Additive Manufacturing Based TPMS Architecture Structure Compact Heat Exchangers Performance

Abstract

Freshwater from humid air technology is available in tropical areas and it is growing significantly where freshwater is hard to find. Also, saturated air that is generated from the water-cooling towers in power plants and district cooling chillers is a source of producing freshwater. Dehumidification is the required process for condensing the water vapor from the humid and saturated air. A heat sink with a high surface area to volume ratio is required to increase freshwater productivity. Triply periodic minimal surfaces (TPMS) structures are characterized by their high surface area to volume ratio and excellent heat transfer performance. The TPMS internal network structure could provide a uniform condensate film of freshwater generation. Moreover, we can increase the surface area of tube by using extend surfaces (Fins) which will lead to enhancement in the heat transfer. The objective of the study is to investigate the TMPS structured architecture that maximizes the freshwater production from humid air at different humidity and flow conditions using 3D computational fluid dynamics (CFD) validated models. These models will be developed to investigate the performance of TPMS architectures at different humid air conditions and compare it with vertical wall condensation to see the improvement in the condensation amount using the TPMS structure. The results show that the gyroid structure will increase the condensation flow rate by maximum factor of 3 and minimum factor of 1.04 compared with vertical wall for various humid air conditions. Another objective of this research is to study the humid air condensation amount for different TPMS design at different surface temperature, relative humidity and air Reynolds number where all the designs have the same porosity with different surface area. The results show that at low air Reynolds number the highest condensation amount will be on the Diamond TPMS structure and at high air Reynolds number the condensation rate will be maximum for the Gyroid sheet structure. A final objective of this research is to study the condensation amount at various relative humidity and air Reynolds number for horizontal and vertical tube and the effect of adding different fins configurations (annular and longitudinal) where both configurations have the same surface area and develop empirical correlation to find the Nusselt number and heat transfer coefficient for both orientations. The result of this study shows that the condensation amount will be maximum for the horizontal tube since the length of the tube is much larger than the diameter. Furthermore, the results show that for the horizontal annular finned tube give us the maximum condensation amount by increase the amount with an average factor of 2.36. However, in terms of vertical tube condensation it is better to add the longitudinal fins than the annular since it will have higher improvement in condensation rate by doubling the amount.

Date of Award	Apr 2023
Original language	American English
Supervisor	MOHAMED Ali (Supervisor)