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PTC heater for fuel ramp with temp 70-80 C
https://www.etanol.nu/forum/viewtopic.php?f=12&t=4534
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Författare:  aryan [ sön 09-11-08 20:09 ]
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I asked one of he Bosch engineers involved in designing the flex start system about the systems coldstart abilities with E85 and the tyoe of glowplugs used and got these answers:

Citat:
Regarding you specific questions:
_ We did some initial studies about the use of the tecnology to start a vehicle at -30 degC. We used a brazilian car, with the same oil, using the brazilian gasoline to prepare the ethanol and we could start a vehicle down to -25 degC. I do believe ther is room for improvement, once as I said it was a basic evaluation of the potential. One critical point here is that the system requires a pre-heating time for the fuel to reach a minimum temperature. This could be minimized by incresing the gasoline content in the fuel misture during winter.

_ Although the heating elements looks like a typical Diesel glow plug, they are not. They are designed to resist the continuous exposition to E100 (93% Ethanol + 7% Water) with no problems and the power in higher.

I had the opportunity to have preliminary discussions about the technology with SAAB, about one year ago.

Författare:  Obormot [ sön 09-11-08 20:31 ]
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as i understood:

1. this is usual glowplug, but with spesial anticorrosion coating or something like that

2. engine can be started with only fuel heating up to -25...-30 C

is it correct?

Författare:  aryan [ sön 09-11-08 20:53 ]
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Obormot skrev:
as i understood:

1. this is usual glowplug, but with spesial anticorrosion coating or something like that

2. engine can be started with only fuel heating up to -25...-30 C

is it correct?


Yes this is how I understood it too, but I think for -25°C they mixed a E85 from ethanol and gasoline.

With waterfree E85 one does not neet to be concerned about the glowplugs corrosion, I would ot be so worried about that anyway.


/Aryan

.

Författare:  Obormot [ sön 09-11-08 21:29 ]
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we using ethanol with 7-8% of water - an i not see any sense to remove it, if we will not use gasoline to mix with ethanol.

additives solving all problems with corrosion - we made tests with copper, aluminium, steel, lead and tin - glass cans with this metals was filled with our fuel and everything is OK.

and there are visible corrosion on metals in cans, filled with pure 92% ethanol.

Författare:  askilje [ sön 09-11-08 21:33 ]
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this is OT but where do you find 92% ethanol.

Författare:  aryan [ sön 09-11-08 22:50 ]
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Brasil & Ukraine :-)

I wish we could get it here too.

/Aryan

Författare:  aryan [ lör 09-11-14 00:45 ]
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This is what the Brasilian flexstart engineer tells me about their tests:

Citat:
aryan skrev:
- Did I understand correctly that you could start at -25°C with a mixture of 15% Brazilian gasoline and 85% anhydrous (waterfree) ethanol if you waited long enough for the flex start system o heat the fuelrail or was it with even less (no?) gasoline in the fuel?


_ We were able to start a vehicle @ -25°C using a mixture of 15% Brazilian Gasoline + 85 Hidrated Ethanol (~ 7% water).


Not bad with the 7% water!

Citat:
aryan skrev:
- Are the heating plugs that you use internally temperature controlled like a PTC so that they are preset for a temperature of for example 100°C or does the electronic controle system control the temperature of the plugs?


_ The heating elements have a PTC feature in the sense their resistance increases with temperature but they are not like typical ceramic PTCs in which the temperature is pre-detrmined by the composition of the ceramic.


So they are probably using current controlled fast glowplugs, like I suspected.

Citat:
aryan skrev:
- Would it not be an even better solution to start with electric heated fuel and than hose a heat exhanger before the fuel rail to continue to heat the fuel with the cooling liquid once the engine gets warm? If that can help to evapourate the fuel more completely before ignition, both fuel consumption and also HC and CO emissions should become lower, but may be NOx would get higher?


_ Regarding your idea of using the heat generated by the engine to sustain the fuel heating, it is a nice idea.
Indeed we have evaluated it. The concern is that we basically need to heat up the fuel only for the engine to start and
during the warm-up phase because once the water temperature increases to a minimum value the engine reachs a good
burning efficiency and you do not need to keep heating the fuel. Basically 90% of the emission occurs in the first 90s of
operation. Another issue is the control of the fuel temperature in all opetaing condition which is not cheap.
Normally when HC is reduced the NOx increases, but this can be compensated by re-adjusting the catalyst converter operating window.

Författare:  karlmb [ fre 09-12-25 17:03 ]
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Obormot skrev:
now temperature is about 0 ... -2 C, gasoline in ethanol is 2-3%, engine with 3-4 min of fuelrail preheating starts pretty good - in 2-3 second of cranking.

i try to turn off heating when driving - difference is big, driveability decreases, fuel consumption in city mode increases, about 0.8 l/100 km.

middle of fuelrail is hot, but the ends are just warm - i think if heating will be more uniform it will work much better.

power consumption of heaters on hot engine is about 20-30 W.


This shows that Bosch engineer are not telling all the truth, also during running with warm engine it is beneficial to heat the fuel.
But Bosch saw a too high price for such a system and choosed to not include a coolant heat exchanger before the heated fuel rail.
Economics ruined a good idea, again...

Författare:  mbuhre [ fre 10-01-22 16:22 ]
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Powerful but unfortunately too hot, I'm afraid:

http://www.conrad.se/?article=532894

I have not found suitable PTC elements for sale in Sweden. Anyone else?

Resistance wire would be simple to apply on the fuel rail, but the temperature must be monitored, and I'm not sure of how to avoid short circuit. Has anyone found a suitable isolated wire, or another isolation method?

Författare:  askilje [ fre 10-01-22 16:36 ]
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nä jag tror inte den är för varm. Man får endel värmeförluster och etanolen är inte i kontakt med elementet och bränslet i FR hinner bytas ut. Jag funderar på 2 st sånna element och sätta fast på FR som kallstartshjälp.

Författare:  Obormot [ fre 10-01-22 16:45 ]
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those PTC elements much cheaper and have stabilising temperature 80±10ºC

i think i can find such elements with 120±10ºC temp.

Bild

Författare:  J.K Nilsson [ lör 10-01-23 11:23 ]
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askilje skrev:
nä jag tror inte den är för varm. Man får endel värmeförluster och etanolen är inte i kontakt med elementet och bränslet i FR hinner bytas ut. Jag funderar på 2 st sånna element och sätta fast på FR som kallstartshjälp.

På 900:an?

J.K Nilsson

Författare:  askilje [ lör 10-01-23 16:17 ]
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jaa 900an, tror du inte att det fungerar??

Författare:  J.K Nilsson [ lör 10-01-23 18:00 ]
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Enklare att tjuvkoppla värmeplattor. ;)

J.K Nilsson

Författare:  askilje [ lör 10-01-23 18:15 ]
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jodå, det har jag försökt :) jag kopplade 12v + till alla fyra kablarna. jag tyckte inte det fungerade så bra. Och sen hittade jag ingen brytare som höll för så starka strömmar som det handlade om.

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