Experimental observations on the general trends of the steady state and stability behaviour of single-phase natural circulation loops

• Published in: Nuclear engineering and design 2002-06, Vol.215 (1), p.139-152
• Main Author: Vijayan, P.K.
• Format: Article
• Language: English
• Subjects: Applied sciences; Buoyancy; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Fission nuclear power plants; Heat sinks; Installations for energy generation and conversion: thermal and electrical energy; Prandtl number; Solar water heaters; Specific heat; Thermal conductivity
• ISSN: 0029-5493; 1872-759X
• DOI: 10.1016/S0029-5493(02)00047-X

The steady state flow in uniform or non-uniform diameter single-phase natural circulation loops (NCLs) can be expressed as Re ss= C[ Gr m/ N G] r where the constants C and r depend on the nature of the flow (i.e. laminar or turbulent). Testing these correlations with experimental data showed reasonable agreement. The above equation suggests that simulation of the steady state flow in single-phase NCLs can be achieved by simulating the non-dimensional parameter ( Gr m/ N G). The stability behaviour of a non-uniform diameter loop is found to depend on a large number of geometric parameters in addition to the modified Stanton number ( St m) and the ratio ( Gr m) b/(3− b) /( N G) 3/(3− b) . The transient and stability behaviour of a uniform diameter loop can be simulated by simulating the product ( Gr m) b/(3− b) ×( D ̄ / L ̄ t ) 3/(3− b) and St m if the length scales are preserved.