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Replies to post #23299 on Dalrada Financial Corp (DFCO)
Suresh and Saini investigated PCM filled spheres of varying diameter in multiple locations in a tank [13], and found that near the bottom of the tank there is the highest utilization of the PCM. This result was due to the large size of the spherical capsules and relatively low heating power of the water surrounding the PCM in the hot-water tank. For these designs, it was determined the best method to increase the capacity would be to reduce the diameter of the capsule for higher utilization when in contact with water.
Rheem was awarded a patent for using refrigerant in combination with PCM to heat water in which the PCM directly contacts the refrigerant coil in the configuration[14]. Similar to the Rheem design, Sunamp Limited has a very wide-ranging and unawarded patent in which the refrigerant coil is in contact with a wide variety of different temperature PCMs [15]. The patents, as described in Refs. [14,15], are in direct contact with the refrigerant coils and are dissimilar to the Alpha and Beta prototypes in this manner.
Since the past studies did not quantify the thermal performance of the designed capsules under UEF or FHR conditions experimental work was undertaken to quantify the improvements by the FHR and UEF standard tests. These increases were accomplished by experimentally testing two designs – called Alpha (FHR increase 27.7%) and Beta (UEF increase 5.5%). A trade-off between maximizing the FHR and UEF was noticed in these first two experimental studies because the heat transfer is distinctly different between the two tests. The PCM-HPWH designs, experimental setup, analysis and results are shown in the next sections of the paper.
