[Article] Dynamic discharging performance of a latent heat thermal energy storage system based on a PID controller

Most thermal storage systems still operate blindly. At the same time, buildings are experiencing more intense heatwaves, and grids are becoming more unstable. This research explores how adaptive PID control can finally make thermal storage responsive. Our research article, co-authored with colleagues from Southwest Jiaotong University, was published in the Journal of Energy Storage:

Zhang et al. (2023). Dynamic discharging performance of a latent heat thermal energy storage system based on a PID controller. J Energy Storage, 71, 107911. https://orbi.uliege.be/handle/2268/304693

This study introduces a fully coupled PID-controlled latent heat thermal energy storage (LHTES) unit, enabling real-time regulation of discharging behavior through adaptive control of the inlet water velocity. The model is supported by experimental validation (page 4 of the paper) and provides actionable insights for thermal storage applications in buildings and industrial systems.

🚀 Key Technical Insights

Drawing from the numerical and experimental results:

-PID control allows precise tracking of outlet temperature, eliminating the static error typically seen in traditional fixed-flow LHTES systems.

→ Optimal parameters identified: Kp = −0.02 m/(s·K), Ki = −0.15 m/(s²·K), Kd = −0.001 m/K (page 10).

- A higher PCM melting point improves discharging performance, leading to greater total discharging energy

→ Up to 1060 kJ at 200 min for PCM melting point of 327.15 K (page 7).

- Thermal conductivity strongly affects heat release

→ Best case: 0.8 W/m·K gives the maximum rate of 294 W at 200 min (page 8). 

-Latent heat significantly boosts total energy output

→ PCM with 250 kJ/kg latent heat reaches ≈974 kJ, discharging energy at 200 min (page 9).

🔧 Why This Matters

Thermal energy storage helps buildings store heat 🔥 when available and release it when needed ❄️. This supports 🇪🇺 climate goals, smarter energy use ⚡, and efficient buildings 🏢. Most systems still rely on simple controls that cannot react to changing demand 📉📈.

🧩 Example: A building charges during the day ☀️. In the evening 🌙, it should release heat smoothly, but many units overshoot or respond too slowly. Our study shows that real-time PID control 🤖 makes storage systems more accurate, stable and flexible for smart buildings and district heating 🔗🔥. 🌍 Better control means better comfort 🙂, lower energy use 💡, and progress toward Europe’s low-carbon targets ♻️.

📌 Read the article: https://orbi.uliege.be/handle/2268/304693

🌐 Explore the SBD Lab: https://www.sbd.uliege.be/

📚 Check earlier posts and publications: https://www.shadyattia.org/

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