Purdue mechanical engineering doctoral student Hui Zhang, left, and Purdue mechanical engineering professor Issam Mudawar work on a flight apparatus used for experiments on the novel two-phase system.

Purdue mechanical engineering doctoral student Hui Zhang, left, and Purdue mechanical engineering professor Issam Mudawar work on a flight apparatus used for experiments on the novel two-phase system.


 

Scientists want to use so-called "two-phase systems" for future spacecraft and space stations on the moon and Mars. The systems will work analogously to ordinary air conditioners and refrigerators, employing a closed loop in which liquid comes to a boil as it absorbs heat. The liquid then turns into vapor and is returned by pumps so it condenses back into a liquid. In the process, the vapor cools down to repeat the cycle.

Because boiling, vaporizing and condensing a fluid is far more effective at dissipating heat than just using liquid, such systems can be compact and thus ideal for space travel where there is a premium on light weight. The problem is that little is known about the behavior of boiling and condensing liquids in space.

Purdue researchers devised a physical model of new method that looked promising in experiments onboard a NASA KC-135 aircraft that creates reduced gravity conditions. Engineers designed the flight experiment so fluid flowed through a transparent plastic window. The researchers then took high-speed photographs and video of the flowing fluid during the flights to study its behavior in minute detail.