Building on previous work performed under contract to the US Department of Energy (Choi 1993), a mixture of two n-alkanes (paraffin waxes) was developed that has a phase-change temperature between the usual supply and return temperatures of chilled-water systems. Adding such a material to chilled water significantly increases its volumetric thermal capacity. Covers the selection of the phase-change material (PCM) and a surfacant that prevents pipe-clogging of the frozen PCM. While many properties of laboratory-grade materials were available, their high cost rules out their use in building chilled-water systems, and technical-grade materials must be used. Flow and thermal properties of technical-grade PCMs and water-PCM-surfactant mixtures were determined by analysis and confirmed by tests. Instrumentation for these as well as for succeeding flow-loop tests was calibrated. The results of flow-loop tests producing quantitative values for the increase in volumetric thermal capacity are presented in a companion paper (Lorsch et al. 1997).

KEYWORDS: year 1997, Changing physical state, materials, chilled water supply, selecting, experiment, calibrating, thermal capacity, thermal properties, paraffin, water, mixtures, viscosity, pressure drop, fluid flow, measuring, energy storage