Compound Heat Transfer Augmentation of a Shell-and-Coil Ice Storage Unit with Metal-Oxide Nano Additives and Connecting Plates

Abstract

Due to the high enthalpy of fusion in water, ice storage systems are known as one of the best cold thermal energy storage systems. The phase change material used in these systems is water, thus it is inexpensive, accessible, and completely eco-friendly. However, despite the numerous advantages of these systems, the phase change process in them is time-consuming and this leads to difficulties in their practical application. To solve this problem, the addition of nanomaterials can be helpful. This study aims to investigate the compound heat transfer enhancement of a cylindrical-shaped unit equipped with double helically coiled coolant tubes using connecting plates and nano additives as heat transfer augmentation methods. Complex three-dimensional numerical simulations are carried out here to assess the best heat exchanger material as well as the impact of various nanoparticle types, including alumina, copper oxide, and titania, and their concentrations in the PCM side of the ice storage unit. The influence of these parameters is discussed on the charging rate and the temperature evolution factor in these systems. The results suggest that using nano additives, as well as the connecting plates, together is a promising way to enhance the solidification rate by up to 29.9%.

Utilization of Carbon-Based Nanomaterials and Plate-Fin Networks in a Cold PCM Container with Application in Air Conditioning of Buildings

“…This means that the addition of these NMs can accelerate the process by 8.34, 10.76, 10.88, and 10.88%, respectively. Aside from the clear superiority of carbon-based NMs, compared to the CuO (up to 2.77%), which is considered the optimal metal-oxide NM for this application according to a previous study [ 32 ], the results with different carbon-based NMs are similar and inconclusive, because, besides the thermal conductivity of the NMs, their other properties affect the process as well. For instance, consider the density of the NMs.…”

“…To select the optimal NM for further examinations, in this section, three different NM types, including GO, SWCNT, and MWCNT, were tested and compared to the best metal-oxide NM recommended for a similar application in a previous study [ 32 ], and the benchmark model without any NM additive at identical NM volume fractions (ψ = 3%). It should be noted that in all of these cases, both horizontal and vertical fins networks are used.…”

“…As was discussed before, the base geometry of the tubes and container is according to the optimal unit of Afsharpanah et al [ 33 ], and here plate-fin networks and NMs are added to provide an even better solidification rate. As recommended in previous studies [ 32 ], copper C11000 alloy is chosen as the material of the fin networks and tubes. Regarding the NMs, GO, SWCNT, and MWCNT carbon-based NMs are tested and compared to one of the most widely used metal-oxide NMs, CuO.…”

“…Since in most cases of the current research, NMs are distributed within the PCM, it is necessary to acquire the properties of these NPCMs according to the data of pure PCM (PCM), and nanomaterials (NMs). Therefore, the following correlations are employed [ 32 ]: where is the NM volume fraction and correlates with the NM mass fraction ( ) by the following equation: …”

“…They also enhanced the flow parameters. They extended this research by adding metal-oxide NMs and revealed that the simultaneous use of cylindrical plate fins and CuO NMs with a fraction of 3% reduce the full charging rate by around 30% [ 32 ]. Afsharpanah et al [ 33 ] presented a numerical investigation of the geometrical and flow parameter improvement in a cuboid shape ice storage unit with serpentine HTF tubes.…”