Theoretical analysis and modeling of flow instability in a mini-channel evaporator

High-frequency thermal-fluidic characterization of dynamic microchannel flow boiling instabilities: Part 1 – Rapid-bubble-growth instability at the onset of boiling

“…Flow boiling instabilities can lead to premature critical heat flux relative to the conventional dryout mechanism (Bergles and Kandlikar, 2005). In an effort to better understand these instabilities and their implications, flow boiling instabilities have received significant attention through experimental and theoretical analyses (Kuang et al, 2017;Ruspini et al, 2010;Van Oevelen et al, 2017;Zhang et al, 2009), as well as a number of reviews on the subject (Boure et al, 1973;Kakac and Bon, 2008;Ruspini et al, 2014). A review of flow boiling instabilities encountered in microchannels, with an emphasis on techniques to mitigate the effects, was recently compiled by Prajapati and Bhandari (2017).…”

Study on boiling flow characteristics of nanorefrigerant in microchannels under ultrasonic waves

“…微细通 道换热器具有换热效率高、结构紧凑的特点, 在微电 子机械领域广为应用 [1] , 为进一步强化微细通道强化 传热, 常采用有源强化和无源强化两种手段 [2] , 强化 传热技术一定程度上会增大换热效率, 但其对换热 系统压降特性的影响也不容忽略 [3] . 微细通道由于本 身尺寸过小容易造成系统运行阻力增大、 工质流动不 稳定加剧等现象, 不稳定流动可能导致传热恶化甚 至造成设备疲劳损坏 [4,5] . 超声波强化传热技术作为 一种有源强化传热技术, 近年来受到了许多学者关 注. Kofu [6] 在水平塞式颗粒输送线中开展超声波振动 实验, 研究发现超声波振动降低压力损失的效果与 壁面压力有关, 与颗粒种类和管径无关; 颗粒与管道 内壁面摩擦阻力施加超声波振动后较无超声振动时 明显降低, 超声波振动可以防止管道堵塞.…”

Modeling and numerical investigation on the effects of filling ratio in a large separate heat pipe loop

“…Besides, the evaporator is generally divided into 3 sections in the model, as depicted in Figure 5. Each section's length can be determined as given in Equation (24). According to the mass flow rate, boundary conditions and saturation temperature, the length of the single liquid phase section can be estimated as given in Equation (24a).…”

“…In some cases, it may even cause the two-phase flow instabilities in the heat pipe with temperature fluctuations. 23,24 Due to the heat pipe dimensions and low circulation flow rates, flow patterns and fluid distribution in largescale heat pipes differ from those in conventional ones. 25,26 It is necessary to get a deeper insight into the filling ratio effects on the thermal performance of the separate heat pipe.…”