Hi everybody! I thought I would start a new thread, because my work is sort of all over the place, and doesn't fit well in any particular thread. Since the last time I contributed, I've gotten a fair amount of hands on experience with vapor compression refrigeration. If you check out my blog, you can see how I got into things.
Refrigeration Test Bench - Part I
The blog has not been updated for some time, but you can get an idea of where I am, or better yet, check out the Youtube channel.
It is so hard to find any good DIY refrigeration projects on the net (other than here, course.
) I'll try give a brief description of my main project coming up, and if anyone is interested, this could be a good place to answer questions or receive feedback. Refrigeration can be a lonely hobby.
I have many refrigeration projects planned, but my main focus is in building a heat pump to reduce my propane consumption in heating my motorhome this winter. I have logged my LP usage over the past heating season (number of days per 20lb cylinder), and along with the rating on the forced air heater, and the observational evidence of how often it runs, I've decided to build a system with approximately 1/2 ton capacity. This is likely too small to meet all of my heating needs, but I'd rather go to small, with a higher COP and supplement with other sources, than go to large with a lower COP and more cycling.
The compressor will likely be a small rotary unit from an air conditioner. The evaporator will probably be from a larger tonnage unit, and be plumbed up as a gravity flooded system, for greater heat conductivity, and smaller delta T. I have yet to develop a liquid level metering device, but I hope my research provides a solution by fall. Because the refrigerant charge will be rather large, I'm pursuing propane as my refrigerant of choice. This of course alarms some folks, so I will be designing the condenser to heat water, which will be pumped to a radiator in the motorhome. This also allows me to disconnect and move the unit when it comes time to pull up stakes and get out of Dodge.
The condenser / water heat exchanger is planned to be a chest freezer, perhaps further insulated. A series of thermostats will regulate the water temperature, and separate thermostats will regulate the indoor fan and pump.
Compression may very well be two stage, with the first provided by a handmade ejector. I recently constructed one, and I'm having some success with it in an air conditioner I've built in my shop. Anyhow, I'm still learning, and with luck, I will have developed the technologies I'll need to construct this heat pump for the fall. I hope to share my progress as it develops, and look forward to discussing it with any of you interested in such matters.
-Mike
P.S. I was recently turned on to the ejector thread by NiHaoMike (
here), and I'd love to here from him on his progress.