The Ultimate Cooling Showdown: Centrifugal vs. Screw Chillers – Which Powers Your Ice Thermal Storage Better

 In the pursuit of building energy efficiency, ice thermal storage systems stand out as a transformative solution. By producing ice during off-peak nighttime hours and utilizing it for cooling during daytime peak periods, these systems significantly cut energy costs and reduce grid strain.

At the core of this technology lies a critical decision: choosing the right chiller technology—centrifugal or screw. This guide explores their differences and offers insights into making the best choice for your specific needs.

Centrifugal vs. Screw Chillers: Core Advantages

Centrifugal Chillers

Centrifugal units compress refrigerant using high-speed impellers, boasting high single-unit capacity (often >2,000 RT) and exceptional energy efficiency (IPLV ratings over 10.0). Ideal for super-large commercial projects, they maintain strong partial load performance between 40%–100%.
However, they are prone to surge effects at low loads and typically require variable frequency drives or multi-head designs, leading to higher initial costs.

Screw Chillers

Screw chillers rely on twin-rotor compression, offering a compact design, broad cooling capacity range (80–2,000 RT), and excellent load adaptability from 10% to 100%. They handle unstable grid conditions well and support modular expansion. While their COP is slightly lower than centrifugal models at full load, they come with 15–20% lower maintenance costs and better flexibility in mid-scale applications.

Scenario-Based Selection Guide

Large-Scale Complexes (>100,000㎡)

For massive developments, centrifugal chillers reduce system complexity. A data center project using three 2,000 RT centrifugal chillers achieved 30% energy cost savings, thanks to highly efficient ice production and melting cycles.

Mid-Sized Cooling Stations (50,000–100,000㎡)

In hospitals or university campuses, screw chillers offer modular control and automatic mode switching, cutting energy use by 22% annually in one case using 800 RT units.
Retrofit Projects or Historic Buildings
With limited space or height, screw chillers’ smaller footprint and lower vibration levels are ideal. A heritage building retrofit used noise-dampened screw chillers to meet a ≤65dB requirement—seamlessly integrating into the protected structure.

Lifecycle Cost Comparison (10-Year Outlook)

• Initial Investment: Centrifugal chillers cost 20–30% more, but fewer units are required at higher capacities.
• Operating Cost: Centrifugal models save 8–12% in electricity when running above 75% load.
• Maintenance Cost: Screw chillers save approx. ¥15,000 per unit annually due to simpler mechanical components.

4-Step Guide to Optimal Chiller Selection

1. Cooling Capacity:

1,500 RT → centrifugal
<800 RT → screw
In between? Analyze based on actual load curve

2. Load Fluctuation:

Daytime variations >40% → screw chillers offer superior adaptability

3. Electricity Pricing:

Off-peak/peak price ratio >3:1 → centrifugal chillers provide greater thermal storage ROI

4. Space Constraints:

Machine rooms <4m height or limited footprint → screw chillers are easier to install

Final Insights

Choosing between centrifugal and screw chillers isn’t about competition—it’s about complementing project-specific needs. With innovations like magnetic bearings and variable-speed drives, both technologies are advancing rapidly.
For dual-mode ice storage systems, optimal results require a comprehensive evaluation of cooling demand, energy pricing, space limitations, and long-term ROI. With careful planning, your chiller system can become a high-value investment that offers unmatched efficiency, reliability, and sustainability.