Ideation, realization and experimentation of prototype device for measuring farm tractor fuel consumption during dyno tests

Abstract

Abstract.One of the most difficult practical problems to overcome when testing agricultural machines (tractors) at the dyno is measuring the fuel consumption and assessing the engine's global efficiency. Indeed, diesel engines have two fuel-lines: a delivery line (from the tank to the cylinders), and a return line, to convey back in the tank the fuel not injected as a consequence of the accelerator position and pump settings. In principle, to measure the consumption, known the delivery flowrate (proportional to the engine speed), a single flowmeter could be used in the return line only (having a variable flow); unluckily, the real suction flowrate is generally unknown, varying with the model and vehicle age (i.e., with the pump components' wear), so two flowmeters are always needed. But there is another metrological problem to consider: a flowmeter inserted in series in a fuel-supply line could significantly alter the flowrate. Finally, another further problem can arise, when the experimenters are asked to characterize machines not owned by them: modifications to the vehicle under test should be avoided or, at least, limited, e.g., not to void the guarantee. Unfortunately, solutions like the clamp-on ultrasonic flowmeters (placed outside the pipes) are not so suitable for fluids with few particles in suspension, e.g., the fuel processed by the pump. Therefore, it was decided to act upstream of the entire supply line, providing an external tank placed on a precision scale near the tractor, to be used instead of the vehicle's tank. The only, absolutely reversible, needed operation is to connect to the fuel pump two flexible pipes drawing from the external tank. The device gives the net fuel consumption by means of a data logger that acquires the tank mass at periodic intervals. It has been successfully tested on a New Holland 4020V tractor at the dyno, allowing to calculate the instant/hourly/specific consumptions and the engine's global efficiency at six engine speeds (from 800 to 2200 rpm) and full throttle. Keywords: fuel-consumption meter, agricultural machines, diesel engines, dyno test, real-time measurements. IntroductionThe average mass/volumetric fuel consumption (or, simply, "fuel consumption") is measured by the mass/volume of fuel used by an agricultural machine during a specific time-period (typically: in kg·h -1 , ℓ·h -1 ). If the time-period is very short, it is possible to have the instantaneous volumetric fuel consumption (g·s -1 ), expressed as a function of the engine load and speed. The knowledge of the fuel consumptions is a key-point for characterizing the agricultural machinery [1] for several reasons:• the fuel consumption is one of the main parameters for comparing the performances of the driving machines involved in different field-operations (therefore, being equal the effects/achieved results on the field); furthermore, this parameter is greatly taken into account by the end users, because it is linked to the operating costs of the considered machine (it is one of the main income-statem...

Proposal of a Predictive Mixed Experimental- Numerical Approach for Assessing the Performance of Farm Tractor Engines Fuelled with Diesel- Biodiesel-Bioethanol Blends

“…Specifically, these blends were: B15 (85% D, 15% B in volume), B25 (75% D, 25% B), B15E3 (82% D, 15% B, 3% E) and B25E3 (72% D, 25% B, 3% E). An external tank was used during these tests for rapid fuel-substitution and for the measurement of the instant consumptions; a description of such this apparatus is available in [48]. The kinematic viscosity of the fuels involved were measured with a "Simple VIS" portable automated viscometer by Cannon Instrument Company (State College, PA, USA) [49].…”

Set-up of integrated system for real-time detection and recording of many engine parameters of agricultural machines during dyno tests

“…• chrono-gravimetric fuel-consumption meter system (i.e. the plate scale): instant quantity of fuel in an external tank, useful to calculate the instant BSFC of the tested tractor [26]; • gas analyser: chemical composition of the main polluting species, temperature of the gas;…”

Concurrent engineering approach in design of test equipment for detecting farm tractor mechanical performances: Application to development of hub-adapter

“…The starting point is a PTO-dyno already owned by the university (a "SIGMA 50 Mobile" PTO-dyno by N. J. Froment & Co Ltd, Easton-on-the-Hill, East Northamptonshire, England, UK; [4]), useful to apply a breaking torque to the engine. This device is designed to be connected to the tractor PTO (in terms of operative range and mechanical interfaces) to measure the engine output upstream of the transmission, exploiting the direct connection between the engine and PTO [5][6][7][8][9][10]. It is therefore necessary to create a mechanical connection between the tractor propulsion elements and the PTO-dyno.…”