Effect of material arrangement pattern on different-mode-interacting boiling in narrow gaps with two liquid supply systems

Abstract

• Effect of different-mode-interacting boiling in narrow gaps on CHF is investigated. • Different material patterns inside plate with material pitch and gap size are investigated. • Performances are compared for cross and parallel arrangements and conventional form. • Effect of open forms of narrow gaps of 4 sides and 2 sides is also investigated. • Cross arrangement pattern shows significant augmentation of CHF in 4-sides-open. Different-mode-interacting boiling has been proven to improve the critical heat flux (CHF) inside narrow gaps in a water pool in previous studies. This method expands the area of the wetted region and delays the occurrence of CHF with the irregular movement of the vapor and liquid near the boundary between two thermally different materials with interaction of different boiling modes on the non-uniform conductance plate. In the present study, while retaining the characteristics of this method, further improvement of heat transfer characteristics was investigated. To increase the density of different material boundaries, a new arrangement of low-conductance material with cross-type geometry was adopted. The performance on a horizontally arranged 20 mm square copper surface was compared with those of parallel arrangement and the conventional form. Furthermore, performance under the open forms of narrow gaps to surrounding liquid of 2 sides and 4 sides were examined with gap size and material pitch as parameters. Significant enhancements in CHF are achieved in cross-type arrangements. The maximum CHF of 1140 kW/m 2 and 946 kW/m 2 with large increases of 83% and 75% were achieved for 4-sides-open and 2-sides-open systems, respectively.