Running straight WMO with electric pre-heater instead of 2 tank system

ut99dot1

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Wiith rising fuel prices, running 20% RUG in summer (and 40% in winter) is becoming expensive..

Instead of mixing the WMO some people run a 2-tank setup, but then you will be consuming diesel to warm up the car. Approx 5 gallons per month for my situation I calculated.
(Say 10min to warm it up, avg. speed 30mph, 40mpg (car will be using more when cold but let's not go into that much details). In 10min you will do 5miles, so 0.125gal per trip. Driving to work 4weeks, 5 times per week, 2trips per day means 5gal)
Also 2 tank system adds complexity, another tank to fill, need to switch before turning off car.

So then the third option I thought of is an electric pre-heater. Here some calculations, to prove it if it's theoretically possible. I'll be using the metric system cuz its easier;

1. What is achieved by 20%/40% RUG (summer/winter)
- Gasoline viscosity is approx 0.75 cSt at 20C / 60F: https://www.engineeringtoolbox.com/kinematic-viscosity-d_397.html, at 0C I couldn't find but say its 3
- Motoroil (10W40) is approx 250 cSt @ 20C and 1000 cSt @ 0C. See "motoroil_cst" attachment.

20% Rug blend @ 20C: +- 60 cSt
40% Rug blend @ 0C:+- 50 cSt

So we obtain 55-ish cSt. This is in the right ballpark as literature explains 10-15 cSt (but this is marine diesel direct injection, I use IDI, which is more forgiving, needs less pressure, etc)
From the marine diesel engine operational point of view, injection viscosity that is, viscosity at which fuel is injected into the engine, is of critical importance as it will make a difference in the ignition and combustion in the diesel engine. Usually engine makers stipulate a viscosity range of 10 to 15 cSt.

or
Residual Fuels invariably have to be heated to reduce the viscosity to that required for atomization. For diesel engines the injection viscosity is usually in the range 8-27 cSt, while for a steam plant the atomization viscosity is usually in the range 15-65 cSt.

2. What temperature do we need the oil to be at?
Extrapolating data, says approx 45-50C (or 120F) to lower 10W40 viscosity to acceptable range 50-60 cSt (see temp.png)
This can be achieved by using heat from engine coolant, but that will be cold at coldstart. So can we use electric heating?

3. What kind of electric heating do we need to heat the oil?
Before we calculated that we need 0.125gal in order to heat the engine to operating temperature. After that we can use coolant heat.
0.125gal = 0.5liters WMO. And we must heat that to 50C. Some more info's:
- Specific heat of oil is approx 2.0 kJ/kg/C (https://www.researchgate.net/figure...nts-as-function-of-Temperature_fig1_326488375)
- 0.5l wmo is approx 0.425kg

Two scenario's:
a. freezing outside (-10C). From -10 to 50 is 60C of heating
b. normal temp (20C). From 20 to 50 is 30C of heating

In order for the car to start fuel needs to be at right temp. So say you have 0.425kg of fuel in the red part of the fuel system (filter, pump, ...; see preheated_circuit).
- At -10C, if you allow it to warmup for 2.5 minutes, you will need 0.425×2×60×1000 ÷ (2.5×60) = 340W
- At 20C, if you allow it to warmup for 1 minute, you will need 0.425×2×30×1000 ÷ (1×60) = 425W

4. Conclusion
So you will be looking at a ballpark of +- 1kW of heating considering all the heat losses and other inefficiencies. Possibly reducible to 100W if :
- Better insulation (so less heat losses, say cut by 50%)
- Decrease fuel-amount in red part of circuit (say also 50%)
- If you can get away with heating it only to 40C instead of 50C (1 - 40/50 = 20% decrease in energy needs), viscosity would be 60-75ish.
- Willing to wait longer (5 min at -10C, 2.5min at 20C, 50%)
1000 * 0.5*0.5*0.2*0.5 = 25 watt, which is in the 100W ballpark range

100 to 1000W heaters are available, so I will be attempting this. I'll keep you posted.
 

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  • motoroil_cst.png
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NeverHave-I-Ether

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Instead of an electric ore heater which is expensive, troublesome, and inefficient, just run your fuel lines through the coolant line like veggie folks do.

Never-Have-I-Ether
 

ut99dot1

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Instead of an electric ore heater which is expensive, troublesome, and inefficient, just run your fuel lines through the coolant line like veggie folks do.

Never-Have-I-Ether
I'm doubting it would start with 100% WMO during winter, so I plan to use an electric heater for the first couple of minutes until engine is warm. Once it's warm I'll be using the coolant lines like the veggie peoples indeed =)
 

Jesus Freak

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I'm doubting it would start with 100% WMO during winter, so I plan to use an electric heater for the first couple of minutes until engine is warm. Once it's warm I'll be using the coolant lines like the veggie peoples indeed =)
I live on earth too, in NW Florida. I was doing the 2tank thing initially but ended up just running straight WMO. My oil does come from a junkyard so there is gas and diesel and other stuff in it, but I started just cranking my truck up on ether. I'm retiring that truck for a while to do some big maintenance stuff and I'm bringing my tow truck on line (if I can get it insured) but I'm going back to a two tank system...... maybe. I want to use my glow plugs to start it instead of ether. If you look up a thread I started called "how do you start your engine on WMO" there's a bit of people's opinions there.
 

Jesus Freak

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I attempted to understand your technical data, but I'm at a loss.(I barely have a high school education) But I'll say this, I don't think you can efficiently have WMO as a science. There's too many variables that you can't really control, mainly the waste oil you get. I guess you might get some kind of consistency but I don't know.
 

ut99dot1

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yeahhh I have the same feeling. Sometimes I dump in the WMO straight in the tank after filteirng and it runs perfect, other times it smokes like crazy.
In anycase, forget the entire story. Point is, I expect to need to run a 500 to 1000 watt heater for 1 to 2.5 minutes to get the car to start on pure WMO. The electric heater circuit would look like this:

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Then once engine is up to temperature, the electric heating is turned off and the heat exchanger is used:
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I'll keep you posted on progress
 
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Jesus Freak

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Hey, there's a 85 Mercedes 300 turbo diesel on Craigslist not far from me for $800! I'd love to get it and experiment with it myself, but I just don't have the extra $ right now.
 

NeverHave-I-Ether

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Hey, there's a 85 Mercedes 300 turbo diesel on Craigslist not far from me for $800! I'd love to get it and experiment with it myself, but I just don't have the extra $ right now.

Explain to me the different Mercedes. The engine names confuse me. The 2 popular ones I'm aware of are the 606, 617.

Never-Have-I-Ether
 

Jesus Freak

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Explain to me the different Mercedes. The engine names confuse me. The 2 popular ones I'm aware of are the 606, 617.

Never-Have-I-Ether
...I don't know anything about it.....I can tell you they don't say "FORD" anywhere on them, so I know nothing. But there's a cheap one on Craigslist..... and it's a diesel that will run on WMO (you now know alllll that I know)
 

ut99dot1

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I'm back at it, and this time with a more practical approach, with only off the shelf products.

On the 1.2l TDI engine, the fuel pre-heating valve does not open
up the path to the fuel tank until the fuel temperature exceeds
60°C (1.4l TDI engine >30°C).

page38 http://www.volkspage.net/technik/ssp/ssp/SSP_223.pdf
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Forget all calculations above. Basically, if you let this heater run for 2 to 5 minutes the fuel should be warm enough to cold-start on straight WMO.
Best of all less than 50$ total parts;

Parts:
https://aliexpress.com/item/4000516880578.html for filter heater
OE 1J0127250 Clip ($3)
OE 1J0127247C Thermostat ($6)
6Q0127401D Fuel Filter ($10)

I ordered all stuff, will let you know once installed & tested.
 
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ut99dot1

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Didn't install the heater yet, circulation pump got wrecked, waiting on new parts.

Car ran perfect on 50-50 diesel/wmo mix. Then added 5gal of straight WMO.
Was 20F during the night, didnt start this morning at 30F, even 10min +- cranking.
Then 1h later, still 30F, started up immediately. Strange.

I think it got warmed up just a little; even more reasons to believe the electrical heater might work.
 
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