Comparison of Model Predictions and Performance Test Data for a Prototype Thermal Energy Storage Module

Abstract

Although model predictions of thermal energy storage (TES) performance have been explored in previous investigations, relevant test data that enables experimental validation of performance models has been limited. This is particularly true for high-performance TES designs that facilitate fast input and extraction of energy. In this paper, we present a summary of experimental tests of a high-performance TES unit using lithium nitrate trihydrate phase change material (PCM) as a storage medium. Performance data is presented for complete dual-mode cycles consisting of extraction (melting) followed by charging (freezing). These tests simulate the cyclic operation of a TES unit for asynchronous cooling in a variety of applications. The model analysis is found to agree reasonably well, within 10%, with the experimental data except for conditions very near the initiation of freezing, a consequence of subcooling that is required to initiate solidification.

Development and Validation of a Latent Thermal Energy Storage Model Using Modelica

“…The dip in the dashed blue line at ∼2500 s reflects this phenomenon. We've discussed this for the first-principles model in previous work [27].…”

“…In previous works, we established a dimensionless first-principles framework to model transient heat transfer in a TES device [26]. We also presented a summary of experimental tests of a TES prototype using lithium nitrate trihydrate phase change material as a storage medium [27]. The experimental design and numerical framework were summarized in this paper, to be used as benchmarks to validate the performance of a new TES model in Modelica.…”

“…The device has five flow channels and four hermetically sealed storage sections filled with PCM. Experimental testing of this prototype was performed at Texas A&M. The experimental apparatus and procedure are explained in greater detail in previous work [27]. Here, we'll only summarize the major pieces.…”

“…This problem was mathematically challenging by introducing spatially varying initial conditions (due to the nature of cyclic melting and freezing processes), as well as a transient boundary condition (for the varying working fluid temperature from the heat exchangers) [26]. The culmination of previous work provided a great basis for comparison with experimental testing of a TES device and validation of our first-principle numerical framework [27].…”

Techno-economic analysis of thermal energy storage systems

“…Helmns et al 70 analyzed the thermal energy storage unit with encapsulated phase change materials and multiple channels for the flow of heat transfer fluid. The computational model produced the results with reasonable accuracy and thus can be used for the design of high-performance latent energy storage systems.…”