Experimental and lattice Boltzmann simulated operation of a copper micro-channel heat exchanger

Highlights: • General laboratory method for fabricating micro-channel heat exchangers examined. • The two-phase flow inside the heat exchanger provides up to 95% energy transfer. • Internal operation of the heat exchanger verified via lattice Boltzmann model. - Abstract: The inherent inefficiency of many thermodynamic processes provide ample opportunity to harvest waste energy which would otherwise be released to the surrounding environment. A micro-channel heat exchanger (MHE) is presented that optimizes efficiency of energy transference by taking advantage of high thermal conductivity with copper fabrication and two-phase flow with a working fluid. Increasing the efficiency of the MHE, capillary channels allow fluid flow throughout the MHE, removing the necessity of an external work mechanism. For a power input of 3.44 W, the absorbed and transferred energy through the MHE was approximately 95% when working fluid was utilized, compared to 87% for the MHE with no working fluid. In addition to characterizing the MHE experimentally, internal operation was analyzed and reinforced through a lattice Boltzmann method simulation of a single micro-channel. The lattice Boltzmann method is a computationally efficient alternative for multi-phase systems, notoriously difficult systems to simulate. The overall objective was the development of a general laboratory fabrication technique that produced an effective two-phase MHE which was then experimentally characterized for device energy transference efficiency and computationally modeled, using experimental boundary conditions, for internal device operation. Using experimental and simulated methods, the copper MHE has proven a viable option for transferring low-temperature waste energy.