Thermal energy storage system with parallel connected vessels

A thermal energy storage system for storing thermal energy produced by a heat source and for supplying the thermal energy to a thermal load, the thermal energy storage system comprising:

• a working fluid configured to store the thermal energy and transfer the thermal energy between the heat source and the thermal load;
• a plurality of vessels configured to store the working fluid;
• wherein each vessel of the plurality of vessels has a first end, a second end, an interior region, and a floating separator piston located in the interior region to separate a hot portion of the working fluid towards the first end from a cold portion of the working fluid towards the second end;
• a first manifold thermally coupled to an output of the heat source and to an input of the thermal load and fluidly coupled to the interior region proximate the first ends of the plurality of vessels;
• a second manifold thermally coupled to an input of the heat source and an output of the thermal load and fluidly coupled to the interior region proximate the second ends of the plurality of vessels;
• wherein the plurality of vessels are arranged in a parallel configuration;
• wherein each floating separator piston comprises a piston body having a first end, a second end, a central region, and a compressible member which is disposed in the central region of the piston body and which is configured to engage with an inner surface of its respective vessel;
• wherein the compressible member has a porosity level that results in a thermal loss due to leakage of the working fluid from the first end of the piston to the second end of the piston of no more than 5% of an overall thermal loss in the thermal energy storage system;
• and
• wherein the compressible member engages with an inner surface of a respective vessel of the plurality of vessels with an amount of friction that allows movement of the floating separator piston in the respective vessel with a pressure difference of not more than 10 psi between the first end of the piston to the second end of the piston.

A thermal energy storage system for storing thermal energy produced by a heat source and for supplying the thermal energy to a thermal load, the thermal energy storage system comprising:

• a working fluid configured to store the thermal energy and transfer the thermal energy between the heat source and the thermal load;
• a vessel configured to store the working fluid;
• wherein the vessel has a first end, a second end, an interior region, and a floating separator piston located in the interior region to separate a hot portion of the working fluid toward the first end from a cold portion of the working fluid towards the second end;
• a first manifold thermally coupled to an output of the heat source and to an input of the thermal load and fluidly coupled to the interior region proximate the first end of the vessel;
• a second manifold thermally coupled to an input of the heat source and an output of the thermal load and fluidly coupled to the interior region proximate the second end of the vessel;
• a controller configured to maintain the working fluid in a liquid state;
• a thermal expansion system fluidly coupled to one of the first or second manifolds to accommodate a change in working fluid volume;
• wherein the thermal expansion system includes an expansion tank and an injection pump;
• and wherein the controller directs the working fluid from one of the first or second manifolds into the expansion tank when the pressure of the working fluid exceeds a setpoint pressure and the controller causes the injection pump to drive the working fluid from the expansion tank to one of the first or second manifolds when the pressure of the working fluid falls below the setpoint pressure to maintain the working fluid in the liquid state.