EFFECT OF ADDITIVE MANUFACTURED MICROCHANNELS OVER POOL BOILING HEAT TRANSFER IN A DIELECTRIC LIQUID

In the present work, the contribution of micro-finned aluminum surfaces produced by means of additive manufacturing (AM) technology on pool boiling heat transfer coefficient (HTC) and critical heat flux (CHF) was studied. A plain reference surface, three separate samples embossed with rectangular, V-shaped, and inverse V-shaped geometry manufactured by additive manufacturing (AM) technology were tested in saturated Novec HFE-7100 dielectric liquid at atmospheric pressure. To mimic reconstructed operating conditions encountered in real applications and to prove data reliability, measurements were subsequently repeated several times. The experiments reveal that the use of AM technology improved the boiling performance of the plain surface by increasing surface roughness, while AM microchannels boosted the nucleation site density and yielded significantly larger HTC and CHF values. Compared to the reference surface, the inverse V-shaped channel showed the best performance enhancements by 130% for CHF and 386% for HTC at each comparable operating condition. Moreover, a number of detailed high-speed images were recorded to visualize the dynamics of bubble formation and departure.