Prediction and Flow Visualization of Critical Heat Flux of PF-5060 within a Horizontal Rectangular Channel with Single Sided Heating

This study focuses on predicting and exploring the conditions leading to Critical Heat Flux (CHF) of PF-5060 within a 5mm high and 2.5mm wide horizontal rectangular flow channel. The test section allows for both top side and bottom side single-sided heating setup. The top and bottom heating results help in understanding the effect of gravity on the liquid-vapor phases and interactions. Tests were conducted on PF-5060 with inlet velocity within the range of 0.2 to 0.7 m/s. Subcooled inlet conditions were tested with an average inlet subcooling ranging from 5°C to 33°C. The fluid was heated using a custom-designed 100% oxygen free copper heater with a heated length of 114.6mm and 2.5mm width. Images of the boiling phenomena were acquired using a high-resolution camera. Images taken during this study revealed that vapor takes the form of a wavy layer which allows the liquid to stay in contact with the heated surface at intermittent intervals. The flow visualization data provides information on how changes in velocity and subcooling affect the vapor phase of the fluid. It's observed that the vapor phase size increases along the length of the heater. The size of the vapor phase decreases with higher subcooling and higher velocities. The study also provides information regarding the effects of different inlet conditions on the CHF of PF-5060. The study provides key data which is used to validate a theoretical CHF models. Two common theoretical CHF models were utilized to predict the experimental CHF data. However, each model has its own strength and weakness under some certain flow and heating conditions. This study shows good agreement between experimental results and the hydrodynamic instabilities-based CHF model by Huang et. al. [1].