SD-95-19-4 (RP-733) -- Evaluation of RP-459 Algorithms for Modeling External Melt, Ice-on-Pipe Thermal Storage System Components PDF

ASHRAE's TC 6.9 requested an evaluation of the ice-on-pipe and ice storage tank components of RP-459, Component Models for Computer Simulation of Ice Storage Systems. This project, RP-733, was undertaken to perform that evaluation. The work consisted of a thorough re-examination of those algorithms and a comparison of results of a computer simulation employing them with experimental data. The conclusion is that the RP-459 algorithms provide reasonable results for the ice-building portion of the cycle but do not track the melting well. The primary difficulty is that the melting algorithms are based on the assumption that the ice melts off the pipes uniformly. The experimental results indicate that this is not the case; therefore, the algorithms do not model actual system performance. The ice-build algorithms were also compared with a model using faster and less complex algorithms. This comparison indicated that the RP-459 ice-build model does not provide a better match of the data than does the simpler model. Consequently, a description of the simpler algorithm and modelling approach is presented with the recommendation that it be considered for future simulations.

KEYWORDS: year 1995, calculating, algorithms, accuracy, comparing, melting, energy storage, ice, pipes, components, ice storage, tanks, components, performance, heat-flow, experiment, testing