TrombePump countercurrent heat exchanger design

If you look at the drawing (link now works), it is apparent that the machine can be built quite large. There is no need for the trompe tower to be anywhere near the bubble pump tower. There is need for a quite large heat exchanger, with a volume many times that of the towers, so that the flow velocity through the exchanger can be very slow.

I present a perhaps overly concrete (!) design which is not informed by much knowledge of construction practices.

  • Heat flow is always upward, carried by many small diameter heat pipes, made from evacuated metal tubing back-filled with some refrigerant and permanently sealed. Replacing the heat pipes is probably not feasible and they should be designed for the expected lifetime of the machine. The heat pipes are provided with fins.
  • Regularly spaced baffles with perhaps 50% of the area occupied by holes are attached to the walls of the water channels to restrict flow from one chamber to the next. The water in each chamber will tend to stay at a constant temperature. This divides the heat exchanger into perhaps hundreds of segments.
  • A deep trench is excavated between the sites of the trompe tower and the bubble pump tower. This provides insulation and permits other uses for the land over the heat exchanger.
  • The bottom and sides of the trench will be filled with insulating material.
  • Forms are built to define the inside surfaces of the lower water channel.
  • Expansion joints and baffle mounting hardware are provided for. The joints must be well sealed and designed for the hydrostatic pressure which will be created by the trompe and bubble pump towers.
  • Heat pipes are held in place by the forms, extending from the bottom of the lower channel to the top of the upper channel.
  • The entire bottom channel is poured of concrete, one expansion segment at a time, casting the hardware and heat pipes in place.
  • Baffles and the atmospheric pressure air pipe are installed as each segment is cast.
  • A large volume of high heat-capacity material is filled above the bottom channel around the heat pipes with good thermal conductivity to them, forming a large heat reservoir between the lower and upper water channels. Insulating baffles prevent heat flow along the length of the heat reservoir, so that each short segment can maintain a different temperature without short-circuit losses.
  • Forms for the upper water channel are built and the channel is cast over the heat reservoir.

Note that there is no provision for a separate hot and cold heat reservoir. Instead, the outer segments of the heat exchanger serve this purpose. Additional heat is added to water in the bubble pump tower and heat is removed from water in the trompe pump tower whenever external conditions permit, probably using a separate system of heat pipes.

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7 Responses to “TrombePump countercurrent heat exchanger design”

  1. William Says:

    In order to minimize gross ground area I would suggest building the trompe and bubble towers in close proximity the underground heat exchangers can then be in the shape of a “U” or folded in a modified “Z” shape.

    Show the inflow of hot air and it’s temperature as well as any other energy flows to clarify and simplify the description of operation.

  2. archimerged Says:

    Thanks for the comment. You can edit the text at http://renewableenergy.wikia.com/wiki/TrombePump
    Create an account if you don’t want your IP publicly revealed.

    These things could also be build under new highways, with towers every mile or so providing refils for compressed air cars.

    Heat enters the water in the bubble pump tower, preferably where the bubbles are expanding so that the water is kept at maximum temperature during expansion. On sunny days, the heat comes from a solar concentrator. On other days and at night it comes from the ambient. Gravity feed heat pipes are used so if it is colder out than the incomming water, the water isn’t cooled.

    Heat leaves water in the trompe tower, from the downflow pipe, again using heat pipes so heat can’t flow into the water there.

    The incomming atmospheric pressure air is used at ambient temperature. This will cool the hot water slightly if it is cold out, but you can’t win everything. Or you could arrange for alternate locations for air intake ports depending on the outside temperature.

  3. 0xff Says:

    Have you ever seen the enclosed laser channel at the Sandia Lab? Biult to protect a laser beam from atmospheric disturbances over a mile long path, six feet above the desert floor, it has expansion joins every 100 feet that each can accomodate 3 feet of expansion and contraction. The laser detects change in distance from one end of the pipe to the other (earth quakes).

    I envisioned the channel running across (under) an interstate highway with the towers on either side of the roadway in corporated into the concession buildings and service areas.

    Are the tops of both towers open?

    The drawing link is 404.

  4. archimerged Says:

    Link is no longer 404 (I forgot to put in the /wiki/). Top of trompe tower is sealed and hydrostatic pressure is lower than atmospheric, which means the atmospheric pressure air will force its way out of the tube into the water. Downward flow rate is faster than the maximum rate bubbles can move upward through water.

    Yes, towers across the highway would work. You need a separate high pressure air pipe to send air across to the trompe size. And you need the hot air engine and rotary compressor I mentioned somewhere to make high pressure air from hot medium pressure air.

    Making everything so it will last maybe 100 years is the challenge, or else make it cheap enough that you can afford to replace it every 20 years. I’m going to do some calculations real soon now for size vs. power and materials cost, etc…

  5. William Says:

    Aha!
    You must have read Luke 24:28 ” For which of you, intending to build a tower, sitteth not down first, and counteth the cost, whether he have sufficient to finish it?

  6. William Says:

    archimerged Says:
    June 20th, 2006 at 3:18 pm
    “Yes, towers across the highway would work. You need a separate high pressure air pipe to send air across to the trompe size. And you need the hot air engine and rotary compressor I mentioned somewhere to make high pressure air from hot medium pressure air.”

    Operation of any such peripheral MUST be charged to the SYSTEM (TrombePump) with which it is associated. In other words the TrombePump and/or peripherals MUST all be self sustaining else the objective of the entire system or combination thereof cannot be realized.

  7. archimerged Says:

    Right. But the engine uses hot compressed air which is output from the TrombePump, together with some additional heat from the hot heat source, to turn the compressor. The compressor also rejects additional heat to the cold heat sink. Note that this cannot turn a profit into a loss. The only question is how efficiently the conversion is done. Anyway, the AirCar is just an example of a use for compressed air. Unfortunately, very high pressure air is needed to keep the size of the mobile storage tanks down.

    Compressing air does not change the internal energy of the air which is compressed (provided it is cooled during compression so T is constant). But it does change the internal energy per unit volume. The tank of air contains the same PV energy as the large volume of low pressure air which was compressed.

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