Marzie Tabibi; Seyed Mohammad Safieddin Ardebili; Mohammad Javad Sheikhdavoodi
Abstract
Introduction Cooling systems such as refrigeration and air conditioning are considered as basics of everyday life. However, the required energy for the above-mentioned applications is mainly generated by non-renewable electricity. Due to the depletion of fossil fuels as a source of electricity, the development ...
Read More
Introduction Cooling systems such as refrigeration and air conditioning are considered as basics of everyday life. However, the required energy for the above-mentioned applications is mainly generated by non-renewable electricity. Due to the depletion of fossil fuels as a source of electricity, the development of renewable energies for such systems is necessary. Considering all these issues, as cooling needs, most of the time coincides with the solar radiation availability; therefore, exploring solar energy seems an exciting idea. A number of investigations were performed to design/develop new cooling techniques using solar energy. A solar cooling system is capable of considerably reducing the environmental effects of traditional refrigerating machines while allowing significant energy saving. The present work searches for the best choice of configuration/design factors of food refrigeration systems combined with solar-powered absorption chillers unit in Ahvaz as a case study. Materials and Methods In the present study, a linear parabolic collector with specific dimensions, was made, so that first, the initial design of the collector with longitudinal dimensions of 1 and a width of 0.6 meters was selected by Katia software, and then using related relations and calculations of other structural parameters based on which the collector was built, the collector simulation was performed using NASA radiation data for the place and time of the experiments and by using the Transient Simulation Software and its performance in the days of the month July, August and September 2019 were reviewed and evaluated. Also, the necessary calculations were performed on the results of performance tests by Excel software, and diagrams of changes in the radiant energy absorbed by the collector and the efficiency of the radiated energy absorbed were drawn from 10:00 AM to 6:00 PM. Using the diagrams obtained from the system simulation in TRNSYS software, it is concluded that the built-in collector has the ability to produce a fluid with a temperature above 98 degrees Celsius required for the absorption chiller in July, August, and September. Results and Discussion According to the evaluations of the collector's performance in the three months of July, August, and September from 10 AM to 6 PM showed that collector energy and efficiency reached their maximum values in July with 318.240 w-h/m2 and 63.05 %, respectively. While in August, the amount of energy and efficiency was found to be 299.311 w-h/m2 and 61.94%, respectively. The minimum value of the parameters were recorded as 283.379 w-h/m2 and 61% in September, respectively. The potential analysis conducted showed an excellent saving potential in terms of energy obtained. According to the results, the useful collector energy was achieved to be 227.664 w-h/m2, 217.006 w-h/m2, and 210.406 w-h/m2 in July, August, and September, respectively. According to the obtained results, the maximum refrigeration load needed for the studied cold storage was about 126324 w. According to the results, the average energy obtained for the collector in the three months of July, August, and September was about 216.054 w-h/m2. Finally, the area of the collector was calculated, the results showed that the required surface of the collector was found to be 584.687 m2.Conclusion Solar cooling system for food products cold storage in Ahvaz city is a promising and innovative alternative to decline the peak energy consumption generated by the combustion of fossil fuels, especially during the summer months.
Mohsen Soleymani; Vahid Jahangiri Boltaghi; Mohammad Javad Sheikhdavoodi; Zabihollah Mahdavifar
Abstract
Introduction: Biogas, a product of anaerobic digestion of biomass resources, is one of the major renewable energies with the potential to replace fossil fuels. Anaerobic digestion is performed under specific conditions and according to a specific chemical process. Sugar cane is one of the most common ...
Read More
Introduction: Biogas, a product of anaerobic digestion of biomass resources, is one of the major renewable energies with the potential to replace fossil fuels. Anaerobic digestion is performed under specific conditions and according to a specific chemical process. Sugar cane is one of the most common sources of sugar and bioethanol production in the world. In the ethanol distillation process, large quantities of vinasse are produced. The direct consumption of vinasse as fertilizer has many environmental problems. Anaerobic digestion of vinasse is a potential solution to such environmental problems. Factors affecting the performance of an anaerobic digester can be classified into three main categories: (1) raw material characteristics, (2) reactor design, and (3) operating conditions. Among the operating conditions, temperature and pH are the most important parameters, so in this study, these two parameters were investigated.Materials and Methods:The main raw material was vinasse. Some other additives were used to alter its chemical properties. To have a proper substrate composition, the ingredients before loading into the digesters were evaluated for their chemical and physical properties, including pH, concentration and C/N ratio. The bovine rumen contents of 10% of the final volume of input material were added to supply methanogenesis bacteria as well as to modulate the (C/N) ratio.The Total Solid Content (TS), Volatile Solid (VS) and Chemical Oxygen Demand (COD), were evaluated before and after digestion.A series of batch reactor were used to perform the experiment. The experiment was carried out in a split plot design in a completely randomized design. The main and sub-factor was respectively temperature (at four levels of 30, 35, 40 and 45 ° C) and pH (at four levels of 6.8, 7, 7.2 and 7.4), and the experiment was performed in three replication.To measure the volume of gas produced, a 50 ml water tank connected to the digester outlet as a U-tube was used. The amount of water movement in the U-shaped tube is an indicator of the volume of biogas produced. For better detection of water displacement, some color was dissolved in water. Passing the gas produced from the three-molar NaOH solution, its impurities (mainly carbon dioxide) were absorbed, and the resulting pure gas was re-measured using a U-shaped tube. Using the law of complete gases, the biogas volumetric index was converted to the standard gas volume and finally converted to values based on (ml/gVS) and the new values were analyzed by analysis of variance and mean comparison.Results and Discussion:Almost all main and interaction effects on all the factors studied were significant at the 1% probability level. The amount of gas produced increased with increasing temperature but with increasing pH, it first increased and then decreased. The amount of gas produced at 35, 40 and 45 °C was not significantly different. So because of economic and energy constraints, an operating temperature of 35 °C is recommended for anaerobic digestion of vinasse. The graph of the interaction of temperature and pH shows that at higher temperatures the rate of gas production increases with increasing pH. Although the highest gas volume was obtained at pH of 6.8 and 7.4, but the gas produced in the pH range of 7–7.2 was more pure. Therefore, the best combination of pH and temperature to produce the highest and purest gas is 7 and 35 °C, respectively. But since the vinasse produced in the alcohol factories has high temperature and therefore higher temperatures are possible, so 40 °C is also recommended.It was also clearly observed that the smaller the volume of gas produced, the greater its purity.The VS-R factor is also more sensitive to temperature changes than to pH changes. Thus, in anaerobic digestion of vinasse, pH control is more important than temperature control. VS-R performs best at pH 7. This factor was not significantly different at 35, 40 and 45 °C. Therefore, considering the cost of providing more heat at temperatures of 40 and 45 °C compared to 35 °C, 35 °C is the best temperature for manure production with the highest volatile organic matter removal.The COD-R process was similar at all pHs. COD-R at pH 7 was higher at all temperatures than at other pHs. It was also significantly higher at 40 and 45 °C, compared to other temperatures. So like other factors, the best pH and temperature based on this factor are 7 and 40 °C, respectively.Conclusion According to all factors studied, the best pH and operating temperature of anaerobic digestion of sugar cane vinasse is 7 and 35 ° C, respectively. Another important conclusion to be drawn from this study is that changes in all parameters studied are affected by pH changes rather than temperature changes. Therefore, sufficient care must be taken to ensure that pH variations in the anaerobic digestion medium be very low and around the range proposed (about 7).
N Kazemi; M Almasi; H Bahrami; M. J Shaykhdavoodi; M Mesgarbashi
Abstract
Introduction: Identifying and evaluating of variables that impact tractor performance needs correct size of the variables and their effects on parameters during the tractor operations. So it is necessary to measure accurately performance parameters for improving draft performance of tractor. Generally, ...
Read More
Introduction: Identifying and evaluating of variables that impact tractor performance needs correct size of the variables and their effects on parameters during the tractor operations. So it is necessary to measure accurately performance parameters for improving draft performance of tractor. Generally, there must be a proper assessment and identification from operational parameters such as forward speed, slippage, drawbar pull, etc. In this regard, a lot of research has been conducted using various methods to measure and calculate these parameters under various soil condition and different implementations for achieving the maximum overall energy efficiency, analyzing various treatments and predicting experimental models. But to change soil physical properties and different reactions of machinery on the one hand and to do operations related to on the other hand, precision agriculture intervals between the measurement of performance parameters and making decision for applying operational changes in real condition of work should be as short as possible. These conditions are required to be an accurate system with high confidence ratio for executing, measuring and recording simultaneously in farm. Therefore it is necessary to develop data acquisition for calculating field performance parameters in new methods of farm management. Materials and Methods: In this study, nine different sensors were installed on a MF399 tractor for recording engine and wheel speeds, drawbar power, and fuel consumption. A processing unit was designed and the performance parameters values of tractors-implement were fed into a software to a maximum of 1000 data per second real time, and also remotely from 1.5 km distance in Excel Sheet .Early stage testing of different combinations of the nine sensors included pre-installation on the tractor with four wheels on the jack (In workshop, on tractor) and on the farm and asphalt. Results and Discussion: The results showed that for engine and wheels and the fifth wheel speed sensors (actual forward speed) are accurate the slip was calculated real time using ultrasonic flow meters with 150 cc.min-1 flow rate The lowest fuel consumption was related to the no load and stationery is also possible. About draft, load cell measures 10 Nm real time. Generally, to identifying and survey the effect of various variables on performance parameters of tractor-implements, also designing automatic control system, SSCM and spatial variability in accurate agriculture depend on accurate and precise performance data measurement and correct measurement of variables and changes of parameters during operation execution at the same time. So the installed system is designed in such way that it can measure real-time wirelessly 9 main variables to a distance of 1500 meters with max 1000 data per second including forward speed, speed of all wheels, engine speed, net fuel consumption, drawbar pull and performance parameters such as OEE% (overall energy efficiency), SFC (lit/kw-hr),SE (specific energy in Mj/ha), AFC(Ha/hr), average slip of rear and front wheel(%) , drawbar power (kw), draft(kn/m), FCha(lit/ha)… which are calculated based on the nine variables and display data in tables and graph on pc and finally save separately and totally measurement results and all raw data (pulses) in 10 worksheets into an excel file for any sensor.. It is obvious that number and type of parameters, measurement unit and table display are editable in averaged form and totally this system is installable on common tractors with trivial changes in Iran. However, RTPM (remote tractor performance monitoring) was tested in real conditions of work and of library and its performance was found to be satisfactory. With a tractor equipped with an accurate measurement tool and data acquisition unit, this study tries to make actual interval between receiving, processing and displacing data while it provides the right analysis of recorded changes for controlling automatically and applying instructions with types of operators installed on tractor or mounted instruments on it. Finally, it displays measurement results in such a way that they are understandable not only for researchers and designers of agricultural machineries but also for a regular operator. The system can be installed with minimal changes on all conventional tractors in Iran.
E. Asgari Asli Ardeh; M.J. Sheikh Davoodi; Z. Basati; N. Babamiri
Volume 37, Issue 2 , March 2015, , Pages 17-31
Abstract
The aim of this research was to investigate the effect of grain soaking time (at two levels in 2 and 4 days), grain soaking temperature (at two levels 10 and 25 °C) and grain final moisture content (at three levels 8, 11, 14%w.b.) on the percentage of broken grain during husking and whitening processes ...
Read More
The aim of this research was to investigate the effect of grain soaking time (at two levels in 2 and 4 days), grain soaking temperature (at two levels 10 and 25 °C) and grain final moisture content (at three levels 8, 11, 14%w.b.) on the percentage of broken grain during husking and whitening processes for three paddy rice varieties (Hashemi, Hasani and Khazar) which are common in Guilan Province. The results revealed that the effect of main factors and their intractions was significant on the broken grain percentage during husking and whitening processes. The Hashemi variety had the highest broken grain with values 42.99% and 38.48% at husking and whitening processes, respectively. By increasing grain soaking time from two to four days, broken grain mean values at husking and whitening processes decreased significantly from 20.23% to 15.59% and 29.53% to 27.19%, respectively. By increasing soaking temperature from 10 to 25 °C, broken grain mean values at husking and whitening processes decreased significantly from 19.26% to 16.57% and 29.64% to 27.38%, respectively. The increase of final grain moisture content from 8 to 14%w.b. caused a significant decrease of broken grain at husking from mean value 21.39% to 14.88% and a increase significant in broken grains at whitening from mean value 25.91% to 31.05%. Comparison of the mean results of quaternary interactions showed that the least broken grains percent of husking process (4.736%) was obtained at test with Hasani variety, soaking time of four days, soaking temperature of 10°C and grain moisture content of 14 (%w.b.). Also, the hightest broken grain percentage of husking process (56.8%) was obtained at test with Hashemi variety, the soaking time of two days, the soaking temperature of 10 °C and the grain moisture content of 8 w.b.%. The least broken grain percentage of whitening process (9.44 %) was obtained at test with Khazar variety, the soaking time of four days, the soaking temperature of 25 °C and the moisture content of 11 w.b.%. The highest broken grain percentage of whitening process (57.85%) was obtained at test with Hashemi, soaking time of 2 days, soaking temperature of 10 °C and grain moisture content of 14%(w.b.).
Mohammad Javad Sheikhdavoodi; S. Minei
Volume 30, Issue 3 , December 2007
M.J. Sheikhdavoodi; S. Minaee; M. Almasi; B. Ghobadian
Volume 28, Issue 1 , September 2005
