La revisione delle trattrici e delle macchine agricole

L’entrata in vigore del “Testo Unico sulla salute e sicurezza nei Luoghi di Lavoro” (D.lgs. 81/08) ha certamente prodotto notevoli cambiamenti rispetto al passato nella mentalità dei lavoratori e oggi le tematiche legate alla sicurezza sono considerate essenziali per la qualità della vita. Nonostante ciò, numerosi incidenti avvengono in tutti gli ambienti di lavoro senza alcuna distinzione: edilizia, industria, terziario, artigianato; il settore agricolo non è esente soprattutto per l’enorme utilizzo di macchine di diversa tipologia e tecnologia che rende questo comparto ad elevato indice infortunistico

Hydrogen and renewable energy sources integrated system for greenhouse heating

The environmental impact and the cost of fossil fuel system for greenhouse heating are the major limits for the development of protected horticulture. Recent researches are focusing on greenhouses optimal climate control and reduction of energy consumption. The use of suitable microclimate control systems, energy efficiency strategies and renewable energy sources could improve the environmental performance of the greenhouses. Renewable energy sources can be used to produce hydrogen by electrolysis with very high gas purity. Hydrogen can serve the purpose of storing overproduced energy after meeting the requirements of the greenhouse, and later it can be employed as fuel, achieving a stand-alone power system. Therefore a research is under development at the University of Bari in order to investigate the suitable solutions of a power system based on solar energy (photovoltaic) and hydrogen, integrated with a geothermal heat pump for powering a self sustained heated greenhouse. The tests were carried out at the experimental farm of the University of Bari sited in Valenzano, Bari, Southern Italy, latitude 41° N, where two experimental greenhouses, with the same geometric and constructive characteristics, have been realized; the distance between the two greenhouses is 12 m; therefore there is no mutual shading. One of the two greenhouses is heated using a low enthalpy heat pump combined with a vertical ground heat exchanger, in comparison with the other unheated greenhouse. The electrical energy for heat pump operation is provided by a purpose-built array of solar photovoltaic modules, which supplies also a water electrolyser system controlled by embedded pc; the generated dry hydrogen gas is conserved in suitable pressured storage tank. The hydrogen is used to produce electricity in a fuel cell in order to meet the above mentioned heat pump power demand when the photovoltaic system is inactive during winter night-time or the solar radiation level is insufficient to meet the electrical demand of the heat pump during overcast cold sky. This note reports the main elements regarding the integrated system design and building and it shows preliminary results of testing operation

Electrolyzer performance analysis of an integrated hydrogen power system for greenhouse heating a case study

A greenhouse containing an integrated system of photovoltaic panels, a water electrolyzer, fuel cells and a geothermal heat pump was set up to investigate suitable solutions for a power system based on solar energy and hydrogen, feeding a self-sufficient, geothermal-heated greenhouse. The electricity produced by the photovoltaic source supplies the electrolyzer; the manufactured hydrogen gas is held in a pressure tank. In these systems, the electrolyzer is a crucial component; the technical challenge is to make it work regularly despite the irregularity of the solar source. The focus of this paper is to study the performance and the real energy efficiency of the electrolyzer, analyzing its operational data collected under different operating conditions affected by the changeable solar radiant energy characterizing the site where the experimental plant was located. The analysis of the measured values allowed evaluation of its suitability for the agricultural requirements such as greenhouse heating. On the strength of the obtained result, a new layout of the battery bank has been designed and exemplified to improve the performance of the electrolyzer. The evaluations resulting from this case study may have a genuine value, therefore assisting in further studies to better understand these devices and their associated technologies

Study of a pilot photovoltaic-electrolyser-fuel cell power system for a geothermal heat pump heated greenhouse and evaluation of the electrolyser efficiency and operational mode

The intrinsic factor of variability of renewable energy sources often limits their broader use. The photovoltaic solar systems can be provided with a power back up based on a combination of an electrolyser and a fuel cell stack. The integration of solar hydrogen power systems with greenhouse heating equipment can provide a possible option for powering stand-alone greenhouses. The aim of the research under development at the experimental farm of Department of Agro-Environmental Sciences of the University of Bari Aldo Moro is to investigate on the suitable solutions of a power system based on photovoltaic energy and on the use of hydrogen as energy vector, integrated with a ground source heat pump for greenhouse heating in a self sustained way. The excess energy produced by a purpose-built array of solar photovoltaic modules supplies an alkaline electrolyser; the produced hydrogen gas is stored in pressured storage tank. When the solar radiation level is insufficient to meet the heat pump power demand, the fuel cell starts converting the chemical energy stored by the hydrogen fuel into electricity. This paper reports on the description of the realised system. Furthermore the efficiency and the operational mode of the electrolyser were evaluated during a trial period characterised by mutable solar radiant energy. Anyway the electrolyser worked continuously in a transient state producing fluctuations of the hydrogen production and without ever reaching the steady-state conditions. The Faradic efficiency, evaluated by means of an empirical mathematic model, highlights that the suitable working range of the electrolyser was 1.5÷2.5 kW and then for hydrogen production more than 0.21 Nm3h–1

Performance assessment of photovoltaic, ground source heat pump and hydrogen heat generator in a stand-alone systems for greenhouse heating

The energy balance is one of the most important factors of the commercial greenhouses. Diesel, LPG and natural gas are generally used as fuel for greenhouses heating. A great amount of scientific research are focused on innovative renewable energy systems in the agricultural sector. The goal is to reduce the use of fossil sources and to change the energy mix of the traditional greenhouses heating system. However, the renewables energies sources and the micro-generation systems still play a niche role in the energy panorama, mainly due to the intermittence of the energy production. In particular, for the solar energy systems used for greenhouse heating applications, the energy produced must be storage and used at night. Stand-alone energy storage systems is necessary to overcome the discontinuity in the energy production and consumption. In this paper, the performance of the stand-alone renewable energy systems for greenhouse heating during the winter season was analyzed. The aims of this research is to compare the energies efficiency of two different stand-alone systems based on hydrogen. The first systems consist of a photovoltaic array connected to an hydrogen electrolyzer, a pressure tank, a fuel cell and a ground source geothermal heat pump. The second system is analogous to the first but a direct air hydrogen burner was used instead to the fuel cell and the heat pump. The second system was designed in order to shorten the energies chain and to simplify the plant. A performance analysis ware conduct in order to define the energy efficiency and the power productions of the both systems. The results show that the heating power produced by the first system is greater than 30% compared to the second one if the hydrogen production and consumption of the two solutions are the same and the coefficient of performance of the heat pump is 5. Furthermore, the first system increasing the greenhouse temperature by 6°C to 10°C compared with the ambient conditions, while the second system by 3°C to 7°C

An Experimental–Numerical Approach for Modelling the Mechanical Behaviour of a Pneumatic Tyre for Agricultural Machines

settings Open AccessArticle An Experimental–Numerical Approach for Modelling the Mechanical Behaviour of a Pneumatic Tyre for Agricultural Machines by Alexandros Sotirios Anifantis 1OrcID,Maurizio Cutini 2OrcID andMarco Bietresato 3,*OrcID 1 Department of Agricultural and Environmental Science, University of Bari Aldo Moro, via Amendola 165/A, I-70126 Bari (BA), Italy 2 Consiglio per la ricerca in agricoltura e l’analisi dell’economia agraria (CREA)-Centro di ricerca Ingegneria e Trasformazioni agroalimentari (CREA-IT), via Milano 43, I-24047 Treviglio (BG), Italy 3 Faculty of Science and Technology, Free University of Bozen/Bolzano, Piazza Università 5, I-39100 Bolzano (BZ), Italy * Author to whom correspondence should be addressed. Appl. Sci. 2020, 10(10), 3481; https://doi.org/10.3390/app10103481 Received: 20 April 2020 / Revised: 11 May 2020 / Accepted: 14 May 2020 / Published: 18 May 2020 (This article belongs to the Section Mechanical Engineering) Download PDF Browse Figures Abstract The mechanical behaviour of an agricultural tyre is a matter of extreme interest as it is related to the comfort of operators, to the adherence of agricultural machines, and to the compaction of agricultural soil. Moreover, the deformability of the tyres plays a fundamental role in vehicle stability in terms of side rollover. The behaviour of a loaded tyre during its deformation is complex, due to the combined contributions of the carcass components, the tread rubber and the air contained within it. Therefore, this study proposes an experimental–numerical approach for the mechanical characterization of agricultural tyres based on real-scale experiments and matches these results with a finite-element (FE) model. The tyre flattening in the elastic field has been described using two coefficients (Young’s modulus “E”, Poisson’s ratio “ν”), whose values have been identified with an iterative FEM procedure. The proposed approach was applied to two different tyres (420/85 R24 and 460/85 R34), each one inflated at two different pressures (1.0 bar and 1.6 bar). Young’s modulus was appreciated to be highly variable with the inflation pressure “p” of the tyres. Furthermore, the response surface methodology was applied to find two mathematical regression models, useful for studying the variations of the tyre footprint dimensions according to the type of tyre. This simple approach can be applied in other simulations without suffering any loss of accuracy in the description of the phenomenon

Performance comparison between fuel cell coupled with geothermal source heat pump and geothermal source gas engine heat pump system for greenhouse heating: A mathematical study

LPG, diesel and natural gas are generally used for greenhouse conditioning. Alternative technologies should be developed to increase the productivity of the protected environments. Innovative solutions are represented by photovoltaic, geothermal, wind and solar thermal integrated in a stand-alone system in agriculture land. The present paper compares the performances of two renewable energy systems for greenhouse heating based on geothermal and hydrogen technologies. The first integrated system is composed by a photovoltaic array, an electrolyzer, a hydrogen storage tank, a fuel cell and a ground source heat pump connected to a geothermal borehole. The second system, instead, is composed by a photovoltaic array, an electrolyzer, a hydrogen storage tank and a gas engine heat pump connected to a geothermal borehole. In order to compare the two systems, both heat pumps produced the same greenhouse heating power input. The results show a difference between the internal and external greenhouse air temperature from 7 to 15 ºC in winter, considering a deep insulating greenhouse cover material. As regarding the first system, the following energy efficiency has been calculated, photovoltaic arrays 13 %, electrolyzer 50 %, fuel cell 40 % and the ground source heat pump coefficient of performance 400 %. Than the total energy efficiency of the first system is 10.4 %. Instead, the overall efficiency of the second system is 11.9 % considering the same performance of the photovoltaic arrays and the electrolyzer of the first system and the ground source gas engine heat pump's primary energy ratio of 181 %. The primary energy ratio of the ground source gas engine heat pump seems to be low and not competitive respect to the coefficient of performance of a ground source heat pump, but considering the overall efficiencies of the both systems the performances are reversed. Furthermore, the first system is more complex than the second one