AN-92-08-1 -- A Comparison of Chiller-Priority, Storage-Priority and Optimal Control of an Ice-Storage System PDF

Describes a comparison of control strategies for a partial ice storage system installed in an office building in Milwaukee, Wisconsin. Compares optimal control results for this systems in terms of both minimum energy and demand charges with simple chiller priority and storage-priority control strategies. Explains these strategies. The storage priority strategy investigated is termed 'load-limiting' and involves operating the chillers at a constant cooling rate during the on-peak period such that the storage is fully depleted (ie no ice) at the end of the on-peak period. Notes that load-limiting control tends to minimise the cooling plant peak electrical power use,but it was also found to be nearly optimal in terms of energy costs with the present of time-of-day electric rates. The chiller priority strategy gave significantly greater demand and energy costs in the presence of time-of-day rates for off-design days.

KEYWORDS: Controls, offices, comparing, ice storage, energy storage, tariffs