Heat storage devices and circuits for solar steam generation, and associated systems and methods

Abstract

Heat storage devices and circuits suitable for storing solar energy, and associated systems and methods are disclosed. Representative systems can include a solar energy collection system having a first solar field coupled between a first working fluid source and a target heat user via first fluid network, at least one heat storage device, and a second solar field coupled to the at least one heat storage device via a second fluid network. The second fluid network carries a second working fluid and is isolated from fluid communication with the first fluid network. At least one heat exchanger is coupled to the first and second fluid networks to provide thermal communication between the first and second fluid networks.

1 . A solar energy collection system, comprising:
 a first solar field coupled between a first working fluid source and a target heat user via first fluid network;   at least one heat storage device;   a second solar field coupled to the at least one heat storage device via a second fluid network and carrying a second working fluid, the second fluid network being isolated from fluid communication with the first fluid network; and   at least one heat exchanger coupled to the first and second fluid networks, the at least one heat exchanger providing thermal communication between the first and second fluid networks.   
     
     
         2 . The system of  claim 1  wherein the at least one heat exchanger includes a first heat exchanger and a second heat exchanger, and wherein the first heat exchanger is coupled to the first fluid network between the first working fluid source and the first solar field, and wherein the second heat exchanger is coupled to the first fluid network between the first solar field and the target heat user. 
     
     
         3 . The system of  claim 1 , further comprising a controller operatively coupled to the second fluid network and programmed with instructions that, when executed:
 direct the second fluid through the at least one heat storage device in a first direction to heat the at least one heat storage device; and   direct the second fluid through the at least one heat storage device in a second direction opposite the first direction to cool the at least one heat storage device.   
     
     
         4 . The system of  claim 1  wherein the at least one heat storage device operates between a first thermal equilibrium temperature and a second thermal equilibrium temperature less than the first thermal equilibrium temperature, and wherein the system further comprises a controller programmed with instructions that when executed:
 direct the second working fluid through the at least one heat storage device to heat the at least one heat storage device to the first equilibrium temperature; and 
 only after the at least one heat storage device is heated to the first equilibrium temperature, direct the second working fluid through the at least one heat storage device to cool the at least one heat storage device to the second equilibrium temperature. 
 
     
     
         5 . The system of  claim 1 , further comprising a controller coupled to the first and second fluid networks, the controller being programmed with instructions that, when executed:
 direct heat from the second solar field to the at least one heat storage device during a first process, at least until the at least one heat storage device is generally at a first thermal equilibrium;   direct heat from the at least one heat storage device to the target heat user during a second process; and   direct heat from the at least one heat storage device to the first solar field during a third process, at least until the at least one heat storage device is generally at a second thermal equilibrium, the second thermal equilibrium corresponding to a lower average temperature than the first thermal equilibrium.   
     
     
         6 . The system of  claim 1  wherein the at least one heat storage device includes a first heat storage device and a second heat storage device, and wherein the system further comprises a controller programmed with instructions that when executed:
 direct the second working fluid through the first and second heat storage devices in series. 
 
     
     
         7 . The system of  claim 1  wherein the at least one heat storage device includes a first heat storage device and a second heat storage device, and wherein the system further comprises a controller programmed with instructions that when executed:
 direct the second working fluid through the first and second heat storage devices in parallel. 
 
     
     
         8 . The system of  claim 1  wherein first and second working fluids have different compositions. 
     
     
         9 . The system of  claim 8  wherein the first working fluid has a first vaporization temperature and the second working fluid has a second vaporization temperature higher than the first. 
     
     
         10 . The system of  claim 9  wherein the first working fluid includes water and wherein the second working fluid includes a molten salt. 
     
     
         11 . The system of  claim 1  wherein each of the first and second solar fields includes:
 a fluid inlet; 
 a fluid outlet; 
 at least one receiver coupled between the fluid inlet and the fluid outlet; and 
 at least one solar concentrator positioned to direct incoming solar radiation onto the at least one receiver. 
 
     
     
         12 . A solar energy collection system, comprising:
 a solar field, the solar field including:
 a fluid inlet; 
 a fluid outlet; 
 at least one receiver coupled between the fluid inlet and the fluid outlet; and 
 at least one solar concentrator positioned to direct incoming solar radiation onto the at least one receiver; 
   a first heat storage device coupled to the fluid outlet of the solar field;   a second heat storage device coupled to the fluid outlet of the solar field;   a fluid flow network coupled among the solar field, the first and second heat storage devices, and a target heat user; and   a controller coupled to the fluid flow network and programmed with instructions that, when executed:
 direct heat from the solar field to the target heat user during a first process; 
 direct heat from the solar field to the first and second heat storage devices during a second process, at least until the first and second heat storage devices are generally at a first thermal equilibrium; 
 direct heat from the first and second heat storage devices to the target heat user during a third process; and 
 direct heat from the first and second heat storage devices to the solar field during a fourth process, at least until the first and second heat storage devices are generally at a second thermal equilibrium, the second thermal equilibrium corresponding to a lower average temperature than the first thermal equilibrium. 
   
     
     
         13 . The system of  claim 12 , further comprising a working fluid carried by the receiver, and wherein the working fluid includes water. 
     
     
         14 . The system of  claim 12 , further comprising a working fluid carried by the first and second heat storage devices, and wherein the working fluid includes water. 
     
     
         15 . The system of  claim 12  wherein the controller is programmed with instructions that, when executed:
 direct a first quantity of working fluid from the outlet of the solar field to the first heat storage device, and then to the second heat storage device, during the second process; and 
 direct a second quantity of working fluid from the second heat storage device to the first heat storage device, and then to the inlet of the solar field, during the fourth process. 
 
     
     
         16 . The system of  claim 12  wherein the first and second processes are performed simultaneously. 
     
     
         17 . The system of  claim 12  wherein the first and fourth processes are performed simultaneously. 
     
     
         18 . The system of  claim 12  wherein the controller is programmed with instructions that, when executed, direct heat from a gas-fired boiler to the target heat user during a fifth process. 
     
     
         19 . The system of  claim 18  wherein the fifth process is performed simultaneously with the fourth process. 
     
     
         20 . The system of  claim 12  wherein the first thermal equilibrium corresponds to a first temperature distribution in the first and second heat storage devices that is generally fixed for a period of time. 
     
     
         21 . The system of  claim 12  wherein the first heat storage device includes a plurality concrete plates spaced apart to form individual flow channels, and wherein the controller is programmed with instructions that, when executed, direct a working fluid through the flow channels at a laminar flow rate. 
     
     
         22 . A solar energy collection system, comprising:
 a controller coupleable to a fluid flow network that is in turn coupled to a first heat storage device, a second heat storage device, a solar field, and a target heat user, the controller being programmed with instructions that, when executed:
 direct heat from the solar field to the target heat user during a first process; 
 direct heat from the solar field to the first and second heat storage devices during a second process, at least until the first and second heat storage devices are generally at a first thermal equilibrium; 
 direct heat from the first and second heat storage devices to the target heat user during a third process; and 
 direct heat from the first and second heat storage devices to the solar field during a fourth process, at least until the first and second heat storage devices are generally at a second thermal equilibrium, the second thermal equilibrium corresponding to a lower average temperature than the first thermal equilibrium. 
   
     
     
         23 . The system of  claim 22  wherein the controller is programmed with instructions that, when executed:
 direct a first quantity of working fluid from the outlet of the solar field to the first heat storage device, and then to the second heat storage device, during the second process; and 
 direct a second quantity of working fluid from the second heat storage device to the first heat storage device, and then to the inlet of the solar field, during the fourth process. 
 
     
     
         24 . The system of  claim 22 , further comprising:
 the first heat storage device;   the second heat storage device;   the solar field; and   the fluid flow network.   
     
     
         25 . A method for operating a solar collection system, comprising:
 collecting solar energy at a solar field;   directing at least a portion of the solar energy to a target heat user during a first process;   directing heat from the solar field to first and second heat storage devices during a second process at least until the first and second heat storage devices are generally at a first thermal equilibrium;   directing heat from the first and second heat storage devices to the target heat user during a third process; and   directing heat from the first and second heat storage devices to the solar field during a fourth process at least until the first and second heat storage devices are generally at a second thermal equilibrium, the second thermal equilibrium corresponding to a lower average temperature than the first thermal equilibrium.   
     
     
         26 . The method of  claim 25  wherein directing heat from the first and second heat storage devices to the target heat user during the third process includes directing the heat at a first temperature, and wherein the method further comprises halting directing the heat in response to a temperature drop corresponding to a reduction from the first temperature to a second temperature. 
     
     
         27 . The method of  claim 25 , further comprising repeating the second process after completing the fourth process. 
     
     
         28 . A method for operating a solar collection system, comprising:
 collecting first thermal energy at a first solar field and directing at least a portion of the first thermal energy to a target heat user;   collecting second thermal energy at a second solar field and directing at least a portion of the second thermal energy to at least one heat storage device;   during an inter-field discharge process, directing heat from the at least one heat storage device to a working fluid that enters the first solar field; and   during an extra-field discharge process, directing heat from the at least one heat storage device to the target heat user.   
     
     
         29 . The method of  claim 28  wherein at least part of the first process is performed during daylight hours and at least part of the second process is performed during night-time hours. 
     
     
         30 . The method of  claim 28  wherein the working fluid that enters the first solar field is a first working fluid, and wherein heat storage device carries a second working fluid, and wherein directing heat from the heat storage device to the first working fluid includes transferring heat from the second working fluid to the first working fluid at a heat exchanger. 
     
     
         31 . The method of  claim 28  wherein directing heat from the heat storage device to the target heat user includes transferring heat at a heat exchanger from a second working fluid carried by the heat storage device to a first working fluid directed to the target heat user. 
     
     
         32 . The method of  claim 28  wherein the at least one heat storage device includes a first heat storage device and a second heat storage device, and wherein the method further comprises:
 directing heat from the second solar field to the first and second heat storage devices during a first process, at least until the first and second heat storage devices are generally at a first thermal equilibrium; 
 directing heat from the first and second heat storage devices to the target heat user during a second process; and 
 directing heat from the first and second heat storage devices to the first solar field during a third process, at least until the first and second heat storage devices are generally at a second thermal equilibrium, the second thermal equilibrium corresponding to a lower average temperature than the first thermal equilibrium.