Reexamination of Multiple Fuel Injections for Improving the Thermal Efficiency of a Heavy-Duty Diesel Engine

SAE InternationalOlmeda, P.; Martín, J.; García Martínez, A.; Villalta-Lara, D.; Doménech Llopis, V. (2017). A Combination of Swirl Ratio and Injection Strategy to Increase Engine Efficiency. AbstractGrowing awareness about CO2 emissions and their environmental implications are leading to an increase in the importance of thermal efficiency as criteria to design internal combustion engines (ICE). Heat transfer to the combustion chamber walls contributes to a decrease in the indicated efficiency. A strategy explored in this study to mitigate this efficiency loss is to promote low swirl conditions in the combustion chamber by using low swirl ratios. A decrease in swirl ratio leads to a reduction in heat transfer, but unfortunately, it can also lead to worsening of combustion development and a decrease in the gross indicated efficiency. Moreover, pumping work plays also an important role due to the effect of reduced intake restriction to generate the swirl motion. Current research evaluates the effect of a dedicated injection strategy to enhance combustion process when low swirl is used. For this purpose, a combination of theoretical (0D and 1D models) and experimental tools were used. In particular, experiments were conducted in a single-cylinder directinjection light-duty diesel engine. The analysis also included theoretical calculations to estimate pumping losses. Results show that an increase in swirl ratio leads to an increase in the gross indicated efficiency (balancing heat transfer losses and combustion improvement) but the higher pumping losses negate this positive benefit. In the lowest swirl ratio case, a suitable injection strategy based on multiple injections, together with an increase in the injection pressure, can provide similar gross indicated efficiency as high swirl ratio case while avoiding high pumping losses.

Section: Introductionmentioning

confidence: 99%

A Combination of Swirl Ratio and Injection Strategy to Increase Engine Efficiency

Olmeda

Martín

García

et al. 2017

“…For this purpose, calibration curves were obtained by means of a previously calibrated light source, as it is described by Payri et al [29]. The slope of these curves is the transformation factor (C) presented in equation (4).…”

Section: Two Color Methodsmentioning

confidence: 99%

“…Thus, different strategies are proposed to achieve these objectives; thermal management improvement [1,2], indicated cycle optimization [3,4], in-cylinder heat transfer (HT) reduction [5,6], reduction of friction and auxiliaries losses [7,8] or engine downsizing [9] among others. In the present work, the research effort has been focused on improving knowledge of in-cylinder heat transfer.…”

Section: Introductionmentioning

confidence: 99%

An Investigation of Radiation Heat Transfer in a Light-Duty Diesel Engine

Benajes¹,

Martín²,

García³

et al. 2015

In the last two decades engine research has been mainly focused on reducing pollutant emissions. This fact together with growing awareness about the impacts of climate change are leading to an increase in the importance of thermal efficiency over other criteria in the design of internal combustion engines (ICE). In this framework, the heat transfer to the combustion chamber walls can be considered as one of the main sources of indicated efficiency diminution. In particular, in modern direct-injection diesel engines, the radiation emission from soot particles can constitute a significant component of the efficiency losses. Thus, the main of objective of the current research was to evaluate the amount of energy lost to soot radiation relative to the input fuel chemical energy during the combustion event under several representative engine loads and speeds. Moreover, the current research characterized the impact of different engine operating conditions on radiation heat transfer. For this purpose, a combination of theoretical and experimental tools were used. In particular, soot radiation was quantified with a sensor that uses two-color thermometry along with its corresponding simplified radiation model. Experiments were conducted using a 4-cylinder direct-injection light-duty diesel engine fully instrumented with thermocouples. The goal was to calculate the energy balance of the input fuel chemical energy.Results provide a characterization of radiation heat transfer for different engine loads and speeds as well as radiation trends for different engine operating conditions.

“…Then, using the measured mechanical losses in (16) and m fuel is the injected fuel mass. In combustion operation, the power to drive the injection pump was directly obtained from the combination of expressions (16) and (17).…”

Section: Ancillaries Systems Lossesmentioning

confidence: 99%

“…Hence, the market pressure along with the increasing warning due to the effect of GHG emissions is pushing the researchers and manufacturers to search for more efficient engines with lower consumption and CO 2 emissions. The efforts are oriented to different issues such as thermal management [11][12][13][14], indicated cycle optimization [15][16][17], incylinder heat transfer (HT) reduction [18,19], friction and ancillaries losses reduction [20][21][22][23] or engine downsizing [24] between others.…”

Section: Introductionmentioning

confidence: 99%

A New Tool to Perform Global Energy Balances in DI Diesel Engines

Payri¹,

Olmeda²,

Martín³

et al. 2014

The generalization of exhaust aftertreatment systems along with the growing awareness about climate change is leading to an increasing importance of the efficiency over other criteria during the design of reciprocating engines. Using experimental and theoretical tools to perform detailed global energy balance (GEB) of the engine is a key issue for assessing the potential of different strategies to reduce consumption. With the objective of improving the analysis of GEB, this paper describes a tool that allows calculating the detailed internal repartition of the fuel energy in DI Diesel engines. Starting from the instantaneous in-cylinder pressure, the tool is able to describe the different energy paths thanks to different submodels for all the relevant subsystems. Hence, the heat transfer from gases to engine walls is obtained with specific convective and radiative models in the chamber and ports; the repartition of the heat flux throughout the engine metal elements towards the oil and coolant is estimated with a lumped capacitance model; finally, the ancillary systems and friction losses are obtained through specific semiempirical submodels. The validation of the tool is performed in a 4-cylinder DI Diesel engine instrumented to perform detailed experimental GEB. Finally, a simple analysis of combined internal and external analysis in the complete engine map shows the effect of operating conditions on each energy term. Thus it is demonstrated the utility of the proposed tool, that complements the experimental heat flow measurements in Diesel engine researches oriented to the reduction of energy consumption.