Enhancement of air-side heat transfer performance of additively manufactured condensers

• Main Author: Pang, Kang Kwan
• Other Authors: Leong Kai Choong
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2022
• Subjects: Engineering::Mechanical engineering
• Online Access: https://hdl.handle.net/10356/158932
• Institution: Nanyang Technological University

This report details the thermal-hydraulic performances of novel air-cooled heat exchangers. A porous lattice heat exchanger constructed using the Schwarz Primitive surface (P surface) was designed in Solidworks and its thermo-hydraulic properties were numerically investigated in Ansys Fluent simulation. In this study, the effect of varying geometries of the P surface, namely, the diameter (do) and thickness (tp) of the structure, on the thermal and hydraulic performances in a porous lattice heat exchanger will be investigated. The diameter test was conducted by varying do from 2.80 mm to 4.20 mm, with 0.35 mm increments. The thickness test was conducted by varying tp from 0.5 mm to 1.0 mm, with 0.1 mm increments. An optimal design of do = 3.5 mm and tp = 0.6 mm was chosen to investigate its heat transfer coefficient (ha) and pressure drop per unit depth (ΔP/H) by varying the mass flux (Jm) of airflow. The simulations were done using a 16-unit cells structure with incompressible airflow under the shear stress transport − turbulence model. Experiments with a conventional fin-tube heat exchanger were conducted in a wind tunnel to evaluate its thermo-hydraulic properties. The experiments were carried out with a range of Jm similar to the simulations conducted with the P-surface porous lattice heat exchanger. A comparison between the novel P-lattice and conventional fin-tube heat exchanger indicates that the P-lattice heat exchanger requires only 45% of jm required by the fin-tube heat exchanger to achieve the same ha. The remarkably higher ha of the P-lattice heat exchanger was largely due to the interconnected pores of the lattices, which enhances fluid mixing. The P-lattice heat exchanger should operate at ΔP/H above 0.0245 kPa/mm to have a ha advantage over the fin-tube heat exchanger. These findings revealed the potential of incorporating TPMS, particularly the P-surface, into an air-cooled heat exchanger application.