توجه: محتویات این صفحه به صورت خودکار پردازش شده و مقاله‌های نویسندگانی با تشابه اسمی، همگی در بخش یکسان نمایش داده می‌شوند.
۱INVESTIGATING THE EFFECTS OF BIODIESEL FROM WASTE COOKING OIL AND ENGINE OPERATING CONDITIONS ON THE DIESEL ENGINE PERFORMANCE BY RESPONSE SURFACE METHODOLOGY
اطلاعات انتشار: Iranian Journal of Science and Technology Transactions of Mechanical Engineering، سي و هشتم،شماره۲، ۲۰۱۴، سال
تعداد صفحات: ۱۳
In this research, the application of response surface methodology (RSM) was highlighted to investigate the effects of biodiesel (from waste cooking oil) in fuel mixture (biodiesel and diesel fuel No.2) and engine operating parameters on performance characteristics (brake power, brake torque and BSFC) of a diesel engine. The experiments were conducted on a four cylinder direct–injection diesel engine based on three–factor five–level central composite rotatable design. The developed mathematical models were helpful to predict the response parameters, and further, to identify the significant interactions between the input factors on the responses. Results showed that the use of biodiesel reduces brake power and brake torque up to 18% and 17% respectively. On the other hand, BSFC increases 18 to 24% by using net biodiesel. Also, results showed that an increase in engine load appeared to cause an increase in the brake power and torque up to 68 and 69% respectively. On the other hand, BSFC is higher at low engine load and increases up to 15% by reducing the engine load.

۲Modeling the effects of biodiesel–diesel fuel blends on CO2 emission of a diesel engine by response surface methodology
نویسنده(ها): ، ، ،
اطلاعات انتشار: Caspian Journal of Environmental Sciences، چهاردهم،شماره۳، ۲۰۱۶، سال
تعداد صفحات: ۱۲
Nowadays biodiesel is receiving more attention as a most important renewable energy for using in diesel engines. Inthis research, the application of Response Surface Methodology (RSM) was highlighted to investigate the effects of biodiesel–diesel blends (B0, B20, B50 and B100), engine operating parameters (engine load and speed) on CO2 emission of a diesel engine. The experiments were conducted on a four cylinder direct–injection diesel engine based on three–factor five–level central composite rotatable design. The developed mathematical models were helpful to predict the response parameters and further to identify the significant interactions between the input factors and the responses. The use of biodiesel resulted in higher emission of CO2. The results also showed that an increase in engine speed leads to an increase in the emission of CO2.On the other hand,CO2 emission is higher at low engine loads,while is lower at high engine loads.

۳Nondestructive Determination of Tomato Fruit Quality Parameters Using Raman Spectroscopy
اطلاعات انتشار: Journal of Agricultural Science and Technology، سيزدهم،شماره۴، Autumn ۲۰۱۱، سال
تعداد صفحات: ۱۰
Tomato is a major fruit, as well as a major food science product. There is a need of determining the quality attributes of this fruit (nondestructively) due to the increasing demand of the in agro–industrially controlled areas. Most of the commonly employed techniques are time consuming and involve a considerable degree of manual work. Sample preparation, juice making, and laboratory tests are among the limitations. Raman spectroscopy was applied in this study to measure such important quality parameters of tomato as SSC, pH and color. A dispersive Raman instrument was employed and reference analyses were carried out to make calibration models regarding the spectral features and target attributes. Analysis of the spectra revealed that all the three characteristic bands of cartenoids, lycopene, and carotene, were significantly recognizable. Also there were several strong to medium bands recognized as related to carbohydrates. Principal Component Regression (PCR) and Partial Least Square (PLS) were selected as the multivariate calibration models. The prediction models proved to be robust resulting in a desirable mapping between the spectra and output attributes. The Root Mean Square Error of Predictions (RMSEP) through PLS and PCR for modeling the color index using the whole spectrum was obtained as 0.33 and 0.38, respectively. RMSEP for mapping the SSC using PLS and PCR models was resulted in respective figures of 0.30 and 0.38. PCA interpretation depicted that Raman spectra could make a favorable distinction among the samples based on their maturity stages. As a result, there is a great potential to use Raman spectroscopy in industrial approach and in line control.

۴Effective Moisture Diffusivity, Activation Energy and Energy Consumption in Thin–layer Drying of Jujube (Zizyphus jujube Mill)
اطلاعات انتشار: Journal of Agricultural Science and Technology، چهاردهم،شماره۳، May ۲۰۱۲، سال
تعداد صفحات: ۱۰
Jujube (Zizyphus jujube Mill), a valuable medicinal plant, is consumed either as fresh fruit or dried product in Iran. Drying jujube guarantees a longer shelf time while preserving its quality to be used in medical and pharmaceutical industries. In this research paper, the influence of several drying conditions on the effective moisture diffusivity, activation energy, energy consumption and required specific energy in the drying of jujube is presented. Temperature levels of 50, 60 and 70 ºC and hot air velocities of 0.5, 1 and 1.5 (m s–1) were used as the treatments. Effective moisture diffusivity of jujube fruit during the drying process was in the range of 1.1532–5.1895×10–10 (m2 s–1) for the first period and 0.4036–2.3064×10–10 (m2 s–1) for the second period. Also, the values of energy of activation in both periods were determined to be between 34.97 and 74.20 (kJ mol–1). The energy consumption and the required specific energy for drying were in the range of 79.1– 92.46 (kW h) and 203.59 – 900.08 (kW h kg–1), respectively. Results show that energy consumption diminished when temperature increased at each air velocity, while it increased with increasing hot air velocity.

۵Determination of Some Mechanical Properties of Castor Seed (Ricinus communis L.) to Design and Fabricate an Oil Extraction Machine
اطلاعات انتشار: Journal of Agricultural Science and Technology، چهاردهم،شماره۶، Nov ۲۰۱۲، سال
تعداد صفحات: ۹
This study was carried out to determine the effect of seed growing regions and loading speed on some mechanical properties of castor seed. These properties are used to design and improve related machines such as expeller that are used for extraction of oil from castor seed. Mechanical properties of castor seed were expressed in terms of rupture force and energy, bio–yield force, apparent modulus of elasticity and toughness using material testing machine. Factorial test with Completely Randomized Design (CRD) was used to study the effect of velocity (4 levels: 5, 15, 25, 35 mm min–1) and seed growing regions (Izeh, Dezfoul, Baghmalek, Shoushtar and Urmia). The results showed that the effect of seed growing region on force, modulus of elasticity, bio–yield force and rupture energy was significant. Izeh seed had the maximum rupture force (75.11 N) whereas Dezfoul and Shoushtar seed had the minimum amount of rupture force (approximately 42 N). Also, loading speed had a significant effect on modulus of elasticity and rupture energy. With the increase of loading speed modulus of elasticity of Baghmalek seed decreased significantly from 144 to 65.5 MPa. Finally, interaction effect of seed growing region and loading speed was significant for most properties. In this research work, an extrusion system was designed and fabricated for the extraction of castor oil.

۶Optimization of Ultrasonic Reactor Geometry for Biodiesel Production using Response Surface Methodology
نویسنده(ها): ، ، ،
اطلاعات انتشار: Journal of Agricultural Science and Technology، پانزدهم،شماره۴، Jul ۲۰۱۳، سال
تعداد صفحات: ۱۲
Biodiesel fuel, which is produced by transesterification reaction between alcohol and vegetable oil\animal fat is proposed as a clean alternative to petro diesel fuel. Today, one of the new technologies to produce biodiesel is using ultrasonic energy that makes production faster, with improved quality and less expensive. Various factors that affect the design of ultrasonic reactors are ratio of vibrating rod diameter to reactor diameter, reactor height, depth of horn penetration into fluid and chamber characteristics (material and shape). In this paper, two parameters namely the ratio of vibrating rod diameter to reactor diameter and reactor height were studied in order to increase the reaction efficiency. In all performed tests, the horn diameter of 14 mm, molar ratio of alcohol to oil of 5 to 1, catalyst concentration of 0.7% wt?? oil, depth of horn penetration into fluid of 15 mm and a cylindrical reactor were used. Experimental design involved the use of Central Composite Design (CCD) and the statistical Response Surface Methodology (RSM). Considering the empirical model, a significant relationship was found between independent and dependent variables with a regression coefficient of 0.99. Taking into account the desirability of increasing the efficiency, the optimal function of reactor diameter and reactor height were 63 and 110 mm, respectively with a reaction yield of 87%. In order to verify the model, function responses in the defined area were tested with five replicates and the average efficiency of the reaction was 87.2%. The obtained model suggests the simultaneous reverse effects of reactor diameter and height on the reaction efficiency.

۷Harvesting of Microalgae Dunaliella salina Using Electroflocculation
نویسنده(ها): ، ، ،
اطلاعات انتشار: Journal of Agricultural Science and Technology، پانزدهم،شماره۵، Sep ۲۰۱۳، سال
تعداد صفحات: ۹
One of the important bottle–necks in production of microalgae based biodiesel is the lack of an efficient method for harvesting of microalgae from the culture medium. In this study, the electroflocculation method was developed for harvesting of microalgae Dunaliella cells from culture medium. The effect of several parameters such as the current density, electrical conductivity of culture medium, time, electrode gap, and electrode type on harvesting efficiency and energy consumption were also determined. The maximum harvesting efficiency of this method was 97.44% at EC= 1.35 S m–1 and current density of 90 A m–2 during 3 minutes electroflocculation process in a 300 ml beaker. The maximum efficiency was achieved by aluminum electrodes with 1 cm distance between electrodes and the maximum energy consumption for this practice was 0.621 kW h m–3. It was concluded that electroflocculation is an efficient and cost effective method for microalgae harvesting.

۸Drying Kinetics and Quality Characteristics of Saffron Dried with a Heat Pump Assisted Hybrid Photovoltaic–thermal Solar Dryer
اطلاعات انتشار: Journal of Agricultural Science and Technology، شانزدهم،شماره۱، ۲۰۱۴ ، سال
تعداد صفحات: ۱۳
In the present study, saffron was dried using a heat pump–assisted hybrid photovoltaic–thermal solar dryer. The effect of different drying air temperatures at three levels (40, 50, and 60oC) and two different modes of the dryer (with and without heat pump system) were investigated on drying behaviour of saffron. After collecting the pertinent data, eleven drying models were used to describe drying characteristics of saffron. Quality characteristics of the dried products (including: colouring, aromatic strength and bitterness) were also evaluated. The results indicated that drying time decreased by 62% with increasing air temperature from 40 to 60oC. Moreover, applying heat pump with the dryer reduced RH of drying air and, consequently, enhanced drying rate and shortened drying period by 40%. A two–term drying model presented a relatively higher R2 and lower, MBE, and RMSE values at both modes of drying and, therefore, was selected to explain drying behaviour of saffron among the other models. The results of saffron quality evaluation showed that colouring characteristics of saffron improved with drying temperature and heat pump system. Meanwhile, aromatic strength of saffron increased with increasing air temperature. But, no significant change in bitterness was observed at different levels of temperature and heat pump system.
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