The performance of a 118-kW tractor fuelled by pure biodiesel was monitored during a long-term field experiment with\ud
approximately 800 h of engine function. The objective was to demonstrate that B100, a pure biodiesel fuel, is a viable alternative to\ud
traditional diesel oil in terms of long-term mechanical reliability. A bench test on the new engine, performed by attaching a test stand to\ud
the power take-off of the tractor, showed an expected reduction in power (–9%) and torque (–7%) and an increase in specific consumption\ud
(+13%) when biodiesel was used as a complete substitute to diesel oil. Furthermore, with the same setup, the exhaust gas had a Bosch\ud
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\ud
normal field operations, in which both the engine curves and lubricant quality were periodically monitored. These surveys indicated\ud
no significant reduction in engine performance; however, the lubricant was consequently diluted and contaminated by biodiesel, which\ud
caused the lubricant properties to considerably worsen. However, on the basis of the chemical–physical analysis, reducing the oil\ud
change interval from 200 h (manufacturer’s indications for the engine when operating with diesel oil) to 100 h would compensate for\ud
this progressive quality decline. At the end of the trials, the engine was disassembled to check the condition of its components; wear\ud
and lacquer-like coating phenomena were observed, and their levels were acceptable. The obtained results demonstrated that B100\ud
can effectively substitute for diesel oil in a standard compression-ignition engine: the power change is not perceptible during normal\ud
operation of a tractor, and no particular problem will arise in the engine during its life if the lubricant is changed every 100 h
Precision agriculture has been increasingly recognized for its potential ability to improve agricultural productivity, reduce production cost, and minimize damage to the environment. In this work, the current stage of our research in developing a mobile platform equipped with different sensors for orchard monitoring and sensing is presented. In particular, the mobile platform is conceived to monitor and assess both the geometric and volumetric conditions as well as the health state of the canopy. To do so, different sensors have been integrated and effective data-processing algorithms implemented for a reliable crop monitoring. Experimental tests have been performed allowing to obtain both a precise volume reconstruction of several plants and an NDVI mapping suitable for vegetation state evaluations.
The effect of biofuel blends on the engine performance and emissions of agricultural machines can be extremely complex to predict even if the properties and the effects of the pure substances in the blends can be sourced from the literature. Indeed, on the one hand, internal combustion engines (ICEs) have a high intrinsic operational complexity; on the other hand, biofuels show antithetic effects on engine performance and present positive or negative interactions that are difficult to determine a priori. This study applies the Response Surface Methodology (RSM), a numerical method typically applied in other disciplines (e.g., industrial engineering) and for other purposes (e.g., set-up of production machines), to analyse a large set of experimental data regarding the mechanical and environmental performances of an ICE used to power a farm tractor. The aim is twofold: i) to demonstrate the effectiveness of RSM in quantitatively assessing the effects of biofuels on a complex system like an ICE; ii) to supply easy-to-use correlations for the users to predict the effect of biofuel blends on performance and emissions of tractor engines. The methodology showed good prediction capabilities and yielded interesting outcomes. The effects of biofuel blends and physical fuel parameters were adopted to study the engine performance. Among all possible parameters depending on the fuel mixture, the viscosity of a fuel blend demonstrated a high statistical significance on some system responses directly related to the engine mechanical performances. This parameter can constitute an interesting indirect estimator of the mechanical performances of an engine fuelled with such blend, while it showed poor accuracy in predicting the emissions of the ICE (NOx, CO concentration and opacity of the exhaust gases) due to a higher influence of the chemical composition of the fuel blend on these parameters; rather, the blend composition showed a much higher accuracy in the assessment of the mechanical performance of the ICE.
Using agricultural machines on slopes is very risky for operators: drivers difficultly have a correct perception of the stability condition of their vehicles when travelling, especially because it is impossible to instantly check the ground elevation and harshness in correspondence of each wheel. Moreover, the tests that are usually performed to characterize these machines' stability are scarcely helpful in real conditions: these tests check the lateral overturning (maximum angle) in two static configurations only. Evidently, these do not cover most of real situations, do not locate its centre-of-mass and do not consider the centrifugal force (causing load-transfers and dynamically-variable readjustments of the machine's trim in turnings), thus making impossible the setup of eventual active/passive safety-systems to be installed on vehicles.Therefore, with the aim of overcoming the limitations of actual tests, giving a higher level of information to the tractors' manufacturers and users, we have conceived a completely-new test-apparatus to be installed within our laboratory: the Tiltable Platform. It integrates two subsystems, illustrated hereinafter.(1) The tiltable/angleable plane is a wide flat structure (15×15 m), able to simulate different groundgradients, allowing a vehicle to manoeuvre/travel on it along circular paths in a controlled and safe environment. It can also generate an angle at half of its width, transversal to the maximum-slope direction (simulating the exits of an agricultural machine from the inter-rows). (2) The tilting turntable: has a circular shape and is divided into quadrants, each capable of measuring the weight sustained due to a motionless vehicle positioned on them; it is installed on a tilting structure and can rotate around a vertical axis, thus allowing to vary the angular position of the vehicle's longitudinal axis with reference to the maximum-slope direction.Finally, this test-rig will be useful to develop new test-methodologies to certify the agricultural machines' stability in real operating-conditions (e.g. operating with ballast/mounted-implements).
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