In this work, nucleation site interaction and nucleate boiling heat transfer are studied on a hybrid rough surface, a surface with multiple cavities and a pillar on sides of each cavity, using a two-dimensional pseudopotential phase-change lattice Boltzmann method (LBM). To elucidate the effects of incorporation of pillars, the results of the hybrid rough surface are compared with a simple rough surface (a surface with multiple cavities). First, bubble nucleation, growth and departure processes are investigated above the simple and hybrid rough surfaces with three cavities and bubble interactions and their effects on cavity activation/deactivation at low superheat are discussed. The results showed a complete suppression of the central cavity at small pitch distance and left/right cavities at large pitch distance, which are caused by combined suppression effect of adjacent cavities and edge effects of the heater, respectively, for the simple rough surface. But, with the incorporation of pillars the heat transfer area is increased and the effects of induced flow are reduced, resulting in the activation of suppressed cavities, and thus, the higher heat flux is observed for the hybrid rough surface than the simple rough surface. The cavity suppression is also observed for unequal cavity depths or widths. The complete suppression of the central cavity occurs, when the central cavity is narrow or left/right cavities are deep. On the other hand, the highest heat flux is observed for the hybrid rough surface with central deep cavity and left/right shallow cavities due to the activation of all nucleation sites and additional heat transfer from the central deep cavity. Increasing pillar height or decreasing cavity-pillar spacing results in the stability and growth of residual bubbles to the next cycle without waiting periods, which increase the heat flux. Next, heat transfer in the nucleate boiling region is investigated by comparing saturated boiling curves obtained through simulations. The heat flux in the nucleate boiling including the critical heat flux (CHF) is higher for the hybrid rough surface than the simple rough surface. The heat flux also found to be increased in developing region of nucleate boiling, when pillar height is increased. The CHF increases with pillar height up to a certain height. But, with tall pillars at high wall superheats, the excessive nucleation of bubbles can also occur in the inter-pillar spacings, in addition to cavities, increasing the susceptibility of merger of closely spaced bubbles, which reduce the CHF.

在这项工作中，使用二维pseudo势相变格子玻尔兹曼方法（LBM）研究了混合粗糙表面，具有多个空腔的表面以及每个空腔侧面的立柱上的成核位点相互作用和成核沸腾传热。为了阐明合并柱的效果，将混合粗糙表面的结果与简单粗糙表面（具有多个空腔的表面）进行了比较。首先，在具有三个腔的简单和混合粗糙表面之上研究气泡的成核，生长和离开过程，并讨论了气泡相互作用，以及它们在低过热度下对腔活化/失活的影响。结果表明，在小间距距离处完全抑制了中心腔，在大间距距离处完全抑制了左/右腔，对于简单的粗糙表面，它们分别是由相邻空腔的组合抑制作用和加热器的边缘效应共同引起的。但是，通过并入支柱，增加了传热面积，并且减小了感应流的影响，从而导致了抑制型腔的激活，因此，与普通粗糙表面相比，混合粗糙表面的热通量更高。对于不相等的腔深度或宽度，也观察到腔抑制。当中央空腔狭窄或左/右空腔较深时，会完全抑制中央空腔。另一方面，由于所有成核位点的激活和中央深腔的额外传热，具有中央深腔和左/右浅腔的混合粗糙表面观察到最高的热通量。增加支柱高度或减小空腔-支柱间距会导致气泡的稳定性和残留气泡的增长，直到下一个循环而没有等待时间，从而增加了热通量。接下来，通过比较通过模拟获得的饱和沸腾曲线，研究了核沸腾区域中的传热。对于混合粗糙表面，包含临界热通量（CHF）的成核沸腾中的热通量要比简单粗糙表面高。当柱子高度增加时，在核沸腾发展区域的热通量也增加。CHF随柱高增加到一定高度而增加。但是，在高壁过热的情况下，如果有高大的支柱，则除了空腔之外，在柱间间距中还会出现气泡的过度形核，从而增加了紧密间隔的气泡合并的敏感性，从而降低了CHF。