## THERMAL SCIENCE

International Scientific Journal

### COMPUTATIONAL STUDY OF LAMINAR FREE CONVECTION INSIDE TILTING IRREGULAR CAVITY OF A BATCH-TYPE SOLAR COLLECTOR

**ABSTRACT**

Batch-type solar collector is a tilt-able water-heating solar-thermal system comprising an isosceles-trapezoidal enclosure housing a circular-cylinder absorber at the bottom wall, insulated side-walls, and flat-top glazing. Free convection of air inside such trapezoidal enclosure is studied numerically by varying the tilt angle of the whole enclosure from 0°-70°. The influence of tilt on the flow field has been demonstrated by plotting the streamlines and isotherms. The present study successfully identifies the importance of enclosure-tilt in quantifying heat-loss between absorber and glazing by developing a computational correlation between Nusselt and Rayleigh as a function of tilt. The correlation trend is non-monotonic over the range of angular Rayleigh numbers numerically experimented with having a peak around angular Rayleigh number 3⋅105 corresponding to the tilt-angle 30°. The irregular-shaped cavity implies that the heat transfer correlations already existing for regular-shaped cavities may not be used otherwise they will draw implausible conclusions and this argument identifies the novelty of the present study.

**KEYWORDS**

PAPER SUBMITTED: 2020-05-21

PAPER REVISED: 2021-02-03

PAPER ACCEPTED: 2021-02-03

PUBLISHED ONLINE: 2021-03-13

**THERMAL SCIENCE** YEAR

**2022**, VOLUME

**26**, ISSUE

**Issue 1**, PAGES [423 - 435]

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