Ice formation around a finned-tube heat exchanger for cold thermal energy storage

This paper addresses a numerical and experimental investigation of a cold thermal energy storage system involving phase-change process dominated by heat conduction. The problem involves a fluid flowing inside a horizontal finned tube surrounded by a phase-change material (PCM). The objective of this paper is to predict the temperature distribution, the phase front distribution along the tube and to analyze the effect of fin density and size on the dynamic performance of the system. The problem is modeled as axisymmetric and two-dimensional, and a control volume computer code has been developed for the solution of the corresponding mathematical model. In the experimental arrangement of the tube configuration, two different fin diameters; D fn = 2.7 and 3.2 are considered and the fin density at each fin diameter is varied in the range of N fn = 14 – 31 fins ⋅ m −1 . For a particular geometry then the heat transfer fluid inlet temperature assumes values between −10 °C and −20 °C, and the flow Peclet number is varied in the range from 14 350 to 200 900 accordingly. Comparison between the numerical predictions and the experimental data shows good agreement, even though some effects that are produced by heat transfer to the environment especially at high flow rates neglected in the model but unavoidable in the experiments. Finally, time-wise variation of energy stored by the system is evaluated through instant images of solidification fronts and the combined effect of fin parameters and the flow rate on energy storage is discussed.