Effectiveness-NTU Charts for Heat Recovery From Latent Heat Storage Units

The shell-and-tube heat-exchanger with a phase change material on the shell side is the subject of many investigations concerning latent heat storage. Many design calculations have been based on formulae that apply to one-dimensional solidification. In these calculations, axial changes in fluid temperature and solidification rate were neglected, and the coolant temperature was assumed constant. In the present paper, these restrictions are removed. It is shown that complete three-dimensional results can be obtained from the numerical results of a two-dimensional analysis by performing simple calculations. The results are presented in the form of charts giving the effectiveness of a heat-exchanger in terms of its size, the layout of the tubes, and the Biot number. The use of the charts in design is illustrated by numerical examples.