Browse Topic: Adiabatic engines
The fuel consumption and performance of the Internal Combustion (IC) engine is improved by adopting concepts of an adiabatic engine. An experimental investigation for different load conditions is carried out on a water-cooled, constant-speed, twin-cylinder diesel engine. This research is intended to emphasize energy balance and emission characteristic for standard uncoated base engine and adiabatic engine. The inner walls of diesel engine combustion chamber are thermally insulated by a top coat of Metco 204NS yttria-stabilized zirconia (Y2O3ZrO2) powder (YSZ) of a thickness of 350 mm using plasma spray coating technology. The same combustion chamber is also coated with thermal barrier coating (TBC) bond coats of AMDRY 962 Nickle chromium aluminum yttria of thickness of 150 mm. The NiCrAlY powder specially designed to produce coating’s resistance to hot corrosion. The combination of this ceramic material produces excellent high-temperature thermal barrier coating (TBC) resistant to
Insulation of pistons in engines is aimed at reducing the heat losses and thus increasing the indicated efficiency. Thermal barrier coatings (TBCs) were used to simulate adiabatic engines with the intention not only for reduced in-cylinder heat rejection and thermal fatigue protection of underlying metallic surfaces, but also for possible reduction of engine emissions. The application of TBCs reduces the heat transfer to the engine cooling jacket through the combustion chamber surfaces (which include the cylinder head, liner, and piston crown) and piston rings. The insulation of the combustion chamber with this coating, which is ceramic based, influences the combustion process and hence the performance and exhaust emissions characteristics of the engines. In the scenario of fast rising oil prices, insulation technologies are gaining importance as they help in saving fuel. A plasma sprayed thermal barrier coating was deposited on top of a piston for a Diesel engine and its effect on the
The aim of this work is to investigate the possibility of heat insulation by “Temperature Swing”, that is temperature fluctuation, on combustion chamber walls coated with low-heat-conductivity and low-heat-capacity materials. Adiabatic engines studied in the 1980s, such as ceramic coated engines, caused constantly high temperature on combustion wall surface during the whole cycle including the intake stroke, even if it employed ceramic thermal barrier coating methods. This resulted in increase in NOx and Soot, decrease in volumetric efficiency and combustion efficiency, and facilitated the occurrence of engine knock. On the other hand, “Temperature Swing” coat on the combustion chamber walls leads to a large change in surface temperature. In this case, the surface temperature with this insulation coat follows the transient gas temperature, which decreases heat loss with the prevention of intake air heating, and also which is expected to prevent NOx and Soot from increasing. In our
A unique engine, based on the regenerative principle, is being developed with the goal of achieving high brake efficiency over a wide power range. It can be characterized as an internal combustion Stirling engine (ICSE). The engine is a split-cycle configuration with a regenerator between the intake/compression cylinder and the power/exhaust cylinder. The regenerator acts as a counter-flow heat exchanger. During exhaust, the hot gases are cooled by the regenerator. The regenerator stores this heat. On the next cycle, compressed gases flow in the opposite direction and are heated by the regenerator. The gases coming from the regenerator into the power cylinder are very hot (~900°C), which provides the necessary gas temperature for auto-ignition of diesel and other fuels. A simplified Air Cycle analysis of the ICS engine is presented to validate the concept thermodynamics and to show the inherent difference between the ICS and conventional internal combustion engine (ICE) indicated
Energy conservation and efficiency have been the quest of engineers concerned with internal combustion engine. Theoretically, if the heat rejected could be reduced, then the thermal efficiency would be improved, at least up to the limit set by the second law of thermodynamics. Low Heat Rejection engines aim to do this by reducing the heat lost to the coolant. For current work a ceramic coated twin cylinder water-cooled diesel engine using blends of diesel and palm biodiesel as the fuel was evaluated for its performance and exhaust emissions. In recent years, Considerable efforts were made to develop and introduce alternative renewable fuel, to replace conventional petroleum-base fuels. Here, the diesel engine was insulated by Partially Stabilized Zirconia (PSZ) as ceramic material attaining an adiabatic condition. The cycle average gas temperature and metal surface temperature are higher in adiabatic engine. For the present study the biodiesel was prepared in laboratory from non-edible
In order to improve the fuel consumption and control exhaust emissions in a heat insulation engine, fuels reformed CH4 by CO2 and steam were used. Porous metal plate coated Li2ZrO3 was used to make CO2 separate from the exhaust gas of the engine. CH4 and CO2 gas are supplied to the catalytic converter and reformed CO and H2gas increased to 30% on kinetic energy are supplied to the engine as well as gas and steam turbine is installed to recover the exhaust gas energy. As the result the thermal efficiency of the engine systems will be improved to about 57.5% compared with 42% of conventional diesel engine
Joint development of the adiabatic engine by Cummins Engine Company and the U. S. Army began with a feasibility analysis ten years ago. The effort was initially driven by the expectation of substantial performance improvement, a reduction in cooling system size, and several additional benefits. Program emphasis turned quickly to experimentation with the goal of demonstrating the feasibility of the adiabatic engine in working hardware. Several significant achievements were realized as have been reported earlier. Further development of the adiabatic engine is expected to be more evolutionary, paced by available technology in the areas of materials and tribology. Analysis capability necessary for insulated engine development has been found to be inadequate. Additional effort has gone into the development and validation of insulated engine analysis tools, both for cycle simulation and structural modeling. Emphasis is being placed on the analysis of design strategies, prior to test, with a
Cummins Engine Company, Inc. and the U.S. Army have been jointly developing an adiabatic turbocompound engine during the last nine years. Although progress in the early years was slow, recent developments in the field of advanced ceramics have made it possible to make steady progress. It is now possible to reconsider the temperature limitation imposed on current heat engines and its subsequent influence on higher engine efficiency when using an exhaust energy utilization system. This paper presents an adiabatic turbocompound diesel engine concept in which high performance ceramics are used in its design. The adiabatic turbocompound engine will enable higher operating temperatures, reduced heat loss, and higher exhaust energy recovery, resulting in higher thermal engine efficiency. This paper indicates that the careful selection of ceramics in engine design is essential. Adiabatic engine material requirements are defined and the possible ceramic materials which will satisfy these
Recent developments of high performance ceramics have given a new impetus for the advancement of heat engines. The thermal efficiencies of the Otto, Diesel, Brayton and the Stirling cycle can now be improved by higher operating temperatures, reduced heat loss, and exhaust energy recovery. Although physical and chemical properties of the high performance ceramics have been improved significantly, they still fall short of meeting the requirements necessary for application and commercialization of advanced heat engine concepts. Aside from the need for greater strength, the problems of consistency, quality, design, material inspection, insulative properties, oxidation and other important features must be solved before high performance ceramics can be considered a viable material for advanced heat engines. Several approaches in developing an adiabatic engine design in the laboratory are shown. Other possible future improvements such as the minimum friction unlubricated engine through the
THIS PAPER PRESENTS a theoretical analysis of the ideal adiabatic Otto cycle engine. The analysis was made to examine the influence of compression ratio and dissociation on engine thermal efficiency over an extreme range of compression ratios (that is, 4–300) to see if chemical dissociation could limit Otto cycle engine thermal efficiency. Assuming isooctane, benzene, ethyl alcohol, and nitromethane to be the fuels being consumed, the effects of compression ratio and mixture strength on the thermodynamic properties and equilibrium species concentration of the working fluid at every step in the ideal Otto cycle were computed. The calculations were made using a mathematical model of the ideal adiabatic engine which had been programmed to an IBM 704 digital computer. With the model, the effect of compression ratio on engine thermal efficiency was calculated over a wide range of operating conditions. The results of the study showed that engine thermal efficiency continued to increase with
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