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ACHIEVING 44% THERMAL EFFICIENCY in TODAY’S ENGINES “More for Less”2024-01-318811/15/2024
ABSTRACT The US Army is seeking improvements in the fuel efficiency of their military vehicles.. They have initiated a number of R&D projects aimed at advancing the state-of-the-art of powertrain efficiency including demonstration in a laboratory environment. This effort will set a benchmark for the vehicle integrators, allowing them to improve future vehicle offerings. The SAIC, AVL, Badenoch, QinetiQ and Ker-Train Research team offered powertrain solutions from 7 Tons to 40 Tons that achieved the goal of 44% thermal efficiency and the stringent flexible fuel and emissions requirements. In each of these offerings the team was able to identify modifications to existing engines that allowed dramatic improvements in the thermal efficiency. These efficiency improvements were achieved through a combination of techniques, combustion cycle adjustments using in-cylinder pressure monitoring and precise control of fuel injector timing, and turbo-compounding. For the R&D project, the fuel injector timing will be controlled using commercial engine development hardware and software. The high speed hardware emulates the engine control module but allows the developer to finely tune the fuel injection to maximize the 50% Maximum Fuel Burn point (MFB50) with only limited NOx production. This will be accomplished using a variety of fuels and maintaining the output power to within 2% of the engine’s nominal rating. This paper will describe the fundamental diesel combustion process that must be controlled and techniques for usable power extraction from the waste exhaust gases to provide this performance. It will describe the engine development tools that enable these controls changes to be realized within a vehicle development cycle and retain the baseline engine maturity.
McDowell, Jim, Hunter, Gary L., Hennessy, Chris
An Experimental Study of a Waste Heat Recovery System Connected to a Diesel-Gen-Set2017-01-01233/28/2017
In general, diesel engines have an efficiency of about 35% and hence, a considerable amount of energy is expelled to the ambient air. In water-cooled engines, about 25%, 33% and 7% of the input energy are wasted in the coolant, exhaust gas, and friction, respectively. The heat from the exhaust gas of diesel engines can be an important heat source to provide additional power and improve overall engine efficiency. Studies related to the application of recoverable heat to produce additional power in medium capacity diesel engines (< 100 kW) using separate Rankine cycle are scarce. To recover heat from the exhaust of the engine, an efficient heat exchanger is necessary. For this type of application, the heat exchangers are needed to be designed in such a way that it can handle the heat load with reasonable size, weight and pressure drop. This paper describes the study of a diesel generator-set attached with an exhaust heat recovery system. Superheated steam was produced by using two heat exchangers. In authors’ previous study, optimizations using CFD simulations were carried out to design heat exchangers to extract the exhaust heat more effectively. Then, in this research, optimized heat exchangers were manufactured and tests were performed with water/steam as the working fluid. The optimum pressures of the working fluid were found to be 3, 5, 8 and 15 bar at 10.6, 16.1, 21.5, and 26.6 kW of engine powers, respectively. At these optimum pressures, correspondingly 0.34, 0.74, 1.78, 2.71 kW additional powers were produced. At the rated power of 26.6 kW the heat recovery system produced an additional power of 2.71 kW which reduced the brake specific consumption (bsfc) by 11.1%. However, at 40% part load, this bsfc improvement was 3% due to lower exhaust temperature.
Bari, Saiful
Investigation of Engine Processes with Extreme Pressures and Turbocompounding2016-01-05674/5/2016
This work is based on calculations about extreme mean effective and maximum pressures which were published earlier by the author and colleagues. The motivation for the work presented in this paper is to reduce the maximum pressure while keeping a high mep without sacrificing efficiency. It is investigated in a theoretical study in how far this can be accomplished via turbocompounding. The basis is a 320 mm bore four stroke medium speed engine. It is equipped with a state-of-the-art two stage turbocharging system. As a first step turbocompounding is investigated for mean effective pressures from 22 to 80 bar. The bsfc of the turbocharged engine is in the range of 175 to 185 g/kWh depending on mep. With turbocompounding the exhaust pressure before turbine is optimised and figures between 160 and 165 g/kWh are reached. Thermal loading of the engine increases. In the second step strategies to reduce maximum pressure are investigated for an mep of ca. 50 bar. Reduced compression ratio and retarded injection increase the optimum bsfc of the turbocompound engine slightly while a reduced air-fuel-ratio reduces it. With a combination of all three measures maximum pressure can be reduced from 425 to 225 bar while keeping bsfc below 165 g/kWh. The small dependence of bsfc on maximum pressure results because the turbines of the turbocompound engine can utilize the exhaust energy better than those of the turbocharged one. An alternative explanation is found if the Joule cycle is used as the reference cycle for the turbocompound engine.
Eilts, Peter
Application of Rankine Cycle to Passenger Vehicle Waste Heat Recovery - A Review2016-01-01784/5/2016
Rankine cycle (RC) is a thermodynamic cycle that converts thermal energy into mechanical work, which is commonly found in thermal power generation plants. Recently, there are many studies focusing on applying Rankine cycle to recover low-grade waste heat. On-road vehicles, which convert around one third of the fuel energy into useful mechanical energy for propulsion, are moving energy conversion systems that generate considerable waste heat. It was found from many research studies that Rankine cycle has a great potential to be applied to harvest waste heat from automobiles. However, different from other low-grade waste heat sources, vehicles have limited space for the RC system integration and the waste heat is relatively unstable. In the current paper, the efforts in the past few decades related to applying RC to on-road vehicles, specifically passenger cars, are reviewed. Characteristics of the waste heat sources on vehicles and the constraints put on the automotive RC application are identified. Rankine cycle architectures, system components, and working fluids suitable to different vehicle types are summarized to provide a guideline for the future RC system design for automobiles. In the end, an insight into the application of Rankine cycle to vehicle waste heat recovery (WHR) is provided.
Zhou, Feng, Dede, Ercan, Joshi, Shailesh
On Handling Waste Heat from Waste Heat Recovery Systems in Heavy-Duty Vehicles2015-01-27929/29/2015
The automotive industry have become more and more interested in recovering waste heat from internal combustion engines, especially with future, tighter fuel and CO2 emission regulations in sight. In this study, we consider an automotive Rankine Waste Heat Recovery System on a long-haulage truck. This system transforms some of the combustion engine's waste heat into useful energy, but it still needs to return remaining heat to the surrounding, either through a direct condenser or from an indirect condenser via a Low Temperature Radiator, and this in the regular cooling module of the vehicle. We focus on the integration of WHR-dedicated LTR or condenser into a generic, conventional truck-cooling module with an AC condenser, a cross-flow Charge Air Cooler, a down-flow High Temperature Radiator, and a fan. WHR cooling concepts considered are an indirect system with LTR; either in front or back of CAC, a direct system with condenser either in front or back of CAC. In addition, there is a discussion on various modeling problems on the 0D- and component sizing tools used. The results show that it is important to consider when the WHR system is engaged and when it should be bypassed, how to maintain charge air- and coolant cooling needs, and when the fan need to be engaged. It is very dependent on where the LTR or condenser is placed, but at higher loads (∼75%) one should expect that additional fan work could easily be as much as 40% of the regained Rankine system work.
Erlandsson, Olof, Skare, Thomas, Contet, Arnaud
Organic Rankine Cycles with Dry Fluids for Small Engine Exhaust Waste Heat Recovery2013-01-08784/8/2013
Engine manufacturers are considering the implementation of thermodynamic cycles for Waste Heat Recovery (WHR) in order to increase Internal Combustion Engine (ICE) system thermal efficiency. For these secondary cycles, the literature illustrates the preference of Organic Rankine Cycles (ORC's) due to its simplicity and efficient recovery of the medium grade waste heat found in engine exhaust. This paper simulates the heat recovery capacity of eight dry fluids (butane, pentane, hexane, cyclopentane, benzene, toluene, R245fa, and R123) for an ORC based on the exhaust from a single-cylinder diesel engine-generator operating under five different loading conditions. The model, developed using REFPROP and the Matlab Optimization Toolbox, represents the physical components using isentropic pump and expander efficiencies, along with two-zone heat exchangers. All fluids present cycle efficiencies between 10-15%, with the heaviest hydrocarbons generating the largest amount of work. Of these fluids, pentane is the ideal candidate for an ORC. This fluid illustrates an approximate 10% improvement to the engine-generator efficiency across all conditions. Moreover, the simulation predicts low peak pressures and expansion ratios that are compatible with available displacement expanders. In addition, this effort compares evaporator flow configurations (counter vs. parallel), along with condenser air flow rates. For the evaporator, results illustrate that a parallel flow evaporator arrangement can transfer more heat in phase change applications by setting the high temperature difference in the area of low heat transfer coefficients. Different air flow rates across the condenser show little variation in cycle efficiency with the consumption of fan power at high rates reducing the overall power generated.
Sprouse III, Charles, Depcik, Christopher
Review of Rankine Cycle Systems Components for Hybrid Engines Waste Heat Recovery2012-01-19429/24/2012
In any internal combustion engine, the amount of heat rejected from the engine, and associated systems, is a result of the engine inefficiency. Successfully recovering a small proportion of this energy would therefore substantially improve the fuel economy. The Rankine Cycle system has been raising interest for its aptitude to produce systems capable of capturing part of this waste heat and regenerate it as electrical or mechanical power. By integrating these systems into existing hybrid engine environments, it has been proved that Rankine Cycle system, which is more than 150 years old, can play a major role in reducing fuel consumption. The use of such a system for waste heat recovery on a hybrid engine represents a promising compromise in transforming the thermal energy into electricity and feeding this electricity back to the vehicle drivetrain by using the in situ electrical motor system or storing it into batteries. With this aim in mind, a comprehensive background study on the existing technologies and state of the art of small-scale applications of the Rankine Cycle is carried out. For each of the main components of the desired system, a set of available solutions is proposed and their feasibility, performance and maturity are analysed. Conclusions on the optimal solutions available to use in a Rankine Cycle system for waste heat recovery on a hybrid vehicle application are discussed and justified.
Lopes, Jose, Douglas, Roy, McCullough, Geoffrey, O'Shaughnessy, Richard, Hanna, Alister, Rouaud, Cedric, Seaman, Rachel
Engine Terminology and Nomenclature - GeneralJ604_201108 (Current)8/5/2011
This SAE Recommended Practice is applicable to all types of reciprocating engines including two-stroke cycle and free piston engines, and was prepared to facilitate clear understanding and promote uniformity in nomenclature. Modifying adjectives in some cases were omitted for simplicity. However, it is good practice to use adjectives when they add to clarity and understanding.
SAE IC Powertrain Steering Committee
Waste Heat Recovery Concept to Reduce Fuel Consumption and Heat Rejection from a Diesel Engine2010-01-192810/5/2010
Fuel economy is critical for heavy-duty line haul applications. As fuel prices rise and impending fuel economy regulations are implemented, new ways to improve heavy-vehicle fuel economy will be in high demand. AVL Powertrain Engineering has undertaken a research and development project to demonstrate the feasibility of a Rankine Cycle Waste Heat Recovery (WHR) system. The goals of the project were to reduce the overall engine heat rejection, specific emissions and fuel consumption (CO₂ emissions) of heavy-duty diesel engines by converting heat that is typically wasted to the exhaust stack and through the EGR cooler to useable mechanical energy. A detailed thermodynamic analysis was conducted which laid the groundwork for working fluid selection and proper sizing of the WHR components. Based on the system specifications, a prototype WHR system was designed and built. The performance of the system was evaluated on a 10.8-liter heavy-duty on-highway diesel engine.
Teng, Ho
Improving Fuel Economy for HD Diesel Engines with WHR Rankine Cycle Driven by EGR Cooler Heat Rejection2009-01-291310/6/2009
The fuel saving benefit is analyzed for a class-8 truck diesel engine equipped with a WHR system, which recovers the waste heat from the EGR. With this EGR-WHR system, the composite fuel savings over the ESC 13-mode test is up to 5%. The fuel economy benefit can be further improved if the charge air cooling is also integrated in the Rankine cycle loop. The influence of working fluid properties on the WHR efficiency is studied by operating the Rankine cycle with two different working fluids, R245fa and ethanol. The two working fluids are compared in the temperature-entropy and enthalpy-entropy diagrams for both subcritical and supercritical cycles. For R245fa, the subcritical cycle shows advantages over the supercritical cycle. For ethanol, the supercritical cycle has better performance than the subcritical cycle. The comparison indicates that ethanol can be an alternative for R245fa.
Teng, Ho, Regner, Gerhard
EFFECT OF INJECTION PRESSURE AND INJECTION TIMING ON A SEMI-ADIABATIC CI ENGINE FUELED WITH BLENDS OF JATROPHA OIL METHYL ESTERS2008-28-00701/9/2008
A naturally aspirated four stroke single cylinder CI engine was modified to run as semi-adiabatic CI engine. The effect of different injection pressure and injection timing of a standard and semi-adiabatic engine on the combustion performance and emission characteristics of jatropha oil methyl ester (JOME) and its volume blends with diesel is presented in this paper. Performance of the CI engine was evaluated in terms of brake specific energy consumption, brake thermal efficiency, exhaust gas temperature and exhaust gas composition. Five different volume blends of JOME viz. B5, B10, B15, B20 and B25 was used for the combustion studies at various injection pressures viz. 180, 200, 220 and 240 bar and also at different injection timings i.e. 22°,27° and 32° btdc. This experimental study focused on deriving an optimal injection timing and pressure for the satisfactory operation of JOME blends in a semi-adiabatic engine. The study revealed that acceptable brake thermal efficiency, brake specific energy consumption and emission characteristics of the engine were obtained up to B25 of JOME. At injector opening pressure of 220bar, B20 blend fuel showed better combustion performance and lower exhaust emissions compared to other blends and diesel fuel. At this combination the specific energy consumption were 11.67 MJ/kW-hr and brake thermal efficiency were 30.87% for a semi-adiabatic engine, while the same for standard engine (Non Coated), was found to be 12.60 MJ/kW-hr and 28.67% respectively. At full load, with injection timing of 32° btdc and with B20 JOME blend fuel showed the specific energy consumption of 11.52 MJ/kW-hr and thermal efficiency of 31.72% for semi-adiabatic engine, while for standard engine same was found to be 12.21 MJ/kW-hr and 29.28% respectively. This infers that the semi-adiabatic engine showed better combustion than the standard engine.
Dhananjaya, D A, Mohanan, P, Sudhir, C V
Waste Heat Recovery of Heavy-Duty Diesel Engines by Organic Rankine Cycle Part II: Working Fluids for WHR-ORC2007-01-05434/16/2007
In Part I of this paper, the organic Rankine cycle for waste heat recovery (ORC-WHR) from the heavy-duty diesel truck engines was discussed. This work is Part II of the paper. The efficiency of the ORC-WHR system varies considerably with thermodynamic properties of the working fluid. In this work, characteristics of candidate working fluids are discussed on the basis of the thermodynamic theory. The discussion covers inorganic and organic fluids for both pure fluids and binary-mixture fluids. On the basis of the characteristics of the working fluids, the thermal efficiency for the ORC-WHR system is analyzed. Discussions and conclusions of this paper are helpful in selecting proper working fluids for the ORC-WHR system and determining a proper temperature range for system operations.
Teng, Ho, Regner, Gerhard, Cowland, Chris
Waste Heat Recovery of Heavy-Duty Diesel Engines by Organic Rankine Cycle Part I: Hybrid Energy System of Diesel and Rankine Engines2007-01-05374/16/2007
Waste heat from a heavy-duty truck diesel engine is analyzed employing the first and second law of thermodynamics. A hybrid energy system is proposed, with the diesel cycle being hybridized with an organic Rankine cycle for waste heat recovery (ORC-WHR). The charge air cooler and EGR cooler(s) are integrated in the ORC loop as pre-heaters and the ORC working fluid serves as the coolant for these coolers. A supercritical reciprocating Rankine engine is proposed, which avoids using the high-cost evaporator and is easier for the system packaging. It is demonstrated in a case study that up to 20 % of waste heat from the heavy-duty diesel engine may be recovered by the supercritical ORC-WHR system, making the efficiency for the hybrid energy system be ≥ 50%. Discussion on working fluids for the WHR-ORC system is covered in Part II of this paper.
Teng, Ho, Regner, Gerhard, Cowland, Chris
Achieving High Engine Efficiency for Heavy-Duty Diesel Engines by Waste Heat Recovery Using Supercritical Organic-Fluid Rankine Cycle2006-01-352210/31/2006
A supercritical organic Rankine cycle (ORC) system for recovery of waste heat from heavy-duty diesel engines is proposed. In this system, an organic, medium-boiling-point fluid is selected as the working fluid, which also serves as the coolant for the charge air cooler and the EGR coolers. Because the exhaust temperature can be as high as 650 °C during the DPF regeneration, an exhaust cooler is included in the system to recover some of the high level exhaust energy. In the present ORC system, the expansion work is conducted by a uniflow reciprocating expander, which simplifies the waste-heat-recovery (WHR) system significantly. This reciprocating Rankine engine is more appropriate for on-road-vehicle applications where the condition for waste heat is variable. The energy level of waste heat from a heavy-duty diesel engine is evaluated by the analyses of the first and second law of thermodynamics. The second law analysis indicates that, although heat rejection from the engine coolant forms up to 20% of the fuel energy, it is of the least interest to WHR because only a small portion of it can be converted into mechanical work. The study of this paper demonstrates that, with the hybrid power system of the diesel engine and the Rankine engine operated with waste heat, substantial enhancement in engine power and improvement in fuel economy can be achieved.
Teng, Ho, Regner, Gerhard, Cowland, Chris
Evaluation of a Narrow Spray Cone Angle, Advanced Injection Timing Strategy to Achieve Partially Premixed Compression Ignition Combustion in a Diesel Engine2005-01-01674/11/2005
Simultaneous reduction of nitric oxides (NOx) and particulate matter (PM) emissions is possible in a diesel engine by employing a Partially Premixed Compression Ignition (PPCI) strategy. PPCI combustion is attainable with advanced injection timings and heavy exhaust gas recirculation rates. However, over-advanced injection timing can result in the fuel spray missing the combustion bowl, thus dramatically elevating PM emissions. The present study investigates whether the use of narrow spray cone angle injector nozzles can extend the limits of early injection timings, allowing for PPCI combustion realization. It is shown that a low flow rate, 60-degree spray cone angle injector nozzle, along with optimized EGR rate and split injection strategy, can reduce engine-out NOx by 82% and PM by 39%, at the expense of a modest increase (4.5%) in fuel consumption. This PPCI strategy has the potential for meeting upcoming stringent fuel specific NOx emission levels of less than 1 g/kg-fuel and fuel specific PM levels less than 0.25 g/kg-fuel.
Lechner, Guntram A., Jacobs, Timothy J., Chryssakis, Christos A., Assanis, Dennis N., Siewert, Robert M.
SAE Off-Highway Engineering 2003-02-01OFHFEB032/1/2003
The evolution of diesel emissions control The development of clean diesel has been a saga of evolution punctuated by occasional milestones. Heavy-duty engine emissions tests Ricardo recently commissioned from Emprise a new full-dilution emissions measurement system at its Chicago Technical Center. Air entrainment in hydraulic systems Researchers from Opus Systems and Hosei University designed a device to remove bubbles or foam in working oils for improved performance. Turbocompounding revisited Scania has introduced a new in-line six-cylinder engine that uses technology developed 20 years ago to meet tomorrow's emissions requirements.
Evaluation of an Unconventional Diesel Engine as a General Aviation Powerplant2000-01-16855/9/2000
A novel two stroke cycle diesel engine is evaluated as a general aviation aircraft powerplant. Two certificated spark-ignited gasoline reciprocating engines are also evaluated in the same aircraft. The evaluation of aircraft propulsion performance considered only the effects of altered powerplant parameters on the range of an aircraft having a fixed gross weight and payload cruising at a given lift/drag ratio. Thermodynamic analysis finds the diesel engine can have a sea level power rating exceeding the 10,000 foot cruise power requirement by 55% with nearly equal specific fuel consumption, a low engine speed and a modest cylinder pressure. It uses a single-stage, radial turbocharger without intercooling or auxiliary mechanical scavenging. The diesel engine can significantly increase the range of a particular airplane now powered by a certificated turboprop engine. The candidate gasoline engines could not equal the turboprop-powered aircraft performance.
Addoms, Robert
The Development of the Ceramic Gas Engine Co-Generation System1999-01-366710/25/1999
The Japan Gas Association has been engaged in the development of a 200-kW-class ceramic natural gas engine system to be used as a co-generation power source, subsidized by Ministry of International Trade and Industry. The engine has several new concepts to achieve high efficiency and low emissions simultaneously and to enable to use natural gas as fuel supplied with low pressure in spite of diesel engine. The co-generation system needs de-NOx system. So, we developed a urea de-NOx catalyst system for high-temperature exhaust gas. This paper will describe the result in the fiscal year 1998.
Ikeda, Katsumi, Higashino, Akira, Ishizaki, Junichi, Sugishima, Noboru
A Superalloy Low Heat Rejection Engine with Conventional Lubrication9617438/1/1996
Low heat rejection engine (LHRE) technology reduces the heat transfer from the gases in the cylinder of an internal combustion engine by insulating the walls of the combustion chamber. This technology has the potential for gains in fuel efficiency, cooling system size decrease, the use of alternative fuels, etc. Research on many experimental LHRE's has been reported in the literature. However, these engines have used ceramic material and they have two major problems that need to be overcome. They are: (1) the need for a high temperature lubrication system, and (2) brittleness of the ceramics. To overcome these limitations, a novel LHRE design has been developed in this study. In this design, a high temperature superalloy HAYNES®230™ (USN N06230)' is used instead of ceramics, and conventional low temperature lubrication can be employed. A 3.5 HP one cylinder low heat rejection Diesel engine was developed in this study and tested for 1001 hours without failure. This demonstrates the durability of this design and viability of 230 alloy in this application. The measured temperature of the combustion surface during the engine operation was greater than 650 °C. The superalloy combustion surface was studied by optical and electron microscopy and the results are presented. The various alternative designs that led to the final successful design are presented.
Elshindidy, Mohamed, Sampath, W. S., Smith, F. W.
Combustion and Combustion Chamber For a Low Heat Rejection Engine9605062/1/1996
For the purpose of eliminating a cooling device from conventional diesel engines, a heat insulation structure referred to as thermos structure was adapted in a low heat rejection (LHR) diesel engine. The thermosstructure is constructed by a combustion chamber wall made of Si3N4 monolithic ceramics having higher strength and fracture toughness at much higher temperature and the heat insulation layers combined with air gap and gaskets with low thermal conductivity that are located behind the combustion chamber wall. Although the insulated engine achieved reduced heat rejection from the combustion chamber with the thermos structure, improvement in fuel economy and exhaust emissions could not be realized in the case of a diesel engine with Direct Injection (DI) system. Observation of combustion process in the LHR engine suggested that insufficient fuel-air mixing may be attributed to an increase in gas viscosity and deterioration of air entrainment of fuel spray as a result of high combustion temperature. In order to improve combustion in a LHR diesel engine, a centrally located pre-combustion chamber in the cylinder head and throat holes drilled in it as radiating to cylinder inner surface has been developed. The LHR engine with the new pre-combustion chamber realized about 10% improvement in fuel economy compared to a conventional DI engine and could meet the Japan emission standard.
Kawamura, Hideo, Higashino, Akira, Sekiyama, Shigeo
High Output Compound Diesel Engine Schemes - How do they Compare with State-of-the-Art Turbocharged Engines?9520999/1/1995
The paper is divided into two main parts. In the first part, section 2 and 3, the performance of turbocharged and compounded systems based on a hypothetical 6 cylinder, 8 litre, 4 cycle DI Diesel engine is discussed under two subheadings: a) the comparative performance, at rated conditions of 2200 rev/min of the two types of system operating at boost levels of 3 bar and 5 bar. b) a much more detailed comparison of the two systems over the full speed range, at the same rated levels of boost, with the 3 bar system operating with a single stage turbocharger, and the 5 bar system with a 2 stage turbocharger. In the second part, sections 4 and 5, the principle of the differential compound engine (DCE) as an integrated engine-transmission system is briefly described, followed by a comparative performance assessment of two alternative builds, both again using a 6 cylinder, 8 litre DI Diesel engine, in either 4 cycle or 2 cycle form, together with the results of a design study for a 1000 hp military engine. In the concluding section 6 the outstanding torque-speed and transient performance characteristics of the DCE are set against the background of the inevitable compromises involved in using high pressure air not only as the working fluid for the engine, but also for the continuously variable transmission.
Wallace, Frank
Low Heat Rejection Engine with Thermos Structure9509782/1/1995
In order to eliminate a cooling system from an internal combustion engine, we studied structures to reduce heat rejection from a combustion chamber. It was known to be very difficult to increase the heat-insulation rate of a low heat-rejection engine with a coated combustion chamber wall with a zirconia layer to more than 50%. Therefore a heat flux and temperatures were calculated by using the finite-element method in order to develop a new structure for a low heat rejection engine. The calculation results were compared with the temperatures measured in the engine which was fabricated with a silicon nitride combustion chamber wall incorporated in a heat-insulation structure composed of an air gap and a gasket of very low thermal conductivity. The result was that the compound heat-insulation structure was very effective in reducing heat rejection from the combustion chamber wall to the outer cylinder made of cast iron. It was also confirmed that the temperature distributions calculated by F.E.M. correlated nicely with the measured temperature data of the engine if the adjustment was made to the heat transfer coefficient by multiplying a large number to the one for the combustion chamber wall contacting a burning flame and a small number to the one for the wall contacting a gas after burning.
Kawamura, Hideo, Matsuoka, Hiroshi
Waste Heat Recovery of Passenger Car Using a Combination of Rankine Bottoming Cycle and Evaporative Engine Cooling System9308803/1/1993
Rankine bottoming system, which operates on waste heat of engine cooling, has been developped to improve the fuel economy of a passenger car. Evaporative engine cooling system is utilized to obtain high thermal efficiency and simplicity of the Rankine bottoming system. The bottoming system uses HCFC123 as a working fluid, and scroll expander as a power conversion unit. The results indicate that energy recovery, which depends on the ambient temperature, is almost 3 percent of engine output power at ambient temperature of 25°C.
Oomori, Hideyo, Ogino, Shigeru
Development of Model 6105 Adiabatic Engine9309843/1/1993
A commercially available water-cooled engine Model 6105 was modified into an adiabatic engine without independent cooling water system. The modified engine was built to have monolithic ceramic composite pistons and zerconia coatings on the firedeck of cylinder heads, the disk surface of inlet and exhaust valves, and the upper part of cylinder liners. Its supercharging system and fuel injection system were adjusted. The test results showed that such modifiation could lead to an improvement up to 5.5% of fuel consumption over the baseline engine. Having undergone a 400-hour endurance stand test, the engine was installed in a bus, and has been completed a on-board trial covering more than 10000km.
Nanlin, Zhang, Shengyuan, Zhong, Jingtu, Feng, Jinwen, Cai, Qinan, Pu, Yuan, Fan
Design Optimization of the Piston Compounded Adiabatic Diesel Engine Through Computer Simulation9309863/1/1993
This paper describes the concept and a practical implementation of piston-compounding. First, a detailed computer simulation of the piston-compounded engine is used to shed light into the thermodynamic events associated with the operation of this engine, and to predict the performance and fuel economy of the entire system. Starting from a baseline design, the simulation is used to investigate changes in system performance as critical parameters are varied. The latter include auxiliary cylinder and interconnecting manifold volumes for a given main cylinder volume, auxiliary cylinder valve timings in relation to main cylinder timings, and degree of heat loss to the coolant. Optimum designs for either highest power density or highest thermal efficiency (54%) are thus recommended. It is concluded that a piston-compounded adiabatic engine concept is a promising future powerplant.
Assanis, Dennis N.
The Intercooled-Turbocharged Gas Generator/Expander Engine - A Feasibility Study by Computer Simulation - Part I: The Dual-Cylinder Piston-Gasifier9200612/1/1992
A new internal combustion engine is proposed. This engine is one example of gas generator engines, configured according to a newly proposed cycle principle. Turbocharging with intercooling is employed to reduce the energy loss of engine exhaust. A reciprocating piston-gasifier is used to further boost the pressure and to raise the turbine inlet temperature near its material limit. To study the feasibility of the proposed engine, a piston-gasifier is designed to consist of manifolds and pairs of cylinders with different bores. To simulate the operations of the piston-gasifier, a numerical model is developed. The manifolds and cylinders are treated as open systems and combustion is described as a one-zone heat release process. Subprocesses are described in sufficient detail. The operating characteristics of the piston-gasifier are predicted and analyzes over a broad range of operating parameters. In the second part of this article these results are used to predict the operating performance of the whole engine system.
Jeng, Yuan-Liang, Wang, Lin-Shu
The Gas Generator Engine - A New Family of Internal Combustion Engines9200602/1/1992
This paper makes the case for the gas generator engine - a type of compounded engines - as a potential future automotive engine. The existing gas generator engines are characterized by their mediocre performance and fuel economy. The case for the new gas generator engine is based on a proposed cycle principle, which achieves simultaneous improvements in thermal efficiency and power output/weight ratio. This very attractive engineering solution may transform the mediocre existing engines into new engines of exceptional promise, which merit serious consideration.
Wang, Lin-Shu, Jeng, Yuan-Liang
Heat Transfer Studies in an Adiabatic Diesel Engine91250211/1/1991
Numerical calculation based on finite element method are carried out to calculate the temperature field in an adiabatic diesel engine piston having diameter. 127 mm and made of aluminum alloy. The engine cylinder wall have the coated externally by a thin layer of very high grade ceramic insulating material. The isothermic distribution in the piston body and the heat flow rates to the cooling media at different loads have been depicted for both cases with and without insulation coating. The paper first reviews the current state of development of ‘adiabatic’ diesel engine in Europe, U.S.A and the Japan. This review section is followed by a brief description of the common element of hostile features, then comes the experimental program on thermally insulated components for single cylinder engine in the research center of Tabriz and finally by a theoretical section dealing with the performance potential of composed engine schemes based on ‘adiabatic’ engine operation.
Khoshravan, E.
A Simulation Model for a Methanol Fueled Turbocharged Multi-Cylinder Automotive Spark Ignition Engine91241710/1/1991
The development of a computer simulation model for an automotive turbocharged multi cylinder spark ignition engine for gasoline and methanol operations is described in this paper. The model illustrates the simulation of the thermodynamic cycle comprising of compression, combustion, expansion, exhaust and intake processes. The scheme employed for matching the turbocharger and engine is also highlighted. The computed data of the above model is validated with the available experimental data. The model predicts the brake power developed by the engine, brake specific energy consumption, the nitrogen oxide and carbon monoxide emissions for both the gasoline and methanol operations, corresponding to the original and improved manifold design configurations. The overall analysis of the results show an increase in power output, lower nitrogen oxide and carbon monoxide emissions and improved brake specific energy consumption for the methanol fueled engine as compared to the gasoline version for both the original and modified engine designs operating on naturally aspirated and turbocharged conditions.
Mohanan, P., Gajendra Babu, M.K.
High Temperature Diesel Combustion in a Rapid Compression-Expansion Machine9118459/1/1991
According to previous papers on the combustion process in LHR diesel engines the combustion seems to deteriorate in LHR diesel engines. However it has been unclear whether this was caused by the high temperature gas or high temperature combustion chamber walls. This study was intended to investigate the effect of gas temperature on the rate of heat release through the heat release analysis and other measurements using a rapid compression-expansion machine. Experiments conducted at high gas temperatures which was achieved by the employment of oxygen-argon-helium mixture made it clear that the combustion at a high gas temperature condition deteriorated actually and this was probably due to the poorer mixing rate because of the increase in gas viscosity at a high gas temperature condition. THE LHR (Low Heat Rejection) DIESEL ENGINE promises improved engine fuel consumption by eliminating the traditional cooling system and converting part of increased exhaust gas energy into useful shaft work. The ability to burn lower-grade fuels because of the higher cylinder gas temperatures attainable without cooling system is also promising. Several simulation and feasibility studies have been made on the promises and challenges of the LHR engines(1, 2 and 3). The temperatures of the piston and fire deck made of monolithic ceramics are roughly 300 - 400 K higher than those of conventional metal engines. Accordingly the major processes which are involved in the LHR engines are heat transfer, combustion, and tribology. As for combustion, evaluation of the potential of the LHR engine to meet future EPA emission standards has been one of the current concerns to engine developers. The engine high wall temperature brings about a significant reduction in volumetric efficiency in the charge air amount due to heat transfer from walls to the charged air during the intake stroke. Since this essentially results in the deterioration of combustion, experiments of the combustion process in high temperature environment are usually performed at a condition of the same amount of air flow. Wade et al.(4) investigated experimentally fuel economy and emission opportunities using an uncooled light duty DI diesel engine with ceramic coated cylinder head and valves, a heat insulated steel topped piston and a short, partially stabilized zirconia cylinder liner in the area above the piston rings. The single-cylinder diesel engine used in this study has an 80 mm bore x 88 mm stroke and a compression ratio of 21. The combustion system consisted of a helical intake port, an oil cooled multi-hole injector and a re-entrant combustion bowl in the piston. A comparison of the measured indicated specific fuel consumption data for the uncooled and water-cooled baseline engines showed improvements in fuel consumption of the uncooled engine ranged from 4 % at the heavy load condition to 7 % at the light load condition. The test results on emissions showed that generally, HC, NOx and particulate emissions were reduced in the uncooled engine. They attributed the lower HC and NOx emissions to the reduction in the amount of premixed combustion resulting from the shortened ignition delay period. They also explained the trend of lower particulate emissions by the increase in the diffusion combustion rate. Henningsen(5) conducted engine tests similar to Wade's work and compared his results with those by Wade et al. He attempted to simulate LHR conditions in a research engine simply by eliminating cooling, and did not employ ceramic parts for the insulation of the combustion chamber. The start of combustion timing was set at top dead center in all tests as in the Wade's experiments. It is interesting to note that his results for the uncooled engine were contradictory to Wade's results, showing a slight improvement in fuel economy at light load and a slight worsening at high load, a significant increase in HC emission, a slight increase of NOx emission, and slight increase in total particulates at low load and a substantial increase at high load. In order to examine the reason for the discrepancy between the above two studies, he made a close comparison between the apparent rates of heat release in both experiments. He showed that the decrease in ignition delay led naturally to a decrease in premixed combustion and that most of the differences in apparent heat release may be attributed to the different leves of gas temperature which results from different degrees of insulation employed in these studies. It is suggested from this comparison that optimization of temperatures of combustion chamber walls is necessary for achieving better fuel economy and lower emission in an uncooled diesel engine. Recently Kawamura et al (6) investigated the rate of heat release at a high cylinder gas temperature condition using an uncooled light duty DI diesel engine. They found that even if the ignition delay was controlled by changing the cetane number of test fuel the combustion duration observed at a high gas temperature conditions was scarcely affected, and furthermore the combustion duration was always longer than that of a water-cooled baseline engine. Besides they observed the flame evolution on the high speed movies and revealed that the flame evolution was significantly degraded at a high gas temperature condition. The potential for LHR engines to meet current and future EPA heavy duty emission standards is a critical consideration. Dickey (7) conducted LHR enigne tests using a single cylinder test engine with a 137 mm bore, 165 mm stroke and a compression ratio of 14.5. The baseline metal engine was tested with 355 K coolant, while the insulated engine, which uses ceramic coated components, was operated by replacing the coolant with compressed air. He showed that the ceramic engine had significantly lower indicated thermal efficiency, with higher smoke and particulate emissions compared to the baseline metal engine, and that the NOx emissions for the ceramic engine were the same as the baseline metal engine at low load and were slightly reduced at the full load condition. He attributed the poor LHR engine performance to degraded combustion observed in the heat release rate curve. The conflicting results on fuel economy and emissions observed in LHR engine tests, are due to the large number of possible LHR engine configurations, test conditions, and analysis techniques used. As far as the heat release analysis is concerned, it seems difficult with engine experiments to separate the effects of cylinder gas temperature and combustion chamber wall temperatures on the rate of heat release. The present study is intended to investigate experimentally the effect of cylinder gas temperature on the rate of heat release using a rapid compression expansion machine. The cylinder gas temperature was raised to a value which is 300 - 400 K higher than that in conventional cooled engines, while the temperature of the combustion chamber walls was kept constant in all tests conducted.
No, Suk Hong, Kobiri, Shigeharu, Kamimoto, Takeyuki, Enomoto, Yoshiteru
The New 6-Litre 12-Cylinder Engine for the New Mercedes-Benz S-Class9119059/1/1991
Mercedes-Benz presented the new S-class in spring 1991. A new 6-litre, 12-cylinder engine with 4-valve technology has been developed for the top model, the 600 SE/SEL, which is described in this paper. The engine has a maximum power output of 300 kW and a maximum b.m.e.p. of 12.2 bar (= 580 Nm). Maximum permissible constant engine speed is 6000 rpm. The new engine features a light-alloy crankcase and shares the 4-valve cylinder heads as fitted to the 6-cylinder engine, in this case each with two camshafts. Further components are the LH electronic fuel injection system, two motor-driven throttle valves, anti-knock control, two variable valve timing systems. All electronic engine functions are interlinked by a CAN interface.
Abthoff, Jörg, Bachischmid, Reiner, Brüggemann, Hans, Willand, Jürgen
Concepts, Materials, and Efficiencies of Piston Compounded Adiabatic Engines9108952/1/1991
A new practical concept for piston compounding engines is described. The calculated thermal efficiency of a fully insulated, piston compounded, overcharged diesel engine can exceed 60%. The design considerations for construction of such an engine from controlled expansion superalloys is also described.
Bell, James A.E.
Observation of the Combustion Process in a Heat Insulated Engine9104622/1/1991
The technologies which comprise heat insulated turbo compound engine are summarized as (1) establishment of heat insulation structure. (2) improvement of combustion under high temperature ambient condition. (3) establishment of energy recovering from exhaust gas.
Kawamura, Hideo, Sekiyama, Shigeo, Hirai, Katsunori
A Mathematical Simulation and Test to Transient Performance of Turbo-Charged Diesel Engine9016719/1/1990
A large program simulating transient process has settled a few particular questions concerned. The good agreement of calculated and experimental transient performance was obtained. It provides a convenient tool for the study and improvement in the transient performance. The influence in the transient process which was caused by the change of some parameters has been calculated by means of program. The simulating program has been used in the study and analysis for improving transient performance.
Jie, Ma, Hongzhong, Gu
Energy Analysis of High Speed Vehicles in Low Mach Flight Regime9009954/1/1990
In the parametric optimization of an accelerator or a cruise vehicle for hypervelocity missions, five elements of the analysis relate to (i) vehicle configuration, (ii) weights, (iii) trajectory, (iv) propulsion and (v) control. A scheme for the overall system optimization is described. Considering weights, the concept of fixed weight growth factor in relation to gross weight is developed to illustrate the implications of technology development and staging. The analysis of the propulsion system must be based on both energy and energy availability considerations in order to assure not only the highest thrust and propulsive efficiency but also the least dependence on obtaining each component to operate at the highest achievable mechanical efficiency. A few propulsion schemes have been analyzed to illustrate methodology and benefits.
Murthy, S. N. B., Czysz, P.
Structural Ceramics in Automotive Engines-Integration of Design, Development and Manufacturing Procedures9004002/1/1990
This is a descriptive review of the ceramics structural applications developed by Isuzu, Mazda, Nissan, Toyota and General Motors in spark ignition, Diesel and gas turbine automotive engines; new analytical procedures needed for the design of structural ceramics; new silicon nitride ceramics with strength of material properties approaching steel; new ceramics processing techniques which have been reduced to commercial practice in Japan on a mass production scale; and tests of vital structural components fabricated of these ceramics.
Kawamura, Hideo, Suh, Chung M.
Control Design for a Differential Compound Engine8903922/1/1989
A microcomputer-based controller has been designed for a differential compound engine (DCE). Following assessment of the DCE state interactions, single input-output loop strategies were developed using a dynamic simulation. The simulation, control strategies and final implementation are described, and simulated transient responses are presented.
Hall, J., Wallace, F.J.
Transient Response and Route Simulations for Heavy Vehicles with Alternative Engine-Transmission System8903932/1/1989
The paper describes the results of a study of the dynamic response of a 30 tonne truck equipped with two alternative engine-transmission systems, viz. a) the stepless differential compound engine (DCE) b) a highly turbocharged engine of the same rating with a 7 ratio stepped transmission. The comparisons cover: a) 0 - 80 krn/hr acceleration using a true dynamic and a quasi dynamic technique b) a cross country 9 km route. The DCE is shown to have superior acceleration characteristics but route behaviour of the two systems is similar.
Dequan, Zou, Rezaian, M., Wallace, F.J.
Some Developments of the Effect of Fuel and Other Parameters on Diesel Engine Noise Control8901312/1/1989
The purpose of this paper is to review some Research & Developments in diesel engineering that provide pointers to resolving the potential conflict of noise reduction with fuel economy and it's attendant demand for weight reduction. Economy is not the only fuel-related problem that conflicts with noise; future diesel fuels will differ from those to which we have become accustomed, a trend which is already taking place in many parts of the world.
Waters, P. E., Haddad, S. D.
Toyota Newly Developed 2VZ-FE Type Engine88177511/1/1988
Newly developed 2VZ-FE engine for CAMRY is a 2.5-liter water cooled and V-type 6-cylinder engine exported from TOYOTA for the first time. This engine has the TOYOTA original 4-valve DOHC system. That is, exhaust camshafts driven by intake camshafts using scissors gears. By its compact configuration with the gear driven camshafts, this V-type 6-cylinder engine is mounted on a front-wheel-drive vehicle which originally had an in-line 4-cylinder engine. By increasing IVZ-FE engine displacement (for domestic), compact pentroof-type combustion chambers, optimum air-fuel ratio and ignition timing by TCCS (TOYOTA Computer Controlled System) and other technologies, a high performance 153HP/5600rpm and a large torque 155ft·lbs/4400rpm have been achieved with a low fuel consumption. Quietness suitable for high-grade vehicles has been created by the cylinder. block and the crankshaft with high rigidities, a crankshaft pulley with a dual mode damper, a hydraulic-mounting and other advanced technologies.
Mayumi, Kazuhisa, Mizuno, Nobutaka, Matsuo, Masashi, Horio, Kimihide
Development Status of Isuzu Ceramic Engine8800112/1/1988
Ceramics show high degree of heat resistance. But an attempt to build an adiabatic engine using ceramic materials should be carried out by full evaluation of characteristics of each ceramic material. The strength of ceramic parts are dependent on both their manufacturing processes and the mechanical and thermal stresses to which the parts are subjected. Full consideration should be given to these factors in evaluating ceramic parts. Even if a ceramic engine were manufactured after full consideration (1) to these factors, adiabatic engines proposed by R. Kamo and other researchers have had difficulty in realizing performance level and fuel economy as first suggested. Today, the adiabatic turbo compound engine still has many problems and themes to be addressed, some of which are adiabatic efficiency, combustion rate, intake air rate and method of recovering exhaust gas energy. (2),(3) On the other hand, however, an adiabatic engines with ceramic parts have already reached the stage where they can be actually used on automobiles. Further efforts, therefore, should be concentrated on attacking the aforementioned problems and themes to achieve the levels of performance suggested earlier. This paper is intended to report some part of the studies conducted by the author and his group.
Kawamura, Hideo
Ceramic Components for Engines in Japan8700192/1/1987
Various ceramic components are used in many industrial fields in Japan now. Some typical examples include a high precision lathe, a large fan used in steel making and electric power plants, and ball and roller bearings. In the high precision lathe area, components are made of sintered silicon nitride and alumina. The ceramic lathe gives high precision machining capability of about 0.3µm in surface roughness, 0.1µm in surface winding, and 0.03µm in round error, primarily because of the high rigidity and low thermal expansion of the ceramics. In the large fan (∼3 m in diameter), its blade is composed of alumina. The ceramic blade results in longer maintenance-free use for the fan, primarily through the high wear resistance of the ceramic surface. The bearings are made of silicon nitride or alumina. they make it possible to use the bearings at high temperature, in vacuum as well as in dry systems.
Kamigaito, Osami
Future Scope of Diesel Propulsion for Merchant Marine8612079/1/1986
Since the 1973 petroleum crisis, marine diesel engine designers had to cope with the new world market requirements that is to say lower overall transportation cost and consequently: reduced fuel consumption, low maintenance cost, capability to burn the cheapest available fuel and improved reliability. These criteria and specially the two last, are more or less in contradiction. The paper enlights how, thanks to strong research and development strengths, this goal has been achieved taking as examples the SEMT PIELSTICK four stroke medium speed engines: Their specific fuel consumption is below 120 g/HP.hour, They use a Recovery Power Turbine (compound engine) enlarging their range at high torque and reduced speed, They keep their high heat recovery capability, They allow to make freely the best choice of the propeller speed. As soon as the installation (heating, purifying, filtration and water emulsification processes) are all right, they can burn the cheapest heavy fuel available on the market.
Gallois, Jacques
Harnessing the Neglected Potential of Rankine Compounding8605362/1/1986
This paper describes an automobile spark ignition engine which harnesses the neglected potential of Rankine Compounding. (1, 2)* The building blocks of information which support the postulation of such an engine are contained in the technical literature published by SAE, NASA, DOE, and industry. That data is relied upon as authoritative material for the description of an engine which utilizes waste heat more effectively than others of record.
Bradley, Curtis E.
A Review of Ideas for Improving Transient Response in Vehicle Diesel Engines8604542/1/1986
Turbochargers are rightly blamed for disimproving the transient response of vehicle Diesel engines, but the serious effect of engine rotating inertia is often forgotten. Ultimately, a “no coolant” engine with lightweight ceramic parts may give substantial improvements by increasing exhaust gas temperature and at the same time reducing the inertia of engine and turbocharger components. The response of a turbocharger system can also be improved by adding energy to it, but so far such additions have required complex and costly sub-systems. A novel, cheap system is suggested.
Timoney, Seamus G.
Recent Advances in Diesel Engine Research8509715/15/1985
This paper reviews some recent, research in diesel engineering that points the way to possible solutions to the problems facing engine designers in the next 10 to 20 years. These problems are the need for improved thermal efficiency and multifuel capability to deal with future supplies of fuel for transport and the need to make the engine more socially acceptable by reducing its noise and air pollutant emissions. It is shown that engine noise reduction need not be incompatible with the aims of reduced fuel consumption and emissions, provided that trends in these other areas are taken into account in diesel engine noise research and development programmes. It is concluded that the diesel engine of the future will have a light weight, low noise structure and will be adiabatic or limited cooled with some degree of compounding.
Waters, P. E.
Ceramic Valve and Seat Insert Performance in a Diesel Engine8503582/25/1985
STRUCTURAL CERAMICS OFFER exceptional properties in terms of low density and endurance at very high temperatures, those exceeding 1000°C. These and other unique properties such as low thermal conductivity can be harnessed to serve the material needs of the future engines. In the interest of fuel efficiency and multi-fuel capability, future engines will operate at higher temperatures and be lighter in weight. Towards this end, partially stabilized zirconia (PSZ) and SiAlON components were engine tested. In a diesel engine, PSZ exhaust valves seating on PSZ seat inserts failed prematurely due to thermal shock. PSZ seat inserts showed no damage. SiAlON exhaust valves seating on metal seat inserts endured 1000 hours of cyclic operation with the exception of one lock groove failure.
Asnani, Manohar, Kuonen, Frederick L
Reciprocating Engine Combustion Research Needs8503982/1/1985
A discussion of reciprocating engine combustion research needs is presented. Results of a survey ranking 31 specific research topics are also given. The twenty-three respondents gave the five highest grades to; particulate formation and oxidation mechanisms, high temperature ring friction, end gas heat transfer and high pressure transient fuel spray studies.
Borman, Gary
Assessment of Positive Displacement Supercharging and Compounding of Adiabatic Diesel8404302/1/1984
A new alternative to turbocompounding for converting exhaust heat from adiabatic diesels to mechanical energy is evaluated. The concept is based on a positive displacement screw compressor and expander pair applied to an adiabatic diesel for supercharging and mechanical power compounding to form a compact and efficient power system. Predictions of theoretical performance for the system and its components are given, and the technical feasibility and potential advantages of this system are discussed.
Wurm, Jaroslav, Kinast, John A., Bulicz, Tytus
Characterisation of European Truck Diesel Engines, Their Lubrication and Future Development Trends83174910/31/1983
In this paper characteristics of European truck diesel engines with regard to their lubrication are compared with those of North American diesel engines. Comparisons are given concerning the legislation, operational characteristics, characterisation of European diesel engines (engine design, performance, lubricating oil system, piston/liner assembly, valve train, bearings, supercharging) and the future trends of diesel engines for heavy trucks. Some major differences regarding the lubrication of European and North American diesel engines can be seen, leading to special requirements.
Signer, Meinrad
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