Thermal Performance of Packed-Bed Latent Heat Storage Tank Integrated with Flat-Plate Collectors Under Intermittent Loads

Abstract

PBLHS system has been widely studied in the solar energy application area due to its properties of high energy storage density and solving the time-space mismatch of energy and user-side loads. In the actual operation process, the operation of the PBLHS system is related to both the solar energy collector side and the user side. This paper focuses on investing in the cyclic thermal performance of PBLHS tanks integrated with flat-plate collectors under intermittent loads. A 1D transient mathematic model of PBLHS integrated with the solar collector for a particular heat user is established using MATLAB, and the method is validated with the experimental results from literature. In addition, seven operating modes and the operation logic based on solar incidence and temperature variations are described. Based on this model, first, the performance of the PBLHS system under intermittent load in one day was discussed in detail. Then, the influence of different sizes of the tank on performance measures, such as operation modes, PCM and HTF temperature variations, heat storage, and the effective utilization rate are investigated under dynamic operation in a typical week in December. Then based on the optimal results, the effects of different mass flowrates and different inlet temperature limits on the thermal performance of the PBLHS tank are discussed. Further, thermal performances are compared for heating season months, i.e., November, December, January, and February. The results are expected to contribute to a deeper understanding of the operational PBLHS system and provide insight into the optimal design of the PBLHS tank.

Keywords: Thermal energy storage (TES), Latent thermal energy storage, Phase change material (PCM), Solar energy, Intermittent loads