Abstract: A dual rail heat pump cycle includes a low-temperature heat source; a two stage, high-temperature heat exchange process through which, in operation, heat is exchanged with a thermal medium; and a working fluid circuit. The working fluid circuit includes an expansion process; a compression process; a recuperation process, and a pair of parallel flow paths. The recuperation process is interposed between the expansion process and the compression process and has a high-pressure side defined by the compression process and a low pressure side defined by the expansion process. The pair of parallel flow paths between the recuperation process and the high-temperature heat exchange process on the high-pressure side of the recuperation process.

Abstract: A method for operating a pumped thermal energy storage (“PTES”) system includes circulating a working fluid through a working fluid circuit, the working fluid having a mass flow rate and a specific heat capacity and balancing a product of the mass and the specific heat capacity of the working fluid on a high-pressure side of a recuperator and a low side of the recuperator as the working fluid circulates through the working fluid circuit. The PTES system includes a bypass in the working fluid circuit by which a first portion of the working fluid bypasses the high-pressure side of the recuperator while a second portion of the working fluid circulates through the high-pressure side of the recuperator.

Abstract: Systems and methods are provided for charging a pumped thermal energy storage (“PTES”) system. A system may include a compressor or pump configured to circulate a working fluid within a fluid circuit, wherein the working fluid enters the pump at a first pressure and exits at a second pressure; a first heat exchanger through which the working fluid circulates in use; a second heat exchanger through which the working fluid circulates in use; a third heat exchanger through which the working fluid circulates in use, a turbine positioned between the first heat exchanger and the second heat exchanger, configured to expand the working fluid to the first pressure; a high temperature reservoir connected to the first heat exchanger; a low temperature reservoir connected to the second heat exchanger, and a waste heat reservoir connected to the third heat exchanger.