Numerical analysis of sulfur heat transfer characteristics

Karthik Nithyanandam Amey Barde Richard Wirz

Sulfur promises low storage cost, high temperature stability, and high charge and discharge performance since it operates in the liquid-vapor regime at the temperatures of interest relevant to many important applications, such as combined heat and power (CHP) plants and concentrating solar power (CSP) plants with advanced power cycle systems. The present work investigates the thermal performance of elemental sulfur stored isochorically inside the pipes of a shell-and-tube thermal battery configuration with heat transfer fluid flowing over the storage pipes through the shell. We analyze the transient charge and discharge behavior of sulfur inside the pipes using a detailed computational modeling of the complex conjugate heat transfer and fluid flow phenomena.
The computational model is validated against experiments of a single tube with well-defined temperature boundary conditions and internal temperature measurements. Complementary computational, theoretical, and experimental efforts lead to strong understanding of sulfur heat transfer physics for wide range of desirable storage temperatures. We observed excellent thermal charge/discharge rate — much faster than competing PCM and solid based TES — due to the strong assistance of buoyancy driven convection currents was observed. The heat transfer characterization results will be used for system level design and analysis of sulfur based thermal energy storage system for various applications such as high temperature CHP, and CSP.