Thread: Diesel Gas

i would like to agree with Pat here !

i would like to add dyno dynamics dyno's have not been produced to give faulse/useless readings hence why they have probably been used in development in such systems as diesel gas and have not used there own way to figure out the performance of there vehicle via using slopes and product horsepower ratings like "some" people like to do
i see that some people figure out horse power by saying there new intercooler is said to be 25hp gain so add the 25hp to the stock hp of the truck then they go and buy something else that is said to be so much hp gain and so on and so forth until they have came up with a truck that has twice the hp rating of the standard but the problem with that is they did not take into account when the standard engine is tested to be say 50hp the makers done the testing in absolute perfect circumstances (water being forced through the engine,air being forced past the engine via an external source,test fuel not sump oil like australia gets and the engine usually has no auxillaries such as alternator etc etc) so once the engine is put into its environment where it operates the hp rating has droped considerably.

gas injection
1.its not going to be crap considering so many countrys around the world reconise it as being a benefitial upgrade for diesel engines

2.why has it been played with for so long if it is crap??? wouldnt they have gave up on it by now!!!

3.as others have stated it is a bit more complex than pouring coupious amounts of LPG into the air intake

4.and as for this pre ignition that some people are worried about that is probably one of the reasons why the system has a computer system to allow the correct amount of gas in at the correct time.

5.as pat said he has run it on his for "quiet" a few kilometers without any problems and tdi's are a bit more refiened than most other diesel engines on the market and if it has handeled it without any problems i dont see why other diesel engines found in landys would be different.

Originally Posted by c.h.i.e.f

gas injection
1.its not going to be crap considering so many countrys around the world reconise it as being a benefitial upgrade for diesel engines

Actually, which countries is it used in??? To my knowledge it is quite rare outside Australia.

The R&D has all been done by quite small companies. No engine or vehicle manufacturers seem to have shown any interest at all, however they have put a lot of R&D into natural gas.

I agree though that there seem to be increasing numbers of people with these systems fitted, and there don't appear to be any major issues. However there seems to be a need for some serious, independant research on the long term effects of running such a system.

Originally Posted by c.h.i.e.f

i would like to agree with Pat here !

i would like to add dyno dynamics dyno's have not been produced to give faulse/useless readings hence why they have probably been used in development in such systems as diesel gas and have not used there own way to figure out the performance of there vehicle via using slopes and product horsepower ratings like "some" people like to do
i see that some people figure out horse power by saying there new intercooler is said to be 25hp gain so add the 25hp to the stock hp of the truck then they go and buy something else that is said to be so much hp gain and so on and so forth until they have came up with a truck that has twice the hp rating of the standard but the problem with that is they did not take into account when the standard engine is tested to be say 50hp the makers done the testing in absolute perfect circumstances (water being forced through the engine,air being forced past the engine via an external source,test fuel not sump oil like australia gets and the engine usually has no auxillaries such as alternator etc etc) so once the engine is put into its environment where it operates the hp rating has droped considerably.

gas injection
1.its not going to be crap considering so many countrys around the world reconise it as being a benefitial upgrade for diesel engines

2.why has it been played with for so long if it is crap??? wouldnt they have gave up on it by now!!!

3.as others have stated it is a bit more complex than pouring coupious amounts of LPG into the air intake

4.and as for this pre ignition that some people are worried about that is probably one of the reasons why the system has a computer system to allow the correct amount of gas in at the correct time.

5.as pat said he has run it on his for "quiet" a few kilometers without any problems and tdi's are a bit more refiened than most other diesel engines on the market and if it has handeled it without any problems i dont see why other diesel engines found in landys would be different.

There are a multitude of ways to measure power, dismissing one method of measurement because it doesn't involve a big shiney machine with lots of user-set variables suggests a lack of understanding.
Dyno readouts are well known for variation as well as giving the customer the numbers they want, their best use is comparison on the day.

As Isuzurover has said, outside Australia very few people care about lpg fumigation. The only reasons it's done in Australia are cheap gas and government subsidies. If gas cost more than diesel (as it does in most places) and you had to pay the whole $4k yourself. Why would you do it?

In the US and Canada people have run it for power gains, but they seem to have give up. The problem appears to be a lot of broken parts for a small power gain. Diesel alone gives more power without the problems.
So yeah, they've given up on it.

In spite of all the marketing out there, it is about adding lpg to the intake. That's all these systems do, the only things they can change is how much they add and when.

What is the correct amount of gas? How much is safe and at what point does engine damage result?
Simple questions with no forthcoming answer.

Hmm - there seem to be a few studies being done - however mainly on engines combusting small quantities of diesel and large quantities of propane.

Shock tube investigation of propane–air mixtures with a pilot diesel fuel or cotton methyl ester

H.E. Saleha and Mohamed Y.E. Selimb, Corresponding Author Contact Information, 1, E-mail The Corresponding Author

aMech. Power Eng. Dept., Faculty of Eng., Helwan University, Cairo, Egypt

bMech. Eng. Dept., College of Eng., UAE University, Al-Ain 17555, United Arab Emirates
Received 27 June 2008;
revised 9 September 2009;
accepted 10 September 2009.
Available online 25 September 2009.

Abstract

The propane (or LPG) is one of the best candidates as an alternative fuel in dual-fuel engines which operate primarily on any type of gaseous fuel using pilot injection of diesel to achieve ignition. The ignition delay has received considerable attention in the published literature for various gaseous fuels using different dual-fuel engines which showed that the ignition delay in a dual-fuel engine is different from that in a diesel engine especially at low loads. In this research, the measurement of ignition delay of propane–air mixtures with a pilot diesel fuel or cotton methyl ester (CME) similar to mixtures used in dual-fuel engines have been performed in a shock tube. The operating conditions were the equivalence ratio ranging from 0.3 to 1.2, the initial pressure varied from 0.4 to 1.0 bar, the initial temperature varied from 423 to 673 K, the relative mass of pilot liquid fuel and the type of liquid fuel. The ignition-delay times were measured using a piezo-electric pressure transducer, charge amplifier, data acquisition card, PC computer and LabVIEW program. From the results, it is shown that, the minimum ignition-delay time for the dual-fuel combustion was observed at stoichiometric equivalence ratio for propane–air mixtures with a pilot diesel fuel or CME. Higher initial temperatures and pressures reduced the ignition delay. Also, the ignition delays of propane–air mixtures are affected by changes in pilot fuel quantities and properties.

Keywords: Dual-fuel engine; Diesel; Propane; Cotton seed methyl ester; Shock tube



...



5. Conclusions
An experimental study on the ignition-delay times of propane–air mixture with pilot diesel fuel or CME was carried out in a shock tube. The ignition-delay times were measured using a piezo-electric pressure transducer, dual mode charge amplifier, National Instruments NI-DAQmx data acquisition card and data acquisition was managed on a computer using a LabVIEW program. Effects of equivalence ratio, initial temperature, initial pressure and different pilot of diesel fuel or CME on the ignition-delay times were investigated. The results obtained from this work are summarized as follows:

(1) The ignition delay period of propane–air mixture for various classes of pilot diesel fuel or CME is at a minimum at stoichiometric equivalence ratio of 1.

(2) In the lean and rich mixture region, the delay period was greater than the stoichiometric condition.

(3) The ignition-delay times of propane–air mixture with CME are greater than the ignition-delay times of propane–air mixture with diesel fuel.

(4) The ignition-delay time linearly decreases proportionally with the increase in both the initial mixture temperature and pressure.

(5) The value of ignition delay of propane–air mixture decreased with increasing the liquid fuel fraction of diesel fuel or CME. It is minimum value at the highest value of liquid fuel fraction of 50% for both liquid pilot fuels.

(6) The ignition delays of propane–air mixture are affected by changes in pilot liquid fuel properties.

(7) The pilot liquid fuel of diesel engine is suitable than CME for dual-fuel engines operation.

Effect of engine parameters and type of gaseous fuel on the performance of dual-fuel gas diesel engines-A critical review
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Author(s): Sahoo BB (Sahoo, B. B.)2, Sahoo N (Sahoo, N.)1, Saha UK (Saha, U. K.)1
Source: RENEWABLE & SUSTAINABLE ENERGY REVIEWS Volume: 13 Issue: 6-7 Pages: 1151-1184 Published: AUG-SEP 2009
Times Cited: 2 References: 45 Citation MapCitation Map
Abstract: Petroleum resources are finite and, therefore, search for their alternative non-petroleum fuels for internal combustion engines is continuing all over the world. Moreover gases emitted by petroleum fuel driven vehicles have an adverse effect on the environment and human health. There is universal acceptance of the need to reduce such emissions. Towards this, scientists have proposed various solutions for diesel engines, one of which is the use of gaseous fuels as a supplement for liquid diesel fuel. These engines, which use conventional diesel fuel and gaseous fuel, are referred to as 'dual-fuel engines'. Natural gas and bio-derived gas appear more attractive alternative fuels for dual-fuel engines in view of their friendly environmental nature. In the gas-fumigated dual-fuel engine, the primary fuel is mixed outside the cylinder before it is inducted into the cylinder. A pilot quantity of liquid fuel is injected towards the end of the compression stroke to initiate combustion. When considering a gaseous fuel for use in existing diesel engines, a number of issues which include, the effects of engine operating and design parameters, and type of gaseous fuel, on the performance of the dual-fuel engines, are important. This paper reviews the research on above issues carried out by various scientists in different diesel engines. This paper touches upon performance, combustion and emission characteristics of dual-fuel engines which use natural gas, biogas, producer gas, methane, liquefied petroleum gas, propane, etc. as gaseous fuel. It reveals that 'dual-fuel concept' is a promising technique for controlling both NO, and soot emissions even on existing diesel engine. But, HC, CO emissions and 'bsfc' are higher for part load gas diesel engine operations. Thermal efficiency of dual-fuel engines improve either with increased engine speed, or with advanced injection timings, or with increased amount of pilot fuel. The ignition characteristics of the gaseous fuels need more research for a long-term use in a dual-fuel engine. It is found that, the selection of engine operating and design parameters play a vital role in minimizing the performance divergences between an existing diesel engine and a 'gas diesel engine'. (C) 2008 Elsevier Ltd. All rights reserved.



6. Conclusion

Researchers in various countries have carried out many experimental works using gaseous fuels as diesel engine fuel substitute in a dual-fuel mode of operation. An attempt has been made here to review the previous studies on dual-fuel concept. The overall observation from these experimental results is that the engine operating and design parameters, namely, load, speed, pilot fuel injection timing, pilot fuel mass, compression ratio, inlet manifold conditions, and type of gaseous fuel play an important role in the performance of dual-fuel diesel engines. Some of the salient points showing the effect of above listed parameters on the performance of dual-fuel engines are listed below.
6.1. Effect of engine load

• The dual-fuel engine performance decreases at part load conditions. There is a minor reduction in power output and higher BSFC for the engines.

• Lower peak cylinder pressure is for a dual-fuel engine compared to the normal diesel engine at a given load condition, which is encouraging since no danger exists for the engine structure. Pressure rise rate (dP/dθ) increases with increase in load and is always higher than that of diesel fuel case.

• Combustion duration is longer compared to diesel operation at low load.

• Lower NOx and drastic decrease in soot emissions with all gaseous fuels. But, at all load conditions, CO and HC emissions are considerably high compared to the diesel case.

6.2. Effect of engine speed

• Thermal efficiency improves with increasing engine speed. Slightly higher equivalence ratios for a given speed condition of dual-fuel engines.

• Maximum combustion pressure is slightly higher than the diesel fuelling level at constant engine speed.

• Pressure rise rate decreases with increase in engine speed and is higher than that for diesel case.

6.3. Effect of pilot fuel injection timing

• An improvement in thermal efficiency is achieved by advancing the injection timing.

• Maximum pressure and pressure rise rate is higher for the advanced injection timing compared with diesel case.

• Advancing the injection timing at medium and high loads led to early knocking.

• Increase in NOx, and a reduction in CO and UBHC emissions with advance injection timing.

6.4. Effect of mass of pilot fuel inducted

• There is an improvement in thermal efficiency and torque output by increasing the amount of pilot fuel.

• Increasing the pilot fuel mass results in higher maximum combustion pressure but reduced maximum pressure rise rate.

• Early knocking with increase in the amount of pilot fuel at high loads.

• Increasing the pilot fuel and reducing primary fuel reduces the knocking phenomena.

• Higher NOx and reductions in CO and UBHC by increasing the amount of pilot fuel.

6.5. Effect of engine compression ratio

• Knock starts earlier when a high compression ratio is used.

• Increasing the compression ratio generally increases the combustion noise.

6.6. Effect of engine intake manifold conditions

• EGR with intake heating improves thermal efficiency.

• Excessive EGR ratio (>50%) causes the deterioration of combustion characteristics.

• EGR with intake heating reduces THC and NOx emissions.

6.7. Effect of type of gaseous fuel

• The engine performance is not deteriorated much with 40% CO2 in biogas as compared to the engine with NG (96% methane). But, 30% CO2 in biogas improves the engine performance as compared to the same running with NG.

• 60% gasoil substitution is possible by gas mixture without knock.

• Overall efficiency falls with gas mixture substitution and adding CO2 affects this more at higher speed.

• Sharp decrease in soot concentration, lower NO, and high HC and CO emissions with increase in NG mass ratio.

• Increasing the mass of gaseous fuel increases the combustion noise and maximum pressure for methane, CNG and LPG.

It seems that dual-fuel combustion using gaseous fuels is a promising technique for controlling both NO and soot emissions even on existing diesel engines with slight modification to the engine structure. The penalty in ‘bsfc’ experienced is partially compensated by the lower price of gaseous fuels. The observed disadvantages, at low engine load condition, concerning ‘bsfc’, HC and CO can be reduced by applying modifications in engine tuning, i.e. injection timing of the pilot fuel. Again, in diesel dual-fuel engines the ignition characteristics of the gaseous fuels are still to be understood and needs more research on it. Thus, in overall, the engine operating and design parameters, and selection of type of gaseous fuel has to be chosen accordingly for an existing diesel engine to run on dual-fuel concept. This can minimize the engine performance, combustion and emission characteristics divergences between the existing diesel engine and a dual-fuel diesel engine.

cannot say anything about what countrys etc etc because its not my place to say but i do know it is known outside australia!

i do not see how if a correctly setup gas system (such as diesel gas) can damage a engine anymore than running 20psi boost in a engine that is designed for max 13psi???

Originally Posted by c.h.i.e.f

i do not see how if a correctly setup gas system (such as diesel gas) can damage a engine anymore than running 20psi boost in a engine that is designed for max 13psi???

High boost and diesel fuel doesn't cause detonation or sharp rises in cylinder pressure. This is why the two aren't comparable.

Originally Posted by Dougal

High boost and diesel fuel doesn't cause detonation or sharp rises in cylinder pressure. This is why the two aren't comparable.

LPG and diesel doint cause detonation or sharp rises in cyliner pressure! so whats your point ???

Originally Posted by clean32

LPG and diesel doint cause detonation or sharp rises in cyliner pressure! so whats your point ???

Originally Posted by The Diesel Engine Reference Book PP617, Dual Fuel Engines

Propane - Poor detonation characteristics compared to Methane
Butane - Poor detonation characteristics

Only in marketing literature does lpg not detonate.
Maybe "doint" means "do" and we're in agreement.