Sorensen's heat powered bubble pump has a history of successful
deployment in
the Sol Perpetua solar water heater manufactured by
Bubble Action Pumps Ltd. in Kingston, Ontario. Pictures of the pump
may be seen at
http://www.bubbleactionpumps.com/.
Excerpt from the patent:
... reference will be made to the
bubble pump shown in FIG. 2. The bubble pump 1 comprises, preferably
but not essentially, a dome shaped container 2, preferably but not
essentially, made of glass or transparent plastics material for ease of
viewing the operation therein. Container 2 is divided into two separate
chambers 3, and 6 by an impervious divider 5. Chamber 3 is defined as
the separator and chamber 6 is defined as the condenser. Cold
condensate working fluid 4 from condenser chamber 6 passes through a
conduit 7 to the bottom of a solar array 8 where it is heated by solar
energy. The working fluid 4 may be water, or where there is a risk of
freezing, a mixture of ethylene glycol and water or another fluid
having a suitable boiling point and vapour pressure. Solar energy
causes the liquid 4 to boil and form a gas/liquid mixture containing a
large number of vapour bubbles 9 which rise up tube 10 and splash out
of the top thereof, in the manner of a coffee percolator. The vapour
rises into dome 2 and passes into tube 11 which carries the vapour to
the condenser chamber 6 where it condenses in cold working fluid 4. The
hot working liquid thus separated from the vapour falls to the bottom
of the separator chamber 3 from whence it passes via tube 12 to a heat
exchanger (not shown), as described in more detail hereinafter, or to
the external turbine 13 from which the liquid returns to the condenser
chamber of the downstream bubble pump via conduit 14. The pressure in
the condenser chamber 6 is controlled by air purge tube 15 and a hand
operated vacuum pump 16, in conjunction with valve 19, so as to balance
the flow of working fluid in the system and prevent flooding of the
separator or condenser.
End of excerpt from the patent.
The pump generates a pressure difference between the outlet 12 and
inlet 14 due to the difference in the heights of the
surfaces of the working fluids in the separator 3 and the condenser
6.
There is an interesting study of the performance of Sorensen's pump:
Thermal modelling of a bubble pumped solar domestic hot water system,
T.O. Bahomed and S.J. Harrison Solar Calorimetry Laboratory, Queen’s
University, Kingston, Ontario, Canada, K7L 3N6.
http://wire0.ises.org/wire/doclibs/HarareConf.nsf/id/A8A0C0B471237014C12565990050D4F7/$File/BAHO0250.pdf
The bubble pump produces a pressure difference of approximately 3
feet of water. Since this pressure difference is produced between the
tops of a pair of pipes whose fluid contents balance each other,
the heat exchanger and storage tank may be located a greater distance
below the solar water heater.