Chilled-Water Thermal Ride-Through
Converts loop water volume and allowable temperature rise into stored sensible energy and minutes of IT-load...
Example
You enter
- Chilled-water loop volume (gal) 5000
- IT equipment load (kW) 500
- Chilled-water supply temperature (deg F) 45
- Highest tolerable water temperature (deg F) 60
- Generator start and transfer (min) 0.5
- Chiller restart and loading (min) 7
- Smaller comparison loop (gal) 1200
You get
- Stored cooling 625500 Btu
- Loop ride-through 22.0 min
- Ride-through margin 14.5 min
- Smaller loop shortfall (min) 2.22028
- Required volume (gal) 1704.64
Details, formula, and sources
Converts loop water volume and allowable temperature rise into stored sensible energy and minutes of IT-load ride-through, then sizes the volume needed across generator transfer and chiller restart. Usable system volume and transient plant behavior govern.
stored Btu = gallons x 8.34 lb/gal x allowable delta-T; ride-through minutes = stored Btu/(IT kW x 3,412 Btu/hr) x 60.
The water sensible-heat storage relation with ASHRAE TC 9.9 guidance. Chiller restart sequence and usable system volume are manufacturer- and site-specific.
Mass x specific heat x temperature-rise energy storage.
Estimate. AHJ and licensed professional govern.
Field names used by the API: loop_volume_gal, it_load_kw, supply_temp_f, max_temp_f, generator_transfer_min, chiller_restart_min, smaller_loop_volume_gal, stored_cooling_btu, ride_through_min, ride_margin_min, smaller_loop_shortfall_min, required_volume_gal
- Water properties 8.34 lb/gal and 1 Btu/lb-degFstandard water properties
- Load transfer the full entered IT load reaches the chilled-water loop throughout the gapconservative planning case