The influence of the exhaust system unsteady gas flow and insulation on the performance of a turbocharged diesel engine

Abstract A comprehensive digital computer program is used to simulate the unsteady gas flow in the exhaust and inlet systems of a multi-cylinder, turbocharged, medium-high speed, four-stroke diesel engine installed at the authors' laboratory. The simulation assumes one-dimensional, time-varying gas flow in the engine pipes and incorporates numerous realistic fluid dynamic, thermodynamic and heat-transfer features. The characteristic mathematical transformation solution of the gas-flow dynamics partial differential equations is interfaced with First-Law analysis models of the cylinders main chambers and prechambers. The simulation results are compared most favourably against the engine's experimental performance results, which include mean air consumption rate, pressure histories at various locations on the exhaust system, and energy-mean temperature values at the exit of the exhaust system. The simulation results are also utilized for the determination of the various cylinders' exhaust waves intensity, as they are imposed by the design characteristics of the exhaust manifold. The plotting of relevant charts, showing the contour variation of gas pressure, temperature and Mach index against engine crank angle and pipe length, aids the correct interpretation of the observed behaviour. The detailed simulation of the fluid dynamic and heat-transfer fields in the engine exhaust system, permits an interesting parametric study of the influence of the degree of insulation of the exhaust system on the energy and exergy (availability) content of the exhaust gases before the turbocharger turbine, by coupling the above First-Law with Second-Law analysis concepts.

[1]  Constantine D. Rakopoulos,et al.  Evaluation of a spark ignition engine cycle using first and second law analysis techniques , 1993 .

[2]  E. Obert.  Internal combustion engines and air pollution , 1973 .

[3]  N P Kyrtatos,et al.  The Performance Potential of Limited Cooled Diesel Engines , 1983 .

[4]  C. D. Rakopoulos,et al.  A stochastic-experimental investigation of the cyclic pressure variation in a di single-cylinder diesel engine , 1992 .

[5]  S. C. Sorenson,et al.  Heat Transfer in the Straight Section of an Exhaust Port of a Spark Ignition Engine , 1979 .

[6]  Constantine D. Rakopoulos,et al.  DI and IDI diesel engines combustion irreversibility analysis , 1993 .

[7]  Dimitrios T. Hountalas,et al.  Prechamber and main chamber insulation effects on the performance of an IDI diesel engine coupled to power turbine , 1992 .

[8]  Constantine D. Rakopoulos,et al.  Phasing cylinder pressure to crank angle in a direct injection diesel engine, by simulation of compression curve and elaboration of measured pressure data , 1991 .

[9]  E. Eckert,et al.  Analysis of heat and mass transfer , 1971 .

[10]  J. L. Duncan,et al.  Rate-dependent transient extrusion , 1975 .

[11]  Dimitrios T. Hountalas,et al.  An experimental investigation of fuel‐injection‐pressure and engine‐speed effects on the performance and emission characteristics of a divided‐chamber diesel engine , 1993 .

[12]  D. A. Kouremenos,et al.  A FORTRAN program for calculating the evaporation rates in diesel engine fuel sprays , 1992 .

[13]  C. D. Rakopoulos,et al.  Comparative performance and emission studies when using olive oil as a fuel supplement in DI and IDI diesel engines , 1992 .

[14]  Edward Thomas. Vincent.  Supercharging the internal combustion engine , 1948 .

[15]  D. Kouremenos,et al.  THERMODYNAMIC ANALYSIS OF DIRECT INJECTION DIESEL ENGINES BY MULTI-ZONE MODELLING. , 1987 .

[16]  C. D. Rakopoulos,et al.  Influence of ambient temperature and humidity on the performance and emissions of nitric oxide and smoke of high speed diesel engines in the Athens/Greece region , 1991 .

[17]  J. C. Jaeger,et al.  Conduction of Heat in Solids , 1952 .

[18]  Gary L. Borman,et al.  Mathematical Simulation of a Large Turbocharged Two-Stroke Diesel Engine , 1971 .

[19]  Roy J. Primus.  A Second Law Approach to Exhaust System Optimization , 1984 .

[20]  N. Watson,et al.  Turbocharging the internal combustion engine , 1982 .

[21]  S. Churchill,et al.  A Correlating Equation for Forced Convection From Gases and Liquids to a Circular Cylinder in Crossflow , 1977 .

[22]  Dimitrios T. Hountalas,et al.  Thermodynamic analysis of indirect injection diesel engines by two-zone modeling of combustion , 1990 .

[23]  P. C. Baruah,et al.  A simulation model including intake and exhaust systems for a single cylinder four-stroke cycle spark ignition engine , 1975 .

[24]  M. Modest.  Radiative heat transfer , 1993 .

[25]  R. Courant,et al.  Über die partiellen Differenzengleichungen der mathematischen Physik , 1928 .

[26]  Stuart W. Churchill,et al.  Correlating equations for laminar and turbulent free convection from a horizontal cylinder , 1975 .

[27]  Michael J. Moran,et al.  Availability analysis: A guide to efficient energy use , 1982 .

[28]  Constantine D. Rakopoulos,et al.  Availability accumulation and destruction in a DI diesel engine with special reference to the limited cooled case , 1993 .

[29]  Robert E. Wilson,et al.  Fundamentals of momentum, heat, and mass transfer , 1969 .

[30]  E. J. Wright.  Computer Simulation of Engine Gas Dynamic Processes: A Design Package , 1971 .

[31]  Constantine D. Rakopoulos,et al.  Ambient temperature and humidity effects on the performance and nitric oxide emission of spark ignition engined vehicles in Athens/Greece , 1988 .

[32]  R. J. Primus,et al.  A NEW PERSPECTIVE ON DIESEL ENGINE EVALUATION BASED ON SECOND LAW ANALYSIS , 1984 .

[33]  R. S. Benson,et al.  A Comprehensive Digital Computer Program to Simulate a Compression Ignition Engine Including Intake and Exhaust Systems , 1971 .

[34]  Constantine D. Rakopoulos,et al.  Olive oil as a fuel supplement in DI and IDI diesel engines , 1992 .

[35]  John B. Heywood,et al.  Internal combustion engine fundamentals , 1988 .

[36]  A. Shapiro.  The dynamics and thermodynamics of compressible fluid flow. , 1953 .

[37]  J. D. Ledger,et al.  A Finite-Difference Approach for Solving the Gas Dynamics in an Engine Exhaust , 1975 .