Heat exchangers and tower structure for density-driven power generation

An apparatus comprising:

• at least one lower heat-exchange assembly;
• at least one upper heat-exchange assembly;
• a tower structure arranged to support each upper heat-exchange assembly at an elevation higher than that of the lower heat-exchange assembly;
• at least one ascending circulating-fluid column within the tower structure;
• at least one descending circulating-fluid column within the tower structure;
• at least one buoyant cell;
• and
• at least one turbine,
• wherein each ascending column is arranged and connected to receive the circulating fluid from at least one of the lower heat-exchange assemblies and to convey the circulating fluid thus received upward and into at least one of the upper heat-exchange assemblies,
• wherein each descending column is arranged and connected to receive the circulating fluid from at least one of the upper heat-exchange assemblies and to convey the circulating fluid thus received downward and into at least one of the lower heat-exchange assemblies,
• wherein the buoyant cell is filled with a lighter-than-air gas and is arranged to support at least a portion of the weight of the upper heat-exchange assembly or is arranged within the tower structure to support a portion of its weight;
• and
• wherein the turbine is arranged to be driven by flow of circulating fluid.

A method comprising:

• (i) during daylight, transferring heat from lower ambient fluid to a circulating fluid in at least one lower heat-exchange assembly;
• (ii) conveying the circulating fluid from each lower heat-exchange assembly upward through at least one ascending column to at least one upper heat-exchange assembly positioned at an elevation higher than that of the lower heat-exchange assembly;
• (iii) during nighttime, transferring heat from the circulating fluid to upper ambient fluid in each upper heat-exchange assembly;
• (iv) conveying the circulating fluid from each upper heat-exchange assembly downward through at least one descending column in the tower structure;
• and
• (v) driving at least one turbine with flow of the circulating fluid,
• wherein each ascending column is arranged and connected to receive the circulating fluid from at least one of the lower heat-exchange assemblies and to convey the circulating fluid thus received upward and into at least one of the upper heat-exchange assemblies,
• wherein each descending column is arranged and connected to receive the circulating fluid from at least one of the upper heat-exchange assemblies and to convey the circulating fluid thus received downward and into at least one of the lower heat-exchange assemblies, and
• wherein the turbine is arranged to be driven by flow of circulating fluid.

A method comprising:

• (i) transferring heat from lower ambient fluid a circulating fluid in at least one lower heat-exchange assembly to boil the circulating fluid;
• (ii) conveying the circulating fluid from each lower heat-exchange assembly upward through at least one ascending column to at least one upper heat-exchange assembly positioned at an elevation higher than that of the lower heat-exchange assembly;
• (iii) condensing at least about 0.5% of the circulating fluid as it is conveyed through the ascending column;
• (iv) transferring heat from the circulating fluid to upper ambient fluid in each upper heat-exchange assembly to condense the circulating fluid;
• (v) conveying the circulating fluid from each upper heat-exchange assembly downward through at least one descending column in the tower structure;
• and
• (vi) driving at least one turbine with flow of the circulating fluid,
• wherein each ascending column is arranged and connected to receive the circulating fluid from at least one of the lower heat-exchange assemblies and to convey the circulating fluid thus received upward and into at least one of the upper heat-exchange assemblies,
• wherein each descending column is arranged and connected to receive the circulating fluid from at least one of the upper heat-exchange assemblies and to convey the circulating fluid thus received downward and into at least one of the lower heat-exchange assemblies, and
• wherein the turbine is arranged to be driven by flow of circulating fluid.

A heat-exchange assembly comprising multiple heat-exchanging subunits wherein:

• (a) each of the heat-exchanging subunits comprises (i) an ambient-fluid passage, (ii) at least one circulating-fluid inlet, (iii) at least one circulating-fluid outlet, and (iv) multiple heat-exchange tubes, each of the multiple heat-exchange tubes connecting at least one inlet to at least one outlet so as to convey circulating fluid from the connected inlet through the heat-exchange tube to the connected outlet;
• (b) in each of the multiple heat-exchanging subunits, the multiple heat-exchange tubes are arranged at least partly within the ambient-fluid passage so as to enable heat transfer between circulating fluid conveyed through the heat-exchange tubes and ambient fluid flowing through the ambient-fluid passage;
• (c) the multiple heat-exchanging subunits are arranged in at least one substantially horizontal row or ring so as to direct flow of the ambient fluid through the ambient-fluid passages of the multiple subunits;
• and
• (d) each row or ring of multiple heat-exchanging subunits is arranged within the ambient fluid so that a temperature-induced density differential of the ambient fluid, which density differential arises from the heat transfer, drives the flow of the ambient fluid through the ambient-fluid passages.

A heat-exchange assembly comprising:

• (a) an ambient-fluid passage;
• (b) at least one circulating-fluid inlet;
• (c) at least one circulating-fluid outlet;
• and
• (d) multiple heat-exchange tubes, each of the multiple heat-exchange tubes connecting at least one inlet to at least one outlet so as to convey circulating fluid from the connected inlet through the heat-exchange tube to the connected outlet,
• wherein:
• (e) the multiple heat-exchange tubes are arranged at least partly within the ambient-fluid passage so as to enable heat transfer between circulating fluid conveyed through the heat-exchange tubes and ambient fluid flowing through the ambient-fluid passage;
• (f) the ambient-fluid passage is arranged so as to direct flow therethrough of the ambient fluid in a non-horizontal direction;
• (g) the heat-exchange assembly is arranged so as to drive the flow of the ambient fluid through the ambient-fluid passage by a temperature-induced density differential, which density differential arises from the heat transfer, between the flowing ambient fluid at opposing ends of the ambient-fluid passage;
• and
• (h) the heat-exchange assembly is immersed in the ambient fluid, which ambient fluid comprises atmospheric air.