EcoRenovator - View Single Post - Ejector Refrigeration, RV Heat Pump, R-290

marx290 · 08-05-15, 03:17 PM

Very neat, Jeff! I'm certain I will eventually have an issue with the unit frosting up, but I'll address that when it becomes a problem. A fair amount of Our winter here in Portland stays above freezing, with high humidity (much of the time); a good thing for a heat pump. :-D

I hope to minimize frost ups by utilizing a rather oversized evaporator to keep my delta T to a minimum, and evaporator temperature high. I plan on building a flooded heat exchanger to allow me to accomplish this. Hot gas bypass probably won't work well with a flooded system, but then again, if I designed the liquid / vapor separator to be large enough, I might be able to pull it off. It's not a big concern right now, since I'm not trying to replace my existing heating system, just supplement at a high COP.

One idea I like, if you happened to have two evaporators available, is to plumb them up into a series arrangement, where one acts as a liquid subcooler feeding the TXV on the second one which acts as a conventional evaporator. When the evaporator frosts up, a valving arrangement swaps their functions, and the frosted coil is slowly defrosted by the warm high side liquid, while the other coil picks up heat. I became aware of this idea by reading ice storage patents. I'd love to see someone try it!

What kind of water temperatures did you maintain in the styrofoam cooler? Was the unit effective when it wasn't frosted over?

08-05-15, 03:17 PM	#4
marx290 Vapor Compression Goon Join Date: Mar 2013 Location: Portland, OR Posts: 63 Thanks: 11 Thanked 22 Times in 11 Posts	Very neat, Jeff! I'm certain I will eventually have an issue with the unit frosting up, but I'll address that when it becomes a problem. A fair amount of Our winter here in Portland stays above freezing, with high humidity (much of the time); a good thing for a heat pump. :-D I hope to minimize frost ups by utilizing a rather oversized evaporator to keep my delta T to a minimum, and evaporator temperature high. I plan on building a flooded heat exchanger to allow me to accomplish this. Hot gas bypass probably won't work well with a flooded system, but then again, if I designed the liquid / vapor separator to be large enough, I might be able to pull it off. It's not a big concern right now, since I'm not trying to replace my existing heating system, just supplement at a high COP. One idea I like, if you happened to have two evaporators available, is to plumb them up into a series arrangement, where one acts as a liquid subcooler feeding the TXV on the second one which acts as a conventional evaporator. When the evaporator frosts up, a valving arrangement swaps their functions, and the frosted coil is slowly defrosted by the warm high side liquid, while the other coil picks up heat. I became aware of this idea by reading ice storage patents. I'd love to see someone try it! What kind of water temperatures did you maintain in the styrofoam cooler? Was the unit effective when it wasn't frosted over? __________________ To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.