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This topic is inspired by the intriguing idea of Mars_B4_Moon, that there might a a future in which a "steam" boat is deployed on Titan.
For a reminder of what this topic is about, please see: http://newmars.com/forums/viewtopic.php … 97#p212897
This topic starts out with a conversation with ChatGPT (3.5)
We stopped the first conversation after exploring the thought space for a while.
We left off just as ChatGPT asked for specifics to work with, such as the size of the piston/cylinder combination that would be used to deliver mechanical energy given simple thermal energy as input, and Carbon Dioxide gas as the working fluid.
If there is anyone in the forum who would like to see this inquiry pursued, this topic is available.
Please see the last couple of paragraphs of the transcript for suggested next step inputs.
Update: per an article I found in Wikipedia, a Stirling Engine is (apparently) capable of achieving 40% efficiency, under the right circumstances.
However, this topic is NOT about efficiency ... this topic is about raw, massive power delivered on site on Mars, using nothing but a source of thermal energy and the simplest possible mechanical equipment
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Conversation with ChatGPT ...
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tahanson43206
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Hello Again on Saturday 2023/08/12 at 11:28 local time - I have a question about phase change related to mechanical power generation
ChatGPT
Hello! I'd be happy to help you with your question about phase change related to mechanical power generation. Please go ahead and ask your question.User
A member of a forum about Mars asked what seems to me a reasonable question: Is is feasible to build a "steam" engine on Mars, using available resources. Since water is not available on Mars, we considered what ** is ** available, and that is Carbon Dioxide. It ** seems ** feasible to carry a load of dry ice in a "coal car" behind a locomotive, and to heat the dry ice to make CO2 gas which is able to provide power for a mechanical piston. This question should be suitable for your store of knowledge which ends in 2021, because the knowledge you can draw upon should cover this situation. We are assuming the locomotive contains a suitable source of thermal energy. Please compare the energy flows of a water based "steam" engine on Earth, and a dry ice based "steam" engine on Mars. Let's discuss this request before you start work.
ChatGPT
Absolutely, let's discuss this before delving into the comparison. The idea of using dry ice (solid carbon dioxide) as a working fluid for a "steam" engine on Mars is intriguing. In essence, this would involve a similar concept to a steam engine, where a working fluid undergoes a phase change to generate mechanical power.Before we start comparing the energy flows of water-based steam engines on Earth and a hypothetical dry ice-based "steam" engine on Mars, there are a few important factors to consider:
Thermal Source: You mentioned that the locomotive would contain a suitable source of thermal energy. It's crucial to assess the feasibility of this heat source on Mars, as it affects the energy input required for the engine.
Phase Change: In a typical steam engine, water undergoes a phase change from liquid to steam. Dry ice would similarly need to undergo a phase change from solid to gas. The energy required for this phase change (latent heat) is significant and needs to be considered in the comparison.
Working Fluid Properties: Carbon dioxide behaves differently from water in terms of its phase change properties and thermodynamics. Understanding these differences is essential for a meaningful comparison.
Efficiency and Power Output: The efficiency and power output of the dry ice-based engine would depend on various factors, including the quality of insulation, the design of the engine, and the specific heat source.
Resource Availability: While carbon dioxide is abundant in the Martian atmosphere, the process of obtaining and handling dry ice would require infrastructure and energy resources.
Considering these factors, it would indeed be interesting to compare the energy flows of a water-based steam engine on Earth and a dry ice-based "steam" engine on Mars. We would need to analyze the following aspects:
Energy Input: How much energy is required to heat the working fluid (water on Earth, dry ice on Mars) to its phase change point?
Energy Output: How efficiently can the generated steam or CO2 gas perform mechanical work in each system?
Overall Efficiency: What is the overall efficiency of each system, taking into account energy losses, heat transfer efficiency, and other factors?
Resource Requirements: What are the resource requirements for both systems? This includes the availability of water on Earth and the feasibility of obtaining and storing dry ice on Mars.
Environmental Impact: Consider the environmental impact of using each working fluid, including waste products and potential greenhouse gas emissions.
Given that this is a complex comparison involving thermodynamics, fluid dynamics, and engineering considerations, it's important to approach it with a detailed analysis of the specific conditions on both Earth and Mars. While the fundamental principles of phase change and energy conversion remain constant, the practical implementation and efficiency can vary significantly due to the unique characteristics of each environment.
If you'd like, I can help you further by performing calculations or providing more detailed information on the specific thermodynamic properties of water and carbon dioxide. Just let me know how you'd like to proceed!
User
Thank you for opening the line of inquiry and for agreeing to pause so we can try to optimize the use of your time. In reading a bit of the history of the development of steam power on Earth, over many years, I was reminded of the problems of using ordinary ground sourced water. The presence of contaminants in the water led to challenges for engineers and operators. These would not be present in the scenario we are considering for Mars, because the dry ice to be carried in the "coal car" is free of contaminants. Dry ice is produced naturally on Mars, so can be considered to be a resource to be used for this purpose, just as a supply of ground water on Earth would be considered a resource to be used. Of particular interest were problems encountered by engineers and operators when attempting to increase pressure of steam. It appears that most successful steam engines ran at about 250 psi. It appears that many higher pressure systems were tried, but apparently none were ever successful in the marketplace.
ChatGPT
You're welcome! It's great that you're considering the historical context and unique challenges of using different working fluids for power generation. The absence of contaminants in the dry ice used on Mars could indeed simplify some of the challenges associated with using water as a working fluid.Regarding the pressure of steam engines, your observation is correct. While steam engines were capable of running at higher pressures, there were practical limitations and challenges associated with increasing steam pressure significantly. Here are a few reasons why very high-pressure steam engines faced difficulties:
Material Strength: As steam pressure increases, the materials used to build the engine, particularly boilers and pipes, need to be stronger to withstand the pressure. This can lead to heavier and more expensive components.
Safety Concerns: Higher pressures increase the risk of boiler explosions and other safety hazards. Ensuring the safety of the equipment and operators becomes more challenging at higher pressures.
Efficiency Trade-offs: While higher pressure can potentially increase the efficiency of a steam engine by allowing it to extract more work from the same amount of heat, there are diminishing returns. At some point, the added complexity, cost, and safety concerns may outweigh the efficiency gains.
Engineering Challenges: Operating at higher pressures requires more precise engineering and tighter tolerances. Small leaks or failures can have more severe consequences at higher pressures.
Maintenance and Reliability: Higher-pressure systems can require more frequent and rigorous maintenance to prevent failures and maintain efficiency. This can increase operational costs.
Considering these challenges, steam engines on Earth typically operated at pressures around 250 psi (pounds per square inch). It's interesting to consider how these challenges might translate to a dry ice-based "steam" engine on Mars. While some of the issues related to water contamination and material strength might be less relevant, there could still be considerations related to the strength of materials under extreme cold temperatures, the behavior of carbon dioxide during phase changes, and the overall engineering complexity of operating at high pressures.
Ultimately, when designing any power generation system, it's a balance between efficiency, safety, reliability, and cost. While using dry ice as a working fluid on Mars introduces its own set of unique challenges and advantages, careful engineering and analysis would be necessary to determine the feasibility and practicality of a high-pressure dry ice-based "steam" engine on Mars.
User
The challenge facing the engineer in this situation is how to achieve mechanical power using nothing but thermal energy as the input to the system. On Earth a supply of chemical energy was provided by Nature, in the form of stored hydrocarbons for fuel, and free oxygen in the air for oxidizer. On Mars, the energy supply will take some form NOT based upon chemical transformations, since no oxidizer is available on Mars. In your reply, you mentioned the importance of planning for temperature of the working fluid in the context of moving parts, such as pistons moving in cylinders, and valves to admit hot gas into the cylinder and to exhaust cold gas. With this background, let's see if we can compute a system based upon input of dry ice to a heating chamber, and delivery of gas to the piston chamber at the highest feasible pressure, to maximize the efficiency of the system. For comparison, it appears that the most efficient steam locomotives achieved 8% transfer of potential chemical energy into mechanical energy.
ChatGPT
Certainly, let's continue with this line of inquiry and attempt to outline a system that utilizes dry ice as a working fluid for power generation on Mars. Since there's no available oxidizer, we need to focus on utilizing thermal energy to generate mechanical power through a process that doesn't involve chemical reactions.Here's a simplified outline of a hypothetical dry ice-based power generation system on Mars:
Resource Collection: Dry ice (solid CO2) is collected from the Martian atmosphere or regolith and stored in a supply car.
Heating Chamber: The dry ice is loaded into a heating chamber. Thermal energy is supplied to the chamber, causing the dry ice to sublimate (change directly from solid to gas) and increase in pressure. The heating chamber needs to be well-insulated to prevent heat loss.
High-Pressure Gas: The high-pressure carbon dioxide gas generated from sublimation is directed to a high-pressure chamber containing a piston. This chamber serves as the "steam" chamber in this dry ice-based system.
Piston and Mechanical Work: As the high-pressure CO2 gas is introduced into the piston chamber, it pushes the piston, converting the pressure energy into mechanical work.
Exhaust: After doing mechanical work, the CO2 gas is released from the piston chamber and directed to an exhaust system. The gas will cool and expand as it does work, and it needs to be efficiently exhausted to ensure the piston can return to its original position.
Piston Return: A mechanism, such as a spring or another high-pressure gas, can be used to return the piston to its initial position, ready for the next cycle.
Calculating the efficiency of such a system involves several factors:
Energy Input: Calculate the energy required to heat the dry ice in the heating chamber from its initial temperature to its sublimation point. This involves considering the specific heat capacity of dry ice.
Energy Output: Calculate the mechanical work done by the piston using the pressure and volume changes. This involves considering the thermodynamic properties of carbon dioxide.
Efficiency: The efficiency of the system can be calculated as the ratio of the mechanical work output to the energy input.
It's important to note that this is a simplified overview, and the actual design and engineering of such a system would be much more complex. Factors like insulation efficiency, heat transfer losses, valve design, and piston behavior would all play critical roles in determining the overall efficiency and feasibility of the system.
Regarding the comparison to steam locomotives, if the most efficient steam locomotives achieved an 8% transfer of potential chemical energy into mechanical energy, it would be an interesting benchmark to consider when evaluating the potential efficiency of the dry ice-based system on Mars. However, since the dry ice system relies solely on thermal energy without chemical reactions, the efficiency might differ due to the absence of combustion and heat losses associated with chemical reactions.
To proceed with detailed calculations and analysis, I would need specific data such as the initial temperature of the dry ice, the pressure-temperature relationship for carbon dioxide, the piston's dimensions, and more. If you have specific values or parameters in mind, I can certainly assist you in performing more in-depth calculations.
User
This has been a helpful review of the line of inquiry. I'd like to offer our conversation to the group, to see if anyone is interested in pursuing this further. Best wishes to you as you endeavor to assist your thousands of fans, world wide.
ChatGPT
I'm glad to hear that you found our discussion helpful! Feel free to share this conversation with your group. If anyone is interested in pursuing this topic further or has additional questions, I'm here to help. Best of luck with your discussions, and if you or anyone else has more inquiries in the future, don't hesitate to reach out. Thank you for your kind wishes, and take care!Regenerate
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Tahanson I believe Louis would post many scifi concepts in from British and American fiction but I have not seen him post in over a year, the 'steampunk' concept has been considered as a way of moving on the hellish planet of Venus. Titan is unique in having so many features like Earth but it will be difficult to colonize being so cold and so far away. On Mars transport we have an interesting numbers of topics on Rail and Tunnels, an overground Railway and a Subway system on Mars. On Mars there is evidence for access to Methane, CO2 might be used in a heat system, the Phoenix lander showed brine droplets, any system would not have to worry about 'Global Warming' gasses as we do on Earth. on Mars gas such as Water vapor (H2O) Carbon dioxide (CO2) Methane (CH4) on industrial gas 'Sulfur hexafluoride' or SF6 the refrigerants Trichlorofluoromethane, also called freon-11 and Difluoromethane used in industry might improve the Planet's atmosphere, a newly made planet might suddenly have hot spots, out gassing and cold spots, we do have extremophiles on Earth but general temperature range for all life on Earth is 253.15 K or -20°C or −4.00 F to 100°C or 212 F, a hot industrial zone on Mars could be uncomfortable industry region for man but maybe robots would work inside the colony and even a zone we consider 'too hot' or too cold near ice caps might still produce an eco-system or a natural bio-chemical process. Mars could be easier to Terraform than Earth it is about half of Earth's size and the surface area of Mars is about 38% of Earth’s surface area. Any industry zones on Mars too hot or too cold, the human could travel inside protected cars or trains. The Steam Engine on Mars might be a vehicle that Terra-forms the whole planet, adding enough greenhouse gas in an amount sufficient to block thermal radiation from totally leaving the planet. For the moment Terraforming is scifi and theory, the hypothetical process of deliberately modifying the atmosphere, temperature of an offworld civilization
Publication 1976
https://ntrs.nasa.gov/citations/19770005775
On the habitability of Mars: An approach to planetary ecosynthesis.
Here is a NASA article on '14-Year Continuous Operation Milestone'
https://www.nasa.gov/feature/glenn/2020 … -milestone
and the Chinese
For the First Time Ever, China Tested a Stirling Engine in Space
https://www.popularmechanics.com/space/ … ter-china/
The converter could provide a viable source of energy for future space colonies.
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For Mars_B4_Moon re #3
Thanks for your comments and for additional links ...
In particular, your link to a story by DARREN ORF about the Chinese being first to put a Stirling Converter into space ** really ** caught my eye. I was surprised to see that the Chinese are so far ahead of NASA, which has been poking along with it's Stirling design for the KRUSTY power system. A detail that also caught my eye was the (apparent) elimination of a separate generator .... The reporter (ORF) indicated that the pistons inside the Sterling engine are magnetic, and they generate current as they move due to thermal energy. A "normal" Stirling engine/generator setup would require two machines. it sounds as though the Chinese have found a way to go directly from thermal energy to electrical power. That's impressive.
There was a time when Americans and westerners in general indulged in the conceit that the Chinese were copying western work. It seems clear from the example you've provided, that innovation is happening in China. The near total wipe out of the semiconductor industry by Chinese factories is another example. It's one thing to design a system to make something. it's something else entirely to design a system to mass produce complex items at prices that sweep the competition off the board.
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For Mars_B4_Moon ....
Re topic ....
Taking into account that many of your readers may not have a technical background, I'd like to bring to your attention a small detail that might easily be overlooked in considering "steam" locomotives for Mars (or steam boats for Titan)
In neither case is there anything available to burn. The heat source must be brought along to provide the phase change and temperature increases needed for the working fluid.
That heat source would most likely be a nuclear device of some kind.
The "steam" locomotive concept will work on Mars if the working fluid is carried in a "coal car" as dry ice, and heat is supplied to deliver the gas-under-pressure that does physical work.
Thus there will be NO net increase in CO2 in the atmosphere. Back at the supply depot, another process is going to be accumulating dry ice for use in the transportation sector. Dry ice is produced naturally on Mars, so it just needs to be collected and shipped to where it is needed.
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I would like to see this idea of Mars_B4_Moon developed here on Earth.
The mechanism in play is the use of CO2 as the working fluid, much as water was the working fluid during the hay day of steam power in the US. A difference is that on Mars, storing CO2 in solid form is more practical than liquid. This means that additional energy must be invested in the phase change from solid to gas than would be the case for the phase change from liquid go gas.
According to Wikipedia articles I read recently, the best efficiency achieved with steam engines on Earth was in the range of 7 - 8 percent. Efficiency is not the concern here. It is assumed that nuclear thermal power sources produce plenty of thermal energy. The issue is how to transform that thermal energy into mechanical force and motion at remote locations on Mars, and In massive quantities such as for earth moving equipment.
An entire duplicate system can be built and tested on Earth.
I'd like to see this idea developed into fully working hardware, for evaluation for Mars missions.
The hardware to be developed would be competing against other systems for transforming thermal energy into useful work.
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The relative inefficiency of non-condensing steam cycles is a result of the high heat of evaporation of water (2200MJ/kg) and the high specific heat of the liquid. By ejecting steam as a gas, a great deal of enthalpy is wasted. For carbon dioxide, enthalpy of vaporisation is 350KJ/kg.
https://en.m.wikipedia.org/wiki/Carbon_ … data_page)
So far less energy is wasted by venting waste CO2. Also, the low pressure ambient environment on Mars allows excellent expansion of the hot gas.
"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."
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For Calliban re #7
Thank you for adding to this new topic.
While the topic itself was inspired a vision of Mars_B4_Moon, about steam "boats" on Titan, the option to use CO2 as a working fluid for high power machinery on Mars seems reasonable to at least consider.
With your post on the scene, we have the beginnings of what I hope will become a robust collection of numbers showing the way forward.
A concern with any robust machinery, on Mars or anywhere, is availability of adequate lubrication. Titan would appear to be a possible source for lubricants. Otherwise they must be made on site or imported from Earth.
It seems to me that almost any of the steam locomotives designed for Earth would be able to function on Mars, with substitution of dry ice as the stored working fluid, and a nuclear reactor to provide thermal energy.
There's a topic in the forum that pops up whenever Mars_B4_Moon is in the mood, on trains on Mars.
This topic would provide supporting engineering guidance for anyone contemplating large scale transportation on Mars.
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Zubrin calculated the energy cost of liquefied CO2 to 84kWh/tonne on Mars.
https://ntrs.nasa.gov/api/citations/199 … hment=true
This is quite energy cheap, because the temperature of the Martian atmosphere is always beneath the critical point of CO2. Very little compressor work is needed. The harvesting device is also very simple. You need an axial compressor that increases pressure to about 100psi, followed by an array of condenser tubes. The CO2 will condense as liquid on the tubes. The CO2 entering the compressor is cold (circa -50°C), so there probably does not need to be interstage cooling. CO2 refilling stations can therefore be simple devices. A compressor and a steel tank. The vehicle may contain a small fission heat source, RTG, or stored heat charged by a solar concentrator or base reactor waste heat. Much depends upon the application.
"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."
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For Calliban re #9
Thanks for your boost to this new topic! A lot of work in this area has already been done in the forum, in this general area of focus, but I'm hoping this new topic will help to collect the specific knowledge needed to build out a system on Mars.
In the opening of this topic, adapted as it was from an idea of Mars_B4_Moon about "steamboats" on Titan, I imagined that the best way to carry CO2 on a train on Mars is in the form of dry ice. Your opening post here reminds readers of earlier work done with CO2 in the liquid state.
I called up a chart called "Pressure-Temperature phase diagram for CO2" (stevengoddard.wordpress.com).
It shows that CO2 can be liquid if kept under pressure for a wide range of temperatues.
The sublimation point of ice to gas is shown at -78.5 and one atmosphere.
The temperature of CO2 where ice appears to be stable is -140 Cesius or so ....
If you are willing to add to your post, please describe the practical considerations that would influence decision making on Mars, in building a transportation system based upon this technology.
I started things off with the concept of a "coal car" filled with dry ice, because that configuration requires no pressure at all.
Your opening post suggests a preference for CO2 in the liquid phase, and there may be advantages I am not aware of.
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An older article. On the use of CO2 on Earth
Can Carbon Dioxide Replace Steam to Generate Power?
https://www.scientificamerican.com/arti … ate-power/
The U.S. Department of Energy hopes to create a more efficient turbine that uses CO2 to make electricity
A simpler, smaller, cleaner machine
The term "supercritical" describes the state of carbon dioxide above its critical temperature and pressure, 31 degrees Celsius and 73 atmospheres. Under these conditions, carbon dioxide has a density similar to its liquid state and fills containers the way it would as a gas.Coffee producers are already using supercritical carbon dioxide to extract caffeine from beans. Materials companies are also using it to make plastics and ceramics.
"From a thermodynamic perspective, it's a very good process fluid," said Klaus Brun, machinery director at the Southwest Research Institute, a nonprofit research and development group. "You get a fairly efficient cycle and a reasonable firing temperature."
In its supercritical state, carbon dioxide is nearly twice as dense as steam, resulting in a very high power density. Supercritical carbon dioxide is easier to compress than steam and allows a generator to extract power from a turbine at higher temperatures.
The net result is a simpler turbine that can be 10 times smaller than its steam equivalent. A steam turbine usually has between 10 and 15 rotor stages. A supercritical turbine equivalent would have four.
"We're looking at a turbine rotor shaft with four stages on it that's 4 inches in diameter, 4 feet long and could power 1,000 homes," said Richard Dennis, turbine technology manager at the National Energy Technology Laboratory.
He noted that the idea of a supercritical carbon dioxide power cycle dates back to the 1940s, but steam cycles were already very efficient, well-understood and cheap, creating an uphill slog for a new power block to catch on. In addition, engineers were still finding ways to improve the combustion side of power production, so the need to improve the generation side of the plant wasn't as acute until recently.
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Thanks to Mars_B4_Moon for finding and showing the work in the US and elsewhere to consider supercritical CO2 for a turbine.
As I understand the proposal, it does not seem to me to be incompatible with the theme of this topic.
The challenge is to try to find a way to use a simple heat source, such as a fission reactor, to deliver massive amounts of mechanical power on the surface of Mars. The proposal in a nut shell is to sacrifice efficiency for raw power, while using dumb/simple thermal energy as the initial energy supply, and while employing the simplest possible mechanical equipment.
I am hoping that Calliban will evaluate the post of Mars_B4_Moon to see if there might be an opportunity to catch CO2 on it's way from dry ice to gas released to the atmosphere, to drive the turbine as described in the post.
The first alternative is a "traditional" piston powered machine, but such a machine would have many more moving parts than would be the case with the turbine. On the other hand, such a machine would not be dependent upon the supercritical state of CO2, since the need in the case of a piston machine is energetic gas.
It seems to me that the designer of a transportation system for Mars would want to build the most robust possible system at the lowest energy cost, using available materials if at all possible.
I'd like this topic to bend toward practical knowledge and advice for an actual investor, while at the same time providing room for the occasional wild leap off into some alternative vision space.
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Using some concepts from the Nuke powered Car to make a small Train?
The Ford Nucleon was a nuclear-powered concept car developed by Ford Motors, the vehicle was designed to be powered by a small nuclear reactor in the rear of the vehicle
Why The Nuclear-Powered Ford Nucleon Is The Most Extreme Concept Car Ever
https://www.hotcars.com/1950-ford-nucle … ncept-car/
As the name suggests, this was Ford’s attempt to design and explore a nuclear-powered car. An ambitious project that was one of a handful of designs during the 1950s and 1960s that explored nuclear power.
The Nucleon would generate its power for electronic torque converters. Something akin to an electric-motor generator arrangement. This somewhat resembles a modern hybrid. Despite the eye-catching design and intriguing idea of a nuclear car, the 1958 Nucleon vanished as quickly as it arrived that year. All because nuclear technology simply wasn’t ready for a mass-produced car.
2015 Article
'How energy from dry ice could power human colonies on Mars'
https://theconversation.com/how-energy- … mars-38250
We have developed an engine which can harvest energy from dry ice as it turns from solid into gas. For Martian exploration, it could be a game changer.
Experimental Design and Preliminary Analysis of a Mars CO2 Rapid Cycle Adsorption Pump
https://ntrs.nasa.gov/citations/20190029042
Social media ideas
Off the grid heat pump
'DIY Stirling engine CHP to go off the grid in the energy crisis'
https://www.youtube.com/watch?v=QzxW8BD7Fxk
another simple animation
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Hotair Engine Competitions
https://www.beyonddiscovery.org/stirlin … tions.html
EU grant project
Stirling heat pump for high temperature industrial use
https://cordis.europa.eu/project/id/831062
Industrial sectors around the world rely on heat for a myriad of uses including washing, drying, sterilising, process heating and so much more. Demand for heat accounts for most of the industrial energy demand as well as significant global energy consumption, and it contributes to increased emissions. In particular, the demand for high-temperature process heat is on the rise, and it is primarily fuelled by conventional boilers. The EU-funded Highlift project is developing an innovative high temperature heat pump to make industrial processes greener. The system will take in water warmed to low temperatures by waste heat recovery processes and heat it with electricity to produce steam.
Stirling engine
https://www.northernarchitecture.us/ren … power.html
A cultural event on Earth
Driffield Steam Fair 2023: All the best pictures from the heritage event as crowds come out in force
https://uk.finance.yahoo.com/news/driff … 22166.html
There might be future exploration of the outer planets, ESA and NASA are going to Jupiter.
On the subject of Titan Railways and Lakes
'NASA’s Dragonfly Titan Probe Eyes Early Fall Review'
https://aviationweek.com/defense-space/ … all-review
Last edited by Mars_B4_Moon (2023-08-21 17:53:06)
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Tried to put a reply in here, but keep getting an internal server error.
Last edited by Calliban (2023-08-22 03:58:23)
"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."
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Perhaps the right idea for an isolated, harsh, and lethal planet is something hybrid between a train and trucks. Think of a big battery-electric tug vehicle, with big wheels for off-road use, sort of like a mine loader. Add many cargo carrier trailers (also with big off-road wheels) in a string behind it. Put solar panels on the roofs of all of them, and wire them together so that the collected electricity gives the battery-electric tug lots of range. Now, all you need is a graded road, not a track. But it works like a big, slow freight train. Max return for min effort expended.
GW
GW Johnson
McGregor, Texas
"There is nothing as expensive as a dead crew, especially one dead from a bad management decision"
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Tried to put a reply in here, but keep getting an internal server error.
for Calliban ...
The Admins are (slowly, carefully) moving toward solving problems with the forum. I expect it will take a considerable amount of time. There is a lot to learn, and we have to be careful because we've been given access to the Mars Society server. While we wait for conversion to a newer forum package, or for solutions to problems with this one, I am willing to post messages that are blocked by Apache. You are welcome to send the blocked post to the NewMarsMember email, which is given in the Recruiting topic.
In a recent episode with one of GW Johnson's posts, I found a string that was triggering whatever is happening with FluxBB or Apache. By adding spaces between the letters of that sentence, I was able to clear the obstacle, and the rest of the message posted without incident. The behavior is similar to what I would expect if there were an anti-virus scanner looking at incoming text.
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Seems to have posted now
****************************
The nuke car / rover concept would be a lot more practical if progress is made with lattice confinement fusion. The fusion module would sit at the centre of a block of depleted uranium. Some sort of driver assembly would start off fusion. Fusion events would release 14MeV neutrons, leading to fast-fission in the DU, generating heat. The neutrons yielded by fast fission would result in neutronic feedback, driving more fusion events as they collide with deuterium atoms in the fusion module. Gamma rays would have the same effect. Excess neutrons will also breed plutonium in the DU block, increasing reactivity and reducing the driver input needed.
The DU shell would provide substantial gamma and neutron shielding. A bath of molten sodium or lead around the block wouod serve as both additional shielding and heat transfer fluid. A sterling engine, CO2 boiler or steam boiler could be used to convert the heat into mechanical and electrical power.
Last edited by Calliban (2023-08-22 10:18:41)
"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."
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Perhaps the right idea for an isolated, harsh, and lethal planet is something hybrid between a train and trucks. Think of a big battery-electric tug vehicle, with big wheels for off-road use, sort of like a mine loader. Add many cargo carrier trailers (also with big off-road wheels) in a string behind it. Put solar panels on the roofs of all of them, and wire them together so that the collected electricity gives the battery-electric tug lots of range. Now, all you need is a graded road, not a track. But it works like a big, slow freight train. Max return for min effort expended.
GW
A direct solar-electric vehicle drive system would be logistically simple, provided we could tolerate low speed and driving only in sunlight. I think this probably would be tolerable in many applications. Given the dust and jagged rocks on the Martian surface, high speed travel is undesirable in a wheeled vehicle. Also, one would want to avoid flexing the chassis when it is cold and vulnerable to stress fractures, i.e at night.
I can see this working for long distance exploration, where you want to chug along at first gear speeds, for long periods, without the ability to refuel. It would restrict where you can go and when you can go there. For example, one wouldn't want to take a solar powered vehicle too far north or south during the respective hemispheres autumn or winter.
Last edited by Calliban (2023-08-22 10:29:10)
"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."
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While I suggested big off-road wheels, I also suggested a well-graded dirt roadway. While not by any means perfect, it would be a lot smoother than cross-country. And, it would tend to help with steering. These "truck trains" are something AI could drive, provided that one can assure no interlopers get onto the graded roadway.
The grader could be pretty much the same tractor vehicle, fitted with a blade, and a trailer full of batteries. You charge that trailer-load of batteries at night, from one of the new small nuke reactors, located in a second trailer, using the battery trailer as your shielding when you move it. It stays parked well-clear when you are working to grade the roadway.
When locating to a more remote worksite, you need a habitat for the off-duty crew, to be powered by the same nuke reactor trailer. That habitat is just another trailer. When moving it, the hookup is tractor, hab trailer, battery trailer, finally reactor trailer.
These things are big pieces of equipment. The hardest thing to accomplish is getting them to Mars in the first place. Probably in pieces, to be assembled there.
GW
GW Johnson
McGregor, Texas
"There is nothing as expensive as a dead crew, especially one dead from a bad management decision"
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It's time for the Topic Manager to remind everyone that any post contributed to this topic needs to include a reference to the theme of the topic.
The theme of this topic is stated in Post #1 ....
I went back and re-read Post #1 and found it less specific than is needed...
The topic title is clear enough. I thought that the purpose of the topic would be indicated by the title.
It is good to see road building included in the topic, because that is certainly a good use of raw mechanical power on Mars.
What this topic does NOT envision is a trailer full of batteries, which implies an "engine" using electric motors.
This topic is NOT about electric motors used for anything.
This topic is NOT about batteries used for anything other than backup for electronics.
We have plenty of talent available in this forum to develop a strong, robust, practical vision of a mechanical system that uses Carbon Dioxide as the working material, since there is so much of it on Mars, and since other materials are scarce.
I have proposed shipping dry ice with the train in a Mars equivalent of the terrestrial coal car.
The nuclear reactor described by Calliban and by GW Johnson is a necessary component of a land train, because any solution requires lots of raw thermal energy. There are other topics where electric solutions are in development, or in some cases are fully developed.
This topic is intended to develop a fully detailed vision of a mechanical system for transportation or construction work, based upon use of CO2 as the working fluid, and a small nuclear reactor as a source of dumb heat.
This topic is NOT about how to use thermal energy most efficiently on Mars. There are other topics where a focus on efficiency is appropriate.
This topic is about using dumb thermal energy on a large scale to perform mechanical actions, including transportation, road grading, material handling, excavation and whatever other similar mechanical activities our members can imagine.
(th)
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Sorry. We drifted into a discussion of what might actually work best. There are a bunch of similar topics, but as near as I can tell, nothing exactly like what we were discussing.
GW
GW Johnson
McGregor, Texas
"There is nothing as expensive as a dead crew, especially one dead from a bad management decision"
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For GW Johnson re Post #22
There seems to be a strong hint in your post that there might be a technology that would work better than the very simple easy-to-understand system proposed in this topic.
It should be possible to quantify "what might actually work best"
I would very much like to see a topic in the forum which attempts to show "what might actually work best"
Calliban and you (GW Johnson) appear to be the only active members with real on-the-job engineering experience.
It should be possible for the two of you to collaborate on a topic that attempts to define "what might actually work best"
This topic has a different focus ... It should be possible to develop a body of knowledge that can be implemented on Mars to move large quantities of material using nothing but dumb thermal energy as the prime mover.
Of all the possible solutions that might work on Mars, I am sure there must be ** one ** that "might actually work best".
This topic will not attempt to reach that lofty goal ... instead, this topic is intended to deliver a body of knowledge what would "actually work".
I am not an engineer, and I don't pretend to be one. What I ** can ** do is to provide a focus on a particular technology, and encourage our members to contribute to development of a body of knowledge that a suitably trained and experienced team could implement on Mars on a large scale, in a reasonable amount of time, using local materials.
In another topic, Mars_B4_Moon has ** just ** reported on research that is intended to find alternatives to concrete that might be made in locations away from Earth, without calcium, which is (as I understand it) a key component of Portland cement.
I would like to see ** this ** topic attract contributions that support the premise, which is:
1) Load dry ice into "coal" cars for input to the heating process
2) Heat the dry ice using dumb thermal energy to deliver CO2 gas under pressure
3) Harness the mechanical energy of energetic CO2 molecules to drive machinery
4) Exhaust the CO2 to the atmosphere, which is where it came from in the first place
This process does NOT require fancy chemistry.
This process DOES deliver massive amounts of mechanical energy for transportation or material handling.
(th)
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