Heat transfer performance of molten salt (Hitec) flowing in various inclined tubes under uniform/non-uniform heat flux is numerically investigated. The effect of inclination angle (0o, 45o, 90o), inlet temperature (200 – 400 oC) and heat flux (50 – 350 kW/m2) on turbulent heat transfer features of molten salt are discussed, and the differences on heat transfer performance and wall temperature distribution between uniform and non-uniform heating are compared. The results show that increasing inlet temperature can lead to low heat transfer ability, but the tube inclination angle and heat flux have almost no effect on heat transfer features. The lateral side non-uniform heat flux also has little effect on heat transfer performance compared with uniform heat flux, but can cause large temperature gap up to 300 oC around the tube. Comparisons of simulation results with existing Nu-correlations show that Qiu-equation have better prediction accuracy for all researching cases with errors of Â±8%, especially for high Reynolds numbers. The present results can be helpful for the design and operation of concentrating solar receivers.
Keywords Molten salt, Heat transfer performance, Inclined tube, Non-uniform heat flux, Concentrating Solar Receiver