Quote:
Originally Posted by jeff5may
Most of us in the forums engaged in "hacking" together systems of our own are building custom configurations that do not fall within the standards and guidelines that the ASHRAE have dictated. Especially when natural refrigerants are used, heat exchangers, metering devices, and compressors don't act the same. When you feed them "strange" gases or conditions, the entire system tends to stray from the path well travelled.
Our intentions here are more practical than anything. Trying to prove or argue a theoretical point to some endpoint is way beyond what happens in the garage, workshop, or back yard. I for one don't have the resources, time, or desire to change the world.
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One of the problems that popped up in this thread is the difficulty in verifying the supposed efficiency gain commonly associated with the use of R-290. Did you even read the paper? They used off the shelf R22 units, but increased the compressor displacement in order to get the same capacity as R-22. They also adjusted the metering device to make it an even playing ground.
Use of R-290 has essentially the same effect as say putting a 2-ton compressor in a 3-ton system. THERE'S LOSS OF CAPACITY associated with using propane. If you get an old 4-ton 10 SEER unit and replace the compressor with the one taken from another 10 SEER 2-ton, you'll get improvement in efficiency, but a reduction in capacity as well.
Liars are the companies that do nothing more than turd polish propane and spew off marketing gibberish proclaiming hydrocarbon is more efficient but don't mention the loss of capacity, flammability, etc.
Testing at ASHRAE parameters ensures before and after results are at least somewhat consistent, so you don't have R-22 test done at 90F and R-290 test done at 80F to make the results look better in favor of chemically manufactured semi-synthetic petroleum hydrocarbon refrigerant.
A system designed for 60Hz will operate at 5/6 capacity on 50Hz. In the past, R-500 was used instead of R-12 when 60Hz machines had to operate on 50Hz. The higher capacity of R-500 cancelled out the reduction in compressor displacement.
If it operated on original R-12 charge, there would be efficiency gain, but capacity loss on 50Hz. Capacity loss is not something easily measured by DIY backyard window AC tamperer.