Thermoelectric energy storage system with an intermediate storage tank and method for storing thermoelectric energy

摘要

A system and method are provided for storing electric energy in the form of thermal energy. A thermoelectric energy storage system includes a working fluid circuit for circulating a working fluid through a heat exchanger, and a thermal storage medium circuit for circulating a thermal storage medium. The thermal storage medium circuit includes at least one hot storage tank, an intermediate temperature storage tank, and a cold storage tank connected together via the heat exchanger. A proportion of the storage medium is redirected to or from the intermediate storage tank from or to the hot or cold storage tank, joining another proportion which flows directly between the cold and hot storage tank.

主权项

1. A thermoelectric energy storage system having a charging cycle for providing thermal energy to a thermal storage, and a discharging cycle for generating electricity by retrieving the thermal energy from the thermal storage, the thermoelectric energy storage system comprising:
a heat exchanger; a working fluid circuit for circulating a working fluid through the heat exchanger, the working fluid undergoing a transcritical process during heat transfer in the heat exchanger; a thermal storage medium circuit for circulating a thermal storage medium, the thermal storage medium circuit having at least one hot storage tank, an intermediate temperature storage tank and a cold storage tank connected together via the heat exchanger; and means for modifying a rate of flow of the thermal storage medium in the heat exchanger, the means for modifying including an internal stream splitter configured to vary an input rate of flow of the thermal storage medium to the intermediate storage tank, and to vary an output rate of flow of the thermal storage medium from the intermediate storage tank, wherein the means for modifying modifies the rate of flow of the thermal storage medium to minimize a temperature difference between the working fluid and the thermal storage medium during the charging and discharging cycles, and wherein the internal stream splitter is comprised in the heat exchanger, and the internal stream splitter is configured to one of divide and join the stream of the thermal storage medium from the intermediate storage tank.