H. Kargarpour; T. Tavakoli Hashjin; A. Hemmat; B. Ghobadian
Abstract
Introduction The olive fruit (Olea europaea L.) is so sensitive to impact like many other crops that would lead to mechanical damage and bruising which reduce the quality of it. The olive fruit damage includes a brownish bruise at the bruised location. Most mechanical impact damage occurs during harvesting, ...
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Introduction The olive fruit (Olea europaea L.) is so sensitive to impact like many other crops that would lead to mechanical damage and bruising which reduce the quality of it. The olive fruit damage includes a brownish bruise at the bruised location. Most mechanical impact damage occurs during harvesting, handling and transportation. Bruise sensitivity of two common olive cultivars in Iran (cv. Roghani and cv. Conservolea) was studied by free fall method because of development of the area under olive cultivation in Iran, and necessity to mechanical harvest in near future. Materials and Methods Two cultivar of olive fruit named Conservolea and Roghani were collected from Research Orchard of Horticultural Department of Isfahan University of Technology. A free-fall device was designed and built to accomplish an impact experiment which included a load cell monitoring system to measure impact force. The effect of cultivar, height and mass were studied in a factorial experiment. The factors consisted of two cultivar, height at five levels, and mass at three levels with 10 replications. The experiments were performed according to completely randomized design. The effect of impact force and absorbed energy was also studied for the two cultivars. The dimensions of bruising was measured 24 hours after the tests by a caliper with an accuracy of 0.01 mm. The bruising area and volume was calculated assuming the elliptical model for the bruised region. Experimental data were subjected to analysis of variance (ANOVA). Mean comparison was performed based on least significant difference (LSD) test with. Results and Discussion For both cultivars the bruising occurred under the skin and near to the stone. This could show the effect of stone at bruising. The shape of bruised region was elliptical in cv. Roghani and spherical in cv. Conservolea. The bigger stone index and the lower flesh width of cv. Roghani might be one of the reasons of more volume of bruising in this cultivar. This variety could be due to less sphericity in cv. Roghani than cv. Conservolea. The distribution of bruising was more in Roghani cultivar since it had more oil and less water content that might led to more bruising distributed under impact condition so the volume of bruising was more than Conservolea cultivar. The effects of cultivar, height and mass were significant on area and volume of bruising. Increasing height and mass significantly resulted to increase the area and volume of bruising for both cultivars. The bruise area and volume were significantly higher in cv. Roghani. This could be due to differences in physical properties of the cultivars. Roghani cultivar had a higher pit/flesh ratio in comparison with Conservolea cultivars that could contribute to more area of bruising in this cultivar. Increasing the force and energy led to increase in bruise volume for both cultivars. In cv. Roghani, despite the lower levels of force and energy, the bruise volume was more than cv. Conservolea. The reason of lower energy and force in cv. Roghani might be as a result of lower mass than cv. Conservolea. Conclusion The results showed that the effects of independent variables were significant on the volume and area of bruising so that, increasing height and mass increased the volume and area of bruising. The Roghani cv. was significantly more sensitive to bruising compared to Conservolea cv. The energy and force levels were higher in cv. Conservolea since it was heavier than cv. Roghani while the volume of the bruise was more in cv. Roghani. This might be due to the lower sphericity and flesh/pit ratio in cv. Roghani. The shape of mechanical damage which was appeared with a brownish bruising on olive tissue was related to the geometric shape of the fruit i.e. for cv. Roghani and cv. Conservolea the bruising was elliptical in and spherical just like the geometric shape of the cultivars.
S. Abbasi; H. Bahrami; B. Ghobadian; M. Kiani Deh Kiani
Abstract
Introduction The extensive use of diesel engines in agricultural activities and transportation, led to the emergence of serious challenges in providing and evaluating alternative fuels from different sources in addition to the chemical properties close to diesel fuel, including properties such as renewable, ...
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Introduction The extensive use of diesel engines in agricultural activities and transportation, led to the emergence of serious challenges in providing and evaluating alternative fuels from different sources in addition to the chemical properties close to diesel fuel, including properties such as renewable, inexpensive and have fewer emissions. Biodiesel is one of the alternative fuels. Many studies have been carried out on the use of biodiesel in pure form or blended with diesel fuel about combustion, performance and emission parameters of engines. One of the parameters that have been less discussed is energy balance. In providing alternative fuels, biodiesel from waste cooking oil due to its low cost compared with biodiesel from plant oils, is the promising option. The properties of biodiesel and diesel fuels, in general, show many similarities, and therefore, biodiesel is rated as a realistic fuel as an alternative to diesel. The conversion of waste cooking oil into methyl esters through the transesterification process approximately reduces the molecular weight to one-third, reduces the viscosity by about one-seventh, reduces the flash point slightly and increases the volatility marginally, and reduces pour point considerably (Demirbas, 2009). In this study, effect of different percentages of biodiesel from waste cooking oil were investigated. Energy distribution study identify the energy losses ways in order to find the reduction solutions of them. Materials and Methods Renewable fuel used in this study consists of biodiesel produced from waste cooking oil by transesterification process (Table 1). Five diesel-biodiesel fuel blends with values of 0, 12, 22, 32 and 42 percent of biodiesel that are signs for B0, B12, B22, B32 and B42, respectively. The test engine was a diesel engine, single-cylinder, four-stroke, compression ignition and aircooled, series 3LD510 in the laboratory of renewable energies of agricultural faculty, Tarbiat Modarres University. The engine is connected to a dynamometer and after reaching steady state conditions data were obtained (Fig. 1). In thermal balance study, combustion process merely as a process intended to free up energy fuel and the first law of thermodynamics is used (Koochak et al., 2000). The energy contained in fuel converted to useful and losses energies by combustion. Useful energy measured by dynamometer as brake power and losses energy including exhaust emission, cooling system losses and uncontrollable energy losses. Variance analysis of all engine energy balance done by split plot design based on a completely randomized design and the means were compared with each other using Duncan test at 5% probability. Results and Discussion Results showed that, in general, biodiesel use has a significant impact on all components of energy balance. Of total energy from fuel combustion, the share of energy losses to form of exhaust emissions the maximum value in all percentages allocated to biodiesel (Average 51.715 percent) with the maximum and minimum amount of B42 (55.982 percent) and B0 (46.481 percent), respectively (Fig. 2). Also, fuel blend with 12% biodiesel was diagnosed the best blend because of having the most useful power, having the lowest energy losses through the exhaust and cooling system. Conclusion Using biodiesel produced from waste cooking oil by transesterification process, lead to increase the useful power. The addition of biodiesel to pure diesel cause to significant reduction in the waste energy due to friction. In higher amounts of biodiesel increase energy losses especially through the exhaust and cooling system due to higher viscosity.
A. Farhadi; S. Rostami; B. Ghobadian; Sh. Besharati
Abstract
Introduction Nowadays, due to higher environmental pollution and decreasing fossil fuels many countries make decisions to use renewable fuels and restrict using of fossil fuels. Renewable fuels generally produce from biological sources. Biodiesel is an alternative diesel fuel derived from the transesterification ...
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Introduction Nowadays, due to higher environmental pollution and decreasing fossil fuels many countries make decisions to use renewable fuels and restrict using of fossil fuels. Renewable fuels generally produce from biological sources. Biodiesel is an alternative diesel fuel derived from the transesterification of vegetable oils, animal fats, or waste frying oils. Considering the differences between diesel and biodiesel fuels, engine condition should be modified based on the fuel or fuel blends to achieve optimum performance. One of the simplest and yet the most widely used models is the thermodynamic model. After verification of the data obtained by model with experimental data it is possible to generalize the extracted data to an unlimited number of functional conditions or unlimited number of fuel types which saves time and reduces costs for experimental engine tests. Using the second law of thermodynamics, it is possible to calculate and analyze the exergy of the engine.4 Materials and Methods In this work, the zero-dimensional model was used to account for internal energy variations, pressure work, heat transfer losses to the solid walls and heat release. The applied assumptions include: The cylinder mixture temperature, pressure and composition were assumed uniform throughout the cylinder. Furthermore, the one-zone thermodynamic model assumes instantaneous mixing between the burned and unburned gases. The cylinder gases were assumed to behave as an ideal gas mixture, Gas properties, include enthalpy, internal energy modeled using polynomial equations associated with temperature. In this research, the equations 1 to 20 were used in Fortran programming language. The results of incylinder pressure obtained by the model were validated by the results of experimental test of OM314 engine. Then the effects of injection timing on Energy and Exergy of the engine were analyzed for B20 fuel. Results and Discussion Comparing the results of the model with the experimental data shows that there was a good agreement between the model and experimental results. The results showed that advancing fuel injection timing increases the peak cylinder pressure. When fuel injecting occurs before the standard injection timing, the pressure and temperature of the charged air in the cylinder is less than that of the fuel when it is injected at standard injection timing. Thus, ignition delay of the injected fuel extends further. As a consequence, the reaction between fuel and air improves, which prepares a good mixture for burning. When the combustion starts, the rate of heat release increases in the premixed or rapid combustion phase of the combustion process due to the suitability of the mixture of air and fuel and hence the peak pressure of cylinder increases. When the injection timing is retarded, the fuel is injected into charged air that has a high temperature and pressure. Thus, in the injection timing of 10 degrees before top dead center, the maximum of incylinder pressure and temperature are reduced compared to the standard injection timing. By retarding the fuel injection into the cylinder, the indicator availability, the heat loss availability by heat transfer from cylinder walls and irreversibility are increased and by advancing the fuel injection into the cylinder, the indicator availability, the heat loss availability by heat transfer from the cylinder walls and irreversibility are reduced. High temperature will increase the produced entropy, so by advancing the injection timing the produced entropy will increase while the retarding injection timing reduces the produced entropy. Exergy and energy efficiencies increased by advancing the injection timing. At 2000 rpm the total availability and heat loss availability by heat transfer was increased compared to 1200 and 1600 rpm. Conclusion The proposed model was able to predict the pressure and temperature of the cylinder at different injection timings. By advancing the fuel injection timing energy and exergy efficiency and heat loss availability by heat transfer was increased. At 2000 rpm the total availability and heat loss availability by heat transfer was increased.
B. Hosseinzdeh Samani; E. Fayyazi; B. Ghobadian; S. Rostami
Abstract
Introduction
Biodiesel is a promising renewable substitute source of fuel produced from tree born oils, vegetable based oils, fats of animals and even waste cooking oil, has been identified as one of the key solutions for the alarming global twin problems of fossil fuel depletion and environmental degradation. ...
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Introduction
Biodiesel is a promising renewable substitute source of fuel produced from tree born oils, vegetable based oils, fats of animals and even waste cooking oil, has been identified as one of the key solutions for the alarming global twin problems of fossil fuel depletion and environmental degradation. One of the sources for biodiesel production is mastic which is often grown in mountains. Its kernel contains 55% oil which makes it as a valuable renewable resource for biodiesel production. The objective of this research was to study of the feasibility of biodiesel production from Atlas mastic oil using ultrasonic system and optimization of the process using Response surface methodology.
Materials and Methods
In order to supply the required oil for the biodiesel production process, the oil should be prepared before the reaction. Hence, the purified oil was methylated using Metcalf et al (1996) method, and the prepared sample was injected into Gas Chromatography device to determine fatty acids profile and molecular weight of the used oil. An ultrasonic processor (Hielscher Model UP400S, USA.) was used to perform the transesterification reaction.
All the experiments were replicated three times to determine the variability of the results and to assess the experimental errors. The reported values are the average of the individual runs. The different operating parameters used in the present work, to optimize the extent of conversion of Atlas pistache oil, include methanol to oil molar ratio (4:1, 5:1 ,6:1), amplitude (24.1, 62.5 100%), pulse (24.1, 62.5 100%), reaction time (3, 6, 9 min).
Results and Discussion
Results of analyses showed that the independent variables, namely molar ratio, vibration amplitude, pulse and reaction time had significant effects on the amount of produced methyl ester.
By increasing the amplitude and pulse, the methyl ester content increased. Increase in amplitude and pulse cause to increase the mixing effect and physical interface. Increasing the ratio of ultrasonic working time to its idling time caused to an increase in the conversion percent. Because the treating time of the samples by ultrasound in limit time durations is increased, while this increase becomes lower at higher ratios. This is due to the fact that the initial vibrative shock acted on the samples after ultrasonic restarting, finds an identical effect with uniform wave. However, the idling phase of ultrasound caused a decrease in the amount of consumed energy. Similar results have been reported by Chand et al. (2010) for the effect of pulse on conversion percent of methyl ester. Trend of reaction time and molar ratio were different with trend of amplitude and molar ratio on methyl ester content so that they were divided to two sections. It should be mentioned that the increase in biodiesel yield because of molar ratio has some limitations. If the ratio is increased more than a certain extent, biodiesel conversion percent will decrease. The main reason for this result can be related to the amount of methanol increase in the mixture, which leads to more dissolution of glycerin and alcohol in biodiesel which considerably influences its purity.
Optimization was carried out based on Response Surface Methodology (RSM) using Design Experts software. The obtained results from optimization were as follow: 5.45 molar ratio, 0.89 amplitude, 0.71 pulse and 5.99 minutes of time. The conversion percentage obtained as 94.96. It is worthy to note that the experiment was iterated at suggested point by the optimization software and the conversion percent was 94.02. As well as 34792.37 J at the obtained point to be acceptable (1%) difference from the model.
Conclusions
The increase in the ultrasound amplitude resulted in an increase in the conversion percentage which tends to ascend. Also, the increase of reaction time by 5 to 7 minutes increased the conversion percentage, following which is the descend trend. The obtained results from optimization were as follow: 5.45 molar ratio, 0.89 amplitude, 0.71 pulse and 5.99 minutes of time. The conversion percentage and consumed energy obtained as 94.96 and 32421.5 J, respectively. It is worthy to note that the experiment was iterated at suggested point by the optimization software and the conversion percent was 94.02.
M. Bavafa; M. Tabasizadeh; A. Farzad; B. Ghobadian; H. Eshghi
Abstract
Introduction: Depletion of fossil fuels and environmental degradation are two major problems faced by the world. Today fossil fuels take up to 80% of the primary energy consumed in the world, of which 58% is consumed by the transport sector alone (Mard et al., 2012). The combustion products cause global ...
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Introduction: Depletion of fossil fuels and environmental degradation are two major problems faced by the world. Today fossil fuels take up to 80% of the primary energy consumed in the world, of which 58% is consumed by the transport sector alone (Mard et al., 2012). The combustion products cause global warming, which is caused of emissions like carbon monoxide (CO), sulfur dioxide (SO2) and nitrogen oxides (NOX). Thus it is essential that low emission alternative fuels to be developed for useing in diesel engines. Many researchers have concluded that biodiesel holds promise as an alternative fuel for diesel engines. Biodiesel is oxygenated, biodegradable, non-toxic, and environmentally friendly (Qi et al., 2010). Materials and Methods: In this study transesterification method was used to produce biodiesel, because of its simplicity in biodiesel production process and holding the highest conversion efficiency. Transesterification of poultry fat oil and the properties of the fuels: Fatty acid methyl ester of poultry fat oil was prepared by transesterification of oil with methanol in the presence of KOH as catalyst. The fuel properties of poultry fat oil methyl ester and diesel fuel were determined. These properties are presented in Table 1. Tests of engine performance and emissions: After securing the qualitative characteristics of produced biodiesel, different biodiesel fuels of 5%, 10%, 15%, and 20% blended with diesel fuel were prepared. A schematic diagram of the engine setup is shown in Fig.1. The MF-399 tractor engine was used in the tests. The basic specifications of the engine are shown in Table 3. The engine was loaded with an electromagnetic dynamometer. The Σ5 model dynamometer manufactured by NJ-FROMENT was used to measure the power and the torque of the tractor engine. The speed range and capacity of this device are shown in Table 2. A FTO Flow Meter, manufactured by American FLOWTECH Company, was used to measure the fuel consumption (Fig.3). Its measuring range is 37-1537 ml min-1. Results and Discussion: The engine performance was evaluated in terms of engine power, engine torque and specific fuel consumption at different engine speeds. The variation of engine torques with B5, B10, B15, B20 and diesel fuel are presented in Fig. 4. The engine torque for biodiesel blends was more than that by diesel fuel only. The mean engine torques for B5, B10, B15 and B20 were 2.5%, 2.8%, 3%, and 3.5% higher than that by only diesel, respectively. This is due to the better combustion of biodiesel compared to diesel fuel. The variation of engine powers with B5, B10, B15, B20 and diesel fuel are presented in Fig. 5. The engine powers for biodiesel blends were more than that by diesel fuel. The mean engine powers for B5, B10, B15 and B20 were higher than that by diesel by 2.5%, 3%, 3.5%, and 4%, respectively. This is because of good combustion of biodiesel resulted from higher oxygen content. The mean specific fuel consumptions for B5, B10, B15 and B20 were higher than diesel fuel about 4.1%, 7%, 8.8%, and 2%, respectively (Fig. 8). The density of biodiesel was higher than that of diesel fuel, which means the same fuel consumption on volume basis results in higher specific fuel consumption in case of biodiesel. Conclusions: The values of viscosity, density and flash point of poultry fat oil biodiesel were found to be closely matched with ASTM D-6751 standard specifications. Viscosity and density of biodiesel were found more than those for diesel. The calorific value of biodiesel was found to be lower than that of diesel. Poultry fat oil biodiesel cannot be used as a neat diesel fuel in cold weather conditions due to its relatively low cloud point. Preheating and lowering freezing point is required to eliminate this problem. The engine performance with poultry fat oil biodiesel and its blends are comparable with those of pure diesel fuel. Results indicated that B20 blend had the best performance and the lowest specific fuel consumption.
N. Keramat Siavash; Gh. Najafi; S. R. Hassan Beigi Bidgoli; B. Ghobadian
Abstract
Introduction: There are several sources of noise in an industrial and agriculture environment. Machines with rotating or reciprocating engines are sound-producing sources. Also, the audio signal can be analyzed to discover how well a machine operates. Diesel engines complex noise SPL and sound frequency ...
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Introduction: There are several sources of noise in an industrial and agriculture environment. Machines with rotating or reciprocating engines are sound-producing sources. Also, the audio signal can be analyzed to discover how well a machine operates. Diesel engines complex noise SPL and sound frequency content both strongly depend on fuel combustion, which produces the so-called combustion noise. Actually, the unpleasant sound signature of diesel engines is due to the harsh and irregular self-ignition of the fuel. Therefore, being able to extract combustion noise from the overall noise would be of prime interest. This would allow engineers to relate the sound quality back to the combustion parameters. The residual noise produced by various sources, is referred to as mechanical noise. Since diesel engine noise radiation is associated with the operators’ and pedestrians’ discomfort, more and more attention to being paid to it. The main sources of noise generation in a diesel engine are exhaust system, mechanical processes such as valve train and combustion that prevail over the other two. In the present work, experimental tests were conducted on a single cylinder diesel engine in order to investigate the combustion noise radiation during stationary state for various diesel and biodiesel fuel blends.
Materials and Methods: The engine used in the current study is an ASHTAD DF120-RA70 that is a single cylinder 4 stroke water cooled diesel engine and its nominal power is 7.5 hp at 2200 rpm. The experiment has been done at three positions (Left ear of operator, 1.5 and 7.5 meter away from exhaust) based on ISO-5131 and SAE-J1174 standards. For engine speed measurement the detector Lurton 2364 was utilized with a measurement accuracy of 0.001 rpm. To obtain the highest accuracy, contact mode of detector was used. The engine noise was measured by HT157 sound level meter and was digitalized and saved with Sound View software. HT157 uses alow impedance, capacitor microphone with a unidirectional pattern whose size, sensitivity and frequency range are 1/2", 50 mV Pa-1 and 10 Hz to 20 kHz with a flat extrusion, respectively. Choosing the combination of fuel was carried out according to experiments that have been done before determining engine operation parameters.
Results and Discussion: Fuel type has a direct effect on the quality of the IC engine's combustion phenomenon. One of the most important quality parameters that can be fluctuated by fuel type is engine noise. The fuel type has a direct effect on internal fuel ignition engines and affects the quality of fuel ignition. One of the effects of ignition quality is the sound of the engine that is very important in terms of both the health and evaluation of engine performance. Two-wheel tractors are of the most important tools used in agriculture. In addition to agricultural work, they have applications in rural areas as power generators. No research has been carried out so far in Iran on the sound of two-wheel tractors fuelled with diesel and biodiesel fuels. Therefore, the sound of the ignition of biodiesel and diesel mixtures in four stroke, single cylinder, two wheel diesel tractors manufactured by Ashtad Company was studied. The purpose of this study is to analyze the noise parameters of a diesel engine using B0, B5, B10, B15, B20, B25 and B30 biodiesel–diesel blends. Biodiesel was produced from waste oil and blended with net diesel fuel to evaluate the Power tiller's engine noise parameters. This study was carried out at a stationary position and at three positions such as driver's left ear position (DLEP), 1.5 meter (1.5 MAFE) and 7.5 meters (7.5 MAFE) away from the exhaust at 6 engine speeds (1200, 1400, 1600, 1800, 2000 & 2200 rpm). Statistical analysis and frequency analysis were used to analyze sound of the engine. The results showed that the sound pressure levels of the engine for B10 fuel have the least amount of noise level of the sound pressure. However, this fuel has no significant difference at 1% level with B00, B05 and B15 fuel. At the A weight level, that matches the structure of the human ear, and there is no difference between the sound pressure levels of ignition. Sound pressure level increased with increasing engine speed and the difference is significant at the 1% level. With increasing speed engine, noise levels increased up to 7.8 dB. Average sound pressure level was 83.76 dB at the driver's ear position (79.3 dBA), at 1.5 meters away from exhaust it was 85 dB (80.9 dBA) and at 7.5 meters away from exhaust it was 79.5 dB (72.4 dBA). The results proved that the lowest and highest sound pressure levels (SPL) of power tiller take place at B10, and B30, respectively. The SPL increased by 7.8 dB for increasing engine speed from 1200 to 2200 rpm. The test results showed that the average SPL at DLEP was 4.3 dB higher than 7.5 MAFE position.
Conclusions: B10 has minimum sound pressure level (SPL), but its difference with B00 (DIESEL FUEL), B05 and B15 is not significant in 1% error level. Considering the NOISH standard, the operator can work with a machine for 8 hours. In DLPE position, the most overcome frequency is 315 Hz for all blends that resulted from exhaustion and combustion. B10 has a minimum SPL at this peak point significantly lower than other blends. For the used engine in this experiment, by optimizing muffler design it is possible to reduce SPL of engine in this frequency peak point
H. Maghsoudi; S. Minaei; B. Ghobadian; H. Masoudi
Abstract
Electronic canopy characterization to determine structural properties is an important issue in tree crop management. Ultrasonic and optical sensors are the most used sensors for this purpose. The objective of this work was to assess the performance of an ultrasonic sensor under laboratory and field conditions ...
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Electronic canopy characterization to determine structural properties is an important issue in tree crop management. Ultrasonic and optical sensors are the most used sensors for this purpose. The objective of this work was to assess the performance of an ultrasonic sensor under laboratory and field conditions in order to provide reliable estimations of distance measurements to apple tree canopies. To achieve this purpose, a methodology has been designed to analyze sensor performance in relation to foliage distance and to the effects of interference with adjacent sensors when working simultaneously. Results showed that the average error in distance measurement using the ultrasonic sensor in laboratory conditions was 0.64 cm. However, the increase of variability in field conditions reduced the accuracy of this kind of sensors when estimating distances to canopies. The average error in such situations was 3.19 cm. When analyzing interferences of adjacent sensors 30 cm apart, the average error was ±14.65 cm. When adjacent sensors were placed apart by 60 cm, the average error became 6.73 cm. The ultrasonic sensor tested has been proven to be suitable to estimate distances to the canopy in pistachio garden conditions when sensors are 60 cm apart or more and can, therefore, be used in a system to estimate structural canopy parameters in precision horticulture.
