Numerical simulation of small breathing loss in dome roof tanks under solar radiation

ABSTRACT In order to investigate the effect of periodic solar radiation on oil vapor diffusion and small breathing losses in dome roof tanks, a theoretical model of unsteady heat and mass transfer in dome tanks is established based on the ASHRAE clear-sky model and oil evaporation theory. The heat flux UDF is self-programmed, and CFD software is used to simulate the heat and mass transfer process in the gas space of the dome tank. Dynamic mesh technology is used to realize the overpressure relief of the breathing valve and calculate the small breathing losses. The results show that the gas space temperature decreases from top to bottom; it has a concave and convex distribution near the tank wall. The average temperature decreases with increasing liquid level. The vapor concentration in the gas space increases from top to bottom, and there is a clear concentration layer near the liquid level. The average vapor concentration increases with the liquid level. Gas space pressure increases gradually from top to bottom. The number of breathing valve exhausts decreases with the increase in liquid level. The small breathing losses increase with the liquid level and the seasonal warming, and the loss rate increases with the seasonal warming.