Heat transfer enhancement with gas-to-gas micro heat exchangers

Abstract

Micro heat exchangers provide improved heat transfer capacities, but also increased pressure losses due to the small characteristic dimensions. Additional pressure losses are generated by modified micro structure geometries used for heat transfer enhancement of these micro devices. Therefore, an overall heat exchanger assessment needs to be considered to generate energy efficient micro heat exchangers.A characterization of gas-to-gas micro heat exchangers has been performed in terms of pressure loss behavior and heat transfer performance. The gas-to-gas micro heat exchangers differ by partition foil material and partition foil thickness, respectively. The pressure loss behavior is influenced by the density which depends on the temperature and pressure. The heat transfer performance shows overlapping trends due to axial conduction. Comparison between different partition foil materials and partition foil thicknesses showed no significant criteria of the influence of thermal conductivity on the temperature jump effectiveness.An assessment due to overall heat exchanger effectiveness has been performed to compare gas-to-gas micro heat exchangers. For this purpose, the overall exergy loss has been calculated by combination of heat transfer performance and pressure loss behavior. A strong impact of the fluidic exergy loss due to pressure loss has been detected which mainly influences the overall exergy loss of the gas-to-gas micro heat exchangers.