Heat exchangers are widely used in the industrial sector e.g. in the refrigeration air
conditioning petrochemical and agricultural food industry. The high cost of energy and
material has resulted in an increased effort aimed at producing high performance heat exchanger
equipment. Passive methods of heat transfer enhancement do not need external power for
enhancement. One of these kinds of passive technique is twisted tape inserts that enhance the
performance of heat exchangers. Using multiple twisted tape inserts gives better enhancement
than a single twisted tape insert. Using nanofluid gives also better thermal performance than
water. Therefore nanofluid along with twisted tape inserts was used in this study. For this
study different combinations of multiple twisted tape inserts were designed and fabricated.
These different combinations contain dual triple and quadruple twisted tapes. Directions of
twists are also varied which enables to study the effect of different swirl flow generators.
Nanofluid is used with various volume concentrations of 0.07% 0.14% and 0.21% in order to
investigate the effect of nanoparticle concentration on heat transfer enhancement. Experimental
investigation was carried out by having a constant heat flux condition and by varying the
volume flow rate of flow from 2 to 10 lpm.
