A methodology for the capture and analysis of hybrid data: a case study of program debugging

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Identification of the errors related to the estimation of the actual combustion rate of the fuel from the measured cylinder pressure of di diesel engines

Paper presented at the 7th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Turkey, 19-21 July, 2010.As recognized by various researchers the most important source of information for a reciprocating internal combustion engine is the cylinder pressure diagram. Its validity for direct injection (DI) diesel engines is extremely important since the engineer can estimate and understand the effect of various operating or design parameters on the combustion mechanism. But, since the measured cylinder pressure diagram is the result of various thermo-physical processes taking place inside the combustion chamber it cannot provide direct information concerning the combustion rate of fuel. For this reason techniques have been developed to estimate the rate at which energy is released inside the combustion chamber by processing the cylinder pressure diagram. These techniques are referred to as "Heat Release Rate Analysis" and are used to estimate the combustion rate of fuel inside the combustion chamber. During its estimation various errors may arise due to either the cylinder pressure measurement or inadequate description of the various mechanisms, i.e. heat transfer etc. In the present investigation the heat release rate estimation procedure is analyzed at the fundamental level using a detailed simulation model and available experimental data. A source of error is indicated that is higher compared to any of the conventional ones. From the anal is, it is shown that it is not possible to estimate the actual rate of heat release inside the combustion chamber of DI diesel engines from the measured cylinder pressure trace using existing heat release rate analysis techniques even if all mechanisms are described accurately. From the employment of the simulation technique the actual source of this error is revealed.ksb201

Review of Biofuel Effect on Emissions of Various Types of Marine Propulsion and Auxiliary Engines

The International Maritime Organization aims to reduce the maritime industry’s carbon emissions by 40% in the next two decades and has introduced measures to control CO2 emissions. These have significantly increased interest regarding biofuels, which can be used immediately on existing vessels, reducing their carbon footprint. The most common variant is B30, a blend of 70% crude oil and 30% biodiesel. Concerns exist for the potential effect on engine performance and NOx emissions. Scientific works on the subject are limited for two-stroke marine engines, while some studies are available for four-stroke ones, usually auxiliaries. To increase information availability on the subject, in this work, we review the results of testing on multiple marine engine types, two-stroke propulsion and four-stroke auxiliary units using B30 and conventional fuels. The effect on emissions and fuel efficiency is examined and cross-referenced with the available literature. A small increase in specific fuel consumption was observed for B30 use that varied with engine type. The increase was on average 1% for two-stroke and 2.5% for four-stroke engines. The effect of B30 on NOx emissions was low but varied between engines. For low-speed two-stroke engines, NOx increase was on average 4% compared to crude oil, and 2.4% for four-stroke auxiliary units, albeit with higher variance. For some four-stroke units, a decrease in emissions was found. All previous results were in line with other published studies. Overall, it was found that while biofuel effect can vary considerably between applications, 30% biodiesel blends can be used with no concerns regarding emissions and fuel efficiency

A thermodynamic feasibility study of an Organic Rankine Cycle (ORC) for heavy-duty diesel engine waste heat recovery in off-highway applications

Abstract This work assesses the possibility of fitting an organic Rankine cycle (ORC) system in a commercial agricultural tractor, recovering waste heat from a 300-kW brake power heavy-duty diesel engine. Two different cycle architectures are considered: a single evaporator layout to recover tail-pipe exhaust heat, and a parallel evaporator configuration to recover both exhaust and exhaust gas recirculation (EGR) heat. A second lower-temperature cooling circuit is also considered as possible different heat sink for the ORC system. Ten different working fluids have been assessed, and the optimum system configuration, in terms of fuel consumption, has been obtained applying an optimization algorithm to a process simulation model. A preliminary study has been carried out to evaluate the impact of the ORC system on the engine–vehicle-cooling system. A maximum fuel consumption reduction of 10.6% has been obtained using methanol and recovering heat from tail-pipe and EGR. However, considering also components and heat rejection performance, water steam, toluene and ethanol allow to obtain the best compromises between thermodynamic performance and engine–vehicle-cooling circuit impact