Heat transfer of 3-D printed enhanced tube and fin heat exchanger coils
Date of Issue2017
School of Mechanical and Aerospace Engineering
In this project, comparative study on heat transfer performance between 3-D printed and conventional air-cooled heat exchanger coils was performed. The 3-D printed heat exchanger coil was produced by using Selective Laser Melting (SLM) technique using aluminium alloy powder (AlSi10Mg) which consists of composition of 89.5% aluminium, 10% silicon, and 0.5% magnesium. To obtain each of experimental parameters, a test facility was designed and fabricated for the investigation of air-cooled heat exchanger coils. A flow meter was installed at the water inlet to measure the water inlet velocity, while a pitot tube was installed to determine the average air across the heat exchanger coil. Thermocouples were installed at various location points along the inlet and outlet air duct and water pipe in order to increase the accuracy of the data obtained. The experiments were conducted by varying the water inlet mass flow from 20 g/s to 35 g/s and air velocity from 0.67 m/s to 2.06 m/s and the ε – NTU method was used to determine the heat transfer coefficients of each heat exchanger coil under the same condition (i.e. at each air velocity and water inlet velocity). Although the area of heat transfer of 3-D printed heat exchanger coil was significantly smaller, similar heat transfer coefficients were obtained for both heat exchanger coils. In addition, the experimental results also showed that the 3-D printed heat exchanger coil design with perforated fins, on average, performs slightly better in terms of air-side heat transfer coefficient, ho (1% increase on average) as compared to the conventional condenser coil. However, there was a significant decrease in values for both ε and NTU comparing the same variables. This is likely due to the experimental limitation which will be elaborated in the later chapter on this paper. Uncertainty analysis was performed to determine experimental errors such as bias error or/and precision errors which might occur throughout the experimental process. In this paper, calculation methods and formulas used to analyse and obtain heat transfer experimental results were thoroughly elaborated and limitations and difficulties faced during the whole project were also explained.
Final Year Project (FYP)
Nanyang Technological University