US 4,523,629 AGranted

Method and apparatus for operating an improved thermocline storage unit

AssigneeThe United States of America as represented by the United States Department of Energy

InventorRobert J. Copeland

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Abstract

A method and apparatus for operating a thermocline storage unit in which an insulated barrier member is provided substantially at the interface region between the hot and cold liquids in the storage tank. The barrier member physically and thermally separates the hot and cold liquids substantially preventing any diffusing or mixing between them and substantially preventing any heat transfer therebetween. The barrier member follows the rise and fall of the interface region between the liquids as the tank is charged and discharged. Two methods of maintaining it in the interface region are disclosed. With the structure and operation of the present invention and in particular the significant reduction in diffusing or mixing between the hot and cold liquids as well as the significant reduction in the thermal heat transfer between them, the performance of the storage tank is improved. More specifically, the stability of the interface region or thermocline is enhanced and the thickness of the thermocline is reduced producing a corresponding increase in the steepness of the temperature gradient across the thermocline and a more efficiently operating thermocline storage unit.

Claims35

Dependent claims

An improved method for operating a thermocline storage unit, said method comprising the steps of:

(a) providing a tank containing a first fluid at a first density and a second fluid at a second density, said first density being less than said second density wherein said fluids stratify within said tank with said first fluid above the second fluid and forming a natural interface region therebetween extending substantially horizontally,
(b) maintaining said first fluid at a first temperature and maintaining said second fluid at a second temperature, said first temperature being higher than said second temperature,
(c) using a barrier member to substantially separate said first and second fluids from each other substantially at said horizontally extending interface region,
(d) selectively increasing and decreasing the respective volumes of the first and second fluids in said tank wherein said horizontally extending interface region therebetween moves substantially vertically relative to said tank,
(e) maintaining a difference in temperature between said first fluid of said first tank and said second fluid of said second tank, and maintaining such separation of said step (c) as said horizontally extending interface region moves vertically relative to said tank, and
(f) adapting said barrier member to float between said first and second fluids substantially at said interface region as said interface region moves relative to said tank to maintain such separation of step (c) and providing said barrier member with a plurality of nodules, said nodules being situate at said barrier member such that said barrier member is enabled to remain substantially centered relative to said tank while permitting relatively small portions of said fluids to freely pass by said barrier member.

3 more elements

In a thermocline storage unit having a tank containing a first fluid at a first density and a second fluid at a second density, said first density being less than said second density wherein said fluids stratify within said tank with said first fluid above the second fluid and forming a natural interface region therebetween extending substantially horizontally, said unit further including means for selectively increasing and decreasing the respective volumes of the first and second fluids wherein said interface region therebetween moves substantially vertically relative to said tank, the improvement including:

(a) means for substantially separating said first and second fluids from each other substantially at said horizontally extending interface region, and
(b) means for maintaining said separating means substantially at said horizontally extending interface region as said interface region moves vertically relative to said tank, wherein said separating means includes a barrier member extending substantially between said first and second fluids at said interface region, said barrier member including a number of protruding members extending outwardly of said barrier member and spaced thereabout to maintain said barrier member substantially centered relative to said tank while permitting relatively small portion of fluids to freely pass by said barrier member.

Dependencies are inferred from the claim text.