Case Study:

Cooling and Vibration Control System for a Portable Oxygen Concentrator

Client:

SeQual Technologies

Project Scope:

Medical Device Research & Development

Methods:

Cooling System Design, Prototype Design

When San Diego based medical products company SeQual Technologies was developing the their first ambulatory oxygen concentrator, Flometrics redesigned the vibration, thermal and acoustic systems.

Flometrics unique cooling system for the compressor that cooled the oxygen system needed to provide a highly reliable continuous flow and pulse oxygen dose options in a 24/7 portable device. The device was intended for both stationary and ambulatory oxygen needs.

As a result of Flometrics design of cooling and vibration control system for the Eclipse, the small, lightweight unit was successfully launched and immediately revolutionized the industry with clinical features and accessory options that supported user’s active lifestyles.

The Eclipse 3 lowered operational costs by reducing monthly deliveries and simplifying inventory management and space. Now into its third generation, the award-winning product retains all of the initial designed systems. The SeQual Eclipse has become the clear choice for a non-delivery oxygen concentrator model.

Case Study:

Infant Respiratory Device

Client:

Cardinal Health

Project Scope:

Medical Device Research & Development

Methods:

Flow Visualization, Design & Testing, Prototyping

Flometrics designed a Nasal Continuous Positive Airway Pressure (NCPAP) ventilator for Cardinal Health to help premature and sick infants breathe. The ventilator keeps the baby’s lungs inflated as the inhale and exhale. It must keep a positive pressure in the lungs while allowing the baby to breathe easily, i.e the “work of breathing” must be minimized. The ventilator must also be small and lightweight. The photo at right shows a prototype that we designed and built.

The device is based on the jet pump principle but it allows for the flow to be reversed with minimal flow resistance. The jet sizes, flow rates and pressures were determined analytically to meet the customer’s specifications. The prototype ventilator worked as predicted.

We used flow visualization with laser sheet light and fluorescent particles in water to determine the optimum placement of the jets and other features in the device. The flow visualization was conducted in water with the scale adjusted to match Reynolds number.

In the image on the lower right, the two jets combine and help entrain air during the inhalation process. On the right, the exhaled air breaks up the flow pattern and allows the exhaled air to flow freely in the reverse direction. The pressure inside the patients lungs stays constant, regardless of the flow direction.

We used a Labview based data acquisition system to make measurements of the pressure and flow during simulated breathing cycles. The data was used to optimize the design.

Cardinal engineers took the fluid pathway that we developed and designed a ventilator which is less harmful to the baby’s nose than competitor products.

Case Study:

Biofuel Flight Test

Client:

In-House

Project Scope:

Research & Development

Methods:

Thermodynamics, Fluid Dynamics, Design & Testing

We launched the Biofuel rocket on July 11th at the FAR rocket test site near Cantil, CA, east of Edwards Air Force Base. The fuel was a renewable JP-8 developed by the EERC at the University of North Dakota for the Air Force Research Lab at Wright-Patterson. The fuel was developed under a contract with DARPA and was procured for us by Bob Allen at the Fuels and Energy branch of the Air Force Research Lab at Wright Patterson. The Biofuel worked quite well, propelling the rockets to a speed near Mach 1. The rocket propulsion system exceeded expectations. Our predictions for the flight indicated a maximum Mach number of about 0.9, just under the limit of supersonic flight. Although the Biofuel launch had a successful burn, the recovery system failed due to the fins experiencing critical flutter near apogee. We have flown these types of fins, tanks, engines, and pressurization systems before with no problem, therefore, we are left to believe the Biofuel had a much higher specific impulse than expected.

Flometrics originally built the rocket for Discovery Channel’s “Mythbusters” TV show. In addition, we were currently working on biofuel plant fluid dynamics at the time, so we decided to use the rocket to test whether Bio-Diesel would work as a rocket fuel. Besides the obvious environmental perks of using a cleaner, sustainable fuel, one can imagine growing oilseed crops on other planets to provide fuel for return vehicles. Also, there is always interest on how new designer fuels may improve rocket performance.

Flometrics initial static fire test using commercial grade Bio-Diesel proved a success, so we attempted to launch the rocket on Biodiesel. Unfortunately, during the launch the rocket had a hard start, which cracked the oxidizer manifold. However, this revealed a key safety attribute of the renewable fuel. With fuel and oxidizing spraying out on to a live igniter, there is a high potential for disaster. The low flammability/high flash point of the BioDiesel fuel left only an unusually small fire on the launch pad, leaving the rocket practically unscathed and ready for another launch attempt. For more see our article in Biodiesel Magazine.

For the final launch, we slowed down the fuel valve opening to prevent a hard start and used a more robust igniter [made by Jeff Kent with assistance from Ken Mason]. Overall, the fuel performed extremely well, with a flawless burn during the test flight. After the flight, we took apart the rocket engine to observe how the fuel performed. We noticed that the Biofuel burned much cleaner that the Jet A or the RP that we have used in the past. The injector plate normally is covered with a layer of sludge, but in the case of the Biofuel, it was very clean. The inside of the engine was coated with a layer of soot similar to what we usually see, which is good because it reduces the heat transfer. There was no visible damage to the engine, which is also good, because the engine will burn through if there is any reduction in cooling capacity of the fuel. The evidence from the biofuel rocket engine testing promotes confidence that one-day space vehicles will be able to travel using safer, cleaner, and sustainable fuels.

Unlike the red RP-1 [refined kerosene rocket fuel], the biofuel does not have any dye in it, It exhibits an odor of a sweet paint thinner. This fuel was designed to duplicate the properties of JP-8, the current jet fuel used by the U.S. Air Force. A particular challenge was achieving the same freezing temperature in the biofuel. However, it is very possible the fuel could be optimized for the cold temperatures of space. With custom designed biofuels, there is the possibility of increasing the density, heat transfer, and perhaps specific impulse of the fuel