01.2021.99.122

THERMAL PERFORMANCE ENHANCEMENT IN DOUBLE PIPE HEAT EXCHANGER BY USING INWARD AND OUTWARD DIMPLE AND CORRUGATED TAPE

Author(s):

Muataz Abdul Wahhab A. Sattar†, Kadhum Audaa Jehhef‡ and Nabil Jamil Yasin††

Affiliation(s):

††Engineering Technical College-Baghdad, Middle Technical University, Baghdad, Iraq

‡Department of Mechanical Power, Institute of Technology, Middle Technical University, Iraq

††Engineering Technical College-Baghdad, Middle Technical University, Baghdad, Iraq

Corresponding Author Email: motazsatar@gmail.com, kadhumaudaa@gmail.com, drabdullah_dhayea@mtu.edu.iq

This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

The aim of this research is to implement a passive heat transfer improvement technique and to examine how thermal performance is impacted numerically. Specifically, the heat exchanger inner pipe will be improved by using different geometries and devices to enhance the heat transfer. Dimpled inner pipes of (inward and outward) geometries and inserts as corrugated tape were used. Reynold number ranging from 6000 to 15000 are utilized for hot fluid (water) and for cold fluid (water). The hot fluid temperature was 50 oC, while cold fluid temperature was 25 oC. The runs including five models of heat exchangers such as plain pipe, two different direction of dimple pipe with constant pitch ratio of (0.95) and two different pitch ratio corrugated tape of (0.5 and 1). ANSYS design modular and fluent R1-2019 were employed plain pipe and nine models were evaluated to show the effect of the dimple and corrugated and twisted tapes on heat transfer performance and pressure drop. The results showed that the increase of the average Nusselt number for inward staggered dimple pipe model with pitch ratio (x/do=0.95) was about 54.5% while the friction factor is about 136%, while increase of the average Nusselt number when using the corrugated tape with pitch ratio (x/w=0.5)=195.8 % and increase of friction factor was 14.62 time that of plain tube. The average Nusselt number of the mentioned model is 347.10 % for the corrugated tape models is higher than that of plain models with a friction factor of approximately 42 time that of plain pipe.