Dry ice pneumatic tool

tahanson43206 · 2021-03-30 18:04:17

For SpaceNut re #50

Thank you for that (to me ** very ** ) interesting link !!

While the application I'm working on right now is less severe than sand blasting, surely sand blasting will be needed on Mars for any number of situations I can't imagine because I don't have the experience needed, but (hopefully) someone in the forum readership will be able to fill in that part of this record.

If you are such a person, read Post #2 of the Recruiting topic and then write NewMarsMember * gmail.com.

***
This next addition to the record was inspired by kbd512's helpful information that a cubic foot of air at STP weighs .0807 pounds.

He pointed out that the tool needs .807 pounds of air per minute, supplied at 90 psi.

Your (SpaceNut) observation about the effect of the hose is a factor that (hopefully) the tool designers took into account in shaping the metal components of the device. All I can do (at this point) is to confirm that when pressure is 90 psi at the pump, the air travels through a 25 foot hose and various fittings to drive the tool famously. Alas, the joy lasts only 10 seconds, but it does a ** great ** job while it can.

So here is a set of items I collected from sources provided by Google, in an attempt to understand more about the situation:

https://www.calculateme.com/volume/cubi … gallons/10

10 cubic feet = 74.8 gallons at 1000 psi

https://www.omnicalculator.com/physics/air-density

At 1000 psi
Air temperature
70
°F
Air type
Dry air
Air density
5.0957
lb/cu ft

50 pounds is approximately the amount of air needed to support 8 cfm for 60 minutes.

I used: .807 pounds for one minute * 60 minutes >> 48.42 pounds so rounding to 50 ...

The calculations shown appear to indicate that a 75 gallon tank at a pressure of 1000 psi would hold 50 pounds of air.

Now, in practice, on Earth, no one does that ... Instead, they build systems that refill a tank intermittently or in some cases continuously, and the operator waits to let the tank refill as needed.

In the proposed CO2 (dry ice) system that is the focus (and purpose) of this topic, there would a steady injection of dry ice into a boiler, and there would be a steady supply of heat (probably propane) to liberate the CO2 and (in addition) to heat it to 70 degrees (or less if that would benefit the tool by helping to keep it cool).

The boiler would (I presume) hold a pressure above 90 psi but not ** too ** much higher (for safety), and the sensing equipment would regulate the injection of dry ice and the supply of propane as needed.

On Mars, the equivalent heating service would be performed by CO (probably Liquid CO as kbd512 suggested) and O2, and probably Liquid O2, to keep the size of the equipment containers low, and the pressure they are holding down.

In all these posts, I am looking forward to correction, revision, adjustment .... whatever it takes ...

The goal here is to arrive at specification for a practical system that can be tested on Earth and implemented with success on Mars.

Edit#1 .... I'd like to point out a significant advantage of the dry ice system ... there would be NO problem with water interfering with operation of the components, or spoiling spray paint.

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SpaceNut · 2021-03-30 18:50:17

Post 17 has the pressure to have liquid co2 at room temperature.

tahanson43206 · 2021-03-30 20:38:11

For SpaceNut re #52

Thanks for the reminder that the liquid state is a risk for this project.

I had been imagining that the dry ice fed into the boiler would transition to gas phase without going through the liquid phase.

The post you cited in #52 indicates that the liquid phase requires significant levels of pressure.

The pressure I found earlier in the topic (in one of your posts) showed that the greatest pressure used for pneumatic tools is 120 psi.

This is a reminder (to me for sure) to go back and re-read the entire topic.

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tahanson43206 · 2021-03-31 07:43:30

SearchTerm:Boiler steam as prototype for Mars CO2 (dry ice) gas delivery system for pneumatic tools
SearchTerm:Steam boiler
SearchTerm:DryIce System for delivery of CO2 to pneumatic tools on Mars (prototype on Earth)

Humans on Earth have centuries of experience designing, building and operating steam boiler systems.

A version of such a system could convert dry ice to CO2 gas at a pressure and at a flow rate sufficient to operate pneumatic tools on Earth.

kbd512 provided a hint for the mass of air that would be needed. 0.8 pounds of air (to the nearest tenth) would match a required flow rate of 8 cfm. Extrapolating from that, i estimate that 50 pounds of air would supply the needs of a 8 cfm tool for an hour.

Per Google >> chem.libretexts.org >> CO2 has a mass of 44.01 g/mol.
Per Google >> Wikipedia >> O2 mass is 32 g/mol
Per Google >> pubchem.ncbi.nim.nih.gov >> N2 mass is 28.014 g/mol

CO2 is heavier than O2 or N2 ... I'm not sure how that difference translates into estimating the amount of dry ice needed.

Until correction or confirmation arrives, i'll assume that 50 pounds of dry ice is equivalent in effect at the tool to that weight of air.

Extrapolating from ** that ** I estimate that 50 pounds of dry ice would be more than sufficient to provide the required flow rate for an hour.

A local supplier provides dry ice for $1.00 (US) per pound in lots of greater than 20 pounds.

That puts an upper bound on the investment of $50 for the dry ice working material.

It should be possible to compute the energy requirements to convert dry ice to CO2 gas at 70 degrees Fahrenheit temperature and 90 psi.

From that number it should be possible to compute the amount of propane that would be needed to heat the boiler.

Along the way, it should be possible to estimate the minimum size boiler and burner combination needed for this application.

Sensors and control mechanisms are needed, just as would be the case with a steam boiler.

(th)

tahanson43206 · 2021-03-31 08:30:55

Google found this discussion when I asked about a stationary boiler that runs on propane

http://chaski.org/homemachinist/viewtopic.php?t=88465

Re: Small Propane cylinder boiler
Quote
Post by Fender » Sun Dec 05, 2010 9:16 pm
Timothy,
A propane tank is too thin to make a proper boiler out of. It is also likely made of the wrong alloy steel. These tanks are not subject to the heat and corrosion a boiler experiences. A boiler will have a "corrosion allowance", meaning that even if the boiler shell loses some of its thickness, it will still be safe to operate. Also, the boiler steel must be very ductile so that it can flex and take the repeated thermal cycles without cracking. Building a boiler is a lot of work, and you need to use the right materials from the start.
If your engine is truly small, a copper boiler may be a good way to go.

This discussion reminded me that Dayton Engineer is quite knowledgeable about gas powered engines ca 1870-1920, and his fund of knowledge includes some overlap with steam boiler driven engines.

Edit#1:Here's a view of the top end of the field ...

https://www.wabashpower.com/

I deduce from the ongoing success/sales of this company there is a significant demand for steam power on Earth in 2021.

India is still (to the best of my knowledge) still running steam equipment on many of their railroads.

Edit#2: There is a YouTube channel set up by MyFordBoy to offer instruction on shop practice

There is a set of four videos that shows how to make a small copper boiler to drive a model steam engine.

The process involved use of a lathe, hacksaw, scribe, hammer, file, torch (for annealing), drill press and various other tools.

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SpaceNut · 2021-03-31 17:29:56

Steam boiler are not where we are for the initial point in the purification process for dry ice on Mars is going to contain some impurities of salts, dust/dirt and some water with the salt.
The first stage takes the raw frozen product to make gaseous co2 to pump from the initial chamber to a tank to aid in the process to cool and increase pressure.
Since Mars night time temperatures will aid in that process. As volume pressure builds one would move that amount into a stronger pressure vessel.

tahanson43206 · 2021-04-01 07:43:58

For SpaceNut re #56

Thanks for your helpful and insightful observation about the nature of dry ice on Mars.

I expect it to be pure as the glaciers on Earth, but your reminder to be mentally prepared for contamination is helpful as we (humans) progress toward common use of CO2 as a mechanism for delivering pneumatic power on Mars.

On Earth (my understanding is) every snowflake starts out as a "colonization" of a particle of dust by water molecules. However, once the nucleus has been established (again, based upon my understanding (which could be wrong)) the accretion of additional water molecules proceeds without further "contamination". I would expect something similar happens on Mars. There is (apparently) plenty of dust in the air, so every "flake" of CO2 ice would (presumably) contain at least one dust particle.

However, I cannot imagine a mechanism by which salt would become part of a layer of dry ice. If you can imagine such a scenario, I'd be most interested to see the reference you may (well) be able to show.

However, for the purposes of designing a machine on Earth to demonstrate the practicality of the Dry Ice pneumatic tool concept, we have the great benefit of an industrial base that provides all the filtering services needed to deliver pure dry ice at $1.00 (US) per pound in my location, and probably elsewhere as well.

Thanks again for this timely and helpful cautionary advice. Contamination of the feed stock is definitely a concern for anyone planning to build a business around this technology!

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tahanson43206 · 2021-04-01 07:52:18

I have written "Dayton Engineer" to ask for assistance finding a resource to help with setting up a demonstration of the successful use of dry ice as a feedstock for a pneumatic tool. I am hoping his decades of experience/study of gas engines (ca 1870 onward) will overlap with study of steam engines from that era.

It is (remotely) possible there already exists a boiler designed for steam that might be the right size to demonstrate the ability to deliver 8 cfm at 90 psi for 60 minutes. I have a ballpark estimate of $50 (US) for the cost of dry ice for the experiment. I am hoping a forum member may be inspired to work out the quantity of propane needed to heat the dry ice to 70 degrees (or thereabouts) to achieve the needed pressure, and to do so for the full 60 minutes.

On Mars, that service (could) be performed by CO (probably liquefied if that is practical) and LOX (again, if that is practical).

Picking up on the suggestion of SpaceNut in Post #56 ... In an actual business situation, the provider of dry ice would (no doubt) perform analysis of the feedstock to insure contamination is below some reasonable number. It is possible and in fact inevitable that grades of dry ice will be on offer, priced in accordance with the effort needed to insure the specified purity. It is likewise possible (probable) that creative and inventive Mars residents will figure out how to deal with various grades of dry ice, so that all grades can be utilized effectively.

In thinking about the Post of SpaceNut regarding purity of dry ice feedstock, I am reminded of experience (some time ago) feeding and cleaning coal fired furnaces in homes and in a dormitory setting. Coal is most definitely an impure feedstock, and humans have learned how to deal with that reality by designing boilers so that the contamination falls below the burning surface (grate) and into a collection bin. Some similar process may become accepted practice on Mars, if dry ice becomes a common feedstock, and if contamination is found to be a problem.

In the case of a dry ice boiler, the contamination would (presumably) fall to the bottom of the boiler as the feedstock is transformed to gas, and periodically it would be necessary to open the boiler for cleaning.

Unlike with steam, I would expect little damage to occur to the walls of the boiler, since (on Mars) there would be little water mixed with the dry ice. There might indeed be ** some ** water present, but it would be present in relatively low amounts.

Edit#1: In thinking further about the Post of SpaceNut about possible contamination of dry ice, and about the mechanical design of a system to feed dry ice into a boiler, I am wondering if it might make sense to simply design the boiler to be opened to load a charge before a run. The boiler interior can be examined and cleaned if necessary, before the next load is inserted into the space. The mechanical challenge would then shift from dealing with feeding feedstock into the device, to dealing with the practical issue of sealing the halves of a chamber designed to hold pressure.

There may already exist (probability seems high to me) designs to do exactly that on Earth.

(th)

tahanson43206 · 2021-04-01 13:01:35

Following up ... Quora pointed to Wikipedia ...

https://en.wikipedia.org/wiki/Dry_ice

The density of dry ice increases with decreasing temperature and ranges between about 1.55 and 1.7 g/cm3 (97 and 106 lb/cu ft) below 195 K (−78 °C; −109 °F).[3] The low temperature and direct sublimation to a gas makes dry ice an effective coolant, since it is colder than water ice and leaves no residue as it changes state.[4] Its enthalpy of sublimation is 571 kJ/kg (25.2 kJ/mol).

By the range given above, 50 pounds of dry ice would occupy less than one cubic foot, so a "boiler" designed to perform sublimation of the material at a controlled rate need not be larger than one cubic foot, if the charge is 50 pounds.

***
Because of the need to load the container with dry ice before a run, and the need (suggested by SpaceNut) to clean out any suspended matter that might have accumulated in the boiler during the previous run, I'm imagining a pressure vessel designed with a top that slides over the base with overlapping flanges, so that as pressure accumulates the top is pushed away from the bottom, and the flanges are pressed together to improve the seal.

A pressure relief valve set to 200 psi should be about right to insure safety if the normal operating pressure of the tool is 90 psi.

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tahanson43206 · 2021-04-01 13:14:27

Following up further ...

https://www.parrinst.com/contact/parr-usa/

This is a very low priority inquiry at this point. I'm a member of a discussion group that is affiliated with the Mars Society. The proposal under discussion is that dry ice is a suitable material for driving pneumatic tools on Mars. The material is abundant on Mars, and it is delivered naturally in quantity overnight in some locations, and in any case, it is abundant in large deposits.
The question I'm investigating is design of a pressure vessel suitable for this application, ** and ** suitable for testing and evaluation on Earth. The pressure vessel I am thinking about would have a clamshell design, such that as the pressure builds inside the container, the flanges of the top and bottom segments press against each other around most of the perimeter, except for an end where the two halves slide over each other.
There may well be alternatives already in use in practice.
Your reply (along with this question) will be posted in NewMars.com/forums in the topic for Dry Ice Pneumatic Tools.
Thanks for your time!
Posting as tahanson43206
(th)

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kbd512 · 2021-04-01 18:05:35

tahanson43206,

I think you're after the isochoric heating capacity of CO2, although I have no idea how to compute this over the solid / liquid / gas phase transitions. I know that it constantly varies with temperature, so higher fidelity calculations require using the empirically-derived isochoric specific heating capacity values.

Hopefully, this link will help:

Specific heat of Carbon Dioxide gas - CO2 - temperatures ranging 175 - 6000 K

And this one:

Carbon Dioxide - Thermophysical Properties

Anyway, here goes nothing:

Initial Temperature: -78.5C (right at the freezing point of CO2)
Final Temperature: 20C (safely away from turning CO2 into a supercritical fluid, which we don't want to do here)
CO2 gas Specific heat capacity (Cv / isochoric): 0.658kJ/kg C

1kJ = 0.2777Watt-hours

q = mcsΔT
q = (0.658J/kg°C) * (1kg) * (20 - -78.5)°C
q = 0.658 * 1 * 98.5
q = 64.813kJ

64.813kJ * 0.277Wh/kJ = 17.999Wh

That's for 1kg of CO2 gas, but the CO2 will likely be stored as a liquid or dry ice, so that 0.658kJ value won't be accurate.

Enthalpy of sublimation is listed from the above source (engineer's toolbox) as 591kJ/kg, so 29,559kJ / 8,185.35Wh of heat energy must be added, using your 50kg dry ice block example from above, to sublimate 50kg of dry ice without passing through CO2's liquid phase. Using the LHV for CH4 / Methane, that would be equivalent to combusting 0.591kg of Methane to supply the input thermal energy.

In a practical system designed to supply gas heated sufficiently to prevent re-freezing during expansion to supply an air tool, is there some reason why we wouldn't do this electrically by sticking an electrical resistance heating coil / rod inside the tank of liquid CO2?

Edit: I highly recommend you get an engineer or someone who paid more attention in class to double-check this.

Last edited by kbd512 (2021-04-01 18:07:48)

tahanson43206 · 2021-04-01 21:00:46

For kbd512 re Post #61

Thank you for your generous response to my questions in this topic! I just read your post and will need to study it and (hopefully) apply the figures you provided to arrive at a total cost for the exercise.

Regarding heating the "boiler"/"sublimator" with electricity ... I agree completely that is a superior solution for a base where electricity is available. I'm trying to devise a solution that can be transported to a location where electricity is not readily available, which is why propane seemed like a practical solution.

SearchTerm:enthalpy of dry ice
SearchTerm:Calculation of dry ice energy requirement for sublimation to make CO2 for pneumatic tools

See kbd512 in post 61

I have written to an engineer friend about the boiler configuration for this application. I'll see how far I can get with the running start you provided!

Thanks again!

Edit#1: Todo: Return to study the post by kbd512 ... translate the post into requirements for the specific tool in study ... estimate total cost of supplies

Todo(2) follow up on email from pressure vessel supplier <>

(th)

tahanson43206 · 2021-04-02 15:07:30

The following is a reply from a company I contacted about a pressure vessel for the Dry ice pneumatic tool study here in this topic.

I appreciate the courtesy of their reply, and invite forum members to comment upon the suggested solution:

Collins, Conan <conan.collins@parrinst.com>
To:
tahanson43206
Thu, Apr 1 at 5:30 PM
-Tom

Good afternoon! Now there’s an interesting application. I believe I see the allure: harvest dry ice at night, store it in a pressure vessel and during the day it reaches supercritical temp/pressure and therefore becomes a pressurized container whose potential energy you can utilize to run pneumatics.
In concept this should be simple: a pressure vessel which can be opened and filled via robotics, sealed, and then a valve which can be opened when power is needed. You can see our basic pressure vessel design for a 1-L or 2-L vessel at:
www.parrinst.com
Navigate to “non-stirred vessels >> 4600 1-L or 2-L”.
This design has a head and cylinder which can be sealed via o-ring, simplifying the sealing process. The split ring clamp is slid over the flanges on the head and cylinder, and it will hold up to 1900 psi. We manufacture these from solid bar and can customize these in any number of ways including higher pressure, shape, split ring retention, (edit) etc.
If this looks good, please let me know your thoughts and we can work on it. I expect there are a number of details that must be done right to work well via robotics and design it to the right temperature and pressure.
Best regards,
Conan
***********************************
Conan Collins
Parr Instrument Company
PH: 800-872-7720 x236
Direct line: 309-277-1836
FAX: 309-762-9453
conan.collins@parrinst.com
Webpage: www.parrinst.com
***********************************
From: Parr Instrument Company [mailto:parr@parrinst.com]
Sent: Thursday, April 1, 2021 2:12 PM
To: Randolph, Lisa <lisa.randolph@parrinst.com>; Parr <parr@parrinst.com>; Nelson, Jim <Jim.Nelson@parrinst.com>
Subject: United States - Custom Systems Google search for clamshell pressure vessel
From: tahanson43206
Subject: Custom Systems Google search for clamshell pressure vessel
Referring Page:https://www.parrinst.com/contact/parr-usa/
Contact Information:
Custom Systems Google search for clamshell pressure vessel
Message:
This is a very low priority inquiry at this point. I'm a member of a discussion group that is affiliated with the Mars Society. The proposal under discussion is that dry ice is a suitable material for driving pneumatic tools on Mars. The material is abundant on Mars, and it is delivered naturally in quantity overnight in some locations, and in any case, it is abundant in large deposits.
The question I'm investigating is design of a pressure vessel suitable for this application, ** and ** suitable for testing and evaluation on Earth. The pressure vessel I am thinking about would have a clamshell design, such that as the pressure builds inside the container, the flanges of the top and bottom segments press against each other around most of the perimeter, except for an end where the two halves slide over each other.
There may well be alternatives already in use in practice.
Your reply (along with this question) will be posted in NewMars.com/forums in the topic for Dry Ice Pneumatic Tools.
Thanks for your time!
Posting as tahanson43206
(th)

Serial Number:
How did you find us? Other
Message Sent to Visitor:
Thank you for contacting us.
Our customer service will check your message and forward to the best person.
We will get back to you within 2 business days.
Technical Sales Team
Parr Instrument Company
211 Fifty-Third Street, Moline, IL 61265
309-762-7716 | 800-872-7720
www.parrinst.com

(th)

SpaceNut · 2021-04-02 17:52:14

The email was very enlighting to them for the application.

Here another of simular topics use

SpaceNut wrote:

Calliban to further your delight in topics that are related.
Running on Compressed Air?
Compressed gas energy storage.
Hopefully that will get you thinking some more...
You may like this front page Journal article as well Mars Air and Water might be the key to power storage

Finally found pipe diameter to flow rate pressure post...

SpaceNut wrote:

Pipe materials widthstanding the diameter still can only move so much fluid through it to any destination.
A page with through put
https://flexpvc.com/Reference/WaterFlow … Size.shtml

tahanson43206 · 2021-04-03 12:09:58

This post will include an attempt to show a design from Parr Instrument Company for a pressure vessel with a removable head ...

If this attempt succeeds, a cross section of an existing design is shown

I think this design is over-engineered for the Pneumatic Tool use case, but it is definitely a starting point for evaluating options.

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kbd512 · 2021-04-04 00:03:19

tahanson43206,

How well does their pressure vessel design handle fine abrasive dust?

The practicality of any such design is dependent upon its ability to maintain pressure after being loaded with a block of dirty dry ice outside each night. The iron oxide inside should settle to the bottom, and could be "trapped" against the walls of the container using a suitably powerful magnet, but it still needs to seal properly for this to work.

tahanson43206 · 2021-04-04 07:13:17

For kbd512 re #66

Thanks for your contribution to the development of this topic!

I am still trying to find a block of time to work on the numbers post you already provided!

It seems to me there will be grades of dry ice harvested on Mars, and designs for equipment will reflect that. On Earth, oil is available in a wide range of grades, and humans have learned to adapt to each grade with appropriate equipment and practices. I'm thinking of the use of bunker oil by ocean going ships as an example, but there must be many, because almost everything pulled out of the ground gets used for something.

The quality of dry ice will be reflected in the price.

To your question ... I don't know (of course) but these are instruments designed for the chemical (and apparently biological) industry, so there must be a LOT of experience with all sorts of materials.

However, I am interested in the On-Earth application of this concept. I am wondering if this system might prove competitive with traditional mechanical pumping systems. There are two main streams of mechanical pumps (as far as I can tell). The primary and far more common system uses reciprocating piston pumps, and varieties of these are on display at any shop that supplies the trades. A newer variety is the spiral pump, the most notable example of which is the tiny CO2 pump installed in MOXIE on Mars.

In the case of an On-Earth application, supply of Dry Ice is of very high quality for $1.00 (US) per pound in lots of 20 pounds or more.

I am estimating the amount of Dry Ice needed at 50 pounds for a one hour run at 8 CFM, based upon my first scan of the figures you provided.

The pressure vessel shown in the illustration is (apparently) designed to withstand 1900 psi, and the Pneumatic Tool application needs only (about) 200 psi to cover most tool types I've been able to find (to this point).

The pressure vessel for the Pneumatic Tool application needs to be light enough to transport to a job site in the back of a pickup, for example, and equipped with a heating system (electric where practical and gas otherwise). The pressure control system needs to be at least as good as the equipment that came with the little $54 (US) 3 gallon pump I brought home recently.

To your specific point about dust in the Dry Ice .... I'm going to assume that any downstream equipment needs input that is free of abrasive material, so filters would seem (to me at least) necessary in the out flow from the pressure chamber.

The needs of the pressure valve to maintain a good seal would seem (again, to me at least) to require non-abrasive material flow, so that would imply the filter is inside the pressure vessel, ahead of the valve.

It seems to me that operators on Mars may develop the ability to ? visually ? inspect dry ice collected for use in this specialty? I have no direct experience to help in guessing what might be the case, but certainly humans on Earth have developed the ability to evaluate fuels by appearance, behavior and smell.

Smell isn't going to help on Mars! However, appearance may be helpful. Illumination of a slab of dry ice with a beam of light (chosen for effectiveness in this art) may help the operator to confirm the grade of dry ice. There may be a process similar to biting "gold" in olden times to try to judge it's quality.

***
Re-reading Post #66 ... It seems to me that an operator will need to carefully wipe the flanges of the halves of the pressure vessel after dropping the work charge inside, and before capping the tank. There would be no flow of iron oxide through the seal during operation, so contamination could only occur when the vessel is opened after a run. The operator needs to be sure no crud from the run falls onto the surfaces of the flanges.

I think the major concern would be flow from the pressure vessel through the pressure regulator. ** That ** is a seal that is of concern, although I'm not clear (at this point) on whether contamination in the charge could block the pressure regulator. If that is a possibility then there needs to be a safety relief valve, similar to the one I saw on the little 3 gallon pump. And ** that ** valve needs to be designed to operate even coated (on the inside) with a layer of crud.

Thanks again for the helpful question!

If you have time and are so inclined, can you comment upon the seal mechanism of the pressure vessel shown? I confess that from just one cross-sectional drawing, I am having difficulty visualizing how it works. I wrote to the gent in the message reported above, to ask if they have YouTube videos showing operation of the system.

(th)

SpaceNut · 2021-04-04 08:38:58

The top of the image appears to be a bolt on or down flange seal type that is a compression seal of which the washer that is in the hole performs the seal around the bolt entry with rubber on the under side while the ring gasket seal is between the cap and the tank flat areas.

Using multiple tanks of this design would allow for longer lasting periods of use. The regulator can be a fixed regulation type or adjustable for other tools that could require lower levels of pressure to run.

This is an adjustable 0-120 psi capable of Nitrogen and CO2 use with no need for a tank guage as its build in
524340.png?v=20210404

The heating of the tank could be done with a solar dish where the can is placed at the focal point before using each day to aid in the phase change we would require to go from solid to gaseous for use. The coating of the tank being black would allow for conduction of the heat of the suns rays to bring the ice up in temperature.

tahanson43206 · 2021-04-05 05:44:35

For SpaceNut re #68

Thank you for this very nice (and interesting, to me for sure) follow up in the flow of this topic!

I note that you have also noted the suggestion of Mr. Collins to use solar heating to provide the energy needed by the tool.

While I understand the potential value of this approach, I also note that it limits where the tool set can be used. A reasonable expectation of where this tool set would be needed is underground, where excavation of tunnels will be a constant, never-ending activity on Mars.

For the underground scenario, it seems to me that CO/O2 is the logical heating combination that would be needed. Thus, for the Earth-side model of this device, I would recommend substituting propane for the heating supply, since oxygen is available from the local atmosphere.

The question of kbd512, about contamination of the gas supply by dust particles which are naturally present in the atmosphere of Mars, remains a concern as we proceed along this path. The amount of contamination is unknown at this time, except we can be reasonable sure it ** will ** be present, even in months without significant dust activity. And layers of dry ice at the poles will necessarily have received a layer of dust settling out from the global distribution of dust during the windy season.

A related question is how much dust (iron oxide was suggested by kbd512) can be tolerated by a pneumatic tool? I would expect there is detailed information about design of pneumatic tools on the Internet, but the machine where I start the day cannot see most of it.

Note for kbd512 ... I am wrapping up updates to a program for SpaceNut, and am looking forward to returning to your post on calculating heat needed for the dry ice exercise.

(th)

SpaceNut · 2021-04-05 18:19:25

The Underground use of the co or co2 can only be behind an air locked chamber (possibly a garage entrance) as you can not have co2 or co concentrations within a habital space. You are going to be mostly using it with a space suit or breathing apparatus when using the dry ice to gaseous supply of mars air.
The use of propane or methane to heat is also an external of living area use only due to what we have seen with the space x starship.

Inside air use of a air assisted tool would be under a habitat half pressure environment of 3.5 psi; in which 3 psi is oxygen while the other is made up of a mixture of gasses in argon, helium, nitrogen as filler. To gain more pressure one would heat the tank electrically.

I recall a fiber optic light pipe as such being used to heat the inside of a lunar regolith to oxygen chamber where the suns rays were focused on to the end of the fiber cable from the dish so as to carry the energy into the sealed tank. That makes the fiber cable still flexible for bringing a portable unit around for what ever work might need the boost in energy for out side use.

tahanson43206 · 2021-04-05 18:48:09

For SpaceNut re #70 ... thank you for another thoughtful addition to the topic!

Before a living space can be enclosed with a door (or anything else) it has to be excavated from the living rock. I would ** hope ** that work would ** never ** be done personally by a human being in a space suit. It should ** always ** be done by robots supervised by humans in nice safe, secure, warm cabins in mobile transporters. It is the robots who will have to deal with the vibrations of pneumatic jack hammers, not the humans we observe on Earth still engaging with powerful tools like that.

When living spaces are being excavated there won't be any atmosphere present other than Mars ambient.

I would expect ** any ** tool intended for use inside a habitable space to be electric.

The idea of a fiber optic light pipe is certainly interesting. Has anyone fashioned such an exotic device on Earth? Light pipes for data are all over the Earth by now, but if there is one for illumination, I'd be impressed that someone has carried the technology that far.

it is ** very ** possible that the medical field might be pushing the envelope in this particular area. The instruments used to examine the interior of human organs are illuminated at the end where TV equipment resides. The illumination there could be by simple electric light, or it could be by fiber cable.

I ** did ** notice your mention of RobertDyck's recommended interior air pressure on Mars! That suggests (to me at least) the idea is beginning to become "accepted wisdom" within the forum, and that is definitely progress.

(th)

SpaceNut · 2021-04-05 18:54:38

The boring machines of Elon Musk would make short work in making under ground areas but these are not robotic but men controlled and not in a telerobotic method.

Solar Thermal Power System for Oxygen Production from Lunar Regolith:

https://www.photonics.com/Articles/Mini … ar_/a35234
https://www.sbir.gov/sbirsearch/detail/1547793
https://www.lpi.usra.edu/meetings/leagi … ra4011.pdf

Mars it would work but you need more reflective surfaces to gain the needed energy levels....

Edit
Another application of mars air
http://newmars.com/forums/viewtopic.php?id=3479

tahanson43206 · 2021-04-06 08:46:44

For SpaceNut re #72

One of the many benefits of this forum, and it's membership of thoughtful and thought provoking people is the constant opportunity to learn and (sometimes) to correct misunderstandings left over from earlier times, when knowledge was not as far along.

Your mention of the boring machines supporting Mr. Musk underground ventures leads me to imagine the Mars-specific versions of those machines.

It's not clear to me that men are actually located inside the machines. Can you provide some documentation showing that. You seem confident there are men inside the machines, but since Elon Musk is a master of automation, I am wondering if you can provide some support for your expectation?

The ** ideal ** venture along those lines would use remote teleoperation so that ** no ** human beings are anywhere near the construction zone.

(th)

tahanson43206 · 2021-04-06 12:40:03

[Dayton Engineer] replied to my email inquiry about a boiler for dry ice for the Pneumatic Tool topic.

His reply was long, detailed, informative and filled with historical detail about the entire field of pneumatic tools and related machinery.

In the middle of the essay was this gem: The dry ice may have difficulty receiving energy (thermal) supplied via an external source.

I hadn't thought of that. It might turn out that preparing the dry ice for a duty cycle by running it through a mechanical shaver might prove helpful.

In any case, ** that ** is an additional reason to carry out live tests of the concept on the ground (on Earth) before announcing anything at all about suitability of the method for Mars.

The easiest thing to do is to simply drop chunks of dry ice into the boiler, secure the lid, and apply external heat. The heat has to go somewhere, so the dry ice may find a way to accept the thermal energy without our (humans) having to worry about it.

However, the caution from [Dayton Engineer] makes sense (to me for sure) so I've added it here as a [To be resolved] item.

(th)

kbd512 · 2021-04-06 14:47:49

Perhaps we should look into supplying the heat for pressurization and expansion from the Sun, rather than expending energy to pressurize the tank. If we combine a solar concentrator, a tank of molten salt, and a SCO2 gas turbine to provide the pumping power, then we should figure out how to use the molten salt to supply the heat for pumping and expansion, instead of demanding input energy from an electric heating element, hydrocarbon fuel and oxidizer supply, chunk of decaying Plutonium, or any other similarly costly method that involves electrical or electronic systems or other rare elements in short supply. This is a more or less stationary application with a low input energy requirement. Workers are only going to work during the day when they can see, so we have about 16 hours to fill the tank for the next work day. A solar-powered SCO2 engine will pressurize the tank at night using heat stored in a molten salt. It doesn't have to achieve the pinnacle of efficiency to be useful, it just needs to be really simple and extremely durable. I think I like this solution best- no wiring, all-mechanical, very few moving parts, don't need any license to possess the power source. It may weigh more than other solutions, but it will also be field-repairable.

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