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Fuel Aditives


Morningmist

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2 minutes ago, cuthound said:

Data centres varied, but most did a monthly on load test for 5-12 hours, because a lot of money was at stake.

 

I used to know a chap in charge of disaster planning for one of the big UK datacentres. who insisted on real testing of standby power, not simulations.

 

At his new job he ran this test for the first time and all went well. 

 

The second (and last!) time he scheduled the test they discovered that the master plan didn't include replacing the start cartridges in the gensets after conducting the previous test ...

 

 

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3 minutes ago, TheBiscuits said:

 

I used to know a chap in charge of disaster planning for one of the big UK datacentres. who insisted on real testing of standby power, not simulations.

 

At his new job he ran this test for the first time and all went well. 

 

The second (and last!) time he scheduled the test they discovered that the master plan didn't include replacing the start cartridges in the gensets after conducting the previous test ...

 

 

 

In the lead up to the millennium I persuaded BT that a black start (actual mains fail) at each of the then circa 6,500 exchanges was a good idea, to prove that the standby generators would work.as intended should the widely predicted "millennium bug" take out the mains electricity.

 

The project was approved but several issues were noted during its execution..

 

Many customers had installed sensitive mains powered equipment without installing UPSs, who then wanted the project stoppingbecause of the disruption it was causing them.

 

Fortunately the board agreed with me and they had to stump up the cost of the UPSs whist the project continued.

 

At some sites the generators overheated because the Faciliities Department had fixed covers over the air inlet and air exhaust louvres because they saw them as a building security risk. Again the board supported me and Facilities had to find alternative security solutions pronto.

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1 hour ago, cuthound said:

 

Frequency and rigorousness of testing depends on who owns it.

 

The hospitals I've  installed them in tend to go for monthly 5 minute off load tests, presumably because its cheap, even though lives at stake. ?

 

BT did monthly on load tests until the engine had warmed up, plus 5 yearly "black star" (actually fail the mains, rather than use a test button).

 

Data centres varied, but most did a monthly on load test for 5-12 hours, because a lot of money was at stake.

We use to do a weekly load test including paralleling to the gas powered engines

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The hospital that I was based at did a proper blackout test of the generator once a month on a Friday.  The test was for three hours so the engine got up to temperature, supplying the full site load.  This was a mental health hospital, so nowhere near as onerous as an acute hospital.  We did have the main computer centre for the organisation on site, but had a good UPS set up.

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22 hours ago, Tony Brooks said:

I still cant see any reference to fuel consumption in that link or on the Crown website.

 

Me thinks we have another example of  people confusing the benefits of  cetane rating for diesel and octane rating for petrol.

 

Unless I can see either a consumption test result or the energy density of HVO fuel I do beleive better consumption can be legitimately claimed.

 

This is not to denigrate any of its other advantages but I think it vital people do not make claims they can't substantiate.

Sorry Tony, I thought the 10% improvement in fuel consumption claim was in there. In fact I have got it in my notes from a recent Crown Oils webinar which went into much greater detail about the Land & Water trial. I'm afraid I don't have a copy of that particular slide but if you trust my note taking, then the claims re fuel consumption and reduced NoX are true! I back your observations re cetane level as, although no chemist, I recognise that the relationship between power output and cetane levels is less than straightforward and cannot be directly correlated.

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22 hours ago, Tony Brooks said:

 

Ah - taken from an additive company website. Its bullshine.

 

As I explained to LadyG a short while ago the cetane number describes how readily the fuel will ignite and by implication how long the delay period is. The higher the cetane number the faster it ignites and the shorter the delay period, this in turn reduces diesel knock. The delay period is measure in milliseconds or less so shortening it will make little difference to the power produced by burning a  specific quantity of fuel in the engine.

 

In a petrol engine with modern computer control a higher octane number allows the ECU to advance the ignition to the maximum safe degree  as the engine  speeds up. this will give more power and better fuel economy.

 

it may be that modern common rail injection systems can alter the injection timing but I have not heard of any manufacturer fitting a diesel knock sensor yet and without that the the ECU can never know when to advance or retard injection  for maximum performance. Happy to be poven wrong about the knock sensor.

 

Rotary pumps can and do alter the injection timing but its done by indirect reference to pump speed (transfer pump pressure) but the cetane rating can not influence this action in any way.  Very few inline/individual injector pumps have a method of automatically altering the injection timing. They all need a many with spanner to do it.

 

In our types of engines it is unlikely to make a significant difference economy wise.

Your observations re burn patterns and injection timing (if I may take a somewhat simplistic approach) go a long way to explaining in my mind why an engine fuelled by HVO can have the injection timing retarded by 1 deg to reduce NoX by up to 35% while still maintaining the same (or a similar) power output. This was also the case with engines fuelled by 1st generation biodiesel, only in this case the power output took a hit!

 

I do have a copy of the Crown Oils presentation which goes into detail about the properties of HVO (including density) but unfortunately its in pdf form. Happy to share if you pm me with an email address.

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1 hour ago, Up-Side-Down said:

Sorry Tony, I thought the 10% improvement in fuel consumption claim was in there. In fact I have got it in my notes from a recent Crown Oils webinar which went into much greater detail about the Land & Water trial. I'm afraid I don't have a copy of that particular slide but if you trust my note taking, then the claims re fuel consumption and reduced NoX are true! I back your observations re cetane level as, although no chemist, I recognise that the relationship between power output and cetane levels is less than straightforward and cannot be directly correlated.

I fully accept what you said was in good faith and trust our note taking. From what you say I think the energy density of HVO is probably slightly higher than regular DERV so it would return a better fuel consumption. I also suspect the hydrogen-carbon content is different as well to give the lower NOX etc.

1 hour ago, Up-Side-Down said:

Your observations re burn patterns and injection timing (if I may take a somewhat simplistic approach) go a long way to explaining in my mind why an engine fuelled by HVO can have the injection timing retarded by 1 deg to reduce NoX by up to 35% while still maintaining the same (or a similar) power output. This was also the case with engines fuelled by 1st generation biodiesel, only in this case the power output took a hit!

 

I do have a copy of the Crown Oils presentation which goes into detail about the properties of HVO (including density) but unfortunately its in pdf form. Happy to share if you pm me with an email address.

Thanks

 

no need to PM. My email is in the public domain - Tony@tb-training.co.uk.

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1 hour ago, Tony Brooks said:

I fully accept what you said was in good faith and trust our note taking. From what you say I think the energy density of HVO is probably slightly higher than regular DERV so it would return a better fuel consumption. I also suspect the hydrogen-carbon content is different as well to give the lower NOX etc.

 

My understsnding is that NOx is produced by the high combustion temperstures oxidising the nitrogen in the aspiration air.

 

If so, how can using HVO reduce NOx unless the combustion temperature is reduced (perhaps by retarding the timing)?

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1 hour ago, cuthound said:

 

My understsnding is that NOx is produced by the high combustion temperstures oxidising the nitrogen in the aspiration air.

 

If so, how can using HVO reduce NOx unless the combustion temperature is reduced (perhaps by retarding the timing)?

I am a mechanic cum engineer not a combustion expert but it seem to me that there may be nitrates in fuel and the quantity may feed through to the amount of Nox produced. I agree it is normally quoted as combustion temperature related which is why the dilute the charge with EGR and there by reduce the peak temperature.

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NOx IS the nitrogen in the atmosphere getting oxidised by the high temperatures and pressures in the cylinder. Modern electronic controlled diesels run very retarded at high loads to avoid this, and then try to use faster burns to avoid the issues of retarded injection.

 

Measuring fuel consumption is very difficult (I have done it) so I would not put too much emphasis on the report from Land and Water. Unless its done on a test engine on a test bed in controlled conditions then the results are questionable. If you tell people they are using a new fuel or doing a consumption test they will likely drive more carefully. Weather is also a big factor so before and after tests need to be done in similar weather conditions.

 

..............Dave

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21 minutes ago, dmr said:

NOx IS the nitrogen in the atmosphere getting oxidised by the high temperatures and pressures in the cylinder. Modern electronic controlled diesels run very retarded at high loads to avoid this, and then try to use faster burns to avoid the issues of retarded injection.

 

Measuring fuel consumption is very difficult (I have done it) so I would not put too much emphasis on the report from Land and Water. Unless its done on a test engine on a test bed in controlled conditions then the results are questionable. If you tell people they are using a new fuel or doing a consumption test they will likely drive more carefully. Weather is also a big factor so before and after tests need to be done in similar weather conditions.

 

..............Dave

My thoughts exactly. Then you get the marketing people doing their near lies and exaggerations.

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5 minutes ago, MartynG said:

Crown Oil say HVO is a bout 20p per litre above the cost of  diesel.

That's subject to the same duty and vat as diesel it seems .

 

So would people pay that voluntarily ?

 

 

If the choice was £25k-£35k for an electric 'system' OR 20p per litre I think I'd go ................................................................

 

 

for the HVO

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59 minutes ago, Alan de Enfield said:

If the choice was £25k-£35k for an electric 'system' OR 20p per litre I think I'd go ................................................................

 

 

for the HVO

That's what I am thinking .

 

 I am not likely to be ordering a tankful of HVO for tanker delivery  but would consider it if available at the marina pump .

 

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