Dario Friso
University of Padova, Tesaf, Faculty Member
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Rotary drum dryers operating in co-current mode are commonly used for drying food and feed in leaf form, reducing the damage caused by the high air temperatures typical of these dryers, as well as providing advantages including reduced... more
Rotary drum dryers operating in co-current mode are commonly used for drying food and feed in leaf form, reducing the damage caused by the high air temperatures typical of these dryers, as well as providing advantages including reduced drying times and increased energy efficiency. However, drying control to ensure a desirable product exit moisture content is strongly based on empirical practices, which are usually jealously guarded by producers and users, grounded in simplified mathematical modelling. To overcome these uncertainties, in this work, a more complete mathematical modelling approach, based on the solution of ordinary differential equations (ODEs), is developed. The ODEs describe the drying process in the drum dryer, where the air is continuously cooled and humidified as the product dries. The mathematical model developed was experimentally verified in a drum dryer by drying alfalfa, and the maximum relative error was found to be only 2.4%. Finally, a comparison between t...
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In the nursery sector, the transport and planting of trees must occur with the roots wrapped in a ball of the original earth. The cutting of the original soil can be carried out with a semicircular vibrating blade moved by an oscillator... more
In the nursery sector, the transport and planting of trees must occur with the roots wrapped in a ball of the original earth. The cutting of the original soil can be carried out with a semicircular vibrating blade moved by an oscillator mounted on a self-propelled machine. The oscillator produces an excitation torque supplied to the blade together with the soil cutting torque. The advantage of the vibrating blade is a reduction in the cutting torque of up to 70%. However, to correctly design the oscillator, we need to investigate the link between the maximum displacement of the blade, the maximum oscillation velocity, the cutting velocity, the dry friction, the excitation torque, the elastic torque, the cutting torque, the required power, the required energy, and the excitation frequency. The maximum displacement and velocity ratio need to have the right values to minimize the cutting torque and to avoid the springs reaching the end of stroke; otherwise, vibrations are transmitted t...
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The mathematical modeling presented in this work concerns the conveyor-belt dryer with the tangential flow of air with respect to food. This dryer, if operating in co-current, has the advantage of well preserving the organoleptic and... more
The mathematical modeling presented in this work concerns the conveyor-belt dryer with the tangential flow of air with respect to food. This dryer, if operating in co-current, has the advantage of well preserving the organoleptic and nutritional qualities of the dried product. In fact, it has a low air temperature in the final stretch where the product has low moisture content and is therefore more temperature sensitive. It is a bulkier dryer than the continuous through-circulation conveyor dryer with a perforated belt. The latter is therefore more frequently used and has received greater study attention from researchers and designers of the industry. With the aim to propose guidelines for a rational design of the conveyor-belt dryer with tangential flow, a mathematical model was developed here through the differentiation of the drying rate equation followed by its integration performed along the dryer belt. Consequently, and with the assumption that the final moisture content XF of...
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For many years now, manufacturers have been producing supersonic ejectors with a high entrainment ratio for the chemical, oil, and food industries. In the present work, mathematical modelling of the entrainment ratio of such industrial... more
For many years now, manufacturers have been producing supersonic ejectors with a high entrainment ratio for the chemical, oil, and food industries. In the present work, mathematical modelling of the entrainment ratio of such industrial ejectors is carried out, in which a variation of the diffuser efficiency is also assumed to be a function of the Mach number of the motive gas. To determine this unknown relationship, the mathematical modelling was overturned by inserting the entrainment ratios of ten different high-performance industrial ejectors, as identified through an experimental investigation. The mathematical modelling, completed through the use of the relationship between the diffuser efficiency and the Mach number of the motive gas, was applied to sixty-eight ejectors, built and tested experimentally over the last twenty years as part of research aimed at the development of thermal ejector refrigeration systems (ERSs), to obtain the entrainment ratios proposed by the manufac...
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Research Interests: Mechanical Engineering, Agricultural Engineering, Computer Science, Vibrations, Agicultural Machinery Design, and 14 moreFarm Power and Machinery, Vibration, Design and Development of Agricultural Machinery, Kinematics, Mechanical Vibrations, Mechanical Engineering Design, Kinematics of Machines, Oscillators, Mechanical vibration, Power and Machinery, Agricultural Machinery, Farm Machinery and Power, Mechanical Vibration and Machinery System Dynamics, and Machinery Design(Farm Power and Machinery, Vibration, Design and Development of Agricultural Machinery, Kinematics, Mechanical Vibrations, Mechanical Engineering Design, Kinematics of Machines, Oscillators, Mechanical vibration, Power and Machinery, Agricultural Machinery, Farm Machinery and Power, Mechanical Vibration and Machinery System Dynamics, and Machinery Design)
(Farm Power and Machinery, Vibration, Design and Development of Agricultural Machinery, Kinematics, Mechanical Vibrations, Mechanical Engineering Design, Kinematics of Machines, Oscillators, Mechanical vibration, Power and Machinery, Agricultural Machinery, Farm Machinery and Power, Mechanical Vibration and Machinery System Dynamics, and Machinery Design)
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This work presents the mathematical modeling of the conveyor-belt dryer with tangential flow operating in co-current, which has the advantage of improving the preservation of the organoleptic and nutritional qualities of the dried food.... more
This work presents the mathematical modeling of the conveyor-belt dryer with tangential flow operating in co-current, which has the advantage of improving the preservation of the organoleptic and nutritional qualities of the dried food. On the one hand, it is a more cumbersome dryer than the perforated cross flow belt dryer but, on the other hand, it has a low air temperature in the final section where the product has a low moisture content and, therefore, it is more heat sensitive. The results of the mathematical modeling allowed a series of guidelines to be developed for a rational design of the conveyor-belt dryer with tangential flow for the specific case of the moisture content of the final product XF lower than the critical one XC (XF < XC). In fact, this work follows a precedent in which a mathematical model was developed through the differentiation of the drying rate equation along the dryer belt with the hypothesis that the final moisture content XF of the product was hi...
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The mathematical investigation presented in this paper concerns the conveyor-belt dryer with tangential flow operating in co-current. This dryer is bigger than the continuous through-circulation conveyor dryer but has the advantage of... more
The mathematical investigation presented in this paper concerns the conveyor-belt dryer with tangential flow operating in co-current. This dryer is bigger than the continuous through-circulation conveyor dryer but has the advantage of better preserving the organoleptic and nutritional qualities of the dried product. In a previous work a mathematical modeling of the conveyor-belt dryer with tangential flow was carried out to offer guidelines for its optimized design. The last of those design guidelines indicated the need for an optimized adjustment of the dryer to ensure the constant maintenance of the final moisture content of the product. The fast and very precise measurement of the moisture content as the first step in the feedback chain was therefore necessary. Considering the difficulty of this type of measurement, two specific ordinary differential equations (ODEs) were obtained with the mathematical investigation of this work. Their solution became a relationship between the f...
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The cheese industry has high energy consumption, and improvements to plant efficiency may lead to a reduction of its environmental impact. A survey on a sample of small-medium Italian cheese factories was carried out in order to assess... more
The cheese industry has high energy consumption, and improvements to plant efficiency may lead to a reduction of its environmental impact. A survey on a sample of small-medium Italian cheese factories was carried out in order to assess the efficiency of heat recovery of the milk pasteurization equipment for the cheese production. Then, an exergetic analysis to calculate the related exergy loss was carried out together with a cost-benefit analysis to identify the optimized value of the heat efficiency. The exergy loss reduction was determined throughout an exergy analysis that takes into account this last value and the comparison with the previous exergy losses. Finally, the feasibility and the consequent additional reduction of exergy losses were verified, if a cogeneration heat and power (CHP) combined to the pasteurization equipment is assumed. Results show a current heat recovery efficiency of 93.2% in the Italian cheese factories; a close connection between the exergetic losses ...
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The velocity of air that crosses the canopy of tree crops when using orchard sprayers is a variable that affects pesticide dispersion in the environment. Therefore, having an equation to describe air velocity decay through the canopy is... more
The velocity of air that crosses the canopy of tree crops when using orchard sprayers is a variable that affects pesticide dispersion in the environment. Therefore, having an equation to describe air velocity decay through the canopy is of interest. It was necessary to start from a more general non-linear ordinary differential equation (ODE) obtained from the momentum theorem. After approximating the non-linearity with some piecewise linear terms, analytic solutions were found. Subsequently, to obtain a single equation for velocity decay, a combination of these solutions was proposed by using rectangle functions formed through the hyperbolic tangent function. This single equation was assessed in comparison to the experimental value obtained on a vineyard row by measuring the air velocity at exit of canopy. The results have shown good correspondence, with a mean relative error of 6.6%; moreover, there was no significant difference. To simplify, a combination of only two linearized so...
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AbstractIndoor laboratory tests were carried out to determine the accuracy with which the coefficient of manufacturing variation (CV), the discharge coefficient (K), and the emitter discharge expon...
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Research Interests: Engineering, Agricultural Engineering, Engineering Mechanics, Biomedical Engineering, Agicultural Machinery Design, and 15 moreAcceleration Studies, Farm Machinery and Mechanization, Biosystems engineering, Advanced powertrain system research focusing on system optimization and control design, Atuomobile Powertrain System, Agricultural Machinery Design, Acceleration, Acceleration Time, Agricultural mechanics, CVT, Farm machinery, Agricultural Machinery, Automotive Powertrain, Conventional Automotive Powertrains, and a Continuously Variable Transmission cvt(Acceleration Studies, Farm Machinery and Mechanization, Biosystems engineering, Advanced powertrain system research focusing on system optimization and control design, Atuomobile Powertrain System, Agricultural Machinery Design, Acceleration, Acceleration Time, Agricultural mechanics, CVT, Farm machinery, Agricultural Machinery, Automotive Powertrain, Conventional Automotive Powertrains, and a Continuously Variable Transmission cvt)
(Acceleration Studies, Farm Machinery and Mechanization, Biosystems engineering, Advanced powertrain system research focusing on system optimization and control design, Atuomobile Powertrain System, Agricultural Machinery Design, Acceleration, Acceleration Time, Agricultural mechanics, CVT, Farm machinery, Agricultural Machinery, Automotive Powertrain, Conventional Automotive Powertrains, and a Continuously Variable Transmission cvt)
ABSTRACT A pipeline network that collects and transports animal wastes to a treatment plant (e.g., a digester) is an interesting alternative to vehicles (no traffic increase, -61.31% CO2 emissions, -42.46% energy consumption in the case... more
ABSTRACT A pipeline network that collects and transports animal wastes to a treatment plant (e.g., a digester) is an interesting alternative to vehicles (no traffic increase, -61.31% CO2 emissions, -42.46% energy consumption in the case study presented here). However, pipeline networks require careful design to minimise installation costs, costs that depend on pipe length more than diameter. The optimisation can therefore be modelled as a &quot;Euclidian Steiner minimum tree&quot; problem that can be solved by using Kruskal&#39;s and Simpson&#39;s algorithms respectively to delineate a preliminary minimum-spanning-tree path and to optimise the paths by introducing new bifurcation points. The presented case study involved 32 dairy farms belonging to a milk consortium in a 1000-km(2) area. The proposed procedure resulted in a network that extended 98.75 km. However, this was reduced to 97.47 km by introducing additional branching points (total length -1.30%, locally up to -8.54%). Another possibility for cost minimisation is to select farms based on their position. If only farms within 20 km from the centre were considered, the network length decreases to 69.25 km and was optimised to 67.97 km (-1.84%). Although the decreases achieved by optimisation were small, they fall within the estimated range (mu = 2.35%, sigma- = 1.24%) and correspond to 73 632 epsilon and 76 696 epsilon in investment savings. Economically speaking, selecting farms is more efficient with -30.15% of the investment and annual costs and -21.83% of the cost-per-mass-unit. The universality and versatility of the algorithms used makes the proposed approach suitable for designing piping networks in extended geographical areas.
Research Interests: Engineering, Agricultural Engineering, Biomedical Engineering, Road Transport, Logistics, and 15 moreNetwork Analysis, Agriculture, Algebra and Topology, Pipeline, Fertilizer Management, Network, Biosystems engineering, Pipelines, Slurry Transport, Agriculture engineering, Slurry, Euclidean Steiner Tree, Analysis of Pipelines, Pipeline Issues, and Other Engineering
... Analisi teorico-sperimentale del raffreddamento in aria libera di liquidi alimentari imbottigliati. Autores: Friso Dario; Localización: Rivista di ingegneria agraria, ISSN 0304-0593, Nº 3, 2000 , pags. 168-175. © 2001-2011 Universidad... more
... Analisi teorico-sperimentale del raffreddamento in aria libera di liquidi alimentari imbottigliati. Autores: Friso Dario; Localización: Rivista di ingegneria agraria, ISSN 0304-0593, Nº 3, 2000 , pags. 168-175. © 2001-2011 Universidad de La Rioja · Todos los derechos reservados. ...
An analytical approach to correlate the travel distance of the drops from the irrigation sprinkler with the drops water volume was studied.Such approach was used along with a simplified ballistic model, able to define the trajectories of... more
An analytical approach to correlate the travel distance of the drops from the irrigation sprinkler with the drops water volume was studied.Such approach was used along with a simplified ballistic model, able to define the trajectories of the drops produced by the nozzle of the sprinklers, to develop a rapid and simple method to obtain sprinkler drop-size spectrum from the water distribution radial curves.
A new mathematical procedure was developed to correlate g (the difference between the retort and the coldest point temperatures in canned food at the end of the heating process), fh/U (the ratio of the heating rate index to the... more
A new mathematical procedure was developed to correlate g (the difference between the retort and the coldest point temperatures in canned food at the end of the heating process), fh/U (the ratio of the heating rate index to the sterilizing value), z (the temperature change required for the thermal destruction curve to traverse one log cycle) and Jcc (the cooling lag factor). These are the four heat penetration parameters of 57 Stumbo’s tables (18,513 datasets) in canned food. The quantities fh/U, z and Jcc are input variables to determine the g values, which is used in Ball's formula to calculate the heating process time B at constant retort temperature. The new procedure was based on three equations; the first was obtained by the inversion of the function that expresses the process lethality, F, and hence the fh/U parameter. However, the inversion was possible for a sub-domain of the function. The inverse function g=g(fh/U, z, Jcc) was then extended to the entire domain (10°C&l...
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The reduction of the soil cutting force through vibrating tools was the object of many studies during the second half of the last century. These studies initially focused on soil movement by bulldozers and then on soil tillage in... more
The reduction of the soil cutting force through vibrating tools was the object of many studies during the second half of the last century. These studies initially focused on soil movement by bulldozers and then on soil tillage in agriculture. Over the past years, the field of tree-nursery mechanization has been employing this knowledge due to the use of equipment with oscillating tools for root-balling plants. Transportation and planting must be performed with the roots contained in a hemispherical ball of the original soil. This hemispherical root-ball is obtained by using a vibrating semicircular blade that cuts the soil underneath the plant. The blade oscillator is complex because the blade must oscillate and advance in the frame to cut the root-ball. For this reason, we correlated the oscillation and cutting movements with the oscillator features through a dynamic analysis using the Hong's formulae for Coulomb friction with a harmonic forcing torque. The resulting periodic m...
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With the aim of energy saving in cold storage in Italy, an integrated system (Total Energy System - TES) was considered for production of cold air, obtained by assembling compression system, absorption system and cogeneration unit (CHP)... more
With the aim of energy saving in cold storage in Italy, an integrated system (Total Energy System - TES) was considered for production of cold air, obtained by assembling compression system, absorption system and cogeneration unit (CHP) fuelled with methane-gas, in two different plant solutions: 1) TES consisting of the CHP, mechanically coupled with the compression refrigerating machine and thermically with the absorption system both designed to cool the air in the store rooms; 2) TES* characterized by the CHP, mechanically coupled with the compression refrigerating machine, designed to cool the air in the store rooms, and thermically with the absorption system designed to cool the air in a pre-refrigeration plant. A mathematical modeling and a consequent computer simulation of the behavior of both integrated system (TES and TES*) and both related conventional systems (CES consisting of a compression machine to cool the air in the store rooms and CES* characterized by two compressi...
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A mathematical model was developed to get an equation of the decrease of air velocity crossing the canopy of tree crops during pesticide application using air carrier orchard sprayers. The utility of such a model rises from the need for... more
A mathematical model was developed to get an equation of the decrease of air velocity crossing the canopy of tree crops during pesticide application using air carrier orchard sprayers. The utility of such a model rises from the need for an aid to understand the experimental results of several authors, who agree with the opinion that air jet velocity greatly affects environmental pollution from pesticides. Further, probably in the future it will arise the demand to implement the equation of air velocity decay in self-adjustment systems of the fan installed on orchard sprayers to limit spray drift. Based on momentum theorem applied under three assumptions, a differential equation was found and its integration lead to a closed solution that can easily be implemented in a PLC for the self-adjustment system to develop. The integral equation thus obtained, together with the assumptions made, was submitted to on-field verification on three crops (peach, vine and apple). The results show a ...
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A mathematical model was developed to correlate the four heat penetration parameters of 57 Stumbo’s tables (18,513 datasets) in canned food:g(the difference between the retort and the coldest point temperatures in the canned food at the... more
A mathematical model was developed to correlate the four heat penetration parameters of 57 Stumbo’s tables (18,513 datasets) in canned food:g(the difference between the retort and the coldest point temperatures in the canned food at the end of the heating process),fh/U(the ratio of the heating rate index to the sterilizing value),z(the temperature change required for the thermal destruction curve to traverse one log cycle), andJcc, (the cooling lag factor). The quantitiesg,z, andJcc, are input variables for predictingfh/U, whilez,Jccandfh/Uare input variables for predicting the value ofg, which is necessary to calculate the heating process timeB, at constant retort temperature, using Ball’s formula. The process time calculated using thegvalue obtained from the mathematical model closely followed the time calculated from the tabulatedgvalues (root mean square of absolute errors RMS = 0.567 min, average absolute error = 0.421 min with a standard deviation SD = 0.380 min). Because the ...
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Bioenergy production is optimal when the energy production process is both efficient and benefits from local resources. Energetic and exergetic analyses are applied to highlight efficiency differences between small-size systems that are... more
Bioenergy production is optimal when the energy production process is both efficient and benefits from local resources. Energetic and exergetic analyses are applied to highlight efficiency differences between small-size systems that are based on the co-generation of heating and power (CHP) versus the co-generation of heating and power with steam production (CHP-S). Both systems use the Organic fluid Rankine Cycle (ORC). The recovery of heat from flue gases is considered to be a way of increasing energy efficiency. In the ...
Research Interests: Engineering, Environmental Engineering, Chemical Engineering, Technology, Biochemical Engineering, and 15 moreWater quality, Bioenergy, Wastewater Treatment, Italy, Essential Oil, Biofuels, Essential oils, Dwarf pine, Chip, Energy Production, Bioprocessing, Energy efficient, Water Quality, Bioproducts, and Biomass Processing
The performance of a 118-kW tractor fuelled by pure biodiesel was monitored during a long-term field experiment with approximately 800 h of engine function. The objective was to demonstrate that B100, a pure biodiesel fuel, is a viable... more
The performance of a 118-kW tractor fuelled by pure biodiesel was monitored during a long-term field experiment with approximately 800 h of engine function. The objective was to demonstrate that B100, a pure biodiesel fuel, is a viable alternative to traditional diesel oil in terms of long-term mechanical reliability. A bench test on the new engine, performed by attaching a test stand to the power take-off of the tractor, showed an expected reduction in power (-9%) and torque (-7%) and an increase in specific consumption (+13%) when biodiesel was used as a complete substitute to diesel oil. Furthermore, with the same setup, the exhaust gas had a Bosch smoke index equal to 50% of the value for the same engine fuelled with diesel oil. After these initial tests, the tractor was set up for normal field operations, in which both the engine curves and lubricant quality were periodically monitored. These surveys indicated no significant reduction in engine performance; however, the lubricant was consequently diluted and contaminated by biodiesel, which caused the lubricant properties to considerably worsen. However, on the basis of the chemical-physical analysis, reducing the oil change interval from 200 h (manufacturer's indications for the engine when operating with diesel oil) to 100 h would compensate for this progressive quality decline. At the end of the trials, the engine was disassembled to check the condition of its components; wear and lacquer-like coating phenomena were observed, and their levels were acceptable. The obtained results demonstrated that B100 can effectively substitute for diesel oil in a standard compression-ignition engine: the power change is not perceptible during normal operation of a tractor, and no particular problem will arise in the engine during its life if the lubricant is changed every 100 h.
Research Interests: Agricultural Engineering, Biodiesel, Farm Power and Machinery, IC engine design, bio-fuels, Hybrid EV powertrain design, Tractor, and 9 moreTractor and Farm Equipments, IC ENGINES, Agricultural Machinery, IC Engine, Tractors, IC Engine and alternative fuels, Internal Combustion Engine and Alternative Fuels, Combustion And Fuel Engineering (Automobile Engine Performance and Emission Monitoring, Energy Efficiency , Biofuels, Alternative Energy Resources), and Tractor performance(Tractor and Farm Equipments, IC ENGINES, Agricultural Machinery, IC Engine, Tractors, IC Engine and alternative fuels, Internal Combustion Engine and Alternative Fuels, Combustion And Fuel Engineering (Automobile Engine Performance and Emission Monitoring, Energy Efficiency , Biofuels, Alternative Energy Resources), and Tractor performance)
(Tractor and Farm Equipments, IC ENGINES, Agricultural Machinery, IC Engine, Tractors, IC Engine and alternative fuels, Internal Combustion Engine and Alternative Fuels, Combustion And Fuel Engineering (Automobile Engine Performance and Emission Monitoring, Energy Efficiency , Biofuels, Alternative Energy Resources), and Tractor performance)