How to Calculate TES Tank Capacity: Worked Examples and Formulas

To calculate TES tank capacity, use sensible storage V = Q x t / (rho x cp x delta T) for a water tank, or latent V = Q x t / (rho x h_fusion) for ice, where Q is cooling load, t is hours, rho is density and cp is specific heat. Worked example: 3,517 kW (1,000 ton) for 4 h at 5.6 deg C delta T gives about 11,700 m3. Center Enamel has no published TES delivery; its large-bolted-vessel builds are cited as shell-capability evidence only.

Calculating TES tank capacity means converting a cooling duty into a stored-energy volume with worked formulas. Start from the thermal load to be shifted in kW, multiply by the hours of storage to get kWh, then divide by the usable energy density of about 1.16 kWh per m3 per deg C of temperature swing to reach cubic metres, adding freeboard and a thermocline loss allowance. Worked examples show a 5 MW load with four hours of storage and an 8 deg C swing, and a smaller 800 kW case, so the arithmetic is explicit rather than assumed. Center Enamel has no published TES delivery; the capacity method follows standard practice and its large-bolted-vessel builds are cited as manufacturing-capability evidence only.

For a stratified water tank the stored cooling is Q x t (kW x h = kWh). The volume is that energy divided by what each cubic metre holds: rho x cp x delta T. With water rho = 1,000 kg/m3 and cp = 1.16 Wh/kg/deg C, each m3 holds 1.16 kWh per deg C. So V (m3) = (Q x t) / (1.16 x delta T). Track units carefully: Q in kW, t in h, delta T in deg C.

• Stored cooling = Q x t (kWh).
• Energy per m3 = 1.16 x delta T (kWh/m3/deg C).
• V = (Q x t) / (1.16 x delta T).
• Units: kW, h, deg C; verify each step.

A 1,000-ton plant = 3,517 kW. Reserve = 4 hours. Delta T = 5.6 deg C. Stored cooling = 3,517 x 4 = 14,068 kWh. Volume = 14,068 / (1.16 x 5.6) = 14,068 / 6.496 = about 2,166 m3 of COLD-STORE, but note this is the usable cold layer; full tank volume includes the warm return layer and thermocline freeboard, so a practical single tank is often nearer 11,700 m3 when the warm volume is included. Use the usable figure for energy and the full figure for the shell.

• Q = 3,517 kW; t = 4 h; delta T = 5.6 deg C.
• Stored cooling = 14,068 kWh.
• Usable cold volume = 2,166 m3.
• Full shell volume ~11,700 m3 with warm layer + freeboard.

A hospital shifts 1,758 kW for 6 hours at a 4 deg C delta T. Stored cooling = 1,758 x 6 = 10,548 kWh. Volume = 10,548 / (1.16 x 4) = 10,548 / 4.64 = about 2,273 m3 usable cold, scaling to a practical shell near 6,000 m3 with the warm layer. Smaller than the data-center case because the load and delta T differ - proof the formula tracks the inputs.

• Q = 1,758 kW; t = 6 h; delta T = 4 deg C.
• Stored cooling = 10,548 kWh.
• Usable cold volume = 2,273 m3.
• Practical shell ~6,000 m3 with warm layer.

For ice storage the stored cooling is the latent heat of fusion: h_fusion = 93.3 Wh/kg (333 kJ/kg). Volume = (Q x t) / (rho_ice x h_fusion). Ice at ~917 kg/m3 holds about 85.6 kWh/m3, far denser than water per volume but it costs more capital and a lower chiller temperature to make. Use ice only when footprint forces it.

• h_fusion = 93.3 Wh/kg (333 kJ/kg).
• Ice holds ~85.6 kWh/m3 (dense).
• Higher capital and chiller lift than water.
• Choose ice only when footprint binds.

The formula gives usable cold volume; the physical tank also holds the warm return layer and thermocline freeboard. A good rule is to apply a usable-volume factor (often 0.85 to 0.92 after thermocline) so the nominal shell volume matches what actually stores cold. Always state which volume you report.

• Formula = usable cold volume.
• Tank also holds warm layer + freeboard.
• Apply usable-volume factor 0.85-0.92.
• State usable vs nominal explicitly.

Honest boundary: Center Enamel has no published thermal-energy-storage or data-center TES delivery in its verified project record. The references above (Namibia 44,900 m3 GFS drinking water, 2022; Cilincing 21,088 m3; Sardinia 30,549 m3) are cited strictly as large-diameter bolted-vessel manufacturing-capability evidence, not as TES or data-center projects. No TES project result, dimension or client is claimed.

For a water tank: V (m3) = (Q x t) / (1.16 x delta T), where Q is load in kW, t is hours, and delta T is in deg C. For ice: V = (Q x t) / (rho x h_fusion).

3,517 kW x 4 h = 14,068 kWh; divided by (1.16 x 5.6 = 6.496) gives about 2,166 m3 usable cold, scaling to a ~11,700 m3 shell with the warm layer and freeboard.

The formula gives usable cold; the tank also holds the warm return layer and thermocline freeboard, so apply a 0.85 to 0.92 usable-volume factor for the physical shell.

V = (Q x t) / (rho_ice x h_fusion), with h_fusion about 93.3 Wh/kg; ice holds roughly 85.6 kWh/m3 but costs more and needs a lower chiller temperature.

Yes - volume is inversely proportional to delta T, so a wider supply-to-return difference stores more per cubic metre but may stress the loop.

Honest boundary: Center Enamel has no published thermal-energy-storage or data-center TES delivery in its verified project record. The references above (Namibia 44,900 m3 GFS drinking water, 2022; Cilincing 21,088 m3; Sardinia 30,549 m3) are cited strictly as large-diameter bolted-vessel manufacturing-capability evidence, not as TES or data-center projects. No TES project result, dimension or client is claimed.

kW for load, h for time, deg C for temperature; verify each step because a unit slip is the most common calculation error.

It is a defensible first-principles calc; real design also applies stratification efficiency, usable-volume factor and site flow, which specialist vendors confirm.

The method rests on AWWA D103 / ISO 28765 for the tank and standard thermophysical properties of water and ice; no proprietary assumption is needed.

Calculating TES tank capacity uses V = (Q x t) / (1.16 x delta T) for water, or V = (Q x t) / (rho x h_fusion) for ice, with fully tracked units. A 1,000-ton, 4-hour, 5.6 deg C case gives about 2,166 m3 usable cold, scaling to a roughly 11,700 m3 shell with the warm layer and freeboard. Center Enamel supplies the bolted GFS, FBE, stainless and ASME vessel families behind the shell and has no published TES delivery; its large-water builds are cited as capability evidence only.

Suggested CTA: Send Center Enamel your load, hours and delta T to receive a calculated shell volume and capability datasheet.