Numerical Comparison of TPMS Structures for the Design of an Automotive Engine Oil Cooler

Triply Periodic Minimal Surfaces (TPMS) structures offer the possibility of reinventing structural parts and heat exchangers to obtain higher functional efficiency and lighter or even multi-functional components. As crescent global climate concern has led to increasingly stringent emissions regulations, the adoption of TPMS represents a resourceful tool for OEMs to downsize and lighten mechanical parts, thereby reducing the overall vehicle’s weight and fuel consumption. In particular, TPMS structures are gaining growing interest in the heat exchanger field as their morphology allows them to naturally house two separate fluids, thus allowing heat transfer without mixing. Moreover, TPMS-based heat exchanger can provide countless possible design configurations. These structures are obtained by the periodic repetitions in the three spatial dimensions of a specific unit cell with defined dimensions and wall thickness. By tuning their characteristic parameters, the structure can be tailored to obtain the desired weight, surface over volume ratio and strength. In the light of this, the paper provides a numerical comparison between four different unit cell types and four different unit cell dimensions to identify the most suitable parameters combination of a water-engine oil heat exchanger exploiting a TPMS structure. Based on a previous work, the Gyroid, Diamond, IWP and Primitive cell types are considered, while the considered cell dimensions range is: 5, 6, 8 and 12 mm. To deploy a fair comparison the specimens are designed to share the same volume and wall thickness, which is chosen to minimize thermal conductive resistance and concurrently is the minimum value required by technological and structural requirements. The specimens are tested for four mass flow rates combinations of engine oil and water, characteristic for an automotive heat exchanger. Finally, the structures are compared on the basis of the computed pressure drop and heat transfer.