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Pumped thermal energy storage (PTES) technology offers numerous advantages as a novel form of physical energy storage. However, there needs to be a more dynamic analysis of PTES systems. This paper proposes a dynamic simulation model of the PTES system using a multi-physics domain modeling method to investigate the dynamic response of key system parameters during the system's start-up and variable operating conditions. Additionally, the impact of equipment parameters on system characteristics was analyzed. Furthermore, a comparative analysis was conducted to assess the variation in system characteristics when considering the different working medium properties. The results show that the system cavity volume should be selected as 5 m3, and the initial pressure of the system during the charge/discharge period should be selected as 2.1 MPa and 3.8 MPa, respectively. The system runs to the design operating conditions during the start-up process in about 1400 s. In the process of variable operation conditions, the power load in the charge/discharge period can be increased or reduced from the rated value by gas filling or venting, and the system characteristics change accordingly. The simulation model and research findings will offer theoretical insights for optimizing the design of the PTES system. • A dynamic simulation physical model of the PTES system was proposed. • The dynamic changes in system characteristics were analyzed. • The TES tank's thermal inertia and heat management of the PTES system were analyzed. • The effects of main equipment parameters on system characteristics were analyzed. • System characteristics were compared when using different gas properties. [ABSTRACT FROM AUTHOR]

The aim of the paper is to simulate multi-tank storage with the thermocline moving from tank to tank and compare the results against single tank storage. No analysis of this nature has previously been performed. The results lend added impetus to developing this new type of thermal energy storage, especially as heat losses through insulation have already been reduced a minimum. Dividing a seasonal thermal energy storage tank into smaller tanks reduces the negative effect of heat transfer through the thermocline. The work is a continuation of the concept already proposed in available literature of using multiple solar energy stores, but we focus mainly on developing a dynamic model of a system of this type and presenting the results of a time and thermocline dependent simulation. The study also encompassed examination of the thickness of thermal insulation of the storage tanks, with definitions of its critical size. Our study revealed that the use of multi-tank thermal energy storage reduces heat loss through the thermocline. This is illustrated mainly by changes in water temperature in the upper part of the tank, which fluctuates across a much smaller range than for a single tank. In the single tank system, the temperature drops below 60 °C, whereas for the multi-tank system it always remains above 64 °C. In addition, in the multi-tank solution the loss caused by the thermocline occurs in only one tank, leaving 3/4 of the storage system unaffected by thermocline loss. • The concept of multi tank seasonal thermal energy storage is examined. • The examination is based on the dynamic modeling. • Results are compared with the single tank thermal energy storage systems. • The examined system is more efficient due thermocline losses limitation. [ABSTRACT FROM AUTHOR]