Regenerative braking for gas turbine systems
The present invention is directed to an energy storage system comprised of a heat block having a relatively high specific energy capacity. The heat block can be used, for example, with a regenerative braking system for gas turbine powered vehicles to improve fuel efficiency.
1. An energy storage system, comprising:
at least one heat block in thermal communication with at least one energy source, wherein the at least one heat block is configured to store thermal energy;
a thermally insulative enclosure surrounding the at least one heat block; and
at least one heat exchanger in thermal communication with the at least one heat block to transfer heat from the at least one heat block to a working fluid, wherein the working fluid does not flow through the at least one heat block.
2. The energy storage system of claim 1 , wherein the at least one energy source is at least one of a plug-in to a power grid, an electrical generator and a braking system, wherein the at least one heat block is at least one of carbon, graphite, boron nitride, boron carbide, silicon carbide, silicon dioxide, magnesium oxide, tungsten carbide and alumina, and wherein the at least one heat exchanger is in thermal communication with the at least one heat block by means of a heat transfer fluid.
3. The energy storage system of claim 1 , wherein the working fluid is used in an open-cycle gas turbine.
4. The energy storage system of claim 1 , wherein the working fluid is used in a closed-cycle gas turbine.
5. The energy storage system of claim 1 , further comprising at least one intermediate storage block in thermal communication with the at least one heat block, wherein the at least one intermediate storage block is configured to store thermal energy, wherein the at least one heat block is at least one of carbon, graphite, boron nitride, boron carbide, silicon carbide, silicon dioxide, magnesium oxide, tungsten carbide and alumina, and wherein the at least one intermediate storage block is at least one of carbon, graphite, boron nitride, boron carbide, silicon carbide, silicon dioxide, magnesium oxide, tungsten carbide and alumina, and wherein the at least one heat exchanger is in thermal communication with the at least one intermediate storage block, whereby thermal energy flows from the at least one heat block to the at least one intermediate storage block and then from the at least one intermediate storage block to the at least one heat exchanger.
6. The energy storage system of claim 1 , wherein the at least one energy source is one or more motors each associated with an axle of a vehicle, wherein, in a first mode, the vehicle is moving but not braking and the one or more motors are disengaged from the axle and, in a second mode, the vehicle is moving and braking and the one or more motors are engaged with the axle, and wherein the one or more motors, in the second mode, provide braking action by generating an electrical output, the electrical output being directed to a resistive grid in thermal contact with the heat block.
7. The energy storage system of claim 1 , wherein the at least one energy source is one or more motors, wherein, in a first mode, the one or more motors are disengaged from a shaft of an engine and produce substantially no electrical output and, in a second mode, the one or more motors are engaged with the shaft of the engine when the shaft of the engine is disengaged from a transmission and generate an electrical output, the electrical output being directed to a resistive grid in thermal contact with the heat block.
8. The energy storage system of claim 1 , wherein the at least one energy source is one or more traction motors, wherein the one or more traction motors receive, in a driven mode, electrical energy from a mechanical-to-electrical energy conversion device, and, in a braking mode, the one or more traction motors generate an electrical output, the electrical output being directed to a resistive grid in thermal contact with the heat block.
9. The energy storage system of claim 1 , further comprising:
a first thermally conductive pathway interconnecting the at least one energy source and the at least one heat block;
a second thermally conductive pathway interconnecting the at least one heat block and the at least one heat exchanger; and
a working fluid pathway in thermal communication with the at least one heat exchanger, wherein the second thermally conductive pathway and the working fluid pathway are not in fluid communication with each other.
10. The energy storage system of claim 1 , wherein the thermally insulative enclosure is spaced from the at least one heat block, and further comprising:
a first thermally conductive pathway interconnecting the at least one energy source and the at least one heat block;
a second thermally conductive pathway interconnecting the space and the at least one heat exchanger; and
a working fluid pathway in thermal communication with the at least one heat exchanger, wherein the second thermally conductive pathway and the working fluid pathway are not in fluid communication with each other.
11. The energy storage system of claim 10 , wherein the second thermally conductive pathway has a first end and a second end that are positioned within the space.
12. The energy storage system of claim 10 , wherein the space is filled with Helium.