1. Martian Regolith Crushing Midterm Presentation Members: Nick Sestito & Christopher Graham

2. Overall Project Objective  Develop a Martian Regolith Crusher that will:  Crush a solidified Martian regolith permafrost-mix  Be capable of processing 0.5 cubic meters of regolith/sol minimum  Aid in the process of extracting water for a theoretical manned Martian colony  Create an optimal output product for a minimal heating power requirement

3. Gantt Chart

4. Current Project State  What has been done?  Crusher input Justification  Material/Crushing Criteria  Thermal Model to determine output size  What are we in the middle of?  Determining a two-stage process capable of crushing a 1 liter cube of freshwater ice to a range of 1mm to 5 mm grains  Process will be either a:  Jaw crusher to a cone crusher  Jaw crusher to a ball mill grinder process  Where will this lead us?  The formal design of the grinder  Some kind of experimental implementation of functionality/demonstration  Likely 3D-printed model

5. Water Extraction Process/Hot CO2 Oven

6. Thermal Model -Completed  Overall goal of the thermal model:  Set an output range of crushed regolith grains  Conservative assumption: the grains fall at terminal velocity  See if the length of the hot CO2 oven pipe is reasonable  Lumped System Analysis  A uniform body temperature with varying time  Once the center of the body reached above boiling, the water has been extracted  Process running time is intended to be short to reduce power usage from RAPID-L reactor (200kW electrical power, 5MW thermal energy)

7. Requirements/Assumptions of the System  Raise the system pressure from 6mbar to 100kPa (1atm)  Boiling temperature of water is raised above the triple point  Hot CO2 in the system  Raising the Pressure will raise the density  Higher density will aid in heating grains  Requires a Pump in the system  Drawing more energy from the RAPID-L power source

8. Forced Convection on a Falling grain  Vt (Cd)Cd(Re)Re(Vt)  Heat Transfer Co.  Nusselt Number  Pr & Re/Cd  Without a defined Reynolds number or Drag Coefficient the two could be defined simultaneously using:

9. Solving for both Re and Cd Curve-fit trend line equation for 1<Re<1000 (log base 10 scale) log(Cd*Re^2)Cd 3.5740312681.5 3.6532125141.25 3.9084850191 4.4771212550.75 5.6020599910.4 log(Cd*Re^2)Re 3.57403126850 3.65321251460 3.90848501990 4.477121255200 5.6020599911000 Formed by picking 5 points

10. Solving for both Re and Cd Cd as a function of log(CdRe^2):Re as a function of log(CdRe^2): Re = 46.929x -2.77 Cd = 262.67x 2 - 1949x + 3673.2 For 1<Re<1000 or log(CdRe^2)<5.6 If Re>1000, Cd = 0.4 Assumption: The system Reynolds Number would not exceed 10^5

11. Length of pipe determination  Remaining calculations for HTC and Lumped system analysis were routine  Heating times and pipe distances were determined  Blower was added to shorten pipe length significantly

12. Crusher design 1: Jaw Crusher  2 crushers/grinders mandatory  Jaw Crusher is well suited to handling more unusual feed geometries (like cubes)  Out put size is based on the max/min gap  Easy to load, hard to jam.

13. Crusher Design 2: Cone Crusher  Minimum output size after jaw crusher=2.01 mm  Output also based on gap in between plates  Evaluation: Hard to design, but less concerns about gravity  Lots of parts: scaling down to MM size puts most of the success on scaling with parts not failing  Variance in output based on crusher motion in plates

14. Crusher Design 3: Ball Mill Grinder  Output based on mesh screen gap  Minimum output well below 1 mm.  Metal drum spins, the media (steel balls or other hard/heavy objects) repeatedly impact regolith to grind.  Volume versus time considerations  Concerns  95% of the energy running the mill is produced as heat from impacts  Don’t want temp to rise above sublimation temp.  Solution: cooling jacket and mars temp.

15. Grinder determinations  Cone crusher or ball mill grinder almost done.  Mostly set on use of ball mill  Cooling jacket and/or using mars temperatures for cooling  Design work on ensuring the media isn't brittle enough to shatter  Get dimensions of crusher large enough to handle daily grinding requirements  Mesh sizing gives far less variance  US sizing (number of gaps in 1 inch of mesh)  US 18=1mm gaps  US 10=2mm gaps  Input size affects media size  Media has to be larger and more dense than the media  Smaller media produces a finer powder, but media similar size to the feed is very in-efficient

16. Ball Mill Grinder Concern  Have determined formulas to calculate critical speeds, and force of steel ball impact  Combine this with impact strengths of pure ice at 200k, and we will be able to determine whether or not the grinder is viable  If force of impact on reasonable ball mill sizes works, we will take the jaw crusher-ball mill grinder solution  If diameter of mill barrel is to large to be reasonable in order to crush ice, we will use the jaw-cone crushing system.

17. Where will this lead us? Input Size  Thermal Model (Thermo & Heat Transfer Problem)  Output Size  Force Orientation/Requirement Fracture Strength (Strength of Materials Problem)  Crusher Type/Geometry (Design Problem)  Power Required for Crusher Function (Design Problem)  Test and Improve