The Application of Availability and Energy Balances to a Diesel Engine

1988 ◽  
Vol 110 (3) ◽  
pp. 462-469 ◽  
Author(s):  
A. C. Alkidas
Keyword(s):  
Heat Transfer ◽  
Diesel Engine ◽  
Combustion Process ◽  
Operating Conditions ◽  
Second Law ◽  
Heavy Duty ◽  
Efficiency Ratio ◽  
Brake Power ◽  
Laws Of Thermodynamics ◽  
Energy Balances

The maximum power that can be extracted from an engine operating at a given condition was determined by means of analyses based on the first and second laws of thermodynamics. These analyses were applied to a heavy-duty single-cylinder open-chamber diesel engine operated at constant speed. Over the range of operating conditions investigated, the second-law efficiency (ratio of brake power to maximum extractable power) of the engine, which increased with engine load, was found to vary from 22 to 50 percent. It was concluded that besides heat transfer, the combustion process was the most important source of irreversibility and accounted for 25 to 43 percent of the lost power.

Twin-Peak Heat Release Phenomenon Inside a Heavy-Duty Diesel Engine Retrofitted to Natural-Gas Spark Ignition

2019 ◽  
Author(s):  
Jinlong Liu ◽  
Cosmin E. Dumitrescu ◽  
Christopher Ulishney
Keyword(s):  
Diesel Engine ◽  
Natural Gas ◽  
Heat Release ◽  
Energy Release ◽  
Flame Propagation ◽  
Combustion Process ◽  
Spark Ignition ◽  
Operating Conditions ◽  
Heavy Duty ◽  
Double Peak

Abstract Existing compression ignition engines can be modified to spark ignition configuration to increase the use of natural gas in the heavy-duty transportation sector. A better understanding of the premixed natural gas combustion inside the original diesel chamber (i.e., flat-head-and-bowl-in-piston) will help improve the conversion process and therefore accelerate the diesel engine conversion. Previous studies indicated that the burning process in such engines is a two-stage combustion with a fast burning inside the bowl and a slower burning inside the squish. This paper used experimental and numerical results to investigate the combustion process at a more advanced spark timing representative of ultra-lean medium-load operation, which placed most of the combustion inside the compression stroke. At such operating conditions, the high turbulence intensity inside the squish region accelerated the flame propagation inside the squish region to the point that the burn inside the bowl separated less from that inside the squish region. However, several individual cycles produced a double-peak energy-release with the peak locations closer to the only one heat release peak seen in the average cycle. Moreover, RANS CFD simulations indicated that the time at which the flame entered the squish region was near the peak location of the energy-release process for the conditions investigated here. As a result, the data suggests that the double-peak seen in the apparent heat release rate was the result of the cycle-by-cycle variation in the flame propagation.

Second-Law Analysis of Diesel Engine Combustion

1990 ◽  
Vol 112 (1) ◽  
pp. 129-137 ◽  
Author(s):  
J. H. Van Gerpen ◽  
H. N. Shapiro
Keyword(s):  
Heat Transfer ◽  
Diesel Engine ◽  
Combustion Process ◽  
Second Law ◽  
Zone Model ◽  
System Availability ◽  
Second Law Analysis ◽  
Correct Determination ◽  
Chemical Availability ◽  
First Time

A second-law analysis of the combustion process in a diesel engine is presented for a single-zone model. Expressions for availability and the availability balance are developed in detail from the energy and entropy balances and applied in a manner that allows the irreversibility due to combustion to be separated from that associated with heat transfer to the walls. Availability is divided into two components: thermomechanical and chemical availability. For the first time, chemical availability of the cylinder contents is dealt with rigorously, which allows for a correct determination of combustion irreversibilities. The analysis is applied in a parametric study of the effects of combustion timing, mass burning rate, and heat transfer rate on the irreversibility and system availability.

Effects of the Injection Parameters on the Emissions of a Heavy Duty Diesel Engine

2009 ◽  
Author(s):  
M. Yılmaz ◽  
M. Zafer Gul ◽  
Y. Yukselenturk ◽  
B. Akay ◽  
H. Koten
Keyword(s):  
Diesel Engine ◽  
Direct Injection ◽  
Combustion Process ◽  
Design Parameters ◽  
Combustion Model ◽  
Particulate Emissions ◽  
Multiphase Model ◽  
Heavy Duty ◽  
Flow Development ◽  
Air Motion

It is estimated by the experts in the automotive industry that diesel engines on the transport market should increase within the years to come due to their high thermal efficiency coupled with low carbon dioxide (CO2) emissions, provided their nitrogen oxides (NOx) and particulate emissions are reduced. At present, adequate after-treatments, NOx and particulates matter (PM) traps are developed and industrialized with still concerns about fuel economy, robustness, sensitivity to fuel sulfur and cost because of their complex and sophisticated control strategy. New combustion processes focused on clean diesel combustion are investigated for their potential to achieve near zero particulate and NOx emissions. Their main drawbacks are increased level of unburned hydrocarbons (HC) and carbon monoxide (CO) emissions, combustion control at high load and limited operating range and power output. In this work, cold flow simulations for a single cylinder of a nine-liter (6 cylinder × 1.5 lt.) diesel engine have been performed to find out flow development and turbulence generation in the piston-cylinder assembly. In this study, the goal is to understand the flow field and the combustion process in order to be able to suggest some improvements on the in-cylinder design of an engine. Therefore combustion simulations of the engine have been performed to find out flow development and emission generation in the cylinder. Moreover, the interaction of air motion with high-pressure fuel spray injected directly into the cylinder has also been carried out. A Lagrangian multiphase model has been applied to the in-cylinder spray-air motion interaction in a heavy-duty CI engine under direct injection conditions. A comprehensive model for atomization of liquid sprays under high injection pressures has been employed. The combustion is modeled via a new combustion model ECFM-3Z (Extended Coherent Flame Model) developed at IFP. Finally, a calculation on an engine configuration with compression, spray injection and combustion in a direct injection Diesel engine is presented. Further investigation has also been performed in-cylinder design parameters in a DI diesel engine that result in low emissions by effect of high turbulence level. The results are widely in agreement qualitatively with the previous experimental and computational studies in the literature.

scholarly journals An investigation of the fuel injector dedicated to the aircraft opposed-piston two-stroke diesel engine

2019 ◽  
Vol 177 (2) ◽  
pp. 151-155
Author(s):  
Ksenia SIADKOWSKA ◽  
Mirosław WENDEKER ◽  
Łukasz GRABOWSKI
Keyword(s):  
Diesel Engine ◽  
Combustion Process ◽  
Mie Scattering ◽  
Operating Conditions ◽  
Fuel Spray ◽  
Chamber Pressure ◽  
Fuel Injector ◽  
Measuring Point ◽  
Fuel Delivery ◽  
The Moment

The paper presents the research results of the injector construction with the modified injection nozzle. The injector is designed for a prototype opposed-piston aircraft diesel engine. The measurements were based on the Mie scattering technique. The conditions of the experiment corresponded to maximum loads similar to those occurring at the start. The measuring point was selected in line with the analysis of engine operating conditions: combustion chamber pressure at the moment of fuel delivery (6 MPa) and fuel pressure in the injection rail (140 MPa). The analysis focused on the average spray range and distribution, taking into account the differences between holes in the nozzle. As a result of the conducted research, the fuel spray range was defined with the determined parameters of injection. The fuel spray ranges inside the constant volume chamber at specific injection pressures and in the chamber were examined, and the obtained results were used to verify and optimize the combustion process in the designed opposed-piston two-stroke engine.

Analysis of Throttle Opening Variation Impact on a Diesel Engine Performance Using Second Law of Thermodynamics

2009 ◽  
Author(s):  
B. B. Sahoo ◽  
U. K. Saha ◽  
N. Sahoo ◽  
P. Prusty
Keyword(s):  
Diesel Engine ◽  
Direct Injection ◽  
Fuel Efficiency ◽  
Engine Performance ◽  
Second Law Of Thermodynamics ◽  
Operating Conditions ◽  
Second Law ◽  
Engine Fuel ◽  
Availability Analysis ◽  
Second Law Analysis

The fuel efficiency of a modern diesel engine has decreased due to the recent revisions to emission standards. For an engine fuel economy, the engine speed is to be optimum for an exact throttle opening (TO) position. This work presents an analysis of throttle opening variation impact on a multi-cylinder, direct injection diesel engine with the aid of Second Law of thermodynamics. For this purpose, the engine is run for different throttle openings with several load and speed variations. At a steady engine loading condition, variation in the throttle openings has resulted in different engine speeds. The Second Law analysis, also called ‘Exergy’ analysis, is performed for these different engine speeds at their throttle positions. The Second Law analysis includes brake work, coolant heat transfer, exhaust losses, exergy efficiency, and airfuel ratio. The availability analysis is performed for 70%, 80%, and 90% loads of engine maximum power condition with 50%, 75%, and 100% TO variations. The data are recorded using a computerized engine test unit. Results indicate that the optimum engine operating conditions for 70%, 80% and 90% engine loads are 2000 rpm at 50% TO, 2300 rpm at 75% TO and 3250 rpm at 100% TO respectively.

A Study on the Calculation of Heat Release Rate to Compensate the Error Due to Single Zone Assumption in Diesel Engine

2005 ◽  
Author(s):  
Seung Hyup Ryu ◽  
Ki Doo Kim ◽  
Wook Hyeon Yoon ◽  
Ji Soo Ha
Keyword(s):  
Diesel Engine ◽  
Heat Release ◽  
Computational Analysis ◽  
Combustion Process ◽  
Operating Conditions ◽  
Zone Model ◽  
Specific Heats ◽  
Start Of Injection ◽  
Release Analysis ◽  
Improved Model

Accurate heat release analysis based on the cylinder pressure trace is important for evaluating combustion process of diesel engines. However, traditional single-zone heat release models (SZM) have significant limitations due mainly to their simplified assumptions of uniform charge and homogeneity while neglecting local temperature distribution inside cylinder during combustion process. In this study, a heat release analysis based on single-zone model has been evaluated by comparison with computational analysis result using Fire-code, which is based on multi-dimensional model (MDM). The limitations of the single-zone assumption have been estimated. To overcome these limitations, an improved model that includes the effects of spatial non-uniformity has been applied. From this improved single-zone heat release model (Improved-SZM), two effective values of specific heats ratios, denoted by γV and γH in this study, have been introduced. These values are formulated as the function of charge temperature changing rate and overall equivalence ratio by matching the results of the single-zone analysis to those of computational analysis using Fire-code about medium speed marine diesel engine. Also, it is applied that each equation of γV and γH has respectively different slopes according to several meaningful regions such as the start of injection, the end of injection, the maximum cylinder temperature, and the exhaust valve open. This calculation method based on improved single-zone model gives a good agreement with Fire-code results over the whole range of operating conditions.

Applying the Representative Interactive Flamelet Model to Evaluate the Potential Effect of Wall Heat Transfer on Soot Emissions in a Small-Bore DI Diesel Engine

2001 ◽  
Author(s):  
Carl Hergart ◽  
Norbert Peters
Keyword(s):  
Heat Transfer ◽  
Diesel Engine ◽  
Wide Spectrum ◽  
Turbulent Flame ◽  
Combustion Process ◽  
Heat Losses ◽  
Wall Heat Transfer ◽  
Two Phase ◽  
Flamelet Model ◽  
Di Diesel Engine

Abstract Due to the wide spectrum of turbulent and chemical length- and time scales occurring in a HSDI diesel engine, capturing the correct physics and chemistry underlying combustion poses a tremendous modeling challenge. The processes related to the two-phase flow in a DI diesel engine add even more complexity to the total modeling effort. The Representative Interactive Flamelet (RIF) model has gained widespread attention owing to its ability of correctly describing ignition, combustion and pollutant formation phenomena. This is achieved by incorporating very detailed chemistry for the gas phase as well as the soot particle growth and oxidation, without imposing any significant computational penalty. The model, which is based on the laminar flamelet concept, treats a turbulent flame as an ensemble of thin, locally one-dimensional flame structures, whose chemistry is fast. A potential explanation for the significant underprediction of part load soot observed in previous studies applying the model is the neglect of wall heat losses in the flamelet chemistry model. By introducing an additional source term in the flamelet temperature equation, directly coupled to the wall heat transfer predicted by the CFD-code, flamelets exposed to walls are assigned heat losses of various magnitudes. Results using the model in three-dimensional simulations of the combustion process in a small-bore direct injection diesel engine indicate that the experimentally observed emissions of soot may have their origin in flame quenching at the relatively cold combustion chamber walls.

Heat Transfer Characteristics of a Radial Jet Reattachment Flame

1997 ◽  
Vol 119 (2) ◽  
pp. 258-264 ◽  
Author(s):  
J. W. Mohr ◽  
J. Seyed-Yagoobi ◽  
R. H. Page
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Combustion Process ◽  
Local Heat ◽  
Operating Conditions ◽  
Recirculation Region ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Impingement Surface

A Radial Jet Reattachment Combustion (RJRC) nozzle forces primary combustion air to exit radially from the combustion nozzle and to mix with gaseous fuel in a highly turbulent recirculation region generated between the combustion nozzle and impingement surface. High convective heat transfer properties and improved fuel/ air mixing characterize this external mixing combustor for use in impingement flame heating processes. To understand the heat transfer characteristics of this new innovative practical RJRC nozzle, statistical design and analysis of experiments was utilized. A regression model was developed which allowed for determination of the total heat transfer to the impingement surface as well as the NOx emission index over a wide variety of operating conditions. In addition, spatially resolved flame temperatures and impingement surface temperature and heat flux profiles enabled determination of the extent of the combustion process with regards to the impingement surface. Specifically, the relative sizes of the reaction envelope, high temperature reaction zone, and low temperature recirculation zone were all determined. At the impingement surface in the reattachment zone very high local heat flux values were measured. This study provides the first detailed local heat transfer characteristics for the RJRC nozzle.

Thermal modelling of modern diesel engines: proposal of a new heat transfer coefficient correlation

2011 ◽  
Vol 225 (11) ◽  
pp. 1544-1560 ◽  
Author(s):  
C A Finol ◽  
K Robinson
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Heat Transfer Coefficient ◽  
Diesel Engine ◽  
Transfer Coefficient ◽  
Diesel Engines ◽  
Internal Combustion Engines ◽  
Operating Conditions ◽  
Boost Pressure ◽  
Simple Relationship

Existing methods for predicting heat fluxes and temperatures in internal combustion engines, which take the form of correlations to estimate the heat transfer coefficient on the gas-side of the combustion chamber, are based on methodology developed over the past 50 years, often updated in view of more recent experimental data. The application of these methods to modern diesels engines is questionable because key technologies found in current engines did not exist or were not widely used when those methods were developed. Examples of such technologies include: high-pressure common rail and variable fuel injection strategies including retarded injection for nitrogen oxides emission control; exhaust gas re-circulation; high levels of intake boost pressure provided by a single- or double-stage turbocharger and inter-cooling; multiple valves per cylinder and lower swirl; and advanced engine management systems. This suggests a need for improved predicting tools of thermal conditions, specifically temperature and heat flux profiles in the engine block and cylinder head. In this paper a modified correlation to predict the gas-side heat transfer coefficient in diesel engines is presented. The equation proposed is a simple relationship between Nu and Re calibrated to predict the instantaneous spatially averaged heat transfer coefficient at several operating conditions using air as gas in the model. It was derived from the analysis of experimental data obtained in a modern diesel engine and is supported by a research methodology comprising the application of thermodynamic principles and fundamental equations of heat transfer. The results showed that the new correlation adequately predicted the instantaneous coefficient throughout the operating cycle of a high-speed diesel engine. It also estimated the corresponding cycle-averaged heat transfer coefficient within 10 per cent of the experimental value for the operating conditions considered in the analysis.

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