Experimental and Numerical Investigation of a Pilot Scale Latent Heat Thermal Energy Storage for CSP Power Plant

Abstract

A Phase Change Material (PCM) thermal energy storage module has been built and tested successfully at CEA on the LHASSA experimental facility. The test campaign aimed at validating the thermo-hydraulic behavior of the storage module under operating conditions similar to those of commercial Direct Steam Generation CSP plants. The measured performances have been compared to the simulation results given by a dynamic model developed at CEA. Tests gave very satisfactory results, with a measured storage capacity meeting the specifications and a very small degradation of temperature and pressure levels in discharge mode. The storage module tests allowed to validate the modeling approach chosen to assess system performances and dynamics. The simulation model developed within the Dymola platform was proven to accurately reproduce the tests results and therefore can be effectively used for performance predictions and for the definition of operating strategies of commercial CSP plants.

Second test campaign of a pilot scale latent heat thermal energy storage – Durability and operational strategies

“…The performances of the storage module are mainly characterized by an equivalent thermal resistance accounting for the complex 3D arrangement of tubes, fins, inserts, and PCM within the storage [5]. This equivalent thermal resistance is given by the following equation:…”

“…The mass of aluminum inserts corresponds to less than 25% of the PCM mass in the test section. In 2013, the first test campaign showed a high energy quality during discharge, excellent repeatability, and a good agreement between experimental and modeling results [5]. A second test campaign has started in 2014 (and will continue until the last quarter of 2015), aiming at testing the thermal and mechanical endurance of the storage module over a wide range of operating procedures, taking into account non nominal initial conditions, changing inlet mass flow conditions, continuous cycling… The measured performance is compared to the simulation results given by the dynamic model developed at the CEA to check the repeatability of the module's performances.…”

“…Experimental results from this second test campaigns were compared to simulation results from our Dymola model [5], with a good agreement. An example of a partial load charging-discharging test is presented in Fig.…”

Assembly and attachment methods for extended aluminum fins onto steel tubes for high temperature latent heat storage units

“…The fin labeled 'A' is discussed in more detail by Seitz et al [1] as well as in [23]- [26]. The fin labeled 'B' is discussed in more detail by Johnson et al in [27] and [7] and the fin labeled 'C' is discussed in more depth by Laing et al [13]. In this article, the focus is not on the geometry or design of the fins, as this has been discussed elsewhere.…”

“…Finned-tube designs offer significant advantages with regard to heat transfer enhancement at low amounts of additional material and are therefore the focus of this paper. These concepts have been researched by, among many others, Garcia et al [13], [14], Walter et al [15], and Laing et al [16]. One of the reasons for the variety of concepts in development is the relatively low thermal conductivity of PCMs.…”