Assessing the effect of flashing on steady state behavior and Ledinegg instability of a two phase rectangular natural circulation loop. (January 2018)

• Record Type: Journal Article
• Authors: Dewangan, Kush Kumar; Das, Prasanta Kumar
• Is Part Of: International journal of heat and mass transfer. Volume 116(2018)
• Page Start: 218
• Page End: 230
• Publication Date: 2018-01
• Subjects: Natural circulation loop -- Flashing -- Ledinegg instability -- Multiple solution -- Homogeneous equilibrium model -- Drift flux model; Heat -- Transmission -- Periodicals; Mass transfer -- Periodicals; Chaleur -- Transmission -- Périodiques; Transfert de masse -- Périodiques; Electronic journals; 621.4022
• DOI: 10.1016/j.ijheatmasstransfer.2017.08.119
• Languages: English
• ISSNs: 0017-9310

Abstract

Highlights: Effect of flashing on the steady state performance of a rectangular natural circulation loop has been investigated. Both Hem and DFM has been considered for the simulation of two-phase flow. An anomaly in the predication of loop temperature is observed if flashing is neglected. Flashing decreases the steady state circulation rate but reduces the susceptibility to Ledinegg instability. Effect of flashing is more prominent at low pressure and low heat flux. Abstract: In the present work, we propose to study the effect of ignoring flashing on the performance of a natural circulation loop operating under steady state. To this end, the performance of a rectangular natural circulation loop with water as the working fluid has been simulated considering both homogeneous equilibrium model (HEM) and drift flux model (DFM) for the two-phase zone. It has been observed that flashing has a substantial effect on the performance of the loop in certain operating zones and one may even experience an anomaly in the predicted value of local temperature if flashing is neglected. Flashing, in general, reduces the circulation rate under steady operating condition. But at the same time it makes the operation of the loop more stable against Ledinegg instability. In general, the effect of flashing is predominant at low pressure and low heat flux.