Investigating Potential Light-duty Efficiency Improvements through Simulation of Turbo-compounding and Waste-heat Recovery Systems

Modern diesel engines used in light-duty transportation applications have peak brake thermal efficiencies in the range of 40-42% for high-load operation with substantially lower efficiencies at realistic road-load conditions. Thermodynamic energy and exergy analysis reveals that the largest losses from these engines are due to combustion irreversibility and heat loss to the coolant, through the exhaust, and by direct convection and radiation to the environment. Substantial improvement in overall engine efficiency requires reducing or recovering these losses. Unfortunately, much of the heat transfer either occurs at relatively low temperatures resulting in large entropy generation (such as in the air-charge cooler), is transferred to low-exergy flow streams (such as the oil and engine coolant), or is radiated or convected directly to the environment. While there are significant opportunities for recovery from the exhaust and EGR cooler for heavy-duty applications, achieving similar benefits for light-duty applications is complicated by transient, low-load operation at typical driving conditions and competition with the turbocharger and aftertreatment system for the limited thermal resources. We have developed an organic Rankine cycle model using GT-Suite to investigate the potential for efficiency improvement through waste-heat recovery from the exhaust and EGR cooler of a light-duty diesel engine. The modelmore » is used to examine the effects of efficiency-improvement strategies such as cylinder deactivation, use of advanced materials and improved insulation to limit ambient heat loss, and turbo-compounding on the steady-state performance of the ORC system and the availability of thermal energy for downstream aftertreatment systems. Results from transient drive-cycle simulations are also presented, and we discuss strategies to address operational difficulties associated with transient drive cycles and balancing the thermal requirements of waste-heat recovery, turbocharging or turbo-compounding, and exhaust aftertreatment.« less

[1]  Mustafa Canakci,et al.  Energy and exergy analyses of a gasoline engine , 2007 .

[2]  Jerald A. Caton,et al.  A Cycle Simulation Including the Second Law of Thermodynamics for a Spark-Ignition Engine: Implications of the Use of Multiple-Zones for Combustion , 2002 .

[3]  M. J. Moran,et al.  Thermal design and optimization , 1995 .

[4]  Noam Lior,et al.  Sources of Combustion Irreversibility , 1994 .

[5]  John M. E. Storey,et al.  EGR Cooler Performance and Degradation: Effects of Biodiesel Blends , 2008 .

[6]  Takahashi Kazuya,et al.  Study on Maximizing Exergy in Automotive Engines , 2007 .

[7]  Paul Joseph Andersen,et al.  Development of Thermally Durable Cu/SCR Catalysts , 2009 .

[8]  Dimitrios C. Kyritsis,et al.  Parametric Study of the Availability Balance in an Internal Combustion Engine Cylinder , 2001 .

[9]  John M. E. Storey,et al.  Hydrocarbons and Particulate Matter in EGR Cooler Deposits: Effects of Gas Flow Rate, Coolant Temperature, and Oxidation Catalyst , 2008 .

[10]  Pedro J. Mago,et al.  An examination of exergy destruction in organic Rankine cycles , 2008 .

[11]  D. Morris,et al.  Standard chemical exergy of some elements and compounds on the planet earth , 1986 .

[12]  Scott Sluder,et al.  ULSD and B20 Hydrocarbon Impacts on EGR Cooler Performance and Degradation , 2009 .

[13]  Halim Gurgenci.  Performance of power plants with organic Rankine cycles under part-load and off-design conditions , 1986 .

[14]  Robert M. Wagner,et al.  Investigating Potential Efficiency Improvement for Light-Duty Transportation Applications Through Simulation of an Organic Rankine Cycle for Waste-Heat Recovery , 2010 .

[15]  Jeong Kim,et al.  Technical Advantages of Vanadium SCR Systems for Diesel NOx Control in Emerging Markets , 2008 .

[16]  Ronald L. Graves,et al.  Identification of Potential Efficiency Opportunities in Internal Combustion Engines Using a Detailed Thermodynamic Analysis of Engine Simulation Results , 2008 .

[17]  Rainer Storn,et al.  Differential Evolution – A Simple and Efficient Heuristic for global Optimization over Continuous Spaces , 1997, J. Glob. Optim..

[18]  A. C. Alkidas,et al.  The Application of Availability and Energy Balances to a Diesel Engine , 1988 .

[19]  Robert Walter McCabe,et al.  The Effects of Platinum and Rhodium on the Functional Properties of a Lean NOx Trap , 2007 .

[20]  Robert M. Wagner,et al.  A Waste Heat Recovery System for Light Duty Diesel Engines , 2010 .

[21]  J. G. Stevens,et al.  A Second Law Analysis of High Efficiency Low Emission Gasoline Engine Concepts , 2006 .

[22]  C. Stuart Daw,et al.  Study of the Theoretical Potential of Thermochemical Exhaust Heat Recuperation for Internal Combustion Engines , 2010 .

[23]  Friedemann Rohr,et al.  Diesel NOx-Storage Catalyst Systems for Tier 2 BIN5 Legislation , 2008 .

[24]  Jerald A. Caton,et al.  A Review of Investigations Using the Second Law of Thermodynamics to Study Internal-Combustion Engines , 2000 .

[25]  Enrico Tronconi,et al.  Study of a Fe–zeolite-based system as NH3-SCR catalyst for diesel exhaust aftertreatment , 2008 .

[26]  J. Ringler,et al.  Rankine Cycle for Waste Heat Recovery of IC Engines , 2009 .

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

[28]  D. Y. Goswami,et al.  Organic Working Fluids for a Combined Power and Cooling Cycle , 2005 .