3992 -- Experimental Results From Single-Pipe Diffusers for Stratified Thermal Energy Storage PDF

Current practice in stratified storage of thermal energy for cooling often uses diffusers in the form of single pipes with distributed openings. Investigation to identify diffuser parameter values that minimise mixing during and immediately after thermocline formation, thus tending to optimise the performance of stratified tanks that use such diffusers. Data were obtained on the temperature distributions produced by charging a rectangular scale-model tank with chilled water using several different diffusers. Both vertical temperature distributions in the water and flow visualisation were used to assess diffuser performance. The measure of diffuser performance employed was the temperature difference between water near the bottom of the tank and incoming water, divided by the initial temperature difference between water in the tank and incoming water. For the range of parameters investigated, diffuser performance usually improved with decreased diffuser height above the floor and with significantly decreased inlet Reynolds numbers. Use of a larger number of more closely spaced openings tended to improve diffuser performance. Attempts to correlate the results with other parameters were unsuccessful.

KEYWORDS: year 1996, experiment, mixing, temperature difference, energy storage, comparing, temperature stratification, performance, chilled water supply, measuring, testing