Stratification Efficiency of Thermal Energy Storage Systems – A new KPI based on Dynamic Hardware in the Loop Testing - Part I: Test Procedure. (November 2018)

• Record Type: Journal Article
• Authors: Haller, Michel Y.; Haberl, Robert; Persdorf, Patrick; Reber, Andreas
• Is Part Of: Energy procedia. Volume 155(2018)
• Page Start: 188
• Page End: 208
• Publication Date: 2018-11
• Subjects: thermal energy storage -- thermal stratification efficiency -- heat pump -- solar thermal -- performance testing; Power resources -- Congresses; Power resources -- Periodicals; Power resources; Conference proceedings; Periodicals; 333.7905
• DOI: 10.1016/j.egypro.2018.11.056
• Languages: English
• ISSNs: 1876-6102

Abstract

Abstract: Stratified water storage tanks are used for storing solar heat for space heating and domestic hot water in one device. When this kind of storage is used in combination with a heat pump, the temperature stratification of the storage is a decisive factor for the overall efficiency and thus for the consumed end energy of the system. A test method is introduced and a key performance indicator for stratification efficiency is defined based on the second law of thermodynamics, i.e. on the entropy balance of the storage system. The laboratory test is based on a 24 hour cycle where realistic and dynamic charging and discharging is applied according to boundary conditions of real weather data of a day in the year. This particular day of the year was chosen because of its representativeness for the effect of stratification on the system performance, such that the annual performance can be derived directly from the performance shown in the 24 h test cycle.