(724h) A Novel Dynamic Simulation Methodology for High Temperature Packed-Bed Thermal Energy Storage

A Novel Dynamic Simulation Methodology for High Temperature
Packed-Bed Thermal Energy Storage

Thermal energy storage (TES) is becoming an increasingly
attractive technology for improving power production efficiency and capacity. It
has been shown that adding only 4 hours of storage to a solar hybrid steam
injection gas turbine (STIG) cycle can increase the plant’s capacity factor by up
to 50%^[1]. To maximize the benefits of thermal energy storage, it is
necessary to develop storage systems capable of storage at similar temperatures
as those used in the power cycle. Typical industry process temperatures range
between 600–1000°C^[2,3], while current applied TES systems consider
400–600°C to be their highest temperatures^[4]. Demonstration of TES
systems capable of storage at higher temperatures (in the 600-1000°C range) are
necessary for continued progress. In addition, the ability to simulate behavior
of such systems will accelerate their application to industry. Accurate
prediction and simulation of thermal energy storage systems over a range of
operating conditions and various storage media is obtained by reducing the
three-dimensional storage system to two separate one-dimensional models,
representing the thermal profile axially along the device in one, and radially
within the individual storage media beads in the other. These models work
harmoniously together to simulate the storage capabilities of the device. By
modeling the individual storage media, the thermal profile within individual
packing can be determined, and the energy density of the packing, and therefore
the system as a whole, can be accurately predicted at any time during charging
or discharging. In addition, configuration of the model in this manner allows
for it be applicable to devices utilizing both sensible heat storage and latent
heat storage using encapsulated phase change materials (PCM’s). The simulation
results are validated through development and operation of a matching
experimental device. This device was constructed to be capable of using various
types of storage media, while requiring little effort to change configurations
to be suitable for sensible heat or latent heat storage materials. Experiments
were conducted to demonstrate the flexibility of the device design, as well as
to validate the applicability of the simulation model to inherently different
types of systems.