CO2 Sublimation Heat Engine

tahanson43206 · 2020-08-30 05:56:26

For SpaceNut re #24

In the closing paragraph of this post about the student experiment, the question was asked:

Missing details from the 262 gram of dry ice experiment is the temperature, whether it was allowed to continue to climb and how long did the output of 90 psi last to turn the turbine before dropping off if temperature was not continued to be increased.

One detail we can (I think safely) deduce from the description of the experiment is that the room temperature of the facility on Earth is the temperature to which the CO2 ice was allowed to rise. I think it is safe to assume as well that the end state for temperature rise would have been room temperature.

It may be possible to calculate the performance of such an engine. The starting temperature of the solid is likely to be at or below the freezing temperature of CO2, and the end temperature is (about) 70 degrees Fahrenheit or (about) 21 degrees Celsius. The quantity of dry ice can be chosen for the calculation. The volume of gas produced by melting should then be knowable, and the pressure deduced by choosing a volume.

The flow of gas from the pressure vessel will (I expect) follow a mathematical progression if it is not renewed, so the performance of the flow for mechanical translation would (should) be derivable. In practice, I would expect the flow of gas to be managed so output is (near) constant, and it would seem advisable to introduce more dry ice into the pressure vessel, just as water is added to the boiler of a steam engine while the boiler is being heated.

To summarize, I ** think ** the performance of the system should be derivable from the information provided.

Edit#1: From the above, it should be possible to design a production power plant for use on Mars, given:

a) A supply of dry ice
b) A supply of solar energy (either direct or via electric heating from stores accumulated from solar energy)
c) Dimensions of pressure vessel and related mechanical features
d) Dimensions and other characteristics of the power translation equipment (eg, turbine or piston)
e) Dimensions and other characteristics of the electrical generator or mechanical consumer (eg, power tools - "air" hammer, etc)

I recall that kbd512 has discussed use of "air" tools favorably in past posts in other topics.

It should be possible to design a mobile power production facility for use in the field, suitable for driving "air" tools at a construction site.

A supply of dry ice would be comparable to having a supply of coal on Earth, and the source of energy would be comparable to having a supply of oxygen on Earth.

Come to think of it ... this would be an interesting application for one of the 1 KW reactors, which (as designed) would radiate heat to space.

That heat could be diverted from heating the Universe to heating some dry ice.

Edit#1: so how did steam locomotive designers solve the problem of adding water to a hot boiler?

http://cs.trains.com/trn/f/111/t/7866.aspx

The thread at the web site above provides some insight ... A member asked the question, and others answered.

To summarize (as I understand the replies) water was admitted in at least two ways, and possibly a third.

The explanation that seemed most applicable to design of a dry ice boiler for Mars was to use some of the pressure from the boiler to drive more input into the boiler. A chamber outside the boiler is loaded. The loading port is closed. The port to the boiler is openable by pressure from outside the boiler (I assume springs are involved). Steam (in the case of a locomotive) is admitted from the boiler into the loading chamber, and that steam drives the (water in locomotive) into the boiler.

There was some discussion of heating the water to be admitted to the boiler so as to avoid reducing pressure. At least two ways to achieve that were given.

In the case of a Mars dry ice boiler, pre-heating the dry ice would ** not ** be a good idea, since the whole point of the exercise is to deliver the ice into the melting chamber (boiler) to is can be sublimated.

Thus, the Mars dry ice engine would contain automation able to pull dry ice from a tender, grind it up just to the point it can be admitted to the loading chamber, and then the pressure of the boiler itself would be enlisted to push the new raw material into the boiler.

With modern automation, this entire process should operate without human intervention, although not without (some) human supervision.

(th)

Last edited by tahanson43206 (2020-08-30 07:06:30)

SpaceNut · 2020-08-30 07:58:47

The reason is room temperature can be elevated to supercritical gets even higher.

http://marsforthemany.com/wp-content/up … hPaper.pdf

An air hose connected a valve on the bead seater to an angle die grinder, which spun a DC motor, generating power. Current was measured by a multimeter wired in series, while voltage was measured by a Vernier LabQuest wired in parallel, and a 2.5 Volt, 200 mA light bulb from acted as a resistor.
Calculating Quantity of Dry Ice: The amount of dry ice necessary to reach 621 kPa was calculated by using the Ideal Gas Law, (Nave). was PV = nRT R set to 8.314 J , and the mol K other parameters were converted to compatible units. P was set to 621 kPa, or approximately 90 psi, the maximum capacity of the component acting as our turbine, V was set to 18.92 liters or 5 gallons, the volume of our pressure vessel, n unknown, and T was set equal to 293.15K, or room temperature, an estimation because the exact temperature of the tank’s interior could not be determined. Reorganizing the Ideal Gas equation to n = RT and substituting the calculated PV values yields , with units of kPa L mol K J 1 K n = 4.821 1, and cancelling out equivalent units present in both the numerator and denominator and when the units are replaced by their SI base units, kPa by 10 3 kg m 1 s 2 , liters by 10 3 m 3 , and J by kg m 2 s 2 , the two constant terms simplify to 1 and the unit becomes mol kg m 1 s 2 m 3 kg 1 m 2 sec 2 , which, after corresponding units are removed from the numerator and denominator, is simply moles. This value of 4.821 mol can be converted to mass by multiplying it by carbon dioxide’s molar mass of 44.01, yielding a final value of approximately 212 grams of carbon dioxide.

chart contains duration

out put was not regulated and max spin of tool starts out and slows with pressure drop.

tahanson43206 · 2020-08-30 11:22:24

For SpaceNut re #27

Thanks for providing those additional details.

Assuming there is need for someone else to take up the challenge of designing a workable system for dry ice power delivery, this is a good time to extend an invitation to any NewMars forum reader who has an interest along these lines, and the willingness to learn what is needed if you don't already know. Please register and pitch in.

Registration is (relatively) accessible, although the constant flood of spammers means that the available ID's you might use is steadily decreasing.

If you don't get the ID you want on first try, keep trying until you find one that works. Then you can ask SpaceNut to delete the offending Spam ID and let you claim it.

If your email service is blocked for some reason, try one of the free services until you find one that returns the login approval message from the web site.

(th)

Last edited by tahanson43206 (2020-08-30 11:23:10)

louis · 2020-09-12 18:19:45

This thread seems to have lost its way. The attraction of a sublimation heat engine is its simplicity - no need to involve nuclear reactors which will involve huge application of resources.

SpaceNut · 2020-09-12 18:40:00

So as to be fair we are supplying heat to a dry ice filled chamber from a non-nuclear source to create power cycle from it phase change.

Calliban · 2020-09-13 01:25:15

The CO2 is located at the polar regions where there is no natural heat source at all for half of the Martian year. For the rest of the year, there is weak sunlight - with intensity of 43% of what is found at Earth polar regions. That is why it is frozen.

Whilst dry ice is a convenient working fluid for an engine, there still need to be an input heat source to generate power. It is not a free energy source, it is a phase change material that will only generate power from whatever energy you pump into it. This cannot realistically come from the sun at the Martian poles. Geothermal energy is a weak possibility, though the geothermal gradient in the Martian crust is shallower than Earth's, meaning that we would have to drill much deeper.
That means more cost and complexity than already face here on Earth. So it follows that any sublimation heat engine on Mars will be powered by nuclear energy, given that there is no other practical heat source. So its really a question of how to do that best and what type of reactor we could practically build with the resources that we can afford to access.

Last edited by Calliban (2020-09-13 01:50:51)

tahanson43206 · 2020-09-13 05:52:36

For Calliban re reply to Louis ...

It is good to see Louis back on the scene, in full support of solar power and in full opposition to nuclear fission.

It is ** equally ** reassuring to see your robust defense of nuclear fission at the poles of Mars. I like the vision I can build in my mind's eye, of robust communities at the poles supplying all manner of goods and services to customers in lower latitudes.

A concern I do have is supply of fissionable materials. A quick review of Google snippets on the subject indicates that while there ** are ** some signs of Uranium and Thorium on Mars (evidence from satellites, primarily) I would imagine it would take some effort to collect enough from the regolith to deliver useful power in the quantities needed for a productive community.

It is in the collection of fissionable materials that I would think solar power would prove useful. Production can take place as power is available, at unattended facilities.

Here is a solution that allows both solar power and fission to find useful employment in a hostile environment.

(th)

SpaceNut · 2020-09-13 07:27:20

Hence why I was letting the topic ride until Louis spoke up as its that opposition as to why they have been separated now and I need to copy the last 2 posts to that new topic....

SpaceNut · 2020-09-13 07:41:28

Solar heat sources from concentrator panels come to mind for rising the thermal input into a tank boiler wall to cause the phase change to the Dry Ice placed into a chamber for making this work. As Calliban indicated its only 43% of what earth receives per each square meter of that approximate 1,000 watts but going to a PV panel (solar cell array) means even less gets to be used for heating the chamber in electrical form.

We can make that system safe by adding a blind system in front of the concentrator unit close to stop the solar light reflection from happening for when personnel are near the chamber filling it. Once its load and personnel are out of the way it can be reactivated to heat the chamber.

SpaceNut · 2021-01-24 17:37:52

Thermal concentration and a closed loop system would seem to me the choice to make a multi stage machine to create power for the mars local sunlight but with a little help with solar concentrating.

tahanson43206 · 2022-05-12 10:15:04

For Louis .... your topic here has been languishing for a year ... I'm bringing it back into view because (a) I think it deserves further development and (b) because I logged in just now to set up a generic Heat Engine topic. Your topic is in Life Support Systems, and that remains a good place for it.

One of the interesting ideas I'd like to see developed further is the one about a heat engine running up the side of a mountain on Mars.

Best wishes for further progress in evolution of this set of ideas.

(th)

Calliban · 2022-05-12 17:47:26

tahanson43206 wrote:

For Louis .... your topic here has been languishing for a year ... I'm bringing it back into view because (a) I think it deserves further development and (b) because I logged in just now to set up a generic Heat Engine topic. Your topic is in Life Support Systems, and that remains a good place for it.
One of the interesting ideas I'd like to see developed further is the one about a heat engine running up the side of a mountain on Mars.
Best wishes for further progress in evolution of this set of ideas.
(th)

The heat engine running up a mountain (or hill) is an intriguing one. In this concept, the heat source (solar thermal?) would be on the south facing front of the hill, assuming it is in the northern hemisphere. The boiler would be a heat exchanger in a tube containing boiling CO2, running up the hill. The CO2 gas would be dried by stones in the boiler, which form condensation surfaces. At the top of the hill would sit the turbine, which would receive dry CO2 gas and exhaust into a condenser. The north face of the hill would have radiator panels, which cool CO2 exiting the turbine, in a condenser. The condenser would drain into a pipe which would run down the hill into the inlet of the boiler.

As sunlight heats the panels and natural circulation transfers heat to the boiler, the differential gas pressure across the turbine will precisely balance the difference in liquid head pressure across the boiler. In other words, the entire power plant will run without need for any pumps, with gravity head pushing condensate back into the boiler. If the solar heating loop to the boiler also transfers heat by natural convection, then the turbine and generator are the only moving parts. The turbogenerator wouod be contained within a module. When these components reach end of life, they are replaced, with the pipework and panels presumably lasting for centuries.

By storing hot and cold within the rock masses around the boiler and condenser, the powerplant can be run at night, with only small changes in power output across diurnal cycles.

In most cases we would be interested in electric power production. However, it is also poosible to use the turbine to run a compressor producing compressed CO2 to drive purely mechanical tools. If we wanted a system that could pump water from an aquifer, then mechanical jerker lines could be driven by the shaft power of the turbine.

Last edited by Calliban (2022-05-12 18:08:04)

SpaceNut · 2022-05-12 19:49:58

This also makes use of gravity storage as well, solar concentration as part of the total design features.

Mars_B4_Moon · 2022-08-26 05:30:54

At times websites like the BBC have their own chemistry, science sections

States of matter
https://www.bbc.co.uk/bitesize/guides/z … revision/1

even a simple kids book can open up your mind to exploring older more simple ideas which were left unfinished or not fully explored?

Vacuum sublimation
https://www.rsc.org/publishing/journals … MO:0002219

Scaling up the Sublimation Heat Engine
http://large.stanford.edu/courses/2015/ph240/bankman1/

How energy from dry ice could power human colonies on Mars
https://theconversation.com/how-energy- … mars-38250

A sublimation heat engine
https://www.research.ed.ac.uk/en/public … eat-engine

Last edited by Mars_B4_Moon (2022-08-26 05:33:55)

Calliban · 2022-08-26 06:13:04

Open cycle heat engines like gas turbines have far superior power density. That means reduced capital cost, reduced build time and better economics overall. This is why GTs have largely captured the power generation market innthe US.
The problem on Mars is that the frozen CO2 is at the poles. Which is probably a long way from where we intend to build our base. We could pipe liquid CO2 over long distances. But that means a lot of steel and construction, which rather ruins the point.

Last edited by Calliban (2022-08-26 06:15:21)

Mars_B4_Moon · 2022-09-13 18:09:53

Would the CO2 engine work as back up power generation?

Maybe also iodine, potassium kJ/mol Snow and ice sublime, although more slowly, at temperatures below the freezing/melting point temperature line at 0 °C for partial pressures, fused pair of benzene rings Naphthalene is an organic compound with formula C10H8 on Earth iodine vapor can reveals fingerprints, Cadmium and zinc not suitable materials for use in vacuum as they sublime more than other common materials, Enthalpy of sublimation, or thermodynamics heat of sublimation,power required to sublimate one mole of a substance at a given combination of temperature and pressure, usually standard temperature, pressure.

http://aip.scitation.org/doi/10.1063/1.1475333

Sublimation of Organic and Organometallic Compounds 1910–2001

Ocado Retail mulls dry ice alternatives as costs soar | Euronews
https://www.euronews.com/next/2022/09/1 … ok-dry-ice

Last edited by Mars_B4_Moon (2022-09-13 18:19:09)

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#26 2020-08-30 05:56:26

Re: CO2 Sublimation Heat Engine

#27 2020-08-30 07:58:47

Re: CO2 Sublimation Heat Engine

#28 2020-08-30 11:22:24

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#29 2020-09-12 18:19:45

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#30 2020-09-12 18:40:00

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#31 2020-09-13 01:25:15

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#32 2020-09-13 05:52:36

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#33 2020-09-13 07:27:20

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#34 2020-09-13 07:41:28

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#35 2021-01-24 17:37:52

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#36 2022-05-12 10:15:04

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#37 2022-05-12 17:47:26

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#38 2022-05-12 19:49:58

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#39 2022-08-26 05:30:54

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#40 2022-08-26 06:13:04

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#41 2022-09-13 18:09:53

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