Effects of subcooling and two-phase inlet on flow boiling heat transfer and critical heat flux in a horizontal channel with one-sided and double-sided heating. (December 2015)

• Record Type: Journal Article
• Authors: Kharangate, Chirag R.; O'Neill, Lucas E.; Mudawar, Issam; Hasan, Mohammad M.; Nahra, Henry K.; Balasubramaniam, Ramaswamy; Hall, Nancy R.; Macner, Ashley M.; Mackey, Jeffrey R.
• Is Part Of: International journal of heat and mass transfer. Volume 91(2015:Dec.)
• Page Start: 1187
• Page End: 1205
• Publication Date: 2015-12
• Subjects: Flow boiling -- Critical heat flux -- Subcooling -- Two-phase inlet -- Gravity effects; Heat -- Transmission -- Periodicals; Mass transfer -- Periodicals; Chaleur -- Transmission -- Périodiques; Transfert de masse -- Périodiques; Electronic journals; 621.4022
• DOI: 10.1016/j.ijheatmasstransfer.2015.08.059
• Languages: English
• ISSNs: 0017-9310

Abstract

Highlights: This study explored flow boiling of FC-72 along a rectangular channel. Effect of subcooling and two-phase inlet on CHF is investigated. Flow visualization proved gravity effects are dominant for low velocities. CHF increases monotonically with increasing inlet subcooling. Heat utility ratio is seen to assess the influence of subcooling on CHF. Abstract: This study explores the influence of inlet subcooling and two-phase inlet on flow boiling heat transfer and critical heat flux in a horizontal 2.5-mm wide by 5-mm high rectangular channel for top wall heating, bottom wall heating and double-sided heating configurations using FC-72 as working fluid. High-speed video imaging is used to identify dominant interfacial characteristics for different combinations of inlet conditions and heating configurations. Three inlet conditions are compared: highly subcooled liquid, slightly subcooled liquid, and saturated two-phase mixture for mass velocities between 205.1 and 3211.6 kg/m 2 s. Gravity is shown having a dominant influence on interfacial behavior at low mass velocities below 400 kg/m 2 s, while inertia dwarfs gravity effects at high mass velocities around 1600 kg/m 2 s. Overall, CHF increases monotonically with increasing inlet subcooling. CHF variation between the three heating configurations is large for low mass velocities and diminishes for high mass velocities. A dimensionless parameter, heat utility ratio, is shown to be an effective means for assessing the influence of subcooling on CHF.