Figure 3 - uploaded by Ion Marius Sivebaek
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... heat necessary for maintaining the adequate temperature is supplied by a lamp. The reciprocating rig is driven by a magnetic coupling, which is shown schematically in figure 3. As DME dissolves nearly all currently known elastomers, dynamic sealing was avoided. ...
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... is accomplished by adopting the magnetic coupling as the rig, attached to the coupling shaft, then becomes driven by a magnetic field through a shroud. The whole apparatus is thus sealed only by two static gaskets: An O-ring in the magnetic coupling shown in figure 3 and a gasket assembling the two halves of the tank. Both the gaskets are made of PTFE, which is resistant towards DME. ...
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[This corrects the article DOI: 10.1021/acsomega.1c03763.].
Citations
... Also, signs of fuel leaking may reside at the fuel storage tank, injection pump, or injector needle seal [57]. Independent durability studies showed that wear may still be prevalent using the aforementioned additives [58]. The strong solvent nature of DME, especially towards elastomers, requires retrofitting common nitrile rubber seals in the injection pumps to more resistant materials. ...
Review Dimethyl Ether to Power Next-Generation Road Transportation Simon LeBlanc , Xiao Yu , Linyan Wang , and Ming Zheng , * Department of Mechanical, Automotive and Materials Engineering, University of Windsor, 401 Sunset Avenue, Windsor, N9B 3P4 Ontario, Canada * Correspondence: mzheng@uwindsor.ca Received: 20 March 2023 Accepted: 8 June 2023 Published: 19 June 2023 Abstract: The prevailing transportation uses internal combustion engines powered by fossil fuels that bear the reputation of carbon dioxide release among other harmful emissions. As an alternative, dimethyl ether (DME) has shown a high potential to mitigate emission challenges. The properties of DME present a highly reactive and volatile fuel suitable for clean combustion. However, the onboard handling of liquified DME is an ongoing challenge, especially for high-pressure direct injection applications. This paper aims to evaluate the sustainability, fuel handling, and combustion characteristics of DME as a clean and efficient fuel for sustainable on-road transportation. Strategies toward integrating DME fuel for automotive applications are emphasized. An overview of DME production is provided with relevance to current industry practices. Thereafter, the chemical and physical properties of DME are highlighted. The handling challenges of DME are accentuated, and accordingly, recommendations are made for setting up fuel management systems applicable to on-road engines and research laboratories. The DME fueling configurations, e.g., port injection and direct injection, are summarized. Empirical tests studied the engine and emission performance of DME combustion. Ultra-low NOx and smoke emissions, with high combustion efficiency, are achieved.
... The resulting wear scar diameter on the ball expresses the lubricity of the tested lubricant. This set-up has been used to test the lubricity of a series of alkanes [17]. Figure 1 shows the wear scar diameter measured on the ball as a function of the hydrocarbon molecular length [2]. ...
The properties of linear alkane lubricants confined between two approaching solids are investigated by a model that accounts for the roughness, curvature and elastic properties of the solid surfaces. We consider linear alkanes of different chain lengths from C3H8 to C16H34, confined between corrugated solid walls. The pressure necessary to squeeze out the lubricant increases rapidly with the alkane chain length, but is always much lower than in the case of smooth surfaces. The longest alkanes form domains of ordered chains and the squeeze-out appears to nucleate in the more disordered regions between these domains. The short alkanes stay fluid-like during the entire squeeze out process which result in a very small squeeze-out pressure which is almost constant during the squeeze-out of the last monolayer of the fluid. In all cases we observe lubricant trapped in the valley of the surface roughness, which cannot be removed independent of the magnitude of the squeezing pressures.
... The viscosity of DME is very low, and special attention needs to be paid to leakage. In addition to low viscosity, DME has low lubricity (Sivebaek and Sorenson 2000) and is prone to accel erated wear in diesel engine pumping systems. The ignition temperature is much lower than that of gasoline, and comparable to that of good diesel fuels. ...
div class="section abstract"> The majority of transportation systems have continued to be powered by the internal combustion engine and fossil fuels. Heavy-duty applications especially are reliant on diesel engines for their high brake efficiency, power density, and robustness. Although engineering developments have advanced engines towards significantly fewer emissions and higher efficiency, the use of fossil-derived diesel as fuel sets a fundamental threshold in the achievable total net carbon reduction. Dimethyl ether can be produced from various renewable feedstocks and has a high chemical reactivity making it suitable for heavy-duty applications, namely compression ignition direct injection engines. Literature shows the successful use of DME fuels in diesel engines without significant hardware modifications. The lower energy density of DME calls for adjustments in injection parameters (such as injection pressure and duration) or modifications to the injector geometry to align with the energy levels found in diesel fuels. However, detailed direct comparisons between diesel and DME fuel injection characteristics over a wide testing range is lacking.
This study investigates the injection characteristics of DME and diesel fuels in a common rail fuel injection system using the Bosch tube method. It is demonstrated that this method can be effectively applied to measure DME fuel injection characteristics, albeit with some limitations in predicting injector closing delay. The research emphasizes the presence of hydraulic delay, resulting in a ratio of actual to commanded injection duration for DME between 1.5 to 2 under the testing conditions. The study finds that mass-based injection quantities for diesel and DME fuels are quite similar at matching conditions, although the lower heating value of DME results in lower energy-based injection quantities and thus fuel injection scheduling need to be adapted to compensate that. Furthermore, the paper offers valuable insights and suggestions for those considering the modification of diesel-operated engines into DME-operated engines.
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Focusing on a critical aspect of the future clean energy system - renewable fuels - this book will be your complete guide on how these fuels are manufactured, the considerations associated with utilising them, and their real-world applications. Written by experts across the field, the book presents many professional perspectives, providing an in-depth understanding of this crucial topic. Clearly explained and organised into four key parts, this book explores the technical aspects written in an accessible way. First, it discusses the dominant energy conversion approaches and the impact that fuel properties have on system operability. Part II outlines the chemical carrier options available for these conversion devices, including gaseous, liquid, and solid fuels. In the third part, it describes the physics and chemistry of combustion, revealing the issues associated with utilizing these fuels. Finally, Part IV presents real-world case studies, demonstrating the successful pathways towards a net-zero carbon future.
In this paper, dependence of liquid-DME viscosity on temperature and pressure was studied theoretically. It was found that in the saturated-liquid state, the DME viscosity is 0.37 cSt at - 40 ° C and it drops to 0.17 cSt when temperature increases to 80 ° C. In the subcooled-liquid state, viscosity varies linearly with pressure at a given temperature; at 20 ° C, viscosity of the subcooled liquid is 0.23 cSt at 5.3 bar and it increases to 0.33 cSt at 500 bar. The predicted liquid-DME viscosity and its pressure dependence agree with those obtained by measurement. Lubricity of liquid DME also was studied. Polar-headed, long-chain alcohols and fatty acids with chain length of C15 ∼ C22 were found to be candidates of lubricity additives for DME. Castor oil (chemically, it is basically a C 18 fatty acid) was found to be a good additive for improving the DME lubricity. Fuel-system tests on the bench as well as on engines had shown that by adding 1-wt% castor oil into DME, the DME lubricity was improved significantly in comparison to that of pure DME, and no unusual wear of the sliding parts of the fuel system was noticed in a >500-hour test period.
Dimethyl ether (DME) is one of the promising fuels for a compression ignition engine. However, pure DME cannot be used on internal combustion engines directly owing to its low viscosity and poor lubricity. Experimental investigation of the performance of a DME engine with two different kinds of vegetable oil is carried out. Results prove that a certain proportion of rapeseed oil or castor oil dissolves well in DME fuel at the engine's normal operating condition. The lubricity of DME fuel can be improved by adding a proportion of vegetable oil to it, and the plunger surface of the fuel pump has no large wear scars. Also the plunger surface of the fuel pump with DME-rapeseed oil is a little smoother than that with DME-castor oil. The power outputs of a DME engine with these two kinds of vegetable oil are comparable with that of a diesel engine and even exceed that of a diesel engine at low speeds and loads. However, the power output of the engine with DME-castor oil is a little lower than that with DME-rapeseed oil. Smokeless combustion can be realized in a DME engine with these two kinds of vegetable oil, and NO, emission is about 40 per cent of that of a diesel engine. The peak pressure of a DME engine with these two kinds of vegetable oil is lower than that of a diesel engine, which indicates lower noise and ballistic load. Furthermore, the peak cylinder pressure for DME-castor oil operation is a little lower than that for DME-rapeseed oil operation. Experiments prove not only that the drawback of low viscosity and poor lubricity of DME fuel can be overcome but also that high efficiency and clean and low-noise combustion can be realized with the addition of vegetable oil to a DME engine.
Dimethyl ether (DME) has been recognised as a clean substitute for diesel oil as it does not form soot during combustion. DME has a vapour pressure of 6bar at 25°C; so pressurisation is necessary to keep DME liquid at ambient temperature. Inert gases are good candidates as pressurising media, but their effect on DME viscosity is unknown.Argon (Ar), nitrogen (N2), carbon dioxide (CO2), hydrogen (H2) and propane (C3H8) have been investigated at pressure levels of 12–15bar. A Cannon-Manning semi-micro capillary glass viscometer, size 25, enclosed in a cylindrical pressure container, of glass, submerged completely in a constant temperature bath, has been used. A distinct reduction of efflux times was found only for the gas, CO2. The reduction in efflux time was about 9%.The kinematic viscosity of pure DME was determined to be: 0.188±0.001cSt, 25°C. A previously reported viscosity of pure DME has been corrected for the surface tension effect. Viscosity determination was initially based on a direct comparison of efflux times of DME with that of distilled water. The calculation gave a revised viscosity of 0.186±0.002cSt, 25°C, consistent with the above experimental result.
Studies of alternative fuels at Penn State include biodiesel, dimethyl ether (DME) and low sulfur diesel fuels. The fuel studies include bench tests, laboratory engine tests and vehicle tests. DME was evaluated in a campus shuttle bus operating on its regular campus route. A 25:75 vol% mixture of DME and diesel fuel was used. Laboratory engine tests of oxygenated fuels, including biodiesel, resulted in significant particulate reductions. However, some alternative fuels exhibit low lubricity. Bench tests comparing friction and wear characteristics of the fuels are described.
