## THERMAL SCIENCE

International Scientific Journal

### EFFECT OF FLIPPING ON FREE CONVECTIVE HEAT TRANSFER DURING MELTING OF A PHASE CHANGE MATERIAL IN CONCENTRIC HORIZONTAL ANNULI OF DIFFERENT CROSS-SECTION

**ABSTRACT**

Results are presented of a finite element computational study of the free convection-dominated melting of a pure phase change material contained in concentric horizontal annuli of the following configuration:

(a) Square external tube with a circular tube inside - Annulus Type A

(b) Circular external tube with a square tube inside - Annulus Type B

Effect of heating the inside wall at a temperature above the melting point of the material was studied. Flow and temperature patterns within the melt, local heat flux distributions at the heating surface and the cumulative
energy charged as a function of time are presented and discussed. The effect of flipping which involves inverting the container upside-down at pre-selected times after initiation of melting as a measure to
increase the heat transfer rate during the later stage of the melting process is examined and discussed. It is shown that this simple yet
effective technique presents a simple way to enhance the overall melting rate, t.e., the cumulative heat storage.

PAPER SUBMITTED: 1999-02-22

PAPER REVISED: 1999-03-10

PAPER ACCEPTED: 1999-06-28

PUBLISHED ONLINE: 2020-09-27

**THERMAL SCIENCE** YEAR

**1998**, VOLUME

**2**, ISSUE

**Issue 2**, PAGES [27 - 43]

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