Powerboost Exhaust Heat Exchanger Delete

[Samson16]

I think the other big issue is that whenever it's really cold, the ICE stays on. The engine on/vehicle on delta between an auto start/stop 3.5L and a PB is in practice very small, particularly if the PB has heavier tires. In the Aviator hybrid, which has a roughly 2x as powerful electric motor, always wears P rated tires and has a 10x bigger battery, I could see the heat exchanger being a far more important part for warming the drivetrain in a timely fashion.

Most of my traction motor only operation occurs during slow speed driving environments after warmup. From a stop my PB is noticeably smoother than auto start/stop vehicles, but the ICE kicks in during the roll as I'm exiting the intersection. Lighter, stiffer, EV tires would eek out a few more mpg, but it wouldn't be very useful at truck things anymore.

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[amschind]

Fascinating. So your answer to the heat buildup while under heavy load(granted typically at higher altitudes while maintaining or exceeding speed limits..) is to insulate the exhaust pipes and reduce restrictions?

I like it, but I wonder if the largest sources of heat and restriction, the turbos, will render your efforts to that of placing an ice cube in an oven to lower the temperature?

I agree, and I cannot do the math to prove it one way or the other, but here's my logic.

The exhaust system has major restrictions that I like (the turbos) and major restrictions that I want to reduce to the limit of the law (and this truck will never see California, so that helps). While the turbos fix the floor of the restriction above a NA exhaust, they ALSO exacerbate the effect of downstream restrictions by being a very effective radiator for exhaust heat. They're in far more contact with exhaust gas than a piece of exhaust pipe (surface area for exhaust gas, surface area for surrounding engine compartment, more complex gas flow patterns) and as a result magnify the effects of downstream restrictions by capturing and radiating exhaust heat.

So the turbo will LIMIT potential back pressure reduction, but because it also magnifies the negative effects of reduced exhaust flow in terms of heat radiation where you don't want it, the benefits of back pressure reductions are also relatively increased. Numbers would of course be ideal, but I'm not equipped to do those complex flow and heat transfer calculations so I am stuck with guessing. I am worried about trapping heat in the exhaust manifolds and affecting the aluminum heads by transferring more heat to them, so I will probably set up a temperature probe on the manifold/head junction and test it before and after installing the manifold blankets. That data should give some idea of effectiveness, particularly if I also measure under hood temperatures as Hamma suggested in another thread.

 

[amschind]

Most of my traction motor only operation occurs during slow speed driving environments after warmup. From a stop my PB is noticeably smoother than auto start/stop vehicles, but the ICE kicks in during the roll as I'm exiting the intersection. Lighter, stiffer, EV tires would eek out a few more mpg, but it wouldn't be very useful at truck things anymore.

I completely agree. My point was just that when it's cold OR you just have heavier tires, the ICE is on nearly as much as it would be in a regular 3.5L truck.

 

[Samson16]

So the turbo will LIMIT potential back pressure reduction, but because it also magnifies the negative effects of reduced exhaust flow in terms of heat radiation where you don't want it, the benefits of back pressure reductions are also relatively increased.

That is interesting and I hadn't considered the longer the heated gas remains near the turbos, the more heat the oil has to remove from them and by extension the coolant.

I know!

We bond the turbochargers' impeller and shaft with Vanadium Dioxide to minimize heat transfer.

You're welcome Universe

 

[HammaMan]

That is interesting and I hadn't considered the longer the heated gas remains near the turbos, the more heat the oil has to remove from them and by extension the coolant.

The turbo's have coolant running through them as well as oil. The coolant does more cooling on the turbos than the oil does

 

[amschind]

So Hamma finally pressed me on it and I looked through the wiring diagrams.

Determining which wire is "brown" is a bit of a challenge, but now the only remaining task is figuring out the wires on the dummy connector. I believe that the control and sensor wires should reveal their secrets with a multimeter and a 12v and maybe a 5v source: I bet the control wire is an SSR gate, so if and only if I apply 5/12v to that wire, then the 12v source will be in continuity with ground. That doesn't tell me the polarity on the +12v and GND. That leaves the gate wire as the odd man out.

I'm open to ideas.

 

[Samson16]

Determine the pin out convention for the connector. 1-4 one way or the other. From the right 1,2,3,4.

 

[amschind]

Determine the pin out convention for the connector. 1-4 one way or the other. From the right 1,2,3,4.

II'm taking about the wires on dummy connector, which is designed for a BMW motorcycle exhaust sound dampener. That had a completely different connector (I e. BMW motorcycle specific) that I chopped off leaving 4 wires. Thus there's zero reason to expect that the wire order on the dummy plug will have anything to do with the wire order in the Ford harness. It could well be the exact same, but the odds are low enough that I have to assume zero relationship.

Good thoughts, sorry for not providing sufficient detail.

 

[Samson16]

Ahh, well I hope you are able to spoof a properly functioning EHEV

 

[Samson16]

The turbo's have coolant running through them as well as oil. The coolant does more cooling on the turbos than the oil does

I didn't know that. Thanks.
How much energy does the HV AC compressor consume while operating? A second one for the turbos is needed. Finding space is tricky.

 

[amschind]

I didn't know that. Thanks.
How much energy does the HV AC compressor consume while operating? A second one for the turbos is needed. Finding space is tricky.

They kind of did that with the water cooling. A rankine cycle refrigerator (r.g. the AC) is necessary to move heat AGAINST a gradient, but the turbos are very hot vs ambient air even in the hottest desert, so if you can thermally couple the turbos and the rest of the world, heat will just flow without needing to be "pumped". That's where the water cooling comes in: a little added complexity, but way better heat transfer from the turbos to the ambient air.

 

[Samson16]

They kind of did that with the water cooling. A rankine cycle refrigerator (r.g. the AC) is necessary to move heat AGAINST a gradient, but the turbos are very hot vs ambient air even in the hottest desert, so if you can thermally couple the turbos and the rest of the world, heat will just flow without needing to be "pumped". That's where the water cooling comes in: a little added complexity, but way better heat transfer from the turbos to the ambient air.

I was thinking since they've already added a secondary isolated cooling loop whereby the water/coolant mix is cooled by an evaporator coil for the HVB, why not employ a second HV powered AC unit to cool the turbos?

 

[Samson16]

We've already jumped the "complexity" shark for the PB anyway lol.

 

[amschind]

I was thinking since they've already added a secondary isolated cooling loop whereby the water/coolant mix is cooled by an evaporator coil for the HVB, why not employ a second HV powered AC unit to cool the turbos?

The big reason is that the battery's thermal envelope is far narrower than that for something like an engine or in this case a turbo. Pumping heat with a rankine cycle is FAR more energy intensive (read "less efficient") than a simple water pump and radiator, but there's no other way to move heat AGAINST a gradient. In the case of the battery, which has oddly similar temperature requirements to a human body, the ambient temperature may be outside of the desired range. That means that in order to keep the battery below say 90F on a 110F day, we have to make use of a rankine cycle heat pump because a fantastically large water pump and radiator will only get the battery to 110.01F (or may even heat it up, which is exactly the opposite of the goal).

The benefit that the turbo has in terms of cooling over the battery is a very high operating temperature relative to ambient, meaning that the limitation isn't the DIRECTION of heat flow, but only our ability to allow that heat to flow. Practically, that means the size of the cooling circuit within the truck, heat exchange limitations imposed by the shape and material of the turbo itself and pulling so much heat off of the turbo that you are removing energy that it could've safely extracted. A rankine cycle cooler would absolutely work to cool the turbo, but the temperature delta means that we aren't forced to use all of the extra energy that a heat pump would require over a simple radiator.

I hope that makes sense.

 

[Samson16]

A rankine cycle cooler

Mostly over my head, except that I think the turbos require more volume cooling capacity and the high temps they generate negate the need for below ambient temp to draw away the heat. The difference of potential is already there.(I relate most things to voltage and current like pressure and volume so forgive me).

I also now must learn what a rankine cycle is, so thanks for that professor.

I will say however, that high ambient temps do seem to exacerbate the condition(reducing available pressure), and thin air likewise(reducing available volume) sir.

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