pixmanvegas

Thanks for continuing to discuss this, people! I am paying attention. 55 lpm is the volume of air needed to breathe for an adult male under stressful activity (approximate). We need him to be able to breathe air at the target temp while performing a standard cardiopulmonary stress test. Does that help with the calculations?

Do you mean there are "cooling scuba tanks" as in there are scuba tanks that work to cool air. or I should look into making scuba tanks cold? I will check with a local scuba expert. this is a good idea. I like the idea of using dry ice to cool the air inline on the way to the regulator. Good thought. I found a commercial "vortex valve" that will cool compressed air with a 50 degree drop in temperature. That gets us part of the way. Edit: I can word that better... I found a commercial "vortex valve" that will create a 50 degree drop in temperature.

Yeah, sounds pretty horrible. Here's the thing. It's the equivalent of being outside at -40C (or F for that matter) and there is no danger at all to human damage. Studies have been done to determine the effects of cold air on the human lung. The body warms it as it goes down the throat. There was a military study of cold air exposure down to -70F in the arctic that found no negative effects. Although there were a few anecdotal cases added of slight frostbite in the lungs after the study concluded. The pain or discomfort one feels when outside breathing very cold air is not caused by the cold but by dehydration of the membranes of the nasal passages and throat. So.. We don't anticipate any screaming or actual damage. Now back to the question. How to cool the air? Anyone? Anyone.... Thanks Please site your sources. Here's a couple of studies of my sources that indicate there should be no problem... This one was performed at our target temp...(-40 degrees C, dry) Cold air inhalation and esophageal temperature in exercising humans. - PubMed - NCBI http://www.ncbi.nlm.nih.gov/pubmed/7453516 This one at -35C Physiological effects of cold air inhalation during exercise. - PubMed - NCBI http://www.ncbi.nlm.nih.gov/pubmed/7417121 Our reasons are different, hence the new experiment, but it's not unprecedented or dangerous. Thank you for your concern.

Strange, Thank you. We will look into that... Michel, the only person in the room who needs to receive the cool air is the single human subject. Air delivered through a hose attached to a mask. no one else should be affected. The experiment will be performed in an office/room. We can probably exhaust the waste heat through the return vent of the building A/C. We would need to avoid excessive noise though.

I am going to be conducting an experiment in which I need to cool approximately 55 liters of air per minute to as close to -40C as possible. If I can't hit that target, as cold short of that as possible. The air needs to be breathable. If the solution is not pre-cooled or compressed air, I will be starting from an ambient temp of around 20C (standard room temp) Does anyone have any suggestions on a low budget way, or for that matter ANY way, to accomplish this? The solution needs to be portable enough to take to an office building to deploy with a quick set up time. This will be a 3 or 4 event experiment.