Kalina Cycle

[matt brown]

Anyone pondering vapor cycles should study the Kalina Cycle, named after Alex Kalina. This 'steam' cycle is a closed system that uses absorption in lieu of condensation to complete the cycle...similar to the ammonia refrigerator. If unfamiliar with an ammonia refrigerator, ammonia gas solubility in water varies by temperature, whereby at room temperature, 1 volume of water can absorb 700 volumes of ammonia gas to create 2 volumes of 50-50 solution. Now, as we raise the temperature, the ammonia 'cooks off', and we can create a refrigerator or engine cycle. During Einstein's stint as a patent examiner, he and a buddy patented the current ammonia reefer cycle (Servel bought it) which nixed a 'boiler' feed pump via using the partial pressure of an additional gas thruout cycle. No doubt, a slick trick !!!

In the 1970s, Alex Kalina concocted an absorption engine cycle with multiple heat exchangers in an attempt to capture much of the otherwise lost latent heat of vaporization from a relatively low end cycle. Kalina himself favored water and ammonia, but when ammonia is absorbed by water, the "heat of solution" equates to the heat of vaporization. What Kalina did, was to manipulate the temperature of the water and ammonia whereby heat exchangers could capture much of this otherwise lost heat of vaporization. The problem is maintaining control of multiple heat exchangers and making this system economical. I know this system well, since I was working on the same scheme in the late 1970s (same time as Kalina) when he immigrated here from Ukraine.

[matt brown]

The Kalina Cycle has seen very marginal use due to low output (low ROI). I gave up on it due to complexity, but always thought that maybe some additional trick would make it feasible, something akin Einstein's partial pressure gas for ammonia reefer. Back in the day, the best I could dream up was interleaving a liquid fuel amidst standard Kalina scheme whereby absorbed heat was returned to the boiler during combustion. However, there's few fuel candidates for this, and if alcohol production was globally increased for power plants, then the price of tortillas in Mexico would dwarf gasohol nonsense. Nevertheless, this combustion return scheme simplifies the crazy cascade scheme of standard Kalina heat exchangers.