KNUDSEN PUMP

WHAT IS IT?

• Vacuum pump

• Principal of thermal transpiration

• temperature gradient causing the gas molecules to move from one side of the tube to the other

• cold to hot

• Can be used to create high pressure (compressors) or low pressure (vacuum pump)

BENEFITS OF KNUDSEN PUMPS

• No moving parts

• High reliability

• Can efficiently pump light gases; e.g Helium and Hydrogen

KNUDSEN PUMP EXAMPLE

• Size only 1.5mm x 2mm

• One of the few Knudsen Pumps capable of operating at atmospheric pressure

• Generates a pressure of 0.46atm (approx 47,000Pa)

• Max operating pressure is determined by the hydraulic diameter of the narrow channels

• Smaller channel diameter = higher operating pressure

• 80mW of input power

USES: PNEUMATIC ACTUATION

• How it works

• Compressed air enters an opening in a cylinder and pushes against the interior and the piston

• When the force is increased enough the piston drops and the force accelerates the load, converting pneumatic to linear mechanical power

BENEFITS OF PNEUMATIC ACTUATION

• Provide clean, quiet motion

• Less waste heat and electromagnetic interference than electric counterparts

• Good for applications that involve fast repetitive moves, heavy loads or smooth motion profiles

• Safe for hazardous environments where electric sparks must be avoided

STILL TO DO

• Work out what application on aircraft a Knudsen pump could be applied

• Determine the design of the pump for that application

• Test through simulation