Ice Storage Tank For Data Center: Thermal Storage With Ice And PCM
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Ice Storage Tank For Data Center: Thermal Storage With Ice And PCM
An ice storage tank for a data center is a thermal energy storage vessel that stores cooling as latent heat in ice or a phase-change material (PCM), discharging it during peak electrical demand or cooling spikes to shave load and cut cost. Compared with chilled-water thermal storage, ice and PCM store far more cooling per unit volume because they use the latent heat of fusion, but they operate at a lower temperature and impose a larger lift on the refrigeration plant. The tank is a lined bolted or fabricated vessel referenced to AWWA D103-09 and ISO 28765, containing either encapsulated ice balls, a plate-ice system, or a PCM slurry — chosen by the site's peak-shaving goal and the temperature the cooling loop can accept.
Thermal energy storage lets a data center make cooling when it is cheap or abundant and use it when it is expensive or constrained. Chilled-water storage is the familiar form, but it is volume-hungry because it stores sensible heat only. Ice and phase-change storage compress that volume dramatically by storing latent heat, at the cost of a colder, harder-working refrigeration cycle. For a data center chasing peak-shaving, demand-charge reduction or a smaller footprint, ice or PCM can be the better trade. The errors are specifying ice where chilled water would do, ignoring the lower temperature's effect on plant lift, or building a tank whose lining cannot tolerate freeze-thaw and slurry duty.
This guide works the ice storage tank for a data center from the ice/PCM options through the chilled-water comparison to sizing and material.
Ice And PCM Storage Options
Ice and PCM storage come in several physical forms, and the tank design follows the form chosen. The three common approaches differ in how ice is made, stored and melted.
1. Encapsulated ice. Sealed balls or pods filled with a freezing point-suppressed solution sit in a tank of water; the refrigeration plant freezes them at night and the circulating water melts them by day. The tank is a simple contained volume of pods and water.
2. Plate or static ice. Ice forms on plates or coils inside the tank; the refrigerant or brine directly builds and releases the ice. The tank houses the plate stack and the meltwater circuit.
3. Phase-change material (PCM). A formulated material with a tuned melt temperature stores latent heat in a narrower band than water-ice, allowing a tank designed around the data center's useful temperature range rather than 0 °C.
Each form changes the tank internals, the melt/discharge path and the temperature at which the stored cooling is delivered.
Ice And PCM Versus Chilled-Water TES
Ice and PCM store roughly an order of magnitude more cooling per cubic metre than chilled water, but at a lower temperature and a higher plant lift. The comparison is the core selection question.
· Storage density. Chilled water stores sensible heat across a few degrees of lift; ice stores the latent heat of fusion, so a given cooling capacity needs far less tank volume.
· Temperature penalty. Ice and PCM discharge colder than chilled-water TES, so the refrigeration plant works harder (larger lift) to make the ice, trading volume for energy and equipment size.
· Peak-shaving fit. Where the goal is demand-charge reduction or shifting cooling off a peak window, the compact ice/PCM store often pays back despite the penalty.
· When chilled water wins. Where volume is not constrained and the loop temperature is moderate, chilled-water TES avoids the low-temperature lift and is simpler.
The decision is a footprint-versus-lift trade, not a default to the denser option.
Attribute | Chilled-water TES | Ice / PCM storage |
Storage mechanism | Sensible heat | Latent heat (fusion) |
Volume per cooling unit | High | Low (much denser) |
Discharge temperature | Moderate (e.g. 4–7 °C) | Low (near 0 °C or PCM point) |
Plant lift | Lower | Higher |
Best use | Volume-available sites | Peak shaving, footprint-limited |
Tank Material And Freeze-Thaw Duty
An ice or PCM storage tank must survive continuous freeze-thaw and, for slurry forms, abrasion, so the lining and shell are specified for that duty. This is harder than static water storage.
· GFS (glass-fused-to-steel). Enamel fired at 820–930 °C gives a smooth, hard skin (Ra < 0.8 µm, adhesion above 3,450 N/cm²) that resists freeze-thaw cycling and pod/slurry abrasion; every panel is spark-tested at 1,500 V DC.
· FBE-lined bolted. A documented epoxy lining (AWWA C550-style) validated for the freeze-thaw and temperature band.
· Fabricated vessels. For plate-ice or compact PCM units, stainless or FBE-lined fabricated tanks suit the internal coil or plate stack.
· Thermal envelope. Because the store is cold, external insulation and a sealed roof limit heat gain that would prematurely melt the inventory.
The lining is chosen so repeated freezing and any pod/slurry abrasion do not degrade the containment over the decades the plant runs.
Form | Tank internals | Discharge temperature |
Encapsulated ice | Pods in water | Near 0 °C melt |
Plate / static ice | Coil or plate stack | Near 0 °C melt |
PCM | Tuned melt material | PCM melt point |
Sizing For Peak Shaving
An ice storage tank is sized from the cooling capacity to be shifted and the discharge window, expressed as latent-storage volume rather than sensible tonnes. Three inputs set the capacity.
4. Cooling to be shifted. The peak-demand or off-peak-target cooling capacity, in cooling tonnes or kWh, the site wants stored rather than generated at peak.
5. Discharge window. The hours over which the store must discharge during the peak period, which sets the required storage rate as well as total volume.
6. Temperature and lift limit. The lowest useful discharge temperature and the refrigeration lift the plant can accept, bounding whether ice or a higher-temperature PCM is the right choice.
The result is a compact latent store sized to the shifted load and window, referenced to the loop's temperature limits — not a chilled-water volume misapplied to an ice duty.
Integration With The Cooling Plant
The ice or PCM store connects to the data center cooling plant through a charge/discharge circuit that the control system schedules around the peak window. Integration discipline matters.
· Charge at off-peak. The refrigeration plant freezes the store (or sets the PCM) when electricity is cheaper or the central plant has spare capacity.
· Discharge at peak. During the peak window the store feeds the cooling loop, reducing chiller load and demand charges.
· Blend with chilled water. Many sites run a hybrid: chilled-water TES for moderate shifting and ice/PCM for the sharpest peak, scheduled together.
This scheduling converts the dense store into a measurable reduction in peak electrical demand.
Project Case
A dedicated data-center ice-storage reference is not yet part of the delivered portfolio, so this article is written as engineering guidance rather than a project citation. The company's capability to supply large bolted thermal and water-storage tanks is demonstrated in adjacent sectors: overseas fire-protection programs have delivered GFS tanks up to 12,261 m³ (India, 3 tanks, 2024-06) and 1,666 m³ (Singapore, 2 tanks, 2026-01), built to the same bolted-tank standards. Those references evidence large-volume bolted-tank supply and QA for freeze-thaw-capable linings; they are fire-protection projects, not data-center ice-storage installations, and are cited here only as capability context.
Center Enamel Engineering Capability
Center Enamel (Shijiazhuang Zhengzhong Technology Co., Ltd) has designed and fabricated bolted storage tanks since 2008. As the first glass-fused-to-steel (GFS) tank manufacturer in China, the company holds close to 200 enamel-related patents, produces roughly 300,000 enamel-coated steel plates a year, has completed more than 30,000 installed projects and supplies its tanks to over 100 countries. The new 150,000 m² production base was added to raise output capacity, and single tanks are supplied up to 60,000 m³. Manufacturing runs under ISO 9001 and ISO 45001, with product certification including NSF/ANSI 61, WRAS, FDA, LFGB, CE (EN 1090), ISO 28765, FM, BSCI and EUROCODE, and design referenced to AWWA D103-09, AWWA C550, ISO 28765 and NSF/ANSI 61 where the application requires it.
For ice and PCM storage the company supplies GFS and FBE bolted tanks with freeze-thaw- and abrasion-resistant linings, sealed insulated roofs, and coating/spark-test documentation for review.
Frequently Asked Questions
Q1: How is ice storage different from chilled-water TES?
A1: Ice and PCM store latent heat of fusion, giving far higher cooling density per volume than chilled water's sensible heat, but at a lower discharge temperature and a higher refrigeration lift.
Q2: Which is better for peak shaving?
A2: Ice or PCM suits footprint-limited sites and sharp peak-demand windows where the dense store pays back despite the lower temperature and higher lift; chilled water suits volume-available, moderate-temperature sites.
Q3: What are the main ice/PCM forms?
A3: Encapsulated ice (pods in water), plate or static ice (ice on coils/plates), and phase-change material tuned to a useful melt temperature; each changes the tank internals and discharge path.
Q4: How does freeze-thaw affect the tank?
A4: Repeated freezing and any pod/slurry abrasion demand a hard, resistant lining; GFS enamel (Ra < 0.8 µm, 1,500 V DC spark test) or a documented FBE grade is specified, with insulation to limit heat gain.
Q5: How is the tank sized?
A5: From the cooling capacity to be shifted, the discharge window, and the lowest useful temperature/lift the plant accepts — sized as latent-storage volume, not a chilled-water volume.
Q6: Can ice storage blend with chilled-water TES?
A6: Yes. Many sites run a hybrid, using chilled-water TES for moderate shifting and ice/PCM for the sharpest peak, scheduled together by the control system.
Q7: Which standards apply?
A7: AWWA D103-09 for bolted construction and ISO 28765 for vitreous-enamelled design where required; NSF/ANSI 61 and WRAS apply where the loop water contacts a potable-adjacent lining.
An ice storage tank for a data center trades plant lift for storage density, storing cooling as latent heat in ice or PCM to shave peaks and cut demand charges where footprint or sharp peaks make chilled water impractical. Pick the form — encapsulated, plate or PCM — to the site's temperature limits, specify a freeze-thaw- and abrasion-resistant GFS or FBE lining, size the store to the shifted load and window, and reference the fabrication to AWWA D103-09 and ISO 28765. Done that way, thermal storage earns its compact place in the cooling strategy.
Talk to an Engineer
For an ice storage tank for a data center, send us the cooling capacity you want to shift, the peak discharge window, your loop's lowest useful temperature and refrigeration lift limit, and the ice/PCM form you prefer. We will return a storage-form recommendation, a GFS or FBE bolted tank specification with freeze-thaw-resistant lining and insulated roof, and a latent-storage sizing study referenced to AWWA D103-09 and ISO 28765 with coating and spark-test documentation.
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