I May Be Wrong About Water Injection WRT Improving Fuel Economy

[t vago]

Originally Posted by teoman

With an injector or orifice?

Haven't decided yet. I have both water-injection orifices and E85-compatible fuel injectors lying around.

[t vago]

I have in my possession a Lytron LL820G12 heat exchanger that I got off eBay. It's a 20 plate model, stainless steel plates, and is copper-brazed. It's supposed to be able to transfer over 64000 BTU/hr, or 19000 W. I suspect that this heat exchanger should have little trouble heating up a water/ethanol mix at about 150 grams/min to 90 C from whatever ambient temperature is.

It's a long sucker, about 330 mm long. And it apparently had been used in to past to do something with oils or grease, so I got to figure some way to decontaminate it. I've washed it as much as I could with pressurized water from my shower-based waterpik, so I'll probably follow up with denatured ethanol or something.

This, along with my ShurFlow pump that I dug out of storage, and an E-85 capable fuel injector that I have left over from my engine project of last year, will provide the backbone of my system.

[teoman]

Are you going to draw hot fluid from it or push through it?

Make sure your pump will be able to tolerate the heat if you pull through it.

If not, a checkvalve just before your nozzle will help provide a bit of backpressire to keep contents in.

[teoman]

ethanol evaporates at 67 deg C and methanol at 55 deg C if i recall correctly.

[oil pan 4]

Surflo pumps can handle chemicals but are no good for heat.

[t vago]

Originally Posted by teoman

Are you going to draw hot fluid from it or push through it?

I'm going to use the pump to push the water through the exchanger. I'm also considering the use of an accumulator to reduce the dynamic stresses on the water pump and tubing. Good idea on the check valve.

The Lytron unit is not suitable for what I want to do, though. It would appear that copper and ethanol do not play well together, and the Lytron unit uses copper for brazing the stainless steel plates together. For something that i supposed to heat up 50/50 mixtures of water and ethanol to 90 C, it's probably not a good idea to use this exchanger. I have found a nickel-brazed stainless steel heat exchanger,

[teoman]

Heated alcohol will need to be in a pressure vessel. Very mild pressure, but still pressure, or you will realize that your alcohol has escaped. (Or any alcohol that is after the checkvalve, before the nozzle).

If you are going to go that route, and you want to keep a tire pump in the car at all times, you can make the whole thing a pressure vessel and pump it with air. The air will pressurize the fluid and you will not need a waterpump.

[teoman]

Maybe use this to measure the pressure and switch the compressor on/off
https://www.aliexpress.com/item/4-Ba...5-450137b98990

[t vago]

Originally Posted by teoman

Heated alcohol will need to be in a pressure vessel. Very mild pressure, but still pressure, or you will realize that your alcohol has escaped. (Or any alcohol that is after the checkvalve, before the nozzle).

Why?

The water tank will not be heated, so the water-ethanol mixture will be at ambient. If anything, I will probably need to vent the tank to the outside.

The pump will pressurize the water/ethanol mixture to well above 134 kPA, which is the vapor pressure of 50% water/ethanol mixture at 90 C. I'm probably going to shoot for about 600 kPa, which should be at the upper limit of operation for a fuel injector.

The pressurized mixture then fill an accumulator which will even out the pulsations generated by both the pump and the E85 injector, then will travel approximately 3 meters from the rear of the Magnum to the engine compartment. There, the mixture will finally be heated to 90 C in the heat exchanger, then will travel a short distance to the E85 injector itself.

I can't seem to find a reliable check valve that completely prevents backflow, so I'm probably going to use two of these water injection solenoids I have lying around. One solenoid will be placed right after the pump, and the other solenoid will be placed right after the accumulator. All of this water injection equipment I have is from an aborted project to turbocharge the engine in my old Sebring Convertible, before it lost one of its conrod bearings and grenaded itself.

[teoman]

In that case, your alcohol is not heated. So everything i said is irrelevant