Development and mathematical analysis of a modular CNG valve : a thesis presented in partial fulfilment of the requirements for the degree of Master of Engineering, Mechatronics, at Massey University

With the rising cost of oil and uncertainty of supply, there has never been a greater opportunity to offer an alternative fuel into the automotive market than at this present time. Compressed natural gas (CNG) and liquid petroleum gas (LPG) are popular alternatives, producing less green house gasses after the combustion process that add to the raising global warming concern. With high performance fuel injected state of the art engines used in the majority of the late model vehicles, the problem when running on CNG or LPG is poor control of the air/fuel ratio throughout the engine's speed and load range using the conventional zero pressure regulator and mixer combination gas conversion equipment used previously for carburetted engines. This problem is completely eliminated with gas injection system. The Harrison CNG Electronic Gas injection System control valve is a linear proportional valve. Testing on the valve has found that the response is linear under all operating conditions; however the valve exhibits occasional instances of hysteresis. Due to this unfortunate characteristic further analysis is required, in the form of a mathematical analysis, to determine the exact causes of this problem. Another point of concern is the complexity of the valve, due to the many moving parts, this results in high production costs and increased reliability concerns. This masters project will include the mathematical analysis of the current Harrison CNG Electronic Gas injection system, further testing and refinement. The objective is to produce a modular system that can be retrofitted to any make of vehicle. Research will be directed in the development of mathematical equations to analyse valve operation for improvement of operation, to increase performance the valve will be redesigned to reduce complexity and ready it for production. The valve will be tested on a variety of vehicles from a 2 litre sedan to a 5.8 litre diesel engine that has been converted to operate on CNG, to prove the versatility of the valve and its ability to tailor the engine torque curve to that required for the vehicles unique operating requirements

Car Industry developments – oil industry challenges

Automotive industry of Europe is one of the greatest economical powers, the „engine of Europe”. It employs directly 2.2 million people and 10 million in related industries and services. Combined turnover of automotive manufacturers reaches 700 billion EUR (retail another 520 billion EUR). The industry is the largest R&D investor in EU. On the other hand the transport sector carries a huge safety and environmental risk. Thanks to this fact the automotive industry is one of the most regulated sectors in the EU. As a result of these regulations: one average car built in 1970s produced as many pollutant elements as one hundred cars manufactured today. These achievements are based on struggles of both the auto and oil industry as parallel with technology development in car industry fuel quality developments achieved by the oil industry drove to a much “cleaner” fuel quality (unleaded sulphur free petrol, reduction of aromatics, benzene; sulphur free diesel, reduction of density, poly-aromatics, etc.). In the end of the 1990s, and especially for the last few years new challenges came into the focus of the auto and oil industry of the EU and the world. Concerns about high energy prices and price volatility, security of worldwide oil supply and climate change became a main policy agenda of the EU and the world. This new policy is reflected in new regulatory initiatives requiring cars using less energy more efficiently, emitting less carbondioxide and using growing proportion of renewable fuels. The European Commission declared the idea of “Cars for Fuels” instead of “Fuels for Cars”. This article discusses in detail the regulations and challenges that rose towards oil and car industry during the recent years. It describes the possible solutions in order to fulfil the requirements of the EU. After that a wide picture is presented without going into much detail on developments of the automotive industry. Developments are divided between vehicle level, engine level and fuel level technologies, also paying attention to technologies that are less known or rather futuristic

Dual fuel conversion of a direct-injection diesel engine

Dual fuel pilot-injected diesel natural gas engines offer significant potential to reduce oxides of nitrogen (NOx) and particulate matter (PK emissions while maintaining diesel-like efficiency. A 1994 Navistar T444E turbocharger V-8 diesel engine was converted to dual fuel diesel and compressed natural gas (CNG). In an attempt to reduce the overall cost and complexity of conversion, the engine was left completely original, including the diesel fuel injection system. Also, for the sake of simplicity, the method of intake manifold fumigation through an IMPCO, Inc. electronic natural gas control valve was chosen to deliver the CNG. A microprocessor-based electronic control unit was developed to manage the hydraulically-actuated, electronically-controlled unit injectors (HEUI). Pilot injection parameters (start of injection, injection duration, and injection pressure) were varied along with the CNG flowrate to minimize NOx production while still considering hydrocarbon (HC), carbon dioxide (CO2) carbon monoxide (CO), and PM limits. Thermal efficiency and diesel fuel replacement ratio were noted as well. In-cylinder pressure data was collected and used to calculate run-time combustion parameters such as indicated mean effective pressure (IMEP), heat release rate (HRR) and to observe the ignition delay period. Comparative diesel and dual fuel tests were completed at intermediate load (1500 rpm, 335 N-m) and high load (1500 rpm, 580 N-m) operating conditions to determine the emissions benefits of the dual fuel conversion. Compared to diesel operation, optimized dual fuel operation at intermediate load produced a 32% decrease in NOx and a 57% decrease in PM. Dual fuel operation at high load produced a 19% decrease in NOx and a 72% decrease in PM. However, these reductions came with an increase in HC and CO emissions over standard diesel operation

Combustion of Gaseous Alternative Fuels in Compression Ignition Engines

The problem of alternative fuels for combustion engines has been growing in importance recently. This is connected not only with decreasing fossil fuel resources, but also with the growing concern for the natural environment and the fight against global warming. This paper discusses the possibility of utilizing alternative gaseous fuels in compression-ignition engines, using dual-fuel, gas-liquid operation strategy. Current state of the art of this technology had been introduced, along with its benefits and challenges to be countered. The discussion had been supported by authors own research experience on dual-fuel engines. The latest results of research on the impact of gas composition on combustion process in the Common Rail dual fuel engine had been presented, at the same illustrating the environmental benefits of using gaseous fuels. The Utilization of gaseous fuels with varying composition was illustrated systematically, starting with natural gas. The possibility of using fuels with lower content of methane (the so-called low-calorie gases) was shown by the impact of depleting natural gas with carbon dioxide. Industrial gases, such as syngas contain a large amount of hydrogen, carbon monoxide or higher hydrocarbons (ethane, propane). The possibility of fueling CI engines with these gasses was presented by the influence of enriching natural gas with mentioned components. The results cover engine dynamometer tests for different operating conditions with the analysis of the combustion process and detailed emission measurements discussion. The results of experimental studies were supplemented by simulation results, using mathematical models, developed by the authors for multi-fuel enginesr

Electricity powering combustion: hydrogen engines

Hydrogen is ameans to chemically store energy. It can be used to buffer energy in a society increasingly relying on renewable but intermittent energy or as an energy vector for sustainable transportation. It is also attractive for its potential to power vehicles with (near-) zero tailpipe emissions. The use of hydrogen as an energy carrier for transport applications is mostly associated with fuel cells. However, hydrogen can also be used in an internal combustion engine (ICE). When converted to or designed for hydrogen operation, an ICE can attain high power output, high efficiency and ultra low emissions. Also, because of the possibility of bi-fuel operation, the hydrogen engine can act as an accelerator for building up a hydrogen infrastructure. The properties of hydrogen are quite different from the presently used hydrocarbon fuels, which is reflected in the design and operation of a hydrogen fueled ICE (H2ICE). These characteristics also result in more flexibility in engine control strategies and thus more routes for engine optimization. This article describes the most characteristic features of H2ICEs, the current state of H2ICE research and demonstration, and the future prospects

Compound cycle engine for helicopter application

The compound cycle engine (CCE) is a highly turbocharged, power-compounded, ultra-high-power-density, lightweight diesel engine. The turbomachinery is similar to a moderate-pressure-ratio, free-power-turbine gas turbine engine and the diesel core is high speed and a low compression ratio. This engine is considered a potential candidate for future military helicopter applications. Cycle thermodynamic specific fuel consumption (SFC) and engine weight analyses performed to establish general engine operating parameters and configurations are presented. An extensive performance and weight analysis based on a typical 2-hour helicopter (+30 minute reserve) mission determined final conceptual engine design. With this mission, CCE performance was compared to that of a contemporary gas turbine engine. The CCE had a 31 percent lower-fuel consumption and resulted in a 16 percent reduction in engine plus fuel and fuel tank weight. Design SFC of the CCE is 0.33 lb/hp-hr and installed wet weight is 0.43 lb/hp. The major technology development areas required for the CCE are identified and briefly discussed

Diesel Engine

Diesel engines, also known as CI engines, possess a wide field of applications as energy converters because of their higher efficiency. However, diesel engines are a major source of NOX and particulate matter (PM) emissions. Because of its importance, five chapters in this book have been devoted to the formulation and control of these pollutants. The world is currently experiencing an oil crisis. Gaseous fuels like natural gas, pure hydrogen gas, biomass-based and coke-based syngas can be considered as alternative fuels for diesel engines. Their combustion and exhaust emissions characteristics are described in this book. Reliable early detection of malfunction and failure of any parts in diesel engines can save the engine from failing completely and save high repair cost. Tools are discussed in this book to detect common failure modes of diesel engine that can detect early signs of failure

Effect of the Use of Natural Gas-Diesel Fuel Mixture on Performance, Emissions and Combustion Characteristics of a Compression-Ignition Engine

A compression ignition engine with a mechanical fuel system was converted into common rail fuel system by means of a self-developed electronic control unit. The engine was modified to be operated with mixtures of diesel and natural gas fuels in dual-fuel mode. Then, diesel fuel was injected into the cylinder while natural gas was injected into intake manifold with both injectors controlled with the electronic control unit. Energy content of the sprayed gas fuel was varied in the amounts of 0% (only diesel fuel), 15%, 40%, and 75% of total fuel’s energy content. All tests were carried out at constant engine speed of 1500 r/min at full load. In addition to the experiments, the engine was modeled with a one-dimensional commercial software. The experimental and numerical results were compared and found to be in reasonable agreement with each other. Both NO x and soot emissions were dropped with 15% and 40%, respectively, energy content rates in gas–fuel mixture compared to only diesel fuel. However, an increase was observed in carbon monoxide emissions with 15% natural gas fuel addition compared to only diesel fuel. Although smoke emission was reduced with natural gas fuel addition, there was a dramatic increase in NO x emissions with 75% natural gas fuel addition

Design and investigation of a diesel engine operated on pilot ignited LPG

This thesis explores the idea of igniting LPG in a compression ignition diesel engine using pilot diesel injection as spark ignition medium. The main advancement in using this technology on current diesel engines is the establishment of a better balance between NOx and PM emissions without losing too much of the CO2 benefits of diesel. With the advent of common rail diesel engines, it is now possible to get control of pilot diesel injection and make the LPG and diesel control systems work together. Combined diesel and LPG operation is a new subject for engine research, so the thesis moves on to consider the results from detailed engine simulation studies that explore the potential benefits of the mix. Subsequent simulations of a modern four cylinder dCi engine suggest that with closer control over the pilot diesel injection, diesel like performance can be obtained, hopefully with less emissions than currently expected from diesel only operation. A single cylinder variable compression ratio research engine was developed to explore diesel /LPG dual fuel operation. A second generation common rail injection rig was also developed for the engine and for fuel spray characterisation. Engine experiments proved the concept of using a modest charge of pilot injected diesel for igniting a larger dose of port injected LPG. The experimental work results suggest that combining diesel common rail injection technology with the state of the art LPG injection systems, it is possible to establish a better balance between NOx/ PM emissions without losing too much of the CO2 benefits from the diesel operation