Future fuels and engines for railroad locomotives. Volume 1: Summary

The potential for reducing the dependence of railroads on petroleum fuel, particularly Diesel No. 2 was investigated. Two approaches are studied: (1) to determine how the use of Diesel No. 2 can be reduced through increased efficiency and conservation, and (2) to use fuels other than Diesel No. 2 both in Diesel and other types of engines. Because synthetic hydrocarbon fuels are particularly suited to medium speed diesel engines, the first commercial application of these fuels may be by the railroad industry

Utilization of waste heat in trucks for increased fuel economy

Improvements in fuel economy for a broad spectrum of truck engines and waste heat utilization concepts are evaluated and compared. The engines considered are the diesel, spark ignition, gas turbine, and Stirling. The waste heat utilization concepts include preheating, regeneration, turbocharging, turbocompounding, and Rankine engine compounding. Predictions were based on fuel-air cycle analyses, computer simulation, and engine test data. The results reveal that diesel driving cycle performance can be increased by 20% through increased turbocharging, turbocompounding, and Rankine engine compounding. The Rankine engine compounding provides about three times as much improvement as turbocompounding but also costs about three times as much. Performance for either is approximately doubled if applied to an adiabatic diesel

Numerical Modelling and Design Optimisation of Stirling Engines for Power Production

This research is in the area of Thermal Energy Conversion, more specifically, in the conversion of solar thermal energy. This form of renewable energy can be utilised for production of power by using thermo-mechanical conversion systems – Stirling engines. The advantage of such the systems is in their capability to work on low and high temperature differences which is created by the concentrated solar radiation. To design and build efficient, high performance engines in a feasible period of time it is necessary to develop advanced mathematical models based on thermodynamic analysis which accurately describe heat and mass transfer processes taking place inside machines. The aim of this work was to develop such models, evaluate their accuracy by calibrating them against published and available experimental data and against more advanced three-dimensional Computational Fluid Dynamics models. The refined mathematical models then were coupled to Genetic Algorithm optimisation codes to find a rational set of engine’s design parameters which would ensure the high performance of machines. The validation of the developed Stirling engine models demonstrated that there was a good agreement between numerical results and published experimental data. The new set of design parameters of the engine obtained from the optimisation procedure provides further enhancement of the engine performance. The mathematical modelling and design approaches developed in this study with the use of optimization procedures can be successfully applied in practice for creation of more efficient and advanced Stirling engines for power production

DETERMINATION OF A FREE-PISTON STIRLING ENGINE-GENERATOR OPERATING CURVE FOR APPLICATIONS IN ENERGY EXTRACTION

Renewable energy generation faces challenges in energy storage, particularly in providing sustained load management between periods of excess generation, peak demand, and intermittency. Clean and dependable energy storage methods exist, but the need for higher efficiency energy extraction motivates the search for sophisticated methods. One such method is a Liquid Air Energy Storage (LAES) system paired with a Stirling engine. This thesis investigated the power output of a particular Free-Piston Stirling Engine-Generator (FPSEG) for potential use in energy extraction from the aforementioned system to power an islanded microgrid. A full FPSEG testing apparatus was constructed and several heating conditions were tested to obtain an operating curve for the studied FPSEG. Additionally, a basic numerical model was developed for the FPSEG working fluid. Data from these experiments were evaluated to show potential coupling capabilities with a LAES system.Office of Naval Research, Arlington, VA 2203-1995Ensign, United States NavyApproved for public release. Distribution is unlimited

Utilization of waste heat in trucks for increased fuel economy

The waste heat utilization concepts include preheating, regeneration, turbocharging, turbocompounding, and Rankine engine compounding. Predictions are based on fuel-air cycle analyses, computer simulation, and engine test data. All options are evaluated in terms of maximum theoretical improvements, but the Diesel and adiabatic Diesel are also compared on the basis of maximum expected improvement and expected improvement over a driving cycle. The study indicates that Diesels should be turbocharged and aftercooled to the maximum possible level. The results reveal that Diesel driving cycle performance can be increased by 20% through increased turbocharging, turbocompounding, and Rankine engine compounding. The Rankine engine compounding provides about three times as much improvement as turbocompounding but also costs about three times as much. Performance for either can be approximately doubled if applied to an adiabatic Diesel

Assessment of alternative power sources for mobile mining machinery

Alternative mobile power sources for mining applications were assessed. A wide variety of heat engines and energy systems was examined as potential alternatives to presently used power systems. The present mobile power systems are electrical trailing cable, electrical battery, and diesel - with diesel being largely limited in the United States to noncoal mines. Each candidate power source was evaluated for the following requirements: (1) ability to achieve the duty cycle; (2) ability to meet Government regulations; (3) availability (production readiness); (4) market availability; and (5) packaging capability. Screening reduced the list of candidates to the following power sources: diesel, stirling, gas turbine, rankine (steam), advanced electric (batteries), mechanical energy storage (flywheel), and use of hydrogen evolved from metal hydrides. This list of candidates is divided into two classes of alternative power sources for mining applications, heat engines and energy storage systems

Ceramic automotive Stirling engine study

A conceptual design study for a Ceramic Automotive Stirling Engine (CASE) is performed. Year 1990 structural ceramic technology is assumed. Structural and performance analyses of the conceptual design are performed as well as a manufacturing and cost analysis. The general conclusions from this study are that such an engine would be 10-26% more efficient over its performance map than the current metal Automotive Stirling Reference Engine (ASRE). Cost of such a ceramic engine is likely to be somewhat higher than that of the ASRE but engine cost is very sensitive to the ultimate cost of the high purity, ceramic powder raw materials required to fabricate high performance parts. When the design study is projected to the year 2000 technology, substantinal net efficiency improvements, on the order of 25 to 46% over the ASRE, are computed

Recuperation of the exhaust gases energy using a Brayton cycle machine

Lately, car manufacturers have been put to a big challenge to reduce the CO2 emission of their entire fleets. Norms of pollutant emissions limit the ways to achieve the desired CO2 emission goals, as some of the solutions that would lead to lower CO2 emission also lead to higher pollutant emission. Waste Heat Recovery (WHR) could be a good solution to lower the CO2 emission of the Internal Combustion Engine (ICE) without increasing the pollutant emission. In the present thesis different WHR strategies are analysed and the results suggested it would be interesting to further study the Brayton cycle machine. Air Brayton Cycle (ABC) represents a way to recover a part of the heat energy of the ICE exhaust gases and transform it into mechanical energy. Recovered mechanical energy would then be returned to the crankshaft of the ICE, thereby reducing the amount of energy that has to be liberated by combustion of fuel which lowers the fuel consumption and CO2 emission. The study of ABC started with an analysis of the ideal cycle in order to obtain the theoretical maximum of the system. The study continued with an analysis of the semi ideal cycle where all losses are taken into account only by two efficiency coefficients. This analysis showed that for the diesel engine efficiency of the ABC is very low because of the low exhaust gas temperature. For the gasoline engine the cycle could be viable when the ICE is working under steady condition and higher load. These conditions could be fulfilled when the vehicle is driven on the highway. Detailed analysis was aimed at determining the cycle main losses. They were determined to be: pumping losses, losses caused by heat transfer and mechanical losses. Taking into account these main losses along with other direct and indirect losses it was concluded that the cycle is not viable for the types of the WHR machines that were considered in this study. In order for the cycle to be viable some other either existing or new machine type should be tested, that would lower the main losses and offer good isentropic and mechanical efficiency for desired conditions.Últimamente los fabricantes de automóviles se han puesto el gran reto de reducir la emisión de CO2 en la totalidad de sus flotas. Las nuevas normativas para la reducción de las emisiones contaminantes limitan los medios para lograr los objetivos deseados en la emisión de CO2 porque algunas de las soluciones que llevan a la reducción en la emisión de CO2 también dan lugar a un incremento en la emisión de otros contaminantes. La recuperación de calor residual (WHR) podría ser una buena solución para reducir las emisiones de CO2 del motor de combustión interna (ICE) sin poner en peligro la emisión de contaminantes. En la presente Tesis se analizaron diferentes estrategias de WHR y se concluyó que sería interesante estudiar más a fondo la máquina de ciclo Brayton. El Ciclo Brayton de Aire (ABC) permite recuperar una parte del calor de los gases de escape del ICE y transformar este calor en energía mecánica. La energía mecánica recuperada se devuelve al cigüeñal del ICE, reduciendo de ese modo la cantidad de energía que tiene que ser liberada por la combustión del combustible, lo cual permite reducir el consumo de combustible y las emisiones de CO2. En esta Tesis se estudia el ABC mediante un análisis del ciclo ideal con el fin de obtener el máximo teórico del sistema. El modelo se mejora con un análisis del ciclo semi-ideal donde se tienen en cuenta todas las pérdidas mediante el uso de dos coeficientes generales. Este análisis muestra que para el motor diesel la eficiencia del ciclo ABC es muy baja debido a la baja temperatura del gas de escape. Para el motor de gasolina el ciclo podría ser viable cuando el ICE está trabajando bajo condiciones estacionarias y una carga mayor. Estas condiciones se podrían cumplir cuando el vehículo está circulando en autopista. El análisis detallado de este ciclo tiene como objetivo determinar las pérdidas principales de ciclo. Las pérdidas principales se identificaron como: las pérdidas de bombeo, las pérdidas causadas por la transferencia de calor y las pérdidas mecánicas. Teniendo en cuenta estas pérdidas principales junto con otras pérdidas directas e indirectas, se concluyó que el ciclo no es viable para los tipos de máquinas WHR que fueron considerados en este estudio. Para que el ciclo sea viable se tiene que buscar alguna otra máquina existente o un nuevo tipo de máquina que reduzca las principales pérdidas y ofrezca un buen rendimiento isentrópico y mecánico para las condiciones deseadas.Últimament els fabricants d'automòbils s'han posat el gran repte de reduir l'emissió de CO2 de la totalitat de les seues flotes. Les noves normatives de reducció de les emissions contaminants limiten els mitjans per assolir els objectius desitjats d'emissió de CO2 perquè algunes de les solucions que porten a la reducció en l'emissió de CO2 també donen lloc a un increment a l'emissió de altres contaminants. La recuperació de calor residual (WHR) podria ser una bona solució per reduir les emissions de CO2 del motor de combustió interna (ICE) sense posar en perill l'emissió de contaminants. En la present Tesi s'han analitzat diferents estratègies WHR i es va concloure que seria interessant estudiar més a fons el cicle Brayton. El Cicle Brayton d'Aire (ABC) representa una manera de recuperar una part de la calor dels gasos d'escapament de l'ICE i transformar calor a l'energia mecànica. L'energia mecànica recuperada es retorna al cigonyal de l'ICE reduint d'aquesta manera la quantitat d'energia que ha de ser alliberada per la combustió del combustible permitint la reducció del consum de combustible i les emissions de CO2. En aquesta Tesi s'ha començat estudiant un ABC amb una anàlisi del cicle ideal per tal d'obtenir el màxim teòric del sistema. Este model es millora amb una anàlisi del cicle semiideal on es tenen en compte totes les pèrdues amb tan sols dos coeficients d'eficiència. Aquesta anàlisi va mostrar que per al motor dièsel l'eficiència del cicle ABC és molt baixa a causa de la baixa temperatura del gas d'escapament. Per al motor de gasolina el cicle podria ser viable quan l'ICE està treballant sota condicions estacionàries i una càrrega més gran. Aquestes condicions es podrien complir quan el vehicle està circulant en autopista. L'anàlisi detallada del cicle va tenir com a objectiu determinar les pèrdues principals de cicle. Les pèrdues principals es van identificar com: les pèrdues de bombament, les pèrdues causades per la transferència de calor i les pèrdues mecàniques. Tenint en compte aquestes pèrdues principals juntament amb altres pèrdues directes i indirectes, es va concloure que el cicle no és viable per als tipus de màquines WHR que van ser considerats en aquest estudi. Perquè el cicle puga ser viable s'ha de buscar alguna altra màquina existent o un nou tipus de màquina que puga reduir les principals pèrdues i puga oferir un bon rendiment isentròpic i mecànic per a les condicions desitjades.Kleut, P. (2016). Recuperation of the exhaust gases energy using a Brayton cycle machine [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/76807TESI