Experimental and simulation approach of the loop geometry effect on the natural circulation system of the advanced nuclear reactor

Abstract

Summary Lately, natural circulation has become an exciting topic because it has been proposed and applied in some advanced nuclear reactors as a passive safety system. The aim of the present study is to examine the effect of the loop geometry on the natural circulation based cooling system of a given power source. The experimental approach was achieved by the construction of two natural circulation loops with vertical heater and vertical cooler. Both circulation loops were built with a same vertical length of 100 cm and different horizontal lengths, each of 50 and 100 cm, respectively. The heater was realized with a stainless pipe wrapped by a Nichrome wire, whereas the cooling system was designed and built as a pipe in 30 cm long square tube. Thus, the cooling water will circulate around the pipe loop inside the rectangular cooling chamber. The temperature data acquisition was achieved via an Arduino‐based system, controlling four K‐type thermocouple sensors. The numerical simulation part in the present work, was carried out by the COMSOL Multiphysics software, using the dedicated heat transfer and fluid dynamic module, namely the computational fluid dynamic module. The experimental data were considered to parameterize the COMSOL input model. The experimental results showed a clear difference between two passive cooling loops according to the horizontal length. The doublings of the horizontal and vertical lengths of the loop have a direct effect on the fluid flow rate.

Computational fluid dynamics analysis of the natural circulation system in vertical heater horizontal cooler (VHHC) molten salt loop

“…Then, the authors' work has been done on paper [9], demonstrated experimentally that expansion tank placement is crucial in single-phase NCLs. Also, subsequent work by experimental and modelling showed that loop geometry could affect natural circulation-based cooling systems [9][10][11][12]. These studies revealed that the instability of the NCL is influenced by the loop geometry.…”

“…The effect of coolant temperature variations on NCL instability was analysed in paper [19] using the commercial code Fluent 6.3. Also, the authors have modelled the effect of the natural circulation loop geometry using the COMSOL Multiphysics software [10,11]. Motivated from the above description, in this paper, we studied the transient and steady-state of the natural circulation system in the molten salt loop with vertical heater and horizontal cooler using computational fluid dynamics.…”

Numerical Analysis of Flow Stability in a Natural Circulation Loop

“…The study showed that in a certain condition, the mass flow rate due to buoyancy force will be chaotic. A two-dimensional numerical model for the NC loop and its validation was developed by Hariyanto et al [12]. The model represents the mass flow rate of various geometrical and flow rate variations of the system.…”