Partial Thermo analysis of a Crower engine

[Larry27183]

Hi everyone. Some years ago I read about the Crower six cycle engine. Always wanted to understand it better. And now is the time to follow up on that desire.

I’m trying to calculate what happens during the water injection. The goal is to determine the conditions (pressure, temperature) after water injection and before the second expansion / power stroke.

On an intuitive level here’s what I think is happening:
1) The hot air heats the injected water to its boiling point. (above 100C, as determined by the cylinder pressure.)
2) Heating the water cools the air, and reduces the pressure accordingly.
3) The hot air then vaporizes the liquid water, causing two things to happen:
o The air is further cooled by the water’s heat of vaporization (which also reduces the cylinder pressure), and
o The newly formed steam expands greatly, causing the pressure and temperature to increase.

There’s always assumptions. Here are mine:
* To keep things simple, the cylinder starts with hot compressed air instead of combustion exhaust (CO2, steam, and who knows what else). Perhaps I’ll revisit this later.
* The amount of liquid water injected is small. The air displaced by the water is small enough to ignore any pressure increase.

Currently I can calculate steps #1 and #2, but Step #3 has me stumped and befuddled. Perhaps you can walk me through how to get the resulting conditions. Links to previously worked out problems would be great also.

Thanks for your help!

 

[anorlunda]

You'll get better answers if you provide us a link to what you have been reading. Wikipedia does not have anything about the Crower engine.

 

[Larry27183]

Wikipedia's article on six stroke engines is here:
https://en.wikipedia.org/wiki/Six-stroke_engine

An interesting introduction to Bruce Crower and his engine:
https://autoweek.com/article/car-news/inside-bruce-crowers-six-stroke-engine
https://autoweek.com/article/car-news/inside-bruce-crowers-six-stroke-engine
A google search for "six stroke engine" (or "six-stroke engine") turns up many hits. Scholarly papers are available that analyze the engine but I have not found one that shows how the water vaporization process is calculated.

Thanks!

 

[jack action]

You should need to understand two concepts.

First, because there are two gases (air and steam), you need to use the partial pressure concept (Dalton's law).

Second, for the steam, you need to use the steam tables. There is a simple introduction here. Knowing two of the steam properties, you should find all others.

I haven't used these for a long time, so I'm kind of rusty on how to apply it to your problem, but I'm pretty sure this is the way to go. Conservation of enthalpy might be helpful for steam properties.

 

[Larry27183]

Jack,

Thanks for the feedback. I was thinking along similar lines but hoping there was a simpler way. I'll look into it as time allows.

Please excuse the delay in responding. Life threw me a curve ball and gave me a completely unexpected job interview. I got the job today!

 

[jack action]

I got the job today!

Congratulations!