The heat regeneration figures really are mysterious, Buddy.
Don't get me wrong, heat regeneration is a legitimate engineering practice used by all kinds of power stations. It is even found in such things as steam cars and locomotives in the form of heat exchangers which extract heat from the exhaust steam and transfer it to the water entering the boiler. The thing is, there are limitations.
Heat transfer is going to be affected largely by two factors:
1. The temperature difference between the two fluids and/or liquids.
2. The surface area of the heat exchanger.
We'll assume the thermal conductivity of the exchanger itself isn't an issue nor do we have problems with things like laminar flow in the fluids.
The effect of temperature differential can't be overstated. If the difference is 300 degrees, heat readily flows from one substance to another. At 5 degrees, the flow is pretty modest. What this means is that we have a roughly asymptotic curve, it can be pretty aggressive in one region and then flattens drastically. We can offset this to some degree by making the heat exchanger larger (the second factor, above) but this also involves tradeoffs of size, weight, cost, friction and so on.
The most common form of heat regeneration in traditional steam systems has ben the feed water heater. This simple device is a tube through which water heading into the boiler passes. The tube is situated so as to be heated by exhaust steam leaving the engine, thereby returning some of the exhaust heat back to the boiler. This works exceedingly well in such things like locomotives where the water is derived from a tank and is therefore relatively cool. It's also not too bad in water cooled condensing systems operating at high vacuum, since the water leaving these condensers is cool. Unfortunately, Cyclone supposedly uses air cooled condensers. Air is not a great cooling medium and it therefore follows that the condenser is operating far above vacuum pressure … meaning that the water in the condenser is already quite hot, thereby minimizing the temperature differential between it and the exhaust steam. So, not a lot of heat regeneration will be possible. You can cool the condensed water further but that's just throwing heat away and you don't get points for putting heat back that you wasted needlessly.
We can also recycle heat from the combustion gasses leaving the boiler into the air entering the burner. This has a similar limitation --- if the boiler is exceptionally efficient, the exhaust gasses aren't extremely hot and the portion of heat that can be recovered is limited. Cyclone claims an exceptionally efficient boiler and the heat regenerative properties would then be reduced accordingly.
The last route we can take is to transfer heat from the condenser cooling air to the air entering the burner. The big limitation there is that you need a lot more air to operate the condenser than is used in the burner … meaning that only a fraction can even be applied to the heat exchanger in the first place.
Any way you cut it, the heat exchangers for all this regeneration would appear to be quite voluminous but I haven't seen such large structures anywhere.
Anyhow, the heat regeneration issue is the same as many other Cyclone "performance specifications". Am I wrong that they generally give results as single values? Heat regeneration won't be a fixed percentage of output but will vary depending on ambient conditions and throttle setting. This is also true for the engine thermal efficiency. I can't recall Cyclone posting such values in a range (you know, like the EPA does with car fuel economy? At least they give city and highway estimates).
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