There is more than one application for a Martian CO2 compressor. It also has application in pressurizing green houses. As well as keeping the green houses inflated, CO2 enhances plant growth. And the plants will eventually convert the CO2 into oxygen.
There a number of constraints that apply to any non terrestrial compressor.
- light weight
- low volume
- low power consumption
- low maintenance, high reliabililty
Conventional compressors (which are actually pretty similar to pumps) involve blades spinning around a central shaft.
The concept we are proposing is not unique - making use of high Q factor to reduce energy consumption is already being employed in pumps. In order to achieve all the efficiencies we expect to need, the basic concept shown here would need to be given a boost with smart structure capability to optimize the foil shape between input and output strokes
But there are a few additional requirements for Mars - the most significant is being able to run enough cycles to capture the very thin atmosphere. The science adds one addition constraint. The compressor must have no metallic parts that vibrate as vehicle hops.
The flapper, shown in video, is driven by a modal motor. Each stroke is activated by our modal motor an electro-magnet, or voice coils, tuned to drive the flapper at resonance.
To get the Martian atmosphere up to 37.2 Kpa, would take 5 chambers, each of decreasing size to capture enough propellant. The 1st and largest with a volume of 150x150x100 mm 3 would take 175,000 strokes to gather 1 kg pf CO2. At the predicted resonance, this would take 1.1 hours.
Each of the 3 fingers within the fiberglas flap would require 9.7 N of applied force, to generate a tip stroke of 50 mm, assuming Q of 50.
The isentropic compression work to double the pressure in each chamber is 27066 Joules. Power 7.5 Watts. The power requirement for the 1st chamber will be the same for the remaining 4 chambers, though the actuator power will decline with chamber size decrease.
The structural weight of the 1st chamber is 1.816 kg. The weight of power supply & electronics is estimated as 3 kg.