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#51 2019-11-18 19:15:46

Calliban
Member
From: Northern England, UK
Registered: 2019-08-18
Posts: 309

Re: solar power towers on mars - km-high vertical wind tunnel turbo-elec

Carbon dioxide will boil at about 0 degrees Celsius at 30bar.  And it will condense at -40C at a pressure of 10bar.

http://www.chemistry-blog.com/2009/02/0 … xtraction/

Solar heating panels can provide a hot source at about zero Celsius.  The tower would be useful for drying the saturated vapour.  Liquid CO2 droplets will drop back into the boiler by gravity, and the vapour will be much dryer at the top of the tower, whereupon the vapour will enter the turbine.


Interested in space science, engineering and technology.

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#52 2019-11-18 20:52:42

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 17,766

Re: solar power towers on mars - km-high vertical wind tunnel turbo-elec

1. Mars atmospheric pressure is the issue for how to make use of the co2 that it has 610 Pa (0.088 psi) or not even 0.1 bar as the chart of the triple point shows.
2. The average temperature is about minus 80 degrees Fahrenheit (minus 60 degrees Celsius), although it can vary from minus 195 F (minus 125 C) near the poles during the winter to as much as a comfortable 70 F (20 C) at midday near the equator.

So to do anything we need to collect many cubic volumes of mars air and condense it without expending a ton of energy to do so and thats the first hurdle for mars.

We have talked about using the natural temperature swing with obsorbants to bring the co2 levels to a chamber for heating. The releasal would pressurize the co2 in the chamber of which its a simple repeat to build up the volume that we need.

That means timing control, monitoring and a power source that acheives the goal.

Evaluation of Mars CO2 Capture and Gas Separation Technologies
https://ntrs.nasa.gov/archive/nasa/casi … 015862.pdf

Nasa evaluation for The Mars Oxygen ISRU Experiment (MOXIE)
https://ssed.gsfc.nasa.gov/IPM/PDF/1134.pdf

3D modelling of the early martian climate under a denser CO2 ...
http://people.seas.harvard.edu/~rwordsw … et2013.pdf

https://www.kiss.caltech.edu/final_repo … report.pdf

https://www.kiss.caltech.edu/workshops/ … cht_sc.pdf

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#53 2019-11-26 06:40:01

Calliban
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From: Northern England, UK
Registered: 2019-08-18
Posts: 309

Re: solar power towers on mars - km-high vertical wind tunnel turbo-elec

SpaceNut wrote:

1. Mars atmospheric pressure is the issue for how to make use of the co2 that it has 610 Pa (0.088 psi) or not even 0.1 bar as the chart of the triple point shows.

I think this would have to function as a closed system.  The solar collector and boiler would be at the bottom of a tall hill on the south facing side and would generate vapour at a pressure of 30bar.  The CO2 vapour would rise up an upcommer pipe, several hundred metres high and would enter the turbine at the top.  The condenser would be another set of radiator panels on the north side that would condense the CO2 into liquid that would then reenter the boiler at the bottom.  The weight of liquid CO2 in the condenser side would be such that a pump would not be needed.  In fact, the only strictly necessary moving part would be the turbine, as all other components could work on natural circulation, with vapour pressure in the upcommer, balancing the static pressure in the downcommer.

Both the upcommer and downcommer could be shafts drilled into the solid rock, as would the boiler.  The heater panels could be coiled hose beneath a thin layer of regolith.  The condenser would be much the same at the top of the hill.  All components aside from the turbine would be very low tech with low embodied energy.

This is another concept that would work on Mars but not on Earth.  On Mars, the very thin atmosphere allows very large temperature variations between areas in sunlight and shadow.  There could be very significant temperature variations between the south side and north side of a hill.  The system would continue to function at night, thanks to the heat stored in the rock surrounding the boiler.

Last edited by Calliban (2019-11-26 06:51:37)


Interested in space science, engineering and technology.

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#54 2019-11-26 10:46:18

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 17,766

Re: solar power towers on mars - km-high vertical wind tunnel turbo-elec

I agree that a closed chamber that rises from a valley to the top of a small mountain can and could be used with the natural solar and night temperatures to make an energy source for man once built. Like you indicate we have a number of working fluids that man could use to make the system work...
In particular the liquid to vapor change and back is how such a system would work for water, Co2 and Freon or refridgerant class gasses  as well.

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#55 2019-11-26 13:02:26

Calliban
Member
From: Northern England, UK
Registered: 2019-08-18
Posts: 309

Re: solar power towers on mars - km-high vertical wind tunnel turbo-elec

The atmospheric steam engine.

https://eprints.soton.ac.uk/348565/1/Mu … 202013.pdf

An interesting idea for converting low quality heat into mechanical power.  The low pressures and temperatures lead to relatively low efficiency - around 10% for a 69C boiler temperature.  However, the advantage of low pressures and low temperatures are simplicity.  The system is very easy to build using common materials.  There is no danger of explosion, as pressures are <1bar.  The system does not need a pump, as the vapour pressure of water is 20KPa at 60C.  A condensed water column just 2m tall would be sufficient to force return coolant into the boiler.

On Mars, we would probably use something other than water in low temperature heat engines.  CO2 is the most likely choice, though it would mean operating at higher pressures.


Interested in space science, engineering and technology.

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#56 2019-11-26 14:01:59

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 17,766

Re: solar power towers on mars - km-high vertical wind tunnel turbo-elec

Thanks for the link here is some more stuff as it relates
https://www.clarke-energy.com/gas-engin … eneration/
schematic-trigen.gif

Waste heat recovery technologies and applications

Revealing the Secrets – How to design a Heat Driven Refrigeration System

Combined Refrigeration Cycle for Thermal Power Plant Using Low Grade Waste Steam


https://ww2.energy.ca.gov/2018publicati … 18-026.pdf
Building Energy Efficient Cooling and Heating

another working fluid
https://www.goodway.com/hvac-blog/2012/ … lar-power/

https://goldman.com.au/energy/company-n … ller-work/

https://res.mdpi.com/d_attachment/energ … -00234.pdf

  • TABLE 4-2
    Efficiencies of common energy conversion devices
    Energy Conversion Device Energy Conversion Typical
    Efficiency, %
    Electric heater Electricity/Thermal 100
    Hair drier Electricity/Thermal 100
    Electric generator Mechanical/Electricity 95
    Electric motor (large) Electricity/Mechanical 90
    Battery Chemical/Electricity 90
    Steam boiler (power plant) Chemical/Thermal 85
    Home gas furnace Chemical/Thermal 85
    Home oil furnace Chemical/Thermal 65
    Electric motor (small) Electricity/Mechanical 65
    Home coal furnace Chemical/Thermal 55
    Steam turbine Thermal/Mechanical 45
    Gas turbine (aircraft) Chemical/Mechanical 35
    Gas turbine (industrial) Chemical/Mechanical 30
    Automobile engine Chemical/Mechanical 25
    Fluorescent lamp Electricity/Light 20
    Silicon solar cell Solar/Electricity 15
    Steam locomotive Chemical/Mechanical 10
    Incandescent lamp Electricity/Light 5

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#57 2019-11-27 04:08:44

Terraformer
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From: Lancashire
Registered: 2007-08-27
Posts: 3,202
Website

Re: solar power towers on mars - km-high vertical wind tunnel turbo-elec

Calliban wrote:

The atmospheric steam engine.

https://eprints.soton.ac.uk/348565/1/Mu … 202013.pdf

An interesting idea for converting low quality heat into mechanical power.  The low pressures and temperatures lead to relatively low efficiency - around 10% for a 69C boiler temperature.  However, the advantage of low pressures and low temperatures are simplicity.  The system is very easy to build using common materials.  There is no danger of explosion, as pressures are <1bar.  The system does not need a pump, as the vapour pressure of water is 20KPa at 60C.  A condensed water column just 2m tall would be sufficient to force return coolant into the boiler.

On Mars, we would probably use something other than water in low temperature heat engines.  CO2 is the most likely choice, though it would mean operating at higher pressures.

That's still about half the efficiency of solar panels, for a temperature which can be achieved using solar thermal collectors. Hmm.


"I guarantee you that at some point, everything's going to go south on you, and you're going to say, 'This is it, this is how I end.' Now you can either accept that, or you can get to work." - Mark Watney

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#58 2019-11-27 07:21:21

Calliban
Member
From: Northern England, UK
Registered: 2019-08-18
Posts: 309

Re: solar power towers on mars - km-high vertical wind tunnel turbo-elec

Terraformer wrote:

That's still about half the efficiency of solar panels, for a temperature which can be achieved using solar thermal collectors. Hmm.

As I noted on the 'Gravity Storage' thread, solar thermal panels are easier to make, have lower embodied energy and heat can be stored for later use.  That being said, I still think a nuclear reactor is a much better approach.  You get the same amount of power from a device containing a tiny fraction of the materials and embodied energy of any practical solar plant.  And it covers a much smaller area.  Here on Earth, this sensible solution has been regulated to death.  So we are left trying to gather nature's scraps, in the form of ambient solar energy.


Interested in space science, engineering and technology.

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#59 2020-02-13 09:38:47

Grypd
Member
From: Scotland, Europe
Registered: 2004-06-07
Posts: 1,854

Re: solar power towers on mars - km-high vertical wind tunnel turbo-elec

Might I make a recommendation
Building a very high tower is quite an engineering challenge but digging a mile down is a lot easier especially if we just use a large bore machine and pipe. The pipe can then be sealed and the air condensed and a loop created with the air getting heated by undersurface heat.

Of course it would work better with fluids,,


Chan eil mi aig a bheil ùidh ann an gleidheadh an status quo; Tha mi airson cur às e.

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#60 2020-02-13 16:36:37

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 17,766

Re: solar power towers on mars - km-high vertical wind tunnel turbo-elec

Well Hello my friend, its been quite a long time.
I would agree that a hole is easier Grypd.
One issue we have had is nailing down the mass for a given size Boring machine and what energy level it might require for use on mars.

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#61 2020-02-16 06:36:40

Grypd
Member
From: Scotland, Europe
Registered: 2004-06-07
Posts: 1,854

Re: solar power towers on mars - km-high vertical wind tunnel turbo-elec

This is not a project for any initial Mars base it will be for a time where we have done extensive geological surveys of Mars as well as having built up a decent Martian industrial capability. So the drilling machines will have to be made on Mars not sent from Earth.

We will have done it anyway just so we can tap into underground Aquifers.

And it is good to be back


Chan eil mi aig a bheil ùidh ann an gleidheadh an status quo; Tha mi airson cur às e.

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#62 2020-02-16 08:24:32

tahanson43206
Member
Registered: 2018-04-27
Posts: 1,819

Re: solar power towers on mars - km-high vertical wind tunnel turbo-elec

For Grypd re #61

Your line about underground Aquifers is the inspiration for this post.  However, the mention of your long tenure here led me to check out your 1853 posts, or (more accurately) the tip of the long stream of your posts.

http://newmars.com/forums/viewtopic.php … 303#p40303

This topic and several adjacent to it were interesting to me because of the perspective of the English experience with management of crime.

I came away from a brief visit with those posts thinking that your recommendation is that Mars NOT be used as a penal colony.  I found myself in agreement with your recommendation to set up a Canadian Mounties type police force.  I noted your recommendation that this force must be designed to resist and foil any attempt by a would-be dictator to take over the force.

However ... to your post!

The possibility of underground Aquifers makes sense to me, but (to my knowledge at this moment) no technology exists that is capable of finding a particular atom or compound in the interior of Mars.   If you are aware of technologies that are capable of identifying deposits of water or useful minerals under the surface of an object such as a planet, I'd really appreciate your posting about them in the forum.

For consideration of SpaceNut's efforts to try to direct the flow of posts into somewhat meaningful directions, please find out from SpaceNut where such posts should go.

I am aware of these technologies that might help:

1) Radar (various frequencies)
2) Sonar (probably various frequencies but I'm not sure)
3) Measurement of particles of various kinds

This later technology has the greatest potential for planetary interior discovery, but it also requires the greatest investment.

Neutrinos are (I gather) extremely difficult to work with because of their weak interaction with ordinary matter.  However, apparently they CAN be employed to discover facts about matter between their point of origin (eg, the Sun) and the detector.

We on Earth would certainly benefit from discovery of a technology that allowed for precise location of deposits of oil, water, natural gas, minerals of all kinds and specific substances such as Uranium.  To my knowledge, such technology only exists in conceptual form in science fiction and Star Trek episodes.

This topic is about solar power towers on Mars, so I'll admit that discussion of technology to investigate the interior of a planet is a stretch.

The link (if there is one) is your introduction of the idea of digging a well << grin >>

In closing ... you still maintain your point-of-origin as Scotland.  I would imagine you've noted the arrival of Calliban in the forum.  He started out from Scotland, but for political correctness reasons (I'm guessing) he changed to "Northern England".   Americans (I believe) have a tendency to associate Scotland with great engineering feats, and with great engineers, so I appreciate your hanging on to your Scottish connection.

(th)

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#63 2020-02-16 09:30:39

Grypd
Member
From: Scotland, Europe
Registered: 2004-06-07
Posts: 1,854

Re: solar power towers on mars - km-high vertical wind tunnel turbo-elec

Well the best way to find out was underground is by listening to sound waves as they pass through rock. Through the time and the distortion of sound and of course our knowledge from Earth updated to Martian standards we will learn. We already use radar to look for minerals but also we look using changes in magnetism. We know there are Aquifers possibly of non frozen water as we have seen these leak and leave obvious geological features.
Mars has a metallic core as we understand it and it is hot and a liguid it just does not move so no magnetic field. This means as you tunnel down the rocks will get hotter and we can use this possibly through a stirling engine to provide not only power but as a source of heat for Martian domes. Another means of terraforming is creating very large deep holes so the heat could be released to help heat the planet these are called Moholes https://marsproject.com/mohole.htm
And yes im from Scotland in fact im from the Highlands


Chan eil mi aig a bheil ùidh ann an gleidheadh an status quo; Tha mi airson cur às e.

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#64 2020-02-16 11:42:01

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 17,766

Re: solar power towers on mars - km-high vertical wind tunnel turbo-elec

copied posts to Recent water on mars topic

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