N. Sedaghat Herfeh; A. M. Nikbakht; H. Mobli; A. R. Keyhani; A. Piri
Abstract
IntroductionSour cherry concentration is a significant agro-industry in the world. In 2016, world production was 13.8 million tons and most of which were processed in the form of concentrate or frozen products. Iran has the 6th rank among the producers of sour cherry and experienced a highly rise (45%) ...
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IntroductionSour cherry concentration is a significant agro-industry in the world. In 2016, world production was 13.8 million tons and most of which were processed in the form of concentrate or frozen products. Iran has the 6th rank among the producers of sour cherry and experienced a highly rise (45%) in production in 2016. A conventional energy system evaluation is performed using the energy analysis method. The thermodynamic inefficiencies occurring within the system (factors that cause a gap between performance and ideal state) are not identified and evaluated by energy analysis.Materials and MethodsPakdis concentrate production line includes a plate heat exchanger (HE) converter to preheat input juice using condensate water energy and crude juice heat outlet, four multipurpose falling evaporators (E1, E2, E3, E4), a distillation tower for raw juice aromatization (DT) and a juice cooling system (JC).A thermographic camera (G120EXD, NEC Avio, Japan) was used for thermographic recording. Initial examination of the thermography results showed that the external surface temperature of the equipment except for the evaporators (E1, E2, E3, E4), the boilers (B1, B2, B3) and the condensation tank of the evaporation line (CT1) had very little difference with the ambient temperature around them, and therefore, their heat flux was ignored.Due to limitations, the mass flow rates of the evaporation line (except for inlet juice) were not measurable, and therefore, energy analysis was used to calculate them. Energy analysis involves the simultaneous resolution of mass and energy balances for a system.Results and DiscussionThe heat loss rate from the first evaporator (E1) was calculated to be 21.23 kW from which mass/energy balances and mass flows were extracted. Also, heat loss rate from utilities E2, E3, E4, and CT1 were calculated from mass-energy balances. Streams 32, 49, 52, and 54 are not utilized and exit the system. Hence, they are assigned as heat loss streams within the evaporation line.The total energy loss rate in the evaporation line was calculated to be 4920.82 kW which contributes 74.8% of total input energy to the line. However, 73.39% of this loss is assigned to the cooling tower (stream 54). Stream 29 from the 4th stage evaporator enters the condenser, mixes with water, and provides cold water goes to the cooling tower. In the tower, water evaporates and dissipates heat to the environment. Stream 32 is the second loss stream with 14.8%. Also, it should be noted that heat loss from the surface of utilities makes 3.06% of energy loss of the evaporation line which implies that insulations are done properly in utilities.Evaporation performance may be rated simply and primarily by the steam economy. The value was calculated to be 2.63 in the evaporation line, i.e. 2.63 kg water is evaporated per 1 kg steam injected into the systemExergy rate in several streams of evaporation line. The exergy rate of fuel and products, exergy efficiency, exergy destruction rate, and exergy destruction ratio for each element of the line were reported. Total input exergy to the evaporation line is 4832.03 kW from which 1045.85 kW is destructed due to irreversibility and 3786.19 kW is dissipated.Major destruction occurs within barometric condenser (BC), pressure reducing valve (PR), a plate heat exchanger (HE), evaporators 1 and 2 (E1 and E2), cooling tower (CT), and then evaporators 3 and 4 (E3 and E4). The remaining destruction in other utilities is negligible.ConclusionUsing the first and second laws of thermodynamics and instrumentation procedure, sub-systems of the evaporation unit of Pakdis Company were investigated and energy and exergy balances were coupled and solved. Thermographic assessment of likely zones to energy losses was employed. The whole process was monitored and mass-energy balances were developed. The steam economy as a reliable criterion for evaporation was calculated. To extract inefficiencies and possible optimizable unit operations exergetic analyses were carried out and subsequently the share of exergy loss and destruction and capital cost in the whole process was defined. It was found that capital cost is consistently ignorable compared to exergetic faults such as losses and destructions.
A. Nasiri; H. Mobli; S. Hosseinpour; Sh. Rafiee
Abstract
Introduction Stereo vision means the capability of extracting the depth based on analysis of two images taken from different angles of one scene. The result of stereo vision is a collection of three-dimensional points which describes the details of scene proportional to the resolution of the obtained ...
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Introduction Stereo vision means the capability of extracting the depth based on analysis of two images taken from different angles of one scene. The result of stereo vision is a collection of three-dimensional points which describes the details of scene proportional to the resolution of the obtained images. Vehicle automatic steering and crop growth monitoring are two important operations in agricultural precision. The essential aspects of an automated steering are position and orientation of the agricultural equipment in relation to crop row, detection of obstacles and design of path planning between the crop rows. The developed map can provide this information in the real time. Machine vision has the capabilities to perform these tasks in order to execute some operations such as cultivation, spraying and harvesting. In greenhouse environment, it is possible to develop a map and perform an automatic control by detecting and localizing the cultivation platforms as the main moving obstacle. The current work was performed to meet a method based on the stereo vision for detecting and localizing platforms, and then, providing a two-dimensional map for cultivation platforms in the greenhouse environment. Materials and Methods In this research, two webcams, made by Microsoft Corporation with the resolution of 960×544, are connected to the computer via USB2 in order to produce a stereo parallel camera. Due to the structure of cultivation platforms, the number of points in the point cloud will be decreased by extracting the only upper and lower edges of the platform. The proposed method in this work aims at extracting the edges based on depth discontinuous features in the region of platform edge. By getting the disparity image of the platform edges from the rectified stereo images and translating its data to 3D-space, the point cloud model of the environments is constructed. Then by projecting the points to XZ plane and putting local maps together based on the visual odometry, global map of the environment is constructed. To evaluate the accuracy of the obtained algorithm in estimation of the position of the corners, Euclidian distances of coordinates of the corners achieved by Leica Total Station and coordinates and resulted from local maps, were computed. Results and Discussion Results showed that the lower edges have been detected with better accuracy than the upper ones. Upper edges were not desirably extracted because of being close to the pots. In contrast, due to the distance between lower edge and the ground surface, lower edges were extracted with a higher quality. Since the upper and lower edges of the platform are in the same direction, the lower edges of the platform have been only used for producing an integrated map of the greenhouse environment. The total length of the edge of the cultivation platforms was 106.6 meter, that 94.79% of which, was detected by the proposed algorithm. Some regions of the edge of the platforms were not detected, since they were not located in the view angle of the stereo camera. By the proposed algorithm, 83.33% of cultivation platforms’ corners, were detected with the average error of 0.07309 meter and mean squared error of 0.0076. Non- detected corners are due the fact that they were not located in the camera view angle. The maximum and minimum errors in the localization, according to the Euclidian distance, were 0.169 and 0.0001 meters, respectively. Conclusion Stereo vision is the perception of the depth of 3D with the disparity of the two images. In navigation, stereo vision is used for localizing the obstacles of movement. Cultivation platforms are the main obstacle of movement in greenhouses. Therefore, it is possible to design an integrated map of greenhouse environment and perform automatic control by localization of the cultivation platforms. In this research, the depth discontinuity feature in the locations of the edges, was used for the localization of the cultivation platforms’ edges. Using this feature, the size of the points required for establishing the point cloud model and also the associated processing time decreased, resulting improvement in the accuracy of determining coordination of the platforms’ corners.
M. Mohammad Shafie; A. Rajabipour; H. Mobli; M. Khanali
Abstract
Introduction: The pomegranate journey from orchard to supermarket is very complex and pomegranates are subjected to the variety of static and dynamic loads that could result in this damage and bruise occurring. Bruise area and bruise volume are the most important parameters to evaluate fruit damage occurred ...
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Introduction: The pomegranate journey from orchard to supermarket is very complex and pomegranates are subjected to the variety of static and dynamic loads that could result in this damage and bruise occurring. Bruise area and bruise volume are the most important parameters to evaluate fruit damage occurred in harvest and postharvest stages. The bruising is defined as damage to fruit flesh usually with no abrasion of the peel. The two different types of dynamic loading which can physically cause fruit bruising are impact and vibration. The impact and vibration loadings may occur during picking or sorting as the pomegranates are dropped into storage bins and during transportation. The focus of this work was on the impact loading as this appeared to be the most prevalent. In view of the limitations of conventional testing methods (ASTM D3332 Standard Test Methods for Mechanical Shock Fragility of Products), the method and procedure for determining dropping bruise boundary of fruit were also established by adapting free-fall dropping tests.
Materials and Methods: After the ‘Malas-e-Saveh’ pomegranates had been selected, they were numbered, and the weight and dimension of each sample were measured and recorded. Firmness in cheek region of each fruit was also measured. Fruit firmness was determined by measuring the maximum force during perforating the sample to a depth of 10 mm at a velocity of 100 mm min-1 with an 8 mm diameter cylindrical penetrometer mounted onto a STM-5 Universal Testing Machine (SANTAM, Design CO. LTD., England). Free-fall dropping tests with a series of drop heights (6, 7, 10, 15, 30 and 60 cm) were conducted on fresh ‘Malas-e-Saveh’ pomegranates. Three samples were used for each dropping height, and each sample was subjected to impact on two different positions. Before the test was started, it was necessary to control the sample's drop position. The cheek of sample was placed on the fruit holder. An aluminum plate mounted on upper part of the piezoelectric force sensor was the dropping impact surface of the device. After dropping impact, the sample was caught by hand to prevent a second impact due to sample rebound. After impact, the samples were stored at room temperature for 48h, during which time bruise tissues and arils turned brown. The bruise area and bruise volume of each sample were calculated according to equations (1 and 2).
Results and Discussion: Dropping impact acceleration versus time curves for the typical samples at ten drop heights are shown in figure 5. Drop height notably affected the impact acceleration. The peak force increased while contact times decreased with increasing drop height, which resulted in an increase of peak acceleration. Figure 6 shows the dropping impact velocity change during contact by theoretical calculation. The results showed that the velocities at the beginning of contact and the rebound velocities of the samples increased with increasing the drop height. Critical drop height of pomegranate in certain bruise area was determined and linear relationship between drop height and bruise volume for ‘Malas-e-Saveh’ pomegranates were obtained. It is clear that there were obvious differences between dropping bruise boundaries of pomegranates and the conventional damage boundary of products (as shown in figure 9). For the conventional damage boundary, the vertical line, critical velocity (Vc), represents the velocity change below which no damage occurs, regardless of the peak pulse acceleration. The horizontal line, critical acceleration (AC), represents the acceleration at which the product will be damaged if velocity exceeds VC. At the same time, for a conventional product, there is only one damage boundary at one shock condition. However, for fruit, a change in drop height (velocity) will lead to a change in bruise ratio. A series of bruise boundaries can be determined for different bruise ratios. Moreover, even if the velocity approaches zero, the fruit can still be bruised if its acceleration exceeds a certain value. These relationships provide an effective basis to predict and control drop bruising, which may be achieved through the design of reasonable cushioning packaging for fruit.
Conclusions: This research applied the concept of dropping bruise for pomegranate fruits. Because of the limitations in using conventional testing methods to test product of a viscoelastic nature, such as fruit, free fall dropping tests were adapted to determine dropping bruise fragility and bruise boundary for ‘Malas-e-Saveh’ pomegranates at different drop heights. For viscoelastic products such as fruit, even if the dropping impact velocity approached zero, the fruit could be bruised as long as the impact acceleration exceeded a certain value (critical acceleration). A series of bruise boundaries can be established for different levels of bruise ratios, i.e., a contour of constant bruise ratio can be drawn on the velocity acceleration plane.
M. R. Bayati; A. Rajabipour; H. Mobli; A. Eyvani; F. Badii
Abstract
Introduction: Apple fruit (Mauls domestica Borkh, Rosaceae) after citrus fruits, grape and banana, is the fourth important fruit in the world and is considered the most important fruit of temperate regions. In terms of trade volume, Iran is fourth producer and 17th exporter in the world. Among Iranian ...
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Introduction: Apple fruit (Mauls domestica Borkh, Rosaceae) after citrus fruits, grape and banana, is the fourth important fruit in the world and is considered the most important fruit of temperate regions. In terms of trade volume, Iran is fourth producer and 17th exporter in the world. Among Iranian cultivars of apple fruit, known as “Golab apple”. Golab apple is one of the fragrant and tasty varieties and meanwhile is very sensitive and also its period of the postharvest shelf life is very short. In a study, the firmness of pear fruit during 4 weeks of storage was monitored using non-destructive impulse response (I-R) and destructive Magness-Taylor (M-T) puncture tests. The results of this study showed that the dominant frequency, stiffness coefficient and elasticity coefficient as a function of time could be expressed as a decreasing linear function (Gómez et al., 2005). Tiplica et al., (2010), showed that acoustic measurement can be a useful tool to discriminate different apple batches with a low error rate. Starting from the spectrum of the signal recorded by a microphone after the impact of a small hammer on the fruit, 18 key features were identified and used for the classification of apples belonging to 10 different varieties. The study aimed to evaluate apple firmness measured using both the penetrometer and acoustic methods. The methodologies were applied to Royal Gaya and Golden Smoothee apples harvested from 12 different orchards in Catalonia (Spain), on six different dates, and over three seasons. The results obtained showed a noticeable correlation between Magness Taylor firmness and acoustic measurements in Royal Gala, but no correlation was found for Golden Smoothee. In this study, also, acoustic measurements seemed to be a good tool for evaluating changes in tissue firmness during long-term storage (Molina-Delgado et al., 2009). In another study, it was presented a novel approach based on the simultaneous profiling of the mechanical and acoustic response of the flesh tissue to compression, using a texture analyzer coupled with an acoustic device. The methodology was applied to a 86 different apple cultivars, measured after two months postharvest cold storage and characterised by 16 acoustic and mechanical parameters. The results demonstrate the good performance of our combined acoustic-mechanical strategy in measuring apple crispness as it is perceived by human senses (costa et al, 2011). Hence, present study was about postharvest durability evaluation of this apple in cold storage and effect of methylcellulose coating on durability of this sensitive apple for both intact and damaged ones.
Materials and Methods: After obtaining Golab apples, from one of the gardens of Karaj (Alborz province, Iran), 240 of them were selected. Our aim in this study was to evaluate the firmness of apples with two methods: penetration (destructive) and acoustic (non destructive). The tests were performed in Agricultural Engineering Research Institute in Karaj. Firmness is one of the fruit characteristics that changes during storage. In present study, this characteristic of the apple fruit was assessed by two mentioned methods. Half of the apples were damaged with identified and controlled impact. In the next stage, another half of apples in both groups (the intact apples and the bruised apples) were coated with methylcellulose. Effect storage on apple in four groups, including: Intact and uncoated apples, intact and coated (with methylcellulose) apples, bruised and uncoated apples and bruised and coated apples during about ten weeks of cold storage at 2˚C and 85% RH was studied by the acoustic and the penetration tests. Acoustic parameters including: natural frequency, firmness index, elasticity coefficient were measured by recording audio signals resulting from non destructive impacts of a pendulum using a sound analyzer microphone and then the conversion of those parameters were performed from the time domain to the frequency domain by the corresponding formulas and software. Penetration test measurements were performed using a texture analyzer and its software. The tests were carried out every week. Statistical analysis of the results was carried out using Excel 2007 and SPSS 16 software and the significance of the results was determined using Duncan's test at the 5% confidence level.
Results and Discussion: Analysis of variance showed effect of independent variables including: effects of coating, impact and time and also interaction effects on dependent variables including: natural frequency, acoustic index and modulus of elasticity and penetration index on the tested apples. Effects of coating and time were significant at the 5% confidence levelon all dependent variables. But the impact and interaction effect were not significant on dependent variables (Table 1). In general, bruise and lack of coating on the apples during the 10 weeks of storage, were reduced acoustic parameters. In the penetration test, changes were similar to acoustic test (Table 2). In this test, all curves have downward trend and combination of independent variables: coated and intact apples were reasons of more penetration resistance of apples in all of the groups. The condition was continued until the end of storage time, despite of the downwards slopped curves in all groups. In penetration test, coated apples keep more firmness than other groups (groups of apples without coating) and thus the apple's quality would stay better, too (Fig.7).
Conclusions: In general, the following results were obtained from this research: The results showed that the acoustic and penetration parameter were decreased during 10 weeks of storage. Reduction of these parameters continued until the end of storage period, but this reduction was significant only up to eighth week. Also at this time, the acoustic parameters (natural frequency, firmness index, elasticity coefficient) and penetration firmness in intact and coated apples were 14.26%, 4.11%, 14% and 40% respectively higher compared to other apples. Due to the more tangible acoustic parameters changes, especially acoustic index and modulus of elasticity (having the more slope than the penetration firmness). One could use acoustic tests for more accurate evaluation of apples firmness and quality changes. Finding correlation between acoustic parameters and penetration parameter showed that, correlation between acoustic parameters in each case is greater than correlation between these parameters with penetration parameter.
