| dc.description.abstract | Sensible heat storages have extensive use in thermal energy deployment, including concentrated
solar power (CSP) applications. Usually, CSP pants demand various techno-economic features
in sensible heat storage, such as low-cost, high-capacity, efficiency, and ease of operation. These
requirements demand investigations to assess and develop novel strategies to improve the efficacy
of sensible heat thermal energy storage (TES) technology. Accordingly, the present study
focuses on thermo-fluid management and material characterization for stratified TES.
Computational fluid dynamics simulations were employed to analyze near-inlet thermal blending
of hot and cold heat transfer fluid (HTF), molten salt, for a single-tank sensible heat TES
system. Accordingly, a hemispherical diffuser is developed. In addition, a mathematical index
is proposed to quantify the degree of thermal stratification. Further, experiments were conducted
for thermosyphon charging of single-tank stratified storage including both continuous
and pulsatile charging at low (150 °C) and high (250 and 300 °C) temperatures. Dowtherm-A
oil was used as the HTF, and the thermal expansion of HTF was accommodated in an expansion
tank via two different designs (top and bottom connections from the storage tank to the
expansion tank).
From a materials viewpoint, high specific heat capacity (CP ) is essential to improve the energy
density of the storage; which can be improved by adding nanoparticles to molten salt. However,
the literatures show both increment and decrement in CP . Since difficulties are associated with
identifying explicit relations between molten salts and nanoparticles due to complex molecular
interactions, we inquired whether there are common patterns/clusters in the nanofluid samples
reported in earlier studies by employing unsupervised machine learning methods: Hierarchical
cluster analysis (HCA) and Principal component analysis (PCA). Finally, a comparative analysis
is presented to capture the measurement variability in nanofluid samples under random
sampling. In this analysis, the DSC test is employed on small-sized batches (< 10 mg) and the
T-history method on large-sized batches (∼ 20g), and the CP values of both tests are compared
using a nonparametric statistical test, Mann-Whitney U Test. | en_US |
