I've had this idea in my head for a refrigeration cycle which is powered by heat, uses only one fluid, and whose only moving part is the fluid.

I would like to know if my idea is new, or if it's something which was tried and abandoned.

I'll describe my idea in terms of water and steam, but other fluids would likly work just as well.

The system starts with the boiler, where external heat is added, to turn the water passing through into steam.

Some of the steam from the boiler is used to power an old fashioned "steam injector" which is to pump water into the boiler.

The rest of the steam from the boiler is used as the motive fluid for an aspirator (one of two).

The condenser receives steam from the steam powered aspirator, rejects waste heat into the envionment, and turns steam into water.

Some of the water from the condenser is injected into the boiler, the remainder is used as the motive fluid for our second aspirator.

The water powered aspirator sucks in cold steam from the evaporator, and spits it into a gas/liquid separator.

Water from the separator passes through an orifice tube into the evaporator; steam from the separator is sucked out by the steam powered aspirator and discharged into the condenser.

If my idea is in fact new... I would love to know if any thinks it would work, and how it's efficiency might compare with a typical absorption system.

I'm not mechanically inclined, and have no means of testing this myself.

  • $\begingroup$ Many fridges, freezers and ac units use vapor compression and a single fluid called a refrigerant as it changes from liquid to gas. So it exists. $\endgroup$
    – Solar Mike
    Jul 1, 2020 at 5:42

1 Answer 1


The first heat-driven refrigerators over 100 years ago worked on this principle, or something close to it, using water/steam as the working fluid. Beer brewed by the Anchor Brewery was chilled during its manufacture with steam refrigerators, which is why today the product is called Anchor Steam Beer.

Steam refrigeration cannot reach the freezing point of water for coldness, but the ammonia absorption cycle can and is hence is used in RV refrigerators, where it is powered by a small propane flame.

Full-sized ammonia refrigerators can be made to run on propane, natural gas or even kerosene. The leading manufacturer of these was the Servel Co., and such refrigerators are sometimes referred to as running on the servel cycle.

  • $\begingroup$ Did the heat-driven refrigerators of yesteryear work without a mechanical pump to move water into the boiler? Did the refrigerant cycle from condenser to evaporator to boiler, OR were there four different pressures, as in my idea? How many moving parts did they have? An absorption cycle uses two fluids: A refrigerant and an absorbent. I have done some googling, and have found similar (because EVERY refrigeration cycle uses thermodynamics) but not the same. $\endgroup$ Jul 2, 2020 at 18:25
  • $\begingroup$ I do not know how the steam cycle worked but you can google that. The servel cycle uses an ammonia-in-water solution and has no moving parts at all. I tried making a solar-powered refrigerator out of an old servel in 1974. $\endgroup$ Jul 2, 2020 at 18:33

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