Automotive Stirling Engine Development Program

Program status and plans are discussed for component and technology development; reference engine system design, the upgraded Mod 1 engine; industry test and evaluation; and product assurance. Four current Mod 1 engines reached a total of 2523 operational hours, while two upgraded engines accumulated 166 hours

Automotive Stirling engine: Mod 2 design report

The design of an automotive Stirling engine that achieves the superior fuel economy potential of the Stirling cycle is described. As the culmination of a 9-yr development program, this engine, designated the Mod 2, also nullifies arguments that Stirling engines are heavy, expensive, unreliable, demonstrating poor performance. Installed in a General Motors Chevrolet Celebrity car, this engine has a predicted combined fuel economy on unleaded gasoline of 17.5 km/l (41 mpg)- a value 50% above the current vehicle fleet average. The Mod 2 Stirling engine is a four-cylinder V-drive design with a single crankshaft. The engine is also equipped with all the controls and auxiliaries necessary for automotive operation

An investigation into piston ring blowby and its effect on biogas engines

This study has investigated the severe corrosion of Biogas engines by the blowby gases. The formation of blowby its composition and flow rate have been measured and simulated. The nature of the piston ring sealing, lubrication and breakdown has been examined. A study of Biogas engines showed that Copper corrosion of the small end and camshaft bearings by HZS gas was the reason for engine failure. H2S is present in all Biogas at a concentration of usually less than 1%, but succeeds in chemical attack despite its good combustion properties, and the expected reaction with the bases present in the lubrication oil. The HZS was corroding in its gaseous state, but only those bearings with indirect lubrication. The solution to this problem is either to adopt force fed lubrication of the bearings, or to replace the alloy with Aluminium-Tin. The experimental work used four engines of differing wear. The constant speed work showed that the fuel content of blowby gas increases with load despite any increase in fuelling rate. This trend was consistent for all gaseous fuels present including H2S. A series of computer calculations of piston ring blowby were completed, using conventional and novel input data. The resultant blowby flow was within an order of magnitude, confirming that two blowby mechanisms, ring gap blowby and ring seal breakdown, are present on worn engines. The composition results showed that the fuel content of blowby is subject to the complex nature of the quenching process in the combustion chamber. A study of the oil present at the top ring showed that the oil is greatly modified when compared with the sump oil, as a result of thermal degradation and base depletion. The oil has a high acid TAN, which suggests it could encourage corrosive wear of the cylinder liner

Establishment of a novel predictive reliability assessment strategy for ship machinery

There is no doubt that recent years, maritime industry is moving forward to novel and sophisticated inspection and maintenance practices. Nowadays maintenance is encountered as an operational method, which can be employed both as a profit generating process and a cost reduction budget centre through an enhanced Operation and Maintenance (O&M) strategy. In the first place, a flexible framework to be applicable on complex system level of machinery can be introduced towards ship maintenance scheduling of systems, subsystems and components.;This holistic inspection and maintenance notion should be implemented by integrating different strategies, methodologies, technologies and tools, suitably selected by fulfilling the requirements of the selected ship systems. In this thesis, an innovative maintenance strategy for ship machinery is proposed, namely the Probabilistic Machinery Reliability Assessment (PMRA) strategy focusing towards the reliability and safety enhancement of main systems, subsystems and maintainable units and components.;In this respect, the combination of a data mining method (k-means), the manufacturer safety aspects, the dynamic state modelling (Markov Chains), the probabilistic predictive reliability assessment (Bayesian Belief Networks) and the qualitative decision making (Failure Modes and Effects Analysis) is employed encompassing the benefits of qualitative and quantitative reliability assessment. PMRA has been clearly demonstrated in two case studies applied on offshore platform oil and gas and selected ship machinery.;The results are used to identify the most unreliability systems, subsystems and components, while advising suitable practical inspection and maintenance activities. The proposed PMRA strategy is also tested in a flexible sensitivity analysis scheme.There is no doubt that recent years, maritime industry is moving forward to novel and sophisticated inspection and maintenance practices. Nowadays maintenance is encountered as an operational method, which can be employed both as a profit generating process and a cost reduction budget centre through an enhanced Operation and Maintenance (O&M) strategy. In the first place, a flexible framework to be applicable on complex system level of machinery can be introduced towards ship maintenance scheduling of systems, subsystems and components.;This holistic inspection and maintenance notion should be implemented by integrating different strategies, methodologies, technologies and tools, suitably selected by fulfilling the requirements of the selected ship systems. In this thesis, an innovative maintenance strategy for ship machinery is proposed, namely the Probabilistic Machinery Reliability Assessment (PMRA) strategy focusing towards the reliability and safety enhancement of main systems, subsystems and maintainable units and components.;In this respect, the combination of a data mining method (k-means), the manufacturer safety aspects, the dynamic state modelling (Markov Chains), the probabilistic predictive reliability assessment (Bayesian Belief Networks) and the qualitative decision making (Failure Modes and Effects Analysis) is employed encompassing the benefits of qualitative and quantitative reliability assessment. PMRA has been clearly demonstrated in two case studies applied on offshore platform oil and gas and selected ship machinery.;The results are used to identify the most unreliability systems, subsystems and components, while advising suitable practical inspection and maintenance activities. The proposed PMRA strategy is also tested in a flexible sensitivity analysis scheme

Development of a hydrogen-oxygen internal combustion engine space power system

Hydrogen-oxygen internal combustion engine space power syste

Automotive Stirling engine development program

Activities performed on Mod I engine testing and test results, testing of the Mod I engine in the United States, Mod I engine characterization and analyses, Mod I Transient Test Bed fuel economy, upgraded Mod I performance and testing, Stirling engine reference engine manufacturing and reduced size studied, components and subsystems, and the study and test of low cost casting alloys are summarized. The overall program philosophy is outlined, and data and results are presented

The role of testing in the engineering product development process

Testing is essential in developing a successful complex engineering product. System level integration and testing can use between 25 and 50% of development resources. External factors such as legislation and customer requirements drive essential testing whilst internal factors such company experience, affordability and organizational practice frame the overall testing plan. The main objective of this paper is to understand how testing is integrated into the product development process and how different types of testing are scheduled across the stages of product development. The paper reports a case study in a diesel engine company where the balance of virtual and physical testing is a key concern in reducing design time and costs. The importance of dependencies across components, subsystems and tests is highlighted and a model using Design Structure Matrices proposed. Of particular interest are requirements analysis and FMEA stages where testing is planned and resourced Integrating physical and virtual testing is more than process optimization of time and cost. It contributes to recasting the design process in response to change, both in new customer requirements and contingently in design changes which arise during product development

The detection of adhesive wear on cylinder liners for slow speed diesel engine through tribology, temperature, eddy current and acoustic emission measurement and analysis

PhD ThesisThe research concerns the condition monitoring of cylinder liner of large bore diesel engines using various methodologies to identify the onset of scuffing. The reasons of scuffing, improved designs and operational processes to prevent its occurrence were discussed. The research focused on modeling the normal condition of the cylinder liner with sufficient lubrication and detecting the precursor of scuffing by reducing the lubrication. The four detection systems used on the test facilities and field tests of the cylinder liners used tribology, temperature sensor, eddy current sensor and acoustic emission sensor. Experimental assessment of eddy current sensor was conducted for insufficient lubricating oil conditions for different cylinder liner wall pressures using a specially designed test facility. Field tests of temperature sensor and eddy current sensor were carried out on a 800mm bore worn cylinder liner of a container ship in service. Field test of acoustic emission sensor was carried out on a high speed automobile engine. Scuffing detection by temperature sensing should be considered as the last safety barrier, as it registers the after effect of scuffing and solely depends on the localized condition and the material’s thermal status. Mounting eddy current sensors are considered intrusive. Four sensors per cylinder are needed, which are prone to damage by the rings when the liner wears out. Additionally, the sensors measure only small section of the rings and their lubrication condition. Acoustic emission analysis effectively detects onset of scuffing on the cylinder liners and the rings. Initial findings from the lab and the field test on a four stroke engine confirmed this. However, more field tests under various loading condition on a slow speed engine is needed to understand the various event alignment and the non-routine detection, such as scuffing. They can be coupled with thermocouples to serve as a secondary protection

Maturing Technologies for Stirling Space Power Generation

Stirling Radioisotope Power Systems (RPS) are being developed as an option to provide power on future space science missions where robotic spacecraft will orbit, flyby, land or rove. A Stirling Radioisotope Generator (SRG) could offer space missions a more efficient power system that uses one fourth of the nuclear fuel and decreases the thermal footprint of the current state of the art. The RPS Program Office, working in collaboration with the U.S. Department of Energy (DOE), manages projects to develop thermoelectric and dynamic power systems, including Stirling Radioisotope Generators (SRGs). The Stirling Cycle Technology Development (SCTD) Project, located at Glenn Research Center (GRC), is developing Stirling-based subsystems, including convertors and controllers. The SCTD Project also performs research that focuses on a wide variety of objectives, including increasing convertor temperature capability to enable new environments, improving system reliability or fault tolerance, reducing mass or size, and developing advanced concepts that are mission enabling. Research activity includes maturing subsystems, assemblies, and components to prepare them for infusion into future convertor and generator designs. The status of several technology development efforts are described here. As part of the maturation process, technologies are assessed for readiness in higher-level subsystems. To assess the readiness level of the Dual Convertor Controller (DCC), a Technology Readiness Assessment (TRA) was performed and the process and results are shown. Stirling technology research is being performed by the SCTD Project for NASA's RPS Program Office, where tasks focus on maturation of Stirling-based systems and subsystems for future space science missions

Performance analysis on Free-piston linear expander

The growing global demand for energy and environmental implications have created a need to further develop the current energy generation technologies (solar, wind, geothermal, etc.). Recovering energy from low grade energy sources such as waste heat is one of the methods for improving the performance of thermodynamic cycles. The objective of this work was to achieve long-term steady state operation of a Free-Piston Linear Expander (FPLE) and to compare the FPLE with the currently existing expander types for use in low temperature energy recovery systems. A previously designed FPLE with a single piston, two chambers, and linear alternator was studied and several modifications were applied on the sealing and over expansion. An experimental test bench was developed to measure the inlet and outlet temperatures, inlet and outlet pressures, flow rate, and voltage output. A method of thermodynamic analysis was developed by using the first and second law of thermodynamics with air as the working fluid. The experimental tests were designed to evaluate the performance of the FPLE with varying parameters of inlet air pressure, inlet air temperature, and electrical resistance. The initial and steady-state operation of the FPLE were successfully achieved. An uncertainty analysis was conducted on the measured values to determine the accuracies of the calculated parameters. The trends of several output parameters such as frequency, average root mean square (RMS) voltage, volumetric efficiency, electrical-mechanical conversion efficiency, isentropic efficiency, irreversibility, actual expander work, and electrical power were presented. Results showed that the maximum expander frequency was found to be 44.01 Hz and the frequency tended to increase as the inlet air pressure increased. The FPLE achieved the maximum isentropic efficiency of 21.5%, and produced maximum actual expander work and electrical work of 75.13 W and 3.302 W, respectively