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2026 Vol.8, Issue 3 Preview Page

Research Article

Unsteady CFD analysis of thermal stratification characteristics in a P2H hot water thermal storage tank
Sungwan Park1†
,
Yo-seph Lee2†
,
Hoon Seonwoo23*
1Smart Agriculture Major, Sunchon National University, Suncheon 57922, Republic of Korea
2Department of Convergent Biosystems Engineering, Sunchon National University, Suncheon 57922, Republic of Korea
3Interdisciplinary Program in IT-Bio Convergence System, Sunchon National University, Suncheon 57922, Republic of Korea
*Corresponding Author
†These authors equally contributed to this study as first author.
30 September 2026. pp. 256-279
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Abstract

Surplus electricity and power output fluctuations from photovoltaic and wind systems are important challenges with increasing renewable energy use. Power-to-Heat (P2H) technology converts surplus electricity into thermal energy, and hot water thermal storage tanks are essential for improving energy utilization. In this study, three-dimensional unsteady Computational Fluid Dynamics (CFD) simulations were performed to analyze the thermal behavior and stratification characteristics of a P2H hot water thermal storage tank, focusing on the tank as a single component of the P2H system rather than system-level performance. The effects of tank height, tank diameter, inlet and outlet port positions, mass flow rate, initial tank temperature, inlet fluid temperature, heater installation position, and heater operation mode were investigated using a dimensionless thermocline thickness as a quantitative stratification index. Tank height and diameter mainly affected the initial thermal response, with differences among cases narrowing over time. Inlet and outlet port positions affected the diffusion path of cold inlet water and the maintenance of the upper hot water layer. Mass flow rate was the dominant operating factor: the dimensionless thermocline thickness increased from 0.17 to 0.86 as the flow rate rose from 0.05 to 0.20 kg/s. These geometry and flow-rate effects reflect combined changes in tank volume, residence time, and cumulative inflow rather than independent parametric effects. In contrast, initial tank and inlet fluid temperature had limited effects on relative thermal behavior. Heater position and operation mode strongly affected natural convection and temperature distribution; upper-heater-only operation maintained the most stable stratification (thermocline thickness as low as 0.09), whereas the dual-heater case (3000 W, twice the power) showed a thicker thermocline (up to 0.69). These findings indicate that tank geometry, flow conditions, and heater operation strategies significantly influence thermal stratification and should be considered together in the design and operation of P2H hot water thermal storage tanks.

Keywords
Power-to-Heat
Computational Fluid Dynamics
Thermal storage tanks
Stratification
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Information
  • Publisher :Korean Society of Precision Agriculture
  • Publisher(Ko) :한국정밀농업학회
  • Journal Title :Precision Agriculture Science and Technology
  • Journal Title(Ko) :정밀농업과학기술
  • Volume : 8
  • No :3
  • Pages :256-279
  • Received Date : 2026-08-18
  • Revised Date : 2026-09-08
  • Accepted Date : 2026-09-08
  • DOI :https://doi.org/10.22765/pastj.20260019
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