Energy Performance Study of a Data Center Combined Cooling System Integrated with Heat Storage and Waste Heat Recovery System

Overview

The study proposes an integrated energy system for a data centre with different renewable energy sources and waste heat recovery, able to consider partial and unsteady IT load. The modelled data centre has 4 computer rooms and 2 equipment rooms, a computer-room area of 1867.4 m² and 740 racks, each 0.6 × 1.2 × 2.2 m with a maximum power of 4 kW. A full year was simulated and the integrated system compared with a conventional reference plant.

Free natural-resource cooling covers about 28% of the cooling demand. Against the reference case the integrated system saves 16.4% of energy, raises system COP from 3.88 to 4.64, lowers PUE from 1.36 to 1.30 and cuts electricity expenses by 23.45%. The water-source heat pump absorbs 3,575,709.597 kWh of heat from the data centre per year and provides 4,587,711.45 kWh of heating energy. Two 500 m³ hot-water tanks store recovered heat; in winter they consistently supply hot water at 45 °C, and in summer, with the heat pump off, outlet water stays at around 30 °C.

Rooftop PV generates about 370,000 kWh per year, about 8% of the data centre's total electricity use. The study is a useful template for annual-hour simulation of heat recovery from chilled-water return streams.

Limits: the site is a low-density air-cooled hall (at most 4 kW per rack), so results do not transfer directly to high-density AI racks. More heat can be recovered as heating demand increases; heat recovery and PV share were simulated for a single facility and climate.

Key points

1. The modelled Guangzhou data centre has 4 computer rooms and 2 equipment rooms, a computer-room area of 1867.4 m² and 740 racks, each 0.6 × 1.2 × 2.2 m with a maximum power of 4 kW.
2. Free natural-resource cooling covers about 28% of the cooling demand.
3. Against the reference case the integrated system saves 16.4% of energy, raises system COP from 3.88 to 4.64, lowers PUE from 1.36 to 1.30 and cuts electricity expenses by 23.45%.
4. The water-source heat pump absorbs 3,575,709.597 kWh of heat from the data centre per year and provides 4,587,711.45 kWh of heating energy.
5. Two 500 m³ hot-water tanks store recovered heat; in winter they supply hot water at 45 °C, and in summer with the heat pump off outlet water stays at around 30 °C.
6. Rooftop PV generates about 370,000 kWh per year, about 8% of the data centre's total electricity use.

Using it in design

• Assess heat recovery from chilled-water return with a water-source heat pump and hot-water storage in annual-hour simulation; match the winter and summer outlet temperature difference (45 and 30 °C) to the user's need.
• Verify the free natural-resource cooling share (here 28%) with climate data and report the PUE gain (1.36 to 1.30) separately from the heat recovery and PV contribution.
• Label results as low-density (at most 4 kW per rack) air-cooled hall results; do not transfer them directly to high-density racks.

Who should read it

Engineers designing waste-heat recovery from chilled-water return and integrated energy systems.

Document contents

1. 1. Introduction (1.1 Literature Reviews, 1.2 Research Gaps and New Contribution of This Study)
2. 2. Methodology (2.1 Model of Data Center, 2.4 Simulation Model, 2.5 Model Validation)
3. 3. Results and Discussion (3.1 System Energy Consumption, 3.2 System Cooling Capacity, 3.3 Waste Heat, 3.4 System Electricity Balance, 3.5 System Energy Efficiency)
4. 4. Conclusions

Read the document

Publication details

Authors

Chaohui Zhou; Yue Hu; Rujie Liu; Yuce Liu; Meng Wang; Huiheng Luo; Zhiyong Tian

Publisher

Buildings (MDPI AG)

Year

2025

Volume

15

Issue

3

Pages

326

Document language

English

Source type

Scientific

Access

Open licence — downloadable

DOI

10.3390/buildings15030326

Licence

CC BY 4.0 — share with attribution

Licence evidence

www.mdpi.com

Citation