Not boring at all. Very interesting.matt brown wrote: ↑Sun Aug 06, 2023 2:23 pmabsorption_1.jpg
This is a good diagram of small ammonia absorption setup common in RV (aka gas or 3 way reefer). Many guys are familar with this, but few know it was Einstein and 1 or 2 buddies that invented this while he was at the Swiss PTO. Note there's no mechanical pump, instead a sneaky clever thermo siphon is achieved via partial pressure from a third component: hydrogen gas. This is the reefer version that Serval made famous.
absorption_2.png
During my steam days, I spent a few mornings studying absorption systems over breakfast. Note the difference between these 2 diagrams where the first diagram is so detailed that it's hard to see much beyond what's in front of you. However, the second diagram is a simple schematic devoid of clutter (distractions). As I was bouncing between these two diagrams, I became convinced that I was missing something. On the third day at breakfast, the lights went on...in this second diagram, simply remove both condenser and evaporator (the 2 blue parts) and insert an engine.
This is the basic Kalina scheme, and here's the nickel tour. At room temperature, 1 vol of water can absorb 700 vols of ammonia to make 2 vols of solution, but as you raise the temperature, the ammonia "cooks off". My thinking was sweet, a steam cycle without the inherent loss of the heat of vaporization. Well, technically this is correct, but on the other side of the cycle - the absorber - even if the ammonia gas is the same temperature as the "water" (weak ammonia solution) when the ammonia is absorbed, the heat of solution raises the temperature quickly and prevents further solution (solubility a function of temperature). It turns out, that the cooling required to achieve absorption back to start state in this scheme is basically the same as the heat of vaporization for a similar Rankine cycle.
What Kalina did was to manipulate the 'timing' of heat into and out of the cycle via an array of counterflow heat exchangers. My contribution to this scheme is upping the ante while nixing the nasties...forget ammonia-water and go with another combo, maybe 3 element. I spent many hrs checking my CRC and figured water-glycerol would be better baseline. I'll stop here before I bore you guys more, but during this time, my single-phase gas sidebar tookover and I rarely look back.
Last time I tried to read some link about this cycle it seemed like a nightmare of complexity. The patent, or whatever it was seemed like it just kept repeating the same thing over and over. For some reason though, now, relating it to the absorption refrigerator it clicks.
Thanks!