فهرست مطالب هادی صمیمی اخیجهانی

With increasing the world's population, the demand for supply water resources is also increasing. Nevertheless, climate change has severely impacted the accessibility of fresh water resources. Consequently, researchers have been focusing on producing drinkable water from seas and oceans. Iran, with its significant levels of solar radiation and access to open water from the north and south, is an ideal country for fresh water production. Using solar water desalination systems is a reliable and cost-effective solution for producing drinking water from salt water sources. The purpose of this research is to enhance the performance of the solar water desalination system by using the latent heat storage system and a solar tracking system. In this experimental setup for fresh water production, water was used as the working fluid, while a parabolic collector functioned as the source of thermal energy.

The solar water desalination system was designed and built on a laboratory scale at the University of Kurdistan, and then the necessary experiments were carried out. The flowing fluid (water) inside the spiral tube in the tank is pumped into the absorber tube of the parabolic collector. Inside the receiver tube, there is a spiral copper tube with a 7 cm pitch, which contains paraffin. The parabolic mirror reflects the sunlight onto the receiver tube, causing the working fluid, water, to heat up. The cooling process is achieved using a specific source located in the upper section of the distillation tank. In this case, the steam droplets in the tank hit the bottom surface of this cooling tank, which has the shape of an inverted funnel, leading to condensation. The study was conducted over four consecutive days, from 10:00 to 14:00, under identical conditions from August 24th to August 27th, 2022. It took place at the Renewable Energy Laboratory, University of Kurdistan in Sanandaj, Iran, and was conducted for three different volume flow rates of fluid: 1.9, 3.1, and 4.2 l.min-1 with phase change materials (PCM) and 4.2 l.min-1 without phase change materials (WOPCM); the pump’s maximum flow rate was 4.2 l.min-1. Variations of outlet temperature, thermal efficiency, desalination efficiency, and produced water were investigated under different conditions.

The results reveal that by decreasing the pitch of the spiral tube, there is an increase in the amount of heat captured, due to the increase in the Nusselt number. At the beginning of data collection, a significant amount of the energy that enters the receiver tube is absorbed by both the phase change material and the spiral tube inside the receiver and as a result, the initial air temperature is lowered. The highest temperature of salt water occurs when the fluid is flowing at a rate of 4.2 l.min-1, while the lowest temperature is observed at a flow rate of 1.9 l.min-1. With a flow rate of 4.2 l.min-1, the absorbent tube rapidly transfers the absorbed heat to the salt water chamber through the fluid. The input energy to the tank has increased from 1.53 to 2.83, 1.14 to 2.18, and 0.73 to 1.48 MJ for fluid flow rates of 4.2, 3.1, and 1.9 l.min-1, respectively. At a flow rate of 4.2 l.min-1, the thermal efficiency of the system without phase change materials (3.51%) is lower compared to the case with phase change materials (5.02%). Moreover, using a solar tracking mechanism increased the thermal efficiency of the collector by 9.86% compared to the system using a photocell sensor. Based on the water quality values, it can be stated that the level of dissolved solids in the water sample has been significantly decreased. This indicates that the water can be used for drinking.

In this research, the process of thermal changes in a solar water desalination system using PCM was investigated. The obtained results demonstrate that the use of PCM improved the thermal efficiency of the collector and the water obtained from the current system is safe for consumption. Furthermore, by implementing a solar panel tracking system, the efficiency of the solar collector is improved.

Solar energy is one of the sources of renewable energy that can be used in both buildings, industry and agriculture in the form of heat or electrical energy. According to previous researches, energy consumption in the world is doubling every 20 years. However, the use of renewable energy is still less than fossil fuels, which has caused environmental problems in the world. In recent decades, the tendency to use renewable energy, especially solar energy, has increased. A significant portion of the world's energy (about 30%) is spent on agriculture, and about 3.62% is used to dry agricultural products (Iranmanesh et al., 2020). However, thermal and drying efficiency of the solar collectors are not in acceptable range. Applying different ways to improve the performance of solar dryers such as using thermal energy storage system, air recirculation mechanism and using desiccant system. In this paper, phase change materials were placed vertically in consecutive rows at different distances inside the collector and the thermal performance of the collector was investigated. Also, the drying process of Oleaster were evaluated using PCM and air recirculation system.

The indirect solar dryer used in this study includes the chassis, flat plate collector, electric fan, drying cabinet, pipes containing PCM and sensors. 25 copper tubes containing PCM are placed on the absorber plate with fixed intervals. The insulated cabinet of the dryer has three trays. A 220 volt 60 W electric fan is placed in the inlet of the collector and causes to flow air inside the system. The process of drying Oleaster in a solar dryer was carried out for 9 consecutive days in August 1401. The drying process was performed at three positions of PCM pipes at 5, 10 and 15 cm intervals with air flow rate of 0.5, 1 and 2 m/s. The drying kinetics of Oleaster was investigated using five mathematical models considering drying time and related constants. The selected model is selected based on the degree of fit (the highest R2 and the lowest RMSE) on the experimental data. Thermal efficiency was calculated according to ASHRAE standard 2003 (Eltawil et al., 2018). Moreover, to determine the drying efficiency the amount of energy required to heat the dryer and the product and extract water from the Oleaster and the total energy (electrical and thermal) input to the dryer was considered. SCE is defined as the energy required to dry one kilogram of the product.

The drying time of the product by the dryer is reduced from 2.09 to 4.16% on average by changing the position of PCM from 5 cm to 15 cm. On the other hand, with the increase of air velocity from 0.5 to 2 m/s, the drying time decreased from 8.32% to 16.64%. Henderson and Pabis model was the best model to describe and define the drying process of Oleaster with solar dryer. The curves of the drying rate against the time in different conditions illustrated that in the initial stage of drying of samples. The amount of moisture evaporation is high due to the high water content in Oleaster, and a major part of the drying process took place in this period. The value of SEC for the dryer without PCM was 4.26 MJ/kg, while for the case with PCM, it was 2.04 MJ/kg with a distance of 15 cm. By increasing the distance between the tubes, the drying efficiency increases due to the reduction of drying time and energy consumption. In this case, the consumption of electrical energy by the fan (for fluid flow in the dryer and collector) and the thermal energy input to the dryer are reduced. However, with the increase of air speed from 1 m/s to m/s2, there is a significant reduction in drying efficiency. The highest drying efficiency was 36.72% and the lowest was 25.65% for distance 15 cm, air velocity of 1 m/s and distance 5 cm, air speed 2 m/s, respectively. Drying efficiency was improved by at least 12% using PCM.

In this research, the analysis of the thermal process in the solar dryer system in three positions of the tubes containing PCM inside the flat plate collector for the distances of 5, 10 and 15 cm between the tubes at three air velocities of 0.5, 1 and 2 m/s was investigated. Using the return flow system and the phase changing material at the same time improved the thermal efficiency of the flat plate collector by 19.12%.

Every year, a significant part of fruit and vegetable products is lost due to the country's inappropriate transportation systems and storage facilities. The waste of strawberry and apple products in Iran is estimated at 40% and 31%, respectively; which can be considered as a source of biomass in bioenergy production. Despite the good biogas production potential, fruit waste requires pretreatment due to lignocellulosic matter to reduce biological decomposition time. This research investigated the effect of mechanical, chemical and thermal pretreatments on the degradability of fruit waste and the amount of biogas production from its co-digestion with cow manure. Mechanical pretreatment was by crushing apple and strawberry waste into pieces of 5, 10 and 15 mm, chemical pretreatment was by placing fruit waste in sodium hydroxide solution (NaOH) at concentrations of 6, 8 and 10% for 3 hours and heat treatment was done by putting waste together with distilled water inside the microwave at 800 watts for 10, 20 and 30 minutes. The pretreated wastes were co-digested with cow manure and were fed into the batch digesters under anaerobic digestion conditions for 25 days. The results showed that the pretreatments of crushing, sodium hydroxide and the microwave increased biogas production compared to the control by 5%, 50.9% and 27.3%, respectively. Chemical pretreatment can be suggested as a preferred method of pretreatment of the identified wastes.

One of the biggest problems in growing legumes like peas is harvesting these types of crops. During the machine harvesting process the harvest loss is very high. Therefore, in most parts of Iran chickpea harvested by hand and this is very tedious. Based on the literature review there are different types of harvesting machines which designed, constructed and optimized by Miller et al., 1990; Golpira, 2015; Shahbazi, 2011; Jalali and Abdi, 2014; Mahamodi, 2016. But using different varieties of chickpea in mountainous areas has limited the use of harvesting mechanisms. The purpose of this study is mechanization of the harvesting process of chickpea with low losses and suitable performance. Moreover the optimization process of lowering the weight of the header was carried out by modeling of software.

To reduce the amount of chickpea losses from the reel, a perforated plate with defined holes was installed in the header, where the separated chickpea pods fell behind the plate without returning to the farm. By using the plate in the header of the chickpea harvesting machine and by changing the harvesting height at the three levels of 10, 15 and 20 cm and the distance of the cutter at three levels of 3, 5 and 7 mm, the performance of the machine was evaluated. The experiments were carried out with Caboli variety cultivated in Kurdistan province, which is proper for mountainous areas without regular watering condition in three replications. The plants were placed in a fiber, wooden plate considering farm conditions. In addition, the header was modeled statically and dynamically under the influence of the external forces applied to the header using Ansys and Abaqus software. Based on the actual data, the validity of the applied model was determined and according to the verification results the optimization of the header was performed considering minimal weight (to reduce energy consumption).

The evaluation results of the performance of header showed that the effects of using perforated plate and the height of the header for harvesting on the chickpea harvesting and losses are significant at the level of 1% and 5%, respectively, and the interaction between perforated plate and the header height on the chickpea loss is significant at 5%. Using a perforated plate in the harvesting machine increases the amounts of chickpea collected from the farm increases. In this condition the chickpea pods separated from the plant and passed through the plate. With the separation of the stems, due to the proper wear that exists between the plate and the reel, the pods are properly separated and pass through the perforated plate. Moreover, the chickpea loss is higher for the system without perforated plate. The effect of the distance between the reel and header plate is affects the remaining chickpea on the plate. By increasing the distance from 5 mm to 7 mm the amount of harvested had a considerable effect. The best method of harvesting chickpeas is at the kinematic index of 1.5 with perforated plate, the harvesting height of 15 cm and the distance of 5 mm. According to modeling processes of the reel and the results of the static analysis, the minimum and maximum stress values were recorded about 3.31 MPa and 6.50 MPa (based on the von misses criteria), respectively, which is very small compared to the yield stress of the reel constructed with St-37. Also, the results of the dynamic analysis of the reel showed that the maximum von misses stress occurred with increasing the kinematic index. The maximum stress for kinematic index of 1, 1.5 and 2 was observed about 32.2, 40.1 and 52.72 MPa, respectively. The results of 3D model validation showed that the applied model with Abaqus software (R2>0.9264) was able to predict the amount of stress in different parts of the reel.

In this study, the changes were made on the chickpea harvesting machine to get the proper performance and increasing machine efficiency. A perforated plate was used to prevent pea’s losses. The best condition for the harvesting process is obtained with the harvesting height of 15 cm and the distance of 5 mm. By using 3D modeling of the reel weight was reduced about 10%.

the flat solar heating transpired collector can be used for heat buildings and large spaces, industrial applications, and drying of agricultural products. The flow structure and convection heat transfer mechanisms are very important to the air performance of uncovered flat solar heating transpired collector. In these solar air heaters, the air is usually heated by a perforated absorber plate (metal). In this research, copper adsorbent plate has been used and numerical simulation has been performed for mass flow rate (0.007, 0.01, 0.0125, 0.015) kg/s. In order for the simulation to be consistent with the physical reality of the problem, the simulation is three-dimensional, non-continuous with a large computational range and continuous suction. Thermal efficiency, mass flow rate, and outlet temperature parameters were investigated. According to the obtained results, with decreasing mass flow rate, the temperature of the absorber plate and consequently the temperature of the outlet air increases; But increasing the temperature of the absorber plate is more than increasing the temperature of the outlet air. As the mass flow rate increases, the thermal efficiency of the flat solar heating transpired collector increases. The lowest efficiency in mass flow rate is 0.007 kg / s with 66.51 % and the highest efficiency in mass flow rate is 0.015 kg / s with 78.02 %.

Drying of agricultural products is one of the main ways to prevent product spoilage. There are several methods to dry agricultural products, including direct sunlight, hot, sunny weather, microwave, vacuum, and freezer which use different energy sources. Due to  constrain of fossil fuels supply, the price of this type of energy is increasing thus the tendency to use renewable energies is increasing (Purohit and Kandapal, 2005; Purohit et al., 2006). In Iran the drying efficiency of solar dryers is low because less solar energy is converted into thermal energy. Therefore, many measures have been taken to increase the efficiency of solar collectors which causes to obtain the dried samples with better quality and lower cost. In this study a combination of tracking system and phase change materials (PCM) are used to increase the efficiency of solar dryer cabinet with three types of collectors including flat plat (FPC), parabolic trough (PTSC) and evacuated tube (ETSC) collectors.

The dryers used in this study include a cabinet connected to a flat plat, parabolic trough and evacuated tube collectors. In all of the dryers, PCM have been used to maximize solar energy utilization. Moreover to get the maximum solar radiation the tracking system used in FPC and PTSC and a storage tank with fluid pump used in PTSC and ETSC. The air flow rate inside the system was about 0.018 kg.s-1 for all the experiments. The experiments were performed in three continues days from 16 to 18 June 2018, from 8:00 to 24:00. Tomato sample with a thickness of 9 mm was considered for drying process. To describe the drying process of the samples, the moisture ratio versus time was considered. Also, the drying efficiency was defined considering the ratio of energy (thermal and mechanical) consumed to heat the product and extract moisture from the product (Qm) to the total energy used for drying process, including fluid thermal energy (Qf) and mechanical energy (Emec) (Fudholi et al., 2014). In order to evaluate the quality of the dried product at different modes, three quality parameters including color difference, shrinkage and rehydration ratio were considered. Color difference between the fresh and dried samples  was evaluated as one of the most important factors that the customer was considered for selection (Magdic et al., 2009). The change in the volume of the dried product compared to the fresh product is defined as shrinkage. Moreover, to evaluate the rehydration ratio the weight of water absorbed by the samples was considered.

The effect of variations of the intensity of solar radiation on the amount of solar energy taken by the collectors was negligible. The time required to dry tomato slices by the dryer equipped with FPC was longer than the other systems. The results also showed that the highest drying efficiency is related to the dryer with ETSC and it was about 39.02%. The least value is related to the dryer with FPC and it was about 30.12%. Due to the long drying time the use of the fan and the pump increase and the amount of energy consumed to drying the product increases as well. Thus the efficiency of the dryer with FPC decreases. The values of specific energy for the dryer with FPC, PTSC and ETSC were obtained as 7.12, 7.92 and 8.34 MJ/kg, respectively. The results of qualitative evaluation of dried tomato slices showed that the product obtained from the dryer equipped with ETSC, due to the short drying time, the color changes and the shrinkage was suitable  in comparison with the other reports. The amount of rehydration ration was the highest as well. Using PCM had no adverse effect on the quality of the dried samples. The results showed that the dryer with ETSC had higher efficiency (about 39.02%) and the quality of the samples was suitable compared to other systems. Using recycling system can improve the thermal efficiency of the solar dryer.

The presence of various impurities leads to the problems in storage time, transmission, selling and consumption process of any product. Thus it is necessary to separate the impurities from the product for industrial processing. Descurainia Sophia is a tiny grain seed in light brown color with elliptical shape and it grown up in humid climate. Electrostatic method is a proper way for separation and purification of materials which is based on the absorption and diffusion of charged particles in an electrical field with high voltage. An experimental research was carried out for recycling the plastic waste with tribo-electric system. The result of the research on plastic separation of waste materials showed that by increasing the voltage of the system the purification fold increases. The results of the effect of the applied voltage for recycling the plastic particles showed that by increasing the applied voltage in the electrodes the mass and purity of the polycarbonate (PC) increased and the mass and purity of polyamide (PA) decreased. There is a little information about separation and purification of fine grain seeds and this study is about separating of Descurainia Sophia seed and the effect of the parameters using regression analysis.   Descurainiaseed samples were collected from the farms located in Mahan city of Kerman province, Iran. Tribo-airo-electrostatic system contains of funnel and feeding container, the charger unit, the separating unit, air transmission channels and gathering unit. Charging unit consists of two aluminum electrode connected to a high voltage DC power supply adjustable between 0-100 kV. A blower was used to suspend material and increase the exposure time of particles in the electric field. The gathering is a box with different partitions divided by wooden sheets. Separated particles fall in the gaps based on the amounts of charges, weight and shape. The separating process takes place by considering physical properties. There are two important forces that acts on the falling of the object in electric field; the electric force acts in the horizontal direction, gravitational force acts in the vertical direction. Considering the purity of the separated seeds in the box, only four sections of the box were selected for size and frequency analysis. For obtaining gathered seed impurity, the digital pictures of the gathered samples imported in Matlab6.5 software and were analyzed using Image processing toolbar based on the differences between seed and impurity color. For regression analysis of the parameters voltage in the electrodes, the distance of the electrodes, the angle of the electrode and the mass of the boxes was considered. Laser diffraction method used for determination the size of separated particles and for this purpose FRITSCH Laser Particle Size Analyser -ANALYSETTE 22 NanoTec system was used.   The results illustrated that the Descurainiaseed takes negative charge and moves to the positive electrode and impure particles takes positive charge and moves to the negative electrode. The purity calculations of the experiments showed that the average percentage of box No.1 is more than 98%, box No.2 is between 65%-75%, box No.3 is between 30% to 50% and box No.4 is less than 50%. The values of correlation coefficient of the effective parameters for box No.1 was 90% and this means that 90% of the parameters of equation affected on the weight of the box No.1 for about 90%. By increasing the applied voltage and the angle of the electrodes of the separating unit and decreasing the distance of the electrodes, the purity of box increases. The size analysis of Descurainiaseed showed that the particles with larger dimensions take more negative charge and moves to negative electrode. The results of the study showed that tribo-airo-electrostatic system separated Descurainiaseed from waste particles properly. By considering the optimum value of separating parameters the purification increased by 98%. According to the results it can be stated that this system can be used for separation and purification of small grains such as alfalfa and clover.

In this experimental study the effect of using phase change materials (PCM) in the thermal storage tank on the performance of a solar dryer was investigated. The experiments were carried out for three levels of PCM 1.54, 2.45 and 3.6 kg and two levels of fluid flow rate of 0.2 and 0.4 l/min. The results showed that with increasing the fluid flow, the thermal efficiency of the collector from 62.4% to 20.2% for 0.4 l/min. The thermal energy for fluid flow of 0.2 and 0.4 lit/min obtained about 13.31 to 13.63 MJ and 14.45 to 14.92 MJ, respectively. The results also showed that the overall efficiency of the dryer increased with increasing PCM and it changes from 32.92% to 35.55% for the fluid flow rate of 0.2 l/min and 32.19% to 36.02% for 0.4 l/min. Considering the specific energy used for drying of the samples and drying efficiency the fluid flow with 0.2 l/min and PCM with 3.6 kg is a proper choice for drying of apple slices. The payback period was obtained about 20 months.

Nowadays, in modern agriculture, the combination of image processing techniques and intelligent methods has been used to replace smart machine instead of humans. In this study, an artificial image processing and artificial neural network (ANN) method was used to classify strawberry fruit of Parus variety. In the first step, the fruit was divided into 6 classes (ANN outputs) by the expert, and 100 samples were randomly collected from each class. In the next step, the images of the samples were captured and three geometric properties with twelve color properties (as ANN inputs) were extracted. Optimum artificial neural network structures considering root mean squared error (RMSE) and correlation coefficient (R2) were investigated to classification process of the strawberry samples. Finally, the perceptron neural network with a structure of 6-18-15 was selected with an average accuracy of 83.83%.

In this research, to increase the performance of parabolic solar collector, PCM phase change materials were used inside the fluid storage tank. The effect of fluid flow rate at three levels of 1, 2.5 and 5 l/min and PCM mass at two levels of 1.5 and 3.2 kg on output temperature and thermal efficiency of the collector and tank efficiency using experimental methods and CFD and ANN were evaluated and compared. Drying efficiency changed from 21.11 to 25.20% and collector from 62.9 to 64.03. The collector efficiency error of CFD and ANN methods varied from 5.31 to 7.4% and 1.22 to 3.84%, respectively. According to the statistical data and the time spent, it was found that the ANN method can be used to predict the thermal behavior of the system more accurately and less time than the CFD method.

In this study, the amount of produced thermal energy, exergetic and energetic efficiency of a collector at three conditions with porous plate (PS), with recycling system (PRS) and with reflectors (PRE) in a solar dryer was investigated. For all the experiments the fluid flow rate was 0.018 kg/s. Tomato slices with 7 mm thickness were considered for drying process evaluation. All the experiments were carried out during three consecutive days of June of 2018 from 8:00 to 18:00. The value of total energy enters to the dryer for PS, PRS and PRE changed to 21.94, 24.93 and 28.77 MJ, respectively. Moreover, the energy efficiency obtained 21.03-52.30% for PS, 23.12-58.23% for PRS and 30.01-69.75% for PRE. The maximum exergy efficiency for mentioned conditions was calculated about 19.40%, 21.20% and 23.12%, respectively. The specific energy used for drying of the slices for PS, PRS and PRE was obtained 9.68, 9.28 and 8.82 MJ/kg, respectively and this shows that using the reflectors is proper method to increase thermal efficiency of the flat plate collectors.

Strawberry is one of the native and small fruits of moderate regions, which its cultivation  has been increased in all over the world including Iran. Due to the abundance of vitamin C and mineral materials, it is very useful for some diseaseses. Lack of the knowledge in production management, harvesting, cooling, transportion, storage, marketing and processing equipments and connection between these different parts are the main problems throgh industrial production of strawberry fruit (Salami et al., 2010). According to the various studies, the parameters such as color, shape, size and mass are not sufficient for the consumer to purchase the fruit (Abbot, 1991). They would like to have more information about the fruit which is supposed to be purchased (Voca et al., 2008). Several researchers have been investigated physical and chemical properties of different varieties of strawberry fruit (Wojdylo et al., 2009; Salamat, 2011; Nemzer et al., 2018). According to the litrature, any international standard classification for Parus strawberry (which is mostly cultivated in Iran) based on physical and chemical was not found. In this study, some physical, mechanical and chemical properties of strawberry fruit Parus variety, as well as the relationship between them, were investigated. The classification was performed based on the appearance features including color and size with the opinion of the expert in six classes.

In Kurdistan province strawberry fruit is often grown in open area and cultivated areas of Parus variety due to many reasons are increasing. To classify the strawberries, six classes were considered. Physical and mechanical properties such as dimensions, density, porosity, stiffness and biological yield point were measured at least at five replications. The porosity of the strawberries was also calculated through the division of the difference between actual and apparent density to actual density. Also, the stiffness and biological yield point were measured using Universal Instron Testing Machine (Zwick/Roll). Chemical properties of Parus strawberry including vitamin C, acidity, total soluble solids and flavor index were investigated at five replications.

The analysis of variance showed that all chemical properties including ascorbic acid, acidity, total soluble solids, and flavor index, were strongly influenced by the class. The LSD mean comparison showed that the highest levels of vitamin C were related to the ripe fruits which had a direct relationship with fruit size. The acidity values between the classes varied from 0.55 to 1.08, and the lowest value was related to the first, second and third classes, respectively. The total soluble solid material (TSS) was affected by some factors: sugar (as main part), organic acid and organic pectins and was increased by growing strawberries and increasing the amount of sugar. For the first, second and third  classes, TSS was higher than those of the fourth, fifth and sixth clases. The flavor index value for the lower classes (first, second and third) is higher than the higher classes (almost 2 times). The analysis of variance for all physical and mechanical properties indicated that all parameters are affected by the classes. Due to its more soluble materials, the maximum value for actual density was related to the third and second classes, respectively. The apparent density of agricultural products depends on various factors such as geometric shape, size, surface properties, moisture content and measurement method. The apparent density for the first and fourth classes were 561.743 and 498.408 gr.mm-3, respectively. The maximum and minimum value of stiffness was related to first (about 5.2 N.mm-2) and fourth (about 28.2 N.mm-2), respectively. For biological yield the maximumvalue was related to the fourth class, as well.

In this study, the classification of strawberry, variety of Parus was investigated based on physical, mechanical and chemical properties. All properties were affected by changing the classes. The results of this research can be used to design and construct post-harvest and sorting mechanisms of agricultural products which require comprehensive information about physical, mechanical, chemical properties.

One of the ways to use solar energy is to use a solar dryer. But these kind of dryers have low efficiency that optimizes their absorbent plate to increase efficiency and save energy. For this purpose, the air flow inside the compartment of the adsorbent plate of the solar dryer was simulated using the computational fluid dynamics modeling and the heat transfer process, flow distribution and air velocity inside the compartment were analyzed and finally, the plates were compared in vitro. In this research, three different modes of the page with the same input and three different output modes (circular, conventional and perforated) were investigated. In a porous sheet with porosity, the plate was used with a coefficient of 0.0314. The results showed that between analytical and empirical data, the explanatory factor (R2) was above 97%. There are circular and conventional heat accumulation in the corners, which, by changing the type of output and converting it to the perforated output state, Heat and heat accumulation are prevented.

Drying is one of the most common methods for storing food and agricultural products. During drying process, free water that causes the growth of microorganisms and spoilage of products is removed from the product. There are several methods for drying of agricultural products. one of the most important methods of investment is drying by using sunlight. Iran is situated at 25- 43oE longitude and mean solar radiation is about 4.9 kwh.m-2.d-1. Because of the proper solar radiations in 95% of the agricultural areas in Iran, solar drying is widely used for drying of fruits and vegetables. The use of solar dryer causes saving in energy consumption and processing costs for drying of products in farms and gardens. Several researchers investigated heat transfer and heat flow in dryers. Selection of appropriate method was carried out for drying of agricultural products using heat pump. Experiments were done and mathematical relationships were estimated to obtain correlation parameters between Reynolds number and Nusselt number for the three cases of solar dryer (cabinet, indirect and combination).The best working conditions were determined for three types of solar collectors (flat, finned and corrugated). In this study, the process of heat transfer and heat transfer coefficient of a solar dryer with and without rotation of absorber plate was compared.
The experiments were conducted in Azarshahr, East Azarbayjan province, Iran in September 2014. Newton's law of thermodynamic was used to analyze the working condition of solar absorber. For this purpose the absorber plate was divided into four equal parts. According to the thermal equations and related boundary conditions as well as the relationship between heat transfer coefficient and the temperature gradient, equation 1 for the Nusselet number obtained: Beside the relationship between Nusselt number and heat transfer coefficient is defined as equation 2: Finally variation of total heat flow over the time at different surfaces of the collector is determined by using equation 3: Two cases (solar panel with rotation and without rotation) were considered for testing. Data measuring was carried out for 9 hours from 8 to 17. The fluid flow rate was 0.0185m3.s-1. The dryer was installed in an environment with air temperature of 31.6 oC and 31.8 oC, with the air velocity of 0.58 m.s-1 and 0.54 m.s-1 and with the relative air humidity of about 21%and 21.5% at the first and second days, respectively. The dryer had an automatic temperature controller to fix the air temperature with an accuracy of ±0.1 oC. An anemometer Yk-2005AM model was used to regulate the required air velocity. The output data of the thermocouples was recorded by a digital thermometer (DL-9601A, Lutron) that was connected to a computer using RS232 cable and recorded the temperature at required point every an hour. The relative humidity of the ambient was measured every hour with a digital hygrometer (HT.3600, Taiwan), accuracy of 3%. By assembling controlling system with a DC motor, a precious photocell and a proper mechanism, the frame would rotate by the sun and followed solar radiation, therefore more solar energy produced in solar panel.
The results of the experiments showed that the heat transfer process increased in both cases from the early morning and reached to its maximum value around 12 to 14 o’clock. The trend was more homogeneous in the dryer by absorber plate without rotation due to the decline of the heat accumulation. The mean temperature rise in the solar dryer without rotation was 37oC and in the solar dryer with rotation was 54oC. Because of the rotation of solar plate, variations of solar radiation were low. Therefore, by rotation of the solar dryer panel the temperature rise was 27oC. The values of heat transfer coefficient in the solar dryer with rotation were decreased by the time. This reduction in the hours before noon is more than after noon. This is due to the reduction of the temperature gradient in the solar absorber plate. Also the results showed that heat transfer coefficient in the lower levels (S1 and S2) is more than higher levels (S3 and S4). Variations of the heat flow for the solar dryer with rotation is more than the other. Because in the first one, the absorber plate was followed the solar radiation and generated heat in the plate increases and the fan does not have the ability to discharge the generated heat. The total amount of heat transfer in absorber plate with rotation was 36.1% higher than the absorber plate without rotation. To increase the heat transfer from the dryer, design of the system to change air flow rate by increasing temperature, can increase the efficiency of the dryer.
In this study the performance of the absorber plate in a solar dryer in two cases with rotation and without rotation were compared. The results showed that by rotation of the solar absorber plate the output temperature of the collector rises about 27oC. Thermal fluctuation in the rotation solar plate is lower than the solar plate without rotation.

Mechanical weeding is one of the non-chemical methods to control weeds. In this paper a ‎new mechanism has been presented for mechanical cultivation. The machine works based on ‎the manual tools operation, which farmers still use in small scale for weeding and consists of a ‎number of four-bar linkage mechanisms. Each mechanism consists of a blade which moves ‎forward (active course) and backward (passive course). The three precise position methods ‎were applied to design the mechanism. The Matlab software was used for solving the equations ‎and drawing the path of motion. Considering the parameters and solving the equations, a four-‎bar linkage (crank-rocker) was proposed.‎

A new mechanical cultivator was proposed for mechanical weeding in part one. The precise point method was used to geometric design of this new cultivator. The aim of this research is selecting the suitable mechanism of the studied mechanisms in part one. The velocity and acceleration of links (kinematic) is the base of dynamic analysis of the systems. The variation of velocity، acceleration and jerk as the kinematic parameters as well as the joint forces and input torque as the dynamic parameters were investigated. Programming in Matlab was used to solve the equations and draw the diagrams. The program is provided to calculate the values of angular velocity، angular acceleration، angular jerk، joint forces and required input torque of the mechanism and draw the diagrams. The output diagrams showed that the values of the angular acceleration and jerk of the links and the values of the forces of the mechanism''s joints were continues. By considering the values of the forces at joints and links of the mechanism the type of the material and sectional area can be calculated. The value of required input torque was obtained by considering maximum values of the related diagram.