Reynolds number of 15000. The results have been explained using contours of turbulent kinetic energy, turbulent dissipation rate, static temperature and static pressure have also been plotted. Thermo-hydraulic performance was found best at Reynolds number of 9000, relative roughness height of 0.043 and angle of sawtooth of 45°.