Thermal energy storage for space cooling. Technology for reducing on-peak electricity demand and cost

Pacific Northwest National Laboratory (U.S.)

关键词: Coolants;    Eutectics;    Refrigerants;    Storage;    Water;   

DOI  :  10.2172/770996
RP-ID  :  DOE/EE-0241
RP-ID  :  770996

美国|英语

来源: UNT Digital Library

【 摘 要 】

Cool storage technology can be used to significantly reduce energy costs by allowing energy intensive, electrically driven cooling equipment to be predominantly operated during off-peak hours when electricity rates are lower. In addition, some system configurations may result in lower first costs and/or lower operating costs. Cool storage systems of one type or another could potentially be cost-effectively applied in most buildings with a space cooling system. A survey of approximately 25 manufacturers providing cool storage systems or components identified several thousand current installations, but less than 1% of these were at Federal facilities. With the Federal sector representing nearly 4% of commercial building floor space and 5% of commercial building energy use, Federal utilization would appear to be lagging. Although current applications are relatively few, the estimated potential annual savings from using cool storage in the Federal sector is $50 million. There are many different types of cool storage systems representing different combinations of storage media, charging mechanisms, and discharging mechanisms. The basic media options are water, ice, and eutectic salts. Ice systems can be further broken down into ice harvesting, ice-on-coil, ice slurry, and encapsulated ice options. Ice-on-coil systems may be internal melt or external melt and may be charged and discharged with refrigerant or a single-phase coolant (typically a water/glycol mixture). Independent of the technology choice, cool storage systems can be designed to provide full storage or partial storage, with load-leveling and demand-limiting options for partial storage. Finally, storage systems can be operated on a chiller-priority or storage priority basis whenever the cooling load is less than the design conditions. The first section describes the basic types of cool storage technologies and cooling system integration options. The next three sections define the savings potential in the Federal sector, present application advice, and describe the performance experience of specific Federal users. A step-by-step methodology illustrating how to evaluate cool storage options is presented next, followed by a case study of a GSA building using cool storage. Latter sections list manufacturers, selected Federal users, and reference materials. Finally, the appendixes give Federal life-cycle costing procedures and results for a case study.