CFD Analysis of a Tubular Heat Exchanger for the Conditioning of Olive Paste

The use of a heat exchanger for the conditioning of the olive paste could enhance the olive oil extraction process. Particularly, paste pre-heating could reduce the malaxation time and, most of all, improve the temperature control during this process (e.g., 27 ◦C). In this study, a three-dimensional computational fluid dynamics (CFD) analysis of a tubular heat exchanger was carried out to better understand the influence of the inlet conditions of the olive paste on thermal and hydrodynamic behavior within it. CFD analysis was performed with SOLIDWORKS Flow Simulation (ver.2016). The heat exchanger consists of a tube-in-tube module, in which the inner tube was fed with the olive paste, while the jacket was filled of hot water. The main aim was that to predict the heat transfer and pressure drop in paste side of the exchanger. Multiple analyses by varying the mass flow rate and inlet temperature of the paste were carried out, and temperature and pressure drop were estimated. The numerical model has proved very useful in identifying the main factors affecting the optimization of the heat exchanger in order to improve the extraction process of the olive paste

Investigation of an Energy-saving System to Reduce the Energy Consumption of Decanter Machine

This study presents a practical and simple approach to investigate the energy consumption of a decanter centrifuge during the sludge dewatering process. An experimental plan to measure the energy consumption of the decanter fed with sludge at three different flow rates and different differential speed values between bowl and screw (?n) was carried out. The trend of the energy withdrawn from power supply as a function of the energy consumed by the bowl motor and the trend of the energy drawn from bowl motor as a function of that recovered from the regenerative braking system has been identified. Finally, the consumption of the bowl motor and of the energy taken from the mains as a function of the flow rate has been determined. The results show that the energy drawn from the grid and the energy regenerated by the regenerative braking system is linearly correlated with the energy consumed by the main electric motor and with the sludge feed rate. In addition, as the flow rate increases, the power recovered is about ¼ of that consumed. A high correlation of the developed models has been detected. The models developed can be used to provide valuable information about energy use patterns and can be used to identify areas where energy efficiency measures can be implemented

Hyperspectral imaging system to on-line monitoring the soy flour content in a functional pasta

Pasta enriched with soy flour can be considered as a functional food, due to its content in nutraceutical compounds such as isoflavones, carotenoids, and other antioxidants. The quantification of the amount of a functional ingredient is an important step in food authenticity. The availability of non-destructive techniques for quantitative and qualitative analyses of food is therefore desirable. This research was aimed to investigate the feasibility of hyperspectral imaging in reflectance mode for the evaluation of the soy flour content, also to investigate on the possibility to implement a feed-back control system to precisely dose the soy flour during the industrial production of pasta. Samples of pasta in shape of spaghetti were produced with durum wheat semolina and soy flour at increasing percentages (0, to 50%, steps of 5%). A feature selection algorithm was used to predict the amount of soy flour. The most influent wavelengths were selected, and a six-term Gauss function was trained, validated, and tested. The identified transfer function was able to predict the percentage of soy flour with high accuracy, with an R2adj value of 0.98 and RMSE 1.31. The developed system could represent a feasible tool to control the process in a continuous mode

Experimental Evaluation of Functional and Energy Performance of Pneumatic Oenological Presses for High Quality White Wines

In this article, experimental tests on two different kinds of pneumatic presses have been carried out in two Apulian wineries to evaluate energy consumption related to yield performance. The presses are employed to process Bombino Nero variety grapes, crushed and transformed in rosé wine though a pomace less process. The pneumatic pressured press realized a 2 h:48 min long process, with a maximum pressure on the product of 1.4 bar and a must moulding of 69% of extracted must. In regard to the vacuum press, the process duration is 3 h:18 min, with a maximum pressure of 0.9 bar and a must moulding of 58%. During the pressing operation, mean values of must flow rate are comparable: 2.1 L min−1 m−2 for the pressured press and 2.9 L min−1 m−2 for the vacuum press. However, a more detailed analysis gives more insight on the behaviour of the two presses. In regard to the pressured press, a compression phase characterized by few steps and at lowest pressure values has proven particularly effective, especially in the first phase (must moulding of 41% with a must flow rate of 4.6 L min−1 m−2), at the lowest pressure values. On the other hand, by analysing vacuum press process, the phases sequence is much more gradual, must moulding decreases as the extraction proceeds (from 28% to 6%), and in the last three phases a very low amount of must is extracted, with must moulding smaller than 10%. The energy consumption of the pressured press during compression is mainly related to the engine power absorption (one of the two in operation), and it is below 4 kW except during start-up, due to the starting currents. The highest power is reached in the last phase in which the maximum pressure is applied and a great amount of must is extracted. On the other hand, energy consumption in the vacuum press gradually decreases. A similar trend was not observed for the specific energy for either press: while it increases along the whole process for the vacuum press, it reaches a maximum value in the second phase of the pressured one. Results show the need to pursue new studies on single component design and on pressing cycles, especially in high-capacity pneumatic vacuum presses. Several advantages on wine production costs could be achieved, even retaining high quality wines

Energy analysis and numerical evaluation of the decanter centrifuge for wastewater management to allow a sustainable energy planning of the process

The decanter-centrifuge is widely used for dewatering and thickening of civil and industrial sludge. The latest generation decanters, both the bowl motors (main) and the screw (back-drive) are often driven by variable-frequency drives (VFD), with the back-drive able to recover the energy during braking. We created a decanter centrifuge energy model equipped with a braking recovery system during the sludge dewatering process, with the aim of identifying its optimal operating conditions for both energy consumption and product quality. Specific models at 15–20–25 m3 h−1 and various differentials speed (Δn) were used to derive a general model, then validated with experiments at 18–20 m3 h−1. Specific models used to identify the best operating conditions in terms of specific energy (e) and energy recovery (ERec) show that at 15–20–25 m3 h−1 the lowest energy consumptions were 1.88–1.76–1.57 kWh m−3, respectively, instead, ERec was 5.88–0.31–12.10 kW respectively, highlighting that a high recovery is not necessarily linked to an increased energy saving. The accuracy of these models was confirmed by high values of correlation coefficients R2 and very low Root Mean Square Errors (RMSE) in each case. The general model, extrapolated from the specific models, makes it possible to predict specific consumptions at different flow rates within the operating range of the decanter. This was validated with an experimental test at 18–20 m3 h−1 with R2 above 97 % and RMSE 2,59E-02 kWh m3. The dry matter content in the cake decreases when the Δn or the feed rate increases.In conclusion, the decanter centrifuge model could represent a useful tool for optimizing the sludge dehydration process

Modelling the Rheology of Olive Paste for Oil Extraction Plant Automation: Effects of the Crushing Process on the Rheology of Olive Pastes

In extra virgin olive oil production, it is essential to obtain a well-prepared olive paste which allows not only the extraction of the oil drops from the olives, but also the achievement of a high-quality oil while maintaining high yields. This work addresses the problem of determining the effect of three crushing machines on the viscosity of the olive paste: a hammer crusher, a disk crusher and a de-stoner were tested. The tests were repeated on both the paste leaving each machine and the paste to which water was added; this was done with the main aim of considering the different dilutions of the paste while entering the decanter. A power law and the Zhang and Evans model were used to analyse the rheological behaviour of the paste. The experimental results allow validation of the two models with a high (more than 0.9) coefficient of determination between experimental and numerical data. The results also show that the pastes obtained with the two classic crushing methods (hammers and disks) are almost identical, with a packing factor of about 17.9% and 18.6%, respectively. Conversely, the paste obtained with the de-stoner entails higher viscosity values and a smaller solid packing factor, of about 2.8%. At 30% dilution with water, the volume of the solid concentration dropped to about 11.6% for the hammer and disc crushers, while for the de-stoner it only reached 1.8%. This behaviour is also reflected in the evaluation of yields, which were 6% lower with the de-stoner. No significant differences regarding the legal parameters of oil quality were found using the three different crushing systems. Finally, this paper establishes some fundamental pillars in the research for an optimal model for identifying the rheological behaviour of the paste as a function of the crusher used. Indeed, since there is an increasing need for automation in the oil extraction process, these models can be of great help in optimizing this process

A new supporting tool for pig handling in the breeding-slaughterhouse production chain

This paper focuses on a research concerning the operational management of the pig-handling phase, during the period of breeding and before slaughtering. Given the behaviour of these animals during transfers, a particular tool has been designed to manage them in this phase. A total number of 48 animals, divided in 4 groups, were moved without use of the tool (control groups) and by using the tool described in this article. The time required by the control groups to leave the pen ranges from 21 to 125 seconds; while, when the proposed tool was used, the time for the movement of the animals ranged between 10 and 17 seconds. In particular, in the groups where the tool was deployed the 'waiting phase' (before the first animal goes out) lasted less than half of the time of the 'waiting phase' of the control group, thus showing a minimization of the effects of the 'panic phenomenon' among the animals. Thus, the studied device can be considered as valid guide technique, both for the quick exit of the first animal and for those that follow. Once the row has been formed, the animals continue neatly to leave the box. This study also shows that this solution can also be considered appropriate for reducing the identified critical issues in the traditional handling. The need of only 1 worker to move the group of pigs is important to achieve economic saving. The deployment of this tool, thus, make possible to consider the movement of animals no longer a 'critical stage', but as a routine step of the production cycle of pork's meat

Development of a Pressure Control System According to Paste Rheology for Ultrasound Processing in Industrial Olive Oil Extraction

Recent research has demonstrated how ultrasound can benefit the industrial processing of olive paste before oil extraction. However, the absence of a device for controlling pressure inside the sonication cell is a major hindrance to its application. To address this problem, a pneumatic device with a programmable logic controller was implemented to automatically adjust pressure in the sonication cell according to a preset value: its functionality was tested in industrial oil extraction. An experiment was conducted to compare device performance when applied to olive batches with different solid/liquid ratios and differing rheology. The control system adjusted the flow section of the valve at the outlet of the sonication cell and the mass flow rate of the feed pump in order to maintain the pressure preset by the operator. Results indicate that the pressure was 3.0 +/- 0.2 bar, 3.5 +/- 0.2 bar, and 4.0 +/- 0.2 bar when the set point was 3.0 bar, 3.5 bar, and 4.0 bar, respectively: there was thus no significant difference between controlled and set values. This indicates that the device is able to control pressure inside the sonication cell with a maximum deviation of 0.2 bar. In this case, the sonication intensity was stabilized at 135 W/cm(2), 150 W/cm(2), and 165 W/cm(2) at 3.0 bar, 3.5 bar, and 4.0 bar, respectively. This study presents an advancement in ultrasound applications for industrial olive oil extraction: optimal pressure control in the sonication cell