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Calliban

Member

From: Northern England, UK

Registered: 2019-08-18

Posts: 3,449

Cold CO2 powered vehicles

Concept 1: A rocket hopper

At 0°C and 241bar, liquid CO2 expanded through a nozzle has an ISP of 61s.  This amounts to an exhaust velocity of 600m/s.
https://en.m.wikipedia.org/wiki/Cold_gas_thruster

A vehicle with a mass ratio of 2, propelled by a cold gas liquid CO2 rocket, would achieve a final velocity of 416m/s.  Accelerating at a 45° angle, the vehicle could travel some 7.4km in a single hop.  Upon landing, the vehicle would unroll a flexible solar array and compress liquid CO2 into its pressure tank.  A system like this could perform one hop per day, allowing a probe to explore a new site each day.

Concept 2: A CO2 powered rover.  A solar array or small nuclear reactor generates power which is used to compress atmospheric CO2 into a pressure cylinder.  At 0°C, it could be stored as a saturated liquid.  The CO2 can then be expanded through an air motor to provide propulsive power.  If a nuclear reactor is used to compress the CO2, waste heat can be stored in paraffin wax and used to preheat and evaporate the CO2 before its entry into the air motor.

Last edited by Calliban (2023-11-15 12:27:51)

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"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."

tahanson43206

Moderator

Registered: 2018-04-27

Posts: 17,341

Re: Cold CO2 powered vehicles

I am happy to be first on the scene to offer best wishes for success of this interesting and promising new topic!

When you have time, please add text to explain how your concept would work, and perhaps provide links to images or supporting references. 

In the context of Mars where CO2 is abundant, this topic ** should ** have plenty of room to grow.

(th)

Calliban

Member

From: Northern England, UK

Registered: 2019-08-18

Posts: 3,449

Re: Cold CO2 powered vehicles

There are two concepts.  The first a cold gas thruster hopper that releases stored CO2 through a nozzle.  The low energy density of saturated liquid CO2 limits the range of each hop to about 5 miles.  Landing would need to be propulsive.  The short range and long recharge time, make this unsuitable for rapid surface transit.  But it could be useful for a probe that can hop across the surface, allowing it to traverse rough terrain.

The second is a wheeled vehicle in which stored liquid CO2 expands through an air motor, either with or without supplementary heating.  This is rather like a compressed air powered vehicle here on Earth.  The difference is that CO2 can be stored as a liquid, whereas air cannot.  The advantage of this concept is mechanical simplicity.  This is a technology that we can build on Mars.  The major con is short range between refilling.  Refilling involves powering a compressor to fill the LCO2 tank.  This is less of problem if the vehicle operating regime allows it to be driven for say a couple of hours in the morning and then parked allowing it to refill the rest of the day using a rollout solar panel.  OK if you are happy to travel slowly and investigate sites along the way.

Last edited by Calliban (2023-11-15 15:15:39)

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"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."

SpaceNut

Administrator

From: New Hampshire

Registered: 2004-07-22

Posts: 28,970

Re: Cold CO2 powered vehicles

Not all that far from this topic Running on Compressed Air?

Compressed Air

I seem to remember a scene on Armagedón that Bruce Willis and others stared in for the Nasa team selected from an oil rig to fix what the scientist could not solve. Using the Armadillo to jump a gorge or canyon to get to the drilling location by firing the boosters.

Gas Turbine uses Hot Carbon Dioxide - Ideal for Mars

Some where there is the dry ice tool topic

Of course the ICE topic for engines.

Mars_B4_Moon

Member

Registered: 2006-03-23

Posts: 9,378

Re: Cold CO2 powered vehicles

Dry Ice Power
https://www.asme.org/topics-resources/c … -ice-power
The Northumbrian researchers had been toying with dry ice and the Leidenfrost effect for some time. Dry ice vaporizes at a much lower temperature than water, as you know if you’ve ever played with the packaging that your Omaha Steaks came in. The researchers found that they could control the direction that the ice moved across a surface by adding grooves to that surface. “At some point we realized we could wrap the linear substrate into a circle,” says Rodrigo Ledesma-Aguilar, a lecturer in the Department of Physics and Electrical Engineering at the university. “That’s when the penny dropped.”
On the ribbed circular surface, disks of dry ice levitate, and run seemingly endless, frictionless laps. “When we first saw this disk spinning, the first thing that surprised us was how fast they would spin,” says Ledesma-Aguilar. “We weren’t expecting it.” Here was the promise of power. Stick a few magnets in the ice and you’ve got a power generator. And the fact that there was no friction was spectacular. “We are very excited to look at something with no bearing at all.”

tahanson43206

Moderator

Registered: 2018-04-27

Posts: 17,341

Re: Cold CO2 powered vehicles

For Mars_B4_Moon re #5

Thank you for finding and posting the link and the snippet quote about discovery of a "frictionless" surface that might take the place of bearings.

The Large Ship topic has been quiet for a while, but it has inspired other forum members to think about variations on the Large Ship theme. All variations springing from the original Large Ship vision incorporate two or more spinning rings, to counteract the inevitable gyroscopic effects that will challenge any Large Ship builder.

Your post #5 seems to contain a glimmer of an opportunity to deal with the issue of bearings that alternatives to the Large Ship design are going to need.

SearchTerm:bearings frictionless CO2 ice ribbed surface spinning

(th)

Calliban

Member

From: Northern England, UK

Registered: 2019-08-18

Posts: 3,449

Re: Cold CO2 powered vehicles

Compressed CO2 energy storage.
https://en.m.wikipedia.org/wiki/Compres … gy_storage

A single cubic metre (1100kg) of liquid CO2 will release 66kWh of mechanical power if expanded isothermally at room temperature.  Adiabatic expansion will release only half as much.  On Mars, the storage system would not need a gas dome, as the atmosphere provides an infinite reservoir of gaseous CO2.  On Earth, a gas dome would be needed to capture exhausted CO2 ready for recompression.

This may turn out to be a good system for offgrid energy storage.  Unlike batteries, it would have a very long operational life.  Each cubic metre of gas dome will store 2kg of CO2 gas at 0°C.  So to store 1kWh, we need a 10m3 gas dome and a 4.5 litre L-CO2 cylinder.  Compression would generate heat.  This can either be stored and used for expansion reheating, or fed into the household hot water system.

If expansion is adiabatic, then the turbine will only recover about half as much energy.  However, the resulting CO2 gas will be cold.  If the receiver tank is insulated, then the gas can be stored cold.  This will reduce the energy needed for recompression.  Alternatively, the cold resulting from expansion can be used for refrigeration and freezing.  If neccesary, the compression and expansion can be entirely mechanical.  Electrical systems are not necessary.

An integrated system, in which heat from compression is used for water heating and cold from expansion is used for refrigeration, is a more efficient use of work and can make use of simpler mechanical systems.  Mechanical power can be transmitted using hydraulics or LP air, avoiding electricity altogether.  That will please the Amish.

Last edited by Calliban (2023-11-30 03:58:22)

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"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."

NewMarsMember

Member

Registered: 2019-02-17

Posts: 1,264

Re: Cold CO2 powered vehicles

This post is primarily for Calliban but it may be of interest to others ...

I am hoping you might be willing to take a moment to explain why your examples (fairly consistently) seem to use ** liquid ** CO2, instead of solid.  Liquid CO2 requires pressure, so it requires a heavy tank.  Solid CO2 requires no pressure, and can be carried like coal used to be carried in what were called at the time, "coal" cars. 

It seems to be there are other advantages to storing CO2 in solid form.

There may well be advantages to storing CO2 in liquid form, despite the massive tank required to hold it.

Update later ... If someone has the time, this topic would benefit from addition of a block diagram of process flow.

The process would start with the preparation of the CO2 (solid or liquid). 

The process would continue with storage of the CO2 for use in a machine of some kind.

The process would continue with application of the CO2 to achieve some mechanical effect.

The conclusion of the process (on Mars) would (presumably?) show delivery of the exhausted CO2 to the atmosphere.

(th)

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Calliban

Member

From: Northern England, UK

Registered: 2019-08-18

Posts: 3,449

Re: Cold CO2 powered vehicles

This post is primarily for Calliban but it may be of interest to others ...

I am hoping you might be willing to take a moment to explain why your examples (fairly consistently) seem to use ** liquid ** CO2, instead of solid.  Liquid CO2 requires pressure, so it requires a heavy tank.  Solid CO2 requires no pressure, and can be carried like coal used to be carried in what were called at the time, "coal" cars. 

It seems to be there are other advantages to storing CO2 in solid form.

There may well be advantages to storing CO2 in liquid form, despite the massive tank required to hold it.

(the)

Liquids can easily be pumped or pushed through a propellant line into an evaporator.  Solids cannot.  But you could store CO2 as a solid and shovel it into a tank that is then sealed.  The tank could then be heated to liquefy the CO2 and transfer it into the evaporator.  This would have to be done in batches, as the melting tank would have to be pressurised to at least 5.1 bar.  Either way, the CO2 has to build up pressure, because that is how work is produced by an engine or turbine.  They are not strictly heat engines.  They are differential pressure engines and temperature differences are what create the differential pressure which pushes on the blades or pistons.

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"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."

tahanson43206

Moderator

Registered: 2018-04-27

Posts: 17,341

Re: Cold CO2 powered vehicles

For Calliban re  CO2 mechanical systems for Mars ....

Re post #9

Thank you for opening the door to the use of solid for transport/storage ... that makes a lot of sense.

On the ** other ** hand, I like your idea of using a batch process to prepare the solid CO2 for use as a gas to achieve mechanical objectives.

Please reconsider your concept of a "batch" ....

A "batch" can be a small amount of solid CO2, injected under pressure into the 5 bar continuous heating tank (boiler, in steam engine terms).

The process at work is transformation of a solid into a useful form as an energetic gas, using thermal energy provided by a small nuclear reactor.

The injector system would require the invention of a way to force a solid into a 5 bar tank that is under continuous heating.  That would be the province of a mechanical engineer.  Once invented, such an injector could be replicated thousands and eventually millions of times.

Update: I am "talking" to ChatGPT about your proposal, and the question came up ... what temperature are you planning to set for the working temperature of the 5 bar tank?  It occurs to me that a temperature of 70 degrees Fahrenheit (~25 Celsius) would ? could ? be sufficient for this purpose?

(th)

tahanson43206

Moderator

Registered: 2018-04-27

Posts: 17,341

Re: Cold CO2 powered vehicles

For Calliban re topic and specifically, injection into a tank at 5 bar ....

It appears there are off-the-shelf injection systems you can buy that are capable of injecting CO2 in solid form directly into a heated tank whose internal pressure is 5 bar....

You
Your developers/managers have recently given you the ability to search the Internet. Please look for a piston injection system that delivers material into a tank that is under 5 bar of pressure. For the purpose of the search, please assume 25 degrees Celsius for the tank temperature.
ChatGPT
!
ChatGPT
I found a few options that could potentially meet your needs for a piston injection system capable of injecting material into a tank held at 5 bar pressure:
TCS Pneumatic Piston Injection Pump & Metering System: This system is designed to accurately measure, record, and control additive levels with little to no effect from back pressure while filling tanks. It features an air-driven mechanism, capable of measuring additive with +/- 5 PPM accuracy at rates up to 2750 mLPM. This system seems to be quite versatile and could be adapted to a range of industrial applications including those involving high-pressure environments.
PressureJet Industrial High-Pressure Piston Pumps: These are positive displacement triplex piston pumps, suitable for discharging liquids at high pressure with minimal pulsation. The pumps are designed to handle strong suction and pressures up to 100 kg/cm² (approximately 9.8 bar) for piston pump designs, and up to 700 kg/cm² (approximately 68.9 bar) for plunger pump designs. They can be used for various applications, including injecting and dosing, which may suit your requirements for injecting CO2 into a heated tank at 5 bar.
Cryostar Liquid Hydrogen High-Pressure Pumps: Cryostar offers a range

I don't see a need for further delay .... it should be possible to design a line of machinery suitable for manufacture on Earth, and for import to Mars in lots that are small enough for delivery in one of GW Johnson's Orbital Taxi designs.

Please use this topic to develop the components you'll be needing, and the line of related products you will offer to customers on Mars.

(th)

Calliban

Member

From: Northern England, UK

Registered: 2019-08-18

Posts: 3,449

Re: Cold CO2 powered vehicles

Automatic systems that load solid fuels are a tricky proposition.  But maybe something like this?

The hopper at the top loads uniform balls of dry ice down a tube by gravity.  At a predetermined point, the solenoid pin is withdrawn and a sphere falls by gravity into the cup of the rotating globe valve.  As the valve rotates, it drops the dry ice spherule into the melting tank.  Before rotating back to the inlet tube, pressure is relieved to Mars abient via a pressure relief tube.

The problem this faces is that dry ice is quite soft.  If any of the spheres are deformed or crumble, the inlet tube couod get blocked.  Vibration can also interfere with alignments.  But maybe it would work with some operator input.  The level in the tank cannot be allowed to drop too low or the feed pump will start to cavitate.  However, the rotation rate of the globe valve needs to remain constant.  So depending upon the power output of the engine, the feed system will be stopping and starting constantly.  Maybe it will work.

Last edited by Calliban (2023-11-30 09:24:46)

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"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."

tahanson43206

Moderator

Registered: 2018-04-27

Posts: 17,341

Re: Cold CO2 powered vehicles

For Calliban re topic development ...

Thank you for considering the small-batch injection concept for raw material for the boiler.  Your rotating injection system is interesting and it may even be novel. It sure is surprising to me, but ** that's ** not saying much.

One observation I would like to offer as you refine your vision ... Please note that the amount of material to be injected, and the rate of delivery of thermal energy to the boiler, is going to be dependent upon the consumption of the working fluid by the tools.

I would offer for comparison the line of pneumatic pump/tank sets that are on offer at your local industrial supply store.  These generally provide a tank large enough to serve the tool for at least a few seconds, and a mechanical pump to recharge the tank, usually driven by an electric motor.

What is interesting about your proposal, and the reason i am offering such support as I can, is the use of CO2 in solid form as a convenient way to move the working fluid to a job site, while the delivery of thermal energy to the boiler is unlimited in form.  On Earth, the thermal energy can be supplied by a butane tank, or any of a myriad of similar systems.  On Mars, the most obvious heating source is a small nuclear reactor.

You should (I am hoping) be able to design a system for sale here on Earth, where the convenience would outweigh the additional cost of your system.

***
Reminder .... ChatGPT wanted to know the working temperature of the boiler. I suggested room temperature (~25 Celsius) because I have no idea what the ideal temperature might be.

(th)

SpaceNut

Administrator

From: New Hampshire

Registered: 2004-07-22

Posts: 28,970

Re: Cold CO2 powered vehicles

http://www.uigi.com/co2_conv.html

Nice but that means grinding the dry ice to allow it to fit through the entry shout to the chamber for heating.
It is some of the same features that I put into the 1 ft of regolith gathering to get the soil to give up the 9 lt of water that it contains in a baking tray.

Sort of like this

where the hopper has an auger to break the chunks down to size.

That would use co2 as a wash gas to ressurize the chambers rise of steam to the top of the system to slowly cool into a still like tube. Of course the wash gas and the crystal co2 in the soil would also be collected as well.