Abstract
This study performs a 3D turbulent flow numerical simulation to improve heat transfer characteristics of wavy fin-and-tube heat exchangers. A compound design encompassing louver, flat, and vortex generator onto wavy fins can significantly enhance the heat transfer performance of wavy fin-and-tube heat exchangers. Replacement of wavy fins around tubes with flat fins is not effective as far as the reduction of thermal resistance is concerned, although an appreciable pressure drop reduction can be achieved. Adding two louvers with a width of 8 mm to the flat portion can reduce thermal resistance up to 6% in comparison with the reference wavy fin. Increasing the louver number and width can further decrease the thermal resistance. Also, it is found that the optimum louver angle is equal to the wavy angle for offering the lowest thermal resistance. Therefore, compound geometry with three louvers, a width of 12 mm, and the louver angle being equal to wavy angle with waffle height to be the same as fin pitch of the reference wavy fin has the most reduction in thermal resistance of 16% for a pumping power of 0.001 W. Adding punching longitudinal vortex generators on this compound geometry can further decrease thermal resistance up to 18%.
Highlights
Nowadays, high performance air-cooled compact heat exchangers are highly demanded in different applications in industries
SIMPLE algorithm is applied for pressure and momentum coupling and second order upwind is used in order to improve accuracy
Unstructured fine grids are applied for fin region and structured coarse grids are used for upstream and downstream extended regions
Summary
High performance air-cooled compact heat exchangers are highly demanded in different applications in industries. Since the fin side (air side) plays the dominant role in the performance of air-cooled heat exchangers, to augment the performance effectively, enhancements are made available such as through corrugation (e.g., wavy), interruption (e.g., louver) or swirling (vortex generator). Wavy fin-and-tube heat exchangers are still one of the adopted enhanced air-cooled heat exchangers which are widely used in air conditioning systems and refrigeration. In these heat exchangers, air flows outside the Energies 2018, 11, 1959; doi:10.3390/en11081959 www.mdpi.com/journal/energies. Heat transfer coefficients in wavy fins are higher than flat fins but are inferior to the interrupted fins such as louver fins [1]. Researches on other types of fin-and-tube heat exchangers such as flat, round, louver and H-type have been reported in literatures [2,3,4,5], researches on wavy fin-and-tube heat exchangers have still attracted many researchers due to the reliable feature of wavy finned configuration
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
