One of the big stories last week was the announcement of results from clinical trials that suggest a new COVID-19 vaccine developed through the joint effort of the American and German companies Pfizer and BioNTech is strongly effective in providing immunity from the virus. In the midst of what is for many countries the second spike of the global pandemic this news has been received with elation as well as becoming the subject of much political manoeuvring.
While we currently have two vaccine candidates with very positive testing results, one of the most interesting things for us is the need to keep doses of the Pfizer/BioNTech vaccine extremely cold until they are administered. Let’s dig into details of the refrigeration problem at hand.
Continue reading “The Special Fridges Behind The COVID-19 Vaccine, Why It’s Surprisingly Difficult To Be That Cool”
When you’re a kid, one of the surest signs of summer is hearing the happy sound of the ice cream truck crawling through the neighborhood. You don’t worry about how that magical truck is keeping the ice cream cold, only that it rolls down your street, and that the stars align and your parents give you money for a giant ice cream-cookie sandwich with the edge rolled in tiny chocolate chips.
In the early days of mobile refrigeration, ice cream trucks and other food delivery vehicles relied first on ice, and then dry ice to keep perishables cold. Someone eventually invented an electric cooling system, but those had to be recharged periodically at power stations. There was also a short-lived mechanical system, but it was highly susceptible to road vibrations.
Until Frederick McKinley Jones came along, mobile refrigeration was fledgling, and sources of perishable food were extremely localized and limited. In the early 1940s, Frederick patented the first practical automated refrigeration system for trucks, and it revolutionized the shipping and storage of food and medicine.
Continue reading “Fresh Food Year Round? You Can Thank Frederick McKinley Jones”
Many people with Multiple Sclerosis have sensitivity to heat. When the core body temperature of an MS sufferer rises, symptoms get worse, leading to fatigue, weakness, pain, and numbness. For his entry to the Hackaday Prize, [extremerockets] is finding a solution. He’s developing a wearable, personal cooling device that keeps the wearer at a comfortable temperature.
The device is based on a wearable shirt outfitted with small tubes filled with a cooling gel. This setup is extremely similar to the inner garments worn by astronauts on spacewalks, and is the smallest and most efficient way to keep a person’s core body temperature down.
Unlike a lot of projects dealing with heating and cooling, [extremerockets] isn’t working with Peltiers or thermoelectric modules; they’re terribly inefficient and not the right engineering choice for something that’s going to be battery-powered. Instead, [extremerockets] is building a miniature refrigeration unit, complete with a real refrigeration cycle. There are compressors, valves, and heat exchanges in this build, demonstrating that [extremerockets] has at least some idea what he’s doing. It’s a great project, and one we can’t wait to see a working prototype of.
[Ed] from Ed’s Systems, aka [Aussie50] took some time to demo his high pressure Frankenstein air compressor he stitched together from two refrigeration compressors. The two Danfoss SC15 compressors can produce upwards of 400psi and can run all day at the 300 psi range without overheating. The dual units may get up to pressure quickly considering the small accumulator “tank”, but high CFM isn’t the goal with this build. [Ed] uses the system to massacre some LCD panels with lead, ball bearings, and other high speed projectiles shot from a modified sandblasting gun. Just a bit of air at 400 psi is all you need for this terminator toy.
Don’t think the destruction is wasteful either; [Ed] strives to repair, rebuild, reuse, repurpose and a few other R’s before carefully separating and sorting all the bits for recycling. This modification included lots of salvaged hardware from older teardowns such as high pressure hoses, connectors, accumulator and pressure cutoff switches.
At first it seems strange to see something engineered for R22 refrigerant working so well compressing air. Morphing refrigeration systems into air compressor service is something [Ed] has been doing for a long time. In older videos, “fail and succeed”, [Ed] shows the ins and outs of building silent air compressors using higher capacity storage tanks. Being no stranger to all variations of domestic and commercial refrigeration systems, [Ed] keeps home built air compressors running safe and problem free for years.
Don’t think this is the only afterlife for old refrigeration compressors, we’ve seen them suck too. You’ll get a few more tidbits, and can watch [Ed’s] video overview of his home built compressor after the break.
Continue reading “High Pressure Air Compressor Using A Pair Of Refrigeration Compressors”