Case studies of thermal energy storage (TES) systems: Evaluation and verification of system performance

Abstract

We have developed two case studies to review and analyze energy performance of thermal energy storage CMS systems in commercial buildings. Our case studies considered two partial ice storage systems in Northern California. For each case, we compiled historical data on TES design, installation, and operation. This information was further enhanced by data obtained through interviews with the building owners and operators. The performance and historical data of the TES systems and their components were grouped into issues related to design, installation, operation, and maintenance of the systems. Our analysis indicated that (1) almost all problems related to the operation of TES and non-TES systems could be traced back to the design of the system, and (2) the identified problems were not unique to the TES systems. There were as many original problems with conventional'' HVAC systems and components as with TES systems. Judging from the problems related to non-TES components identified in these two case studies, it is reasonable to conclude that conventional systems have as many problems as TES systems, but a failure, in a TES system may have a more dramatic impact on thermal comfort and electricity charges. The objective of the designers of the TES systemsmore » in the case-study buildings was to design just-the-right-size systems so that both the initial investment and operating costs would be minimized. Given such criteria, a system is typically designed only for normal and steady-state operating conditions-which often precludes due consideration to factors such as maintenance, growth in the needed capacity, ease of the operation, and modularity of the systems. Therefore, it is not surprising to find that these systems, at least initially, did not perform to the design intent and expectation and that they had to go through extended periods of trouble-shooting.« less