Quote:
Originally Posted by Christ
In review, you're right. I'm afraid that the information in my head might be a little skewed because of the length of time that has elapsed since the tests were done, and I can't accurately determine whether parts of my statements are memory or "fill in the blanks". (By the way, me saying "I'm gonna have to say yes." was actually just a sarcastic way of saying "I thought you'd just read that in what I already said".)
Remember, I was 10 at the time... so we probably DIDN'T test every possible situation. The emphasis was a question of heated air intake in a diesel engine of specific speed/output, and as such the test was run under those circumstances, from what I remember.
I'm still half thinking about the R18 engine, and how I could implement the offset crankshaft in another engine, and the benefits that could be gained from it. I dunno if I'll ever actually do it.
|
Ok, I looked at the first 500 of about 6000 hits on the SAE site and will paste in five abstracts below that seemed to have some relevance.
One thing that is clear is that the statement, "Engineers and Engine builders alike will stand by these observations. Diesels like it cold, no two ways about it." is not true for all diesel engines under all conditions or fuels.
The Effect of Air Charge Temperature on Performance, Ignition Delay and Exhaust Emissions of Diesel Engines Using W/O Emulsions as FuelDocument Number: 870555
Date Published: February 1987
Author(s):
E. M. Afify - North Carolina State Univ.
N. S. Korah - North Carolina State Univ.
D. W. Dickey - South West Research Institute
Abstract:
Most of the work performed on the use of water/oil emulsions in diesel engines showed that increasing the water content in the emulsified fuel was effective in reducing NO\dx and soot emissions. Unfortunately, the increase in water content in the emulsified fuel also increases the ignition delay and may cause diesel knock. One way to reduce the ignition delay is to increase the air charge temperature. In this study, the effect of increasing the air charge temperature on ignition delay, performance and exhaust emissions was investigated. The experiments were conducted on a CLR diesel engine using baseline diesel fuel #2 and stabilized macroemulsions containing 15 percent, 30 percent and 45 percent water by volume. The air charge temperature was varied from ambient to 75\mDC and 150\mDC. The performance results showed that under same operating conditions, when neat diesel fuel was used, increasing the air charge temperature caused the BSFC to increase. When emulsified fuel was used, especially with low water content, increasing the air charge temperature improved the BSFC at low loads and increased it at high loads. The ignition delay was also effectively reduced with the increase of air charge temperature. The emission results indicated that under the same operating conditions, NO\dx and soot emissions increased with the increase of air charge temperature, while CO and UHC emissions, in general, were slightly reduced at low loads and increased at high loads.
Uncooled EGR as a Means of Limiting Wall-Wetting under Early Direct Injection ConditionsDocument Number: 2009-01-0665
Date Published: April 2009
Author(s):
Michael Boot - Technische Universiteit Eindhoven
Abstract:
Collision of injected fuel spray against the cylinder liner (wall-wetting) is one of the main hurdles that must be overcome in order for early direct injection Premixed Charge Compression Ignition (EDI PCCI) combustion to become a viable alternative for conventional DI diesel combustion. Preferably, the prevention of wall-wetting should be realized in a way of selecting appropriate (most favorable) operating conditions (EGR level, intake temperature, injection timing-strategy etc.) rather than mechanical modification of an engine (combustion chamber shape, injector replacement etc.). This paper presents the effect of external uncooled EGR (different fraction) on wall-wetting issues specified by two parameters, i.e. measured smoke number (experiment) and liquid spray penetration (model). Experiments performed in a dedicated heavy-duty direct injected (HDDI) diesel engine suggest that the elevation of intake temperature caused by delivery of external uncooled exhaust gases led to significant reduction in wall wetting. This is combined with IMEP improvement. In-house spray- and ignition modeling was used to gain insight into the measured trends.
The Effect of Preheating the Inlet Air to Study the Performance and Combustion Characteristics of Diesel Engine using Ethanol Emulsion
Document Number: 2007-01-0628
Date Published: April 2007
Author(s):
Muthuswamy Pillai Ashok - Annamalai Univ.
C. G. Saravanan - Annamalai Univ.
Abstract:
The main objective of this paper is to study the performance, combustion characteristics and to control the emissions of the diesel engine using emulsified fuel by preheating the inlet air. The present work has been carried out using single cylinder, four stroke and water cooled diesel engine. In the first phase, three sets of emulsified fuels 50D: 50E (50% diesel: 50% ethanol - 100% proof), 60D: 40E, 70D: 30E have been prepared and tested. From the experiment, 50D: 50E has given the best performance result than the other emulsified fuel ratios and the diesel fuel. In the second phase, the experiment has been conducted for the diesel fuel and the best result obtained emulsified fuel ratio of 50D: 50E, by preheating the inlet air to 30ºC, 40ºC and 50ºC. From the investigation it is observed that the effect of preheating the inlet air, the emulsified fuel has given the best result than the diesel fuel. Also it has been found that there is reduction in smoke density, particulate matter and exhaust gas temperature with an increase of oxides of nitrogen (NOx) and brake thermal efficiency.
Fuel-Air Mixing and Diesel Combustion in a Rapid Compression Machine
Document Number: 880206
Date Published: February 1988
Author(s):
Eric N. Balles - Arthur D. Little, Inc.
John B. Heywood - Massachusetts Institute of Technology
Abstract:
The influence of charge motion and fuel injection characteristics on diesel combustion was studied in a rapid compression machine (RCM), a research apparatus that simulates the direct-injection diesel in- cylinder environment. An experimental data base was generated in which inlet air flow conditions (temperature, velocity, swirl level) and fuel injection pressure were independently varied. High-speed movies using both direct and shadowgraph photography were taken at selected operating conditions. Cylinder pressure data were analyzed using a one-zone heat release model to calculate ignition delay times, premixed and diffusion burning rates, and cumulative heat release profiles. The photographic analysis provided data on the liquid and vapor penetration rates, fuel-air mixing, ignition characteristics, and flame spreading rates.
Results show that charge temperature is the most significant parameter controlling the ignition delay period and it significantly affects the heat release profile in the premixed combustion phase. Temperature and pressure have little effect on the burning rates after the premixed phase which supports the theory that this latter phase is a mixing controlled process. Variations in injection rate and swirl level have a significant impact on the burning rates. Injection rate affects the entire heat release profile; swirl primarily affects the mixing controlled phase.
Effect of Fuel Temperature on the Performance and Emissions of a Common Rail Diesel Engine Operating with Rapeseed Methyl Ester (RME)
Document Number: 2009-01-1896
Date Published: June 2009
Author(s):
Rizalman Mamat - Univ. of Birmingham
Nik Rosli Abdullah - Students Online
Hongming Xu - Univ. of Birmingham
Miroslaw Wyszynski - Univ. of Birmingham
Athanasios Tsolakis - Univ. of Birmingham
Abstract:
The paper presents analysis of performance and emission characteristics of a common rail diesel engine operating with RME, with and without EGR. In both cases, the RME fuel was pre-heated in a heat exchanger to control its temperature before being pumped to the common rail. The studied parameters include the in-cylinder pressure history, rate of heat release, mass fraction burned, and exhaust emissions. The results show that when the fuel temperature increases and the engine is operated without EGR, the brake specific fuel consumption (bsfc) decreases, engine efficiency increases and NOx emission slightly decreases. However, when EGR is used while fuel temperature is increased, the bsfc and engine efficiency is independent of fuel temperature while NOx slightly increases.