1. A process for storing thermal energy by chemical reaction wherein a flow of heat transfer gas is circulated through a layer of a first hygroscopic salt A then through a layer of a second hygroscopic salt B, the gas being reactive with the salts A and B, the thermodynamic equilibrium curve of the salt A being located further to the left than that of the second salt B in a pressure-temperature phase diagram, the circulation of the flow of gas giving rise to a dehydration reaction both of the first salt A and of the second salt B.
2. A process for releasing thermal energy by chemical reaction wherein a flow of heat transfer gas is circulated through a layer of a first hygroscopic salt A then through a layer of a second hygroscopic salt B, the gas being reactive with the salts A and B, the thermodynamic equilibrium curve of the salt A being located further to the left than that of the salt B of the second salt in a pressure-temperature phase diagram, the circulation of the flow of gas giving rise to a hydration reaction both of the first salt A and of the second salt B.
3. The process for storing or releasing thermal energy as claimed in claim 1, wherein the flow of gas is a flow of moist air.
4. The process for storing and releasing thermal energy as claimed in claim 1 wherein the circulation of the flow of moist air that gives rise to the dehydration reaction takes place, through the salts, in the same direction as that which gives rise to the hydration reaction.
5. The process for storing and releasing thermal energy as claimed in claim 1, wherein the circulation of the flow of moist air that gives rise to the dehydration reaction takes place, through the salts, in the opposite direction to that which gives rise to the hydration reaction.
6. The process as claimed in claim 1, wherein the first salt A is selected from the double sulfate of aluminum and potassium (KAl(SO4)2), strontium hydroxide Sr(OH)2, sodium sulfide Na2S and ammonium aluminum sulfate NH4Al(SO4)2, while the second salt B is respectively selected from strontium bromide (SrBr2), sodium sulfide (Na2S), and nickel sulfate (NiSO4).
7. A fixed bed reactor for storing and releasing thermal energy, comprising at least one stage deposited on which is a stack of a layer of a first hygroscopic salt A on a layer of a second hygroscopic salt B, the thermodynamic equilibrium curve of the first salt A being located further to the left than that of the second salt B in a pressure-temperature phase diagram.
8. The reactor as claimed in claim 6, additionally comprising an open-mesh structure separating the layer of the first salt from the layer of the second salt, the structure not being held mechanically in the reactor.
9. The reactor as claimed in claim 7, wherein the mesh openings of the structure are between 0.05 and 0.1 mm.
10. The reactor as claimed in claim 8, wherein the structure is metallic, made of composite material, made of textile material or made of polymer material.
11. The reactor as claimed in claim 10, wherein the total height of the layer of the first salt and of the layer of the second salt is between 5 and 10 cm.
12. A set of two reactors connected in series to one another, one of the reactors comprising at least one stage deposited on which is a layer of a first hygroscopic salt A, the other of the reactors comprising at least one stage deposited on which is a layer of a second hygroscopic salt B, the thermodynamic equilibrium curve of the first salt A being located further to the left than that of the second salt B in a pressure-temperature phase diagram.
13. An application of the process as claimed in claims 1, to the interseasonal storage of solar heat.
14. An application of the fixed bed reactor as claimed in claim 7 to the interseasonal storage of solar heat.
15. An application of the process as claimed in claim 12 to the interseasonal storage of solar heat.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A method of autoexposure, comprising:
(a) partitioning an image into areas;
(b) for each of said areas, extracting illuminance mean, illuminance variance, illuminance minimum, and illuminance maximum; and
(c) determining exposure using all of the results of step (b).
2. The method of claim 1, wherein:
(a) said determining of step (c) of claim 1 is with a trained neural network.
3. The method of claim 1, wherein:
(a) said areas of an image consist of a center foreground area, an upper area, a lower area, a left side area, and a right side area.