Experimental and Analytical Study on the Heat Transfer Characteristics in a Natural Circulation Loop for an Integral Type Reactor

2010 ◽  
Author(s):  
Hyun-Sik Park ◽  
Ki-Yong Choi ◽  
Seok Cho ◽  
Sung-Jae Yi
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Natural Circulation ◽  
Circulation Loop ◽  
Circulation Flow ◽  
Integral Type ◽  
Heat Transfer Characteristics ◽  
Flow Rates ◽  
Type Reactor ◽  
Natural Circulation Loop

The heat transfer characteristics in a natural circulation loop for an integral type reactor were experimentally investigated by using the VISTA facility and steady-state natural circulation flow rates were acquired for various core powers and feed water flow rates. The experimental data were compared with the predictions from existing correlations of Duffey et al. (1987) and Vijayan et al. (2002). It was shown that Duffey et al. (1987)’s correlation for a two-phase natural flow predicted the experimental data well. Also the experimental data on the natural circulation in the primary loop of the VISTA facility were analyzed by using a best-estimate system analysis code, MARS. The MARS code predicted the overall natural circulation flow characteristics reasonably.

scholarly journals Numerical study on heat transfer characteristics of nanofluid based natural circulation loop

2018 ◽  
Vol 22 (2) ◽  
pp. 885-897 ◽  
Author(s):  
Ramesh Bejjam ◽  
Kiran Kumar
Keyword(s):  
Heat Transfer ◽  
Numerical Study ◽  
Natural Circulation ◽  
Flow Behavior ◽  
Circulation Loop ◽  
Heat Transfer Characteristics ◽  
Step Size ◽  
Particle Volume ◽  
Transfer Characteristics ◽  
Natural Circulation Loop

In this paper the steady-state analysis has been carried out on single phase natural circulation loop with water and water based Al2O3 (Al2O3-water) nanofluid at 1%, 3%, 5%, and 6% particle volume concentrations. For this study, a 3-D geometry of natural circulation loop is developed and simulated by using the software, ANSYS (FLUENT) 14.5. Based on the Stokes number, mixture model is adopted to simulate the nanofluid based natural circulation loop. For the simulations, the imposed thermal boundary conditions are: constant heat input over the range of 200-1000 W with step size of 200 W at the heat source and isothermal wall temperature of 293 K at the heat sink. Adiabatic boundary condition is imposed to the riser and down-comer. The heat transfer characteristics and fluid-flow behavior of the loop fluid in natural circulation loop for different heat inputs and particle concentrations are presented. The result shows that the mass-flow rate of loop fluid in natural circulation loop is enhanced by 26% and effectiveness of the natural circulation loop is improved by 15% with Al2O3-water nanofluid when compared with water. All the simulation results are validated with the open literature in terms of Reynolds number and modified Grashof number. These comparisons confidently say that the present 3-D numerical model could be useful to estimate the performance of natural circulation loop.

Thermal Performance of Water-Based Suspensions of Phase Change Nanocapsules in a Natural Circulation Loop

2013 ◽  
Author(s):  
C. J. Ho ◽  
Chi-Ming Lai
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Natural Circulation ◽  
Pure Water ◽  
Circulation Loop ◽  
Core Material ◽  
Working Fluid ◽  
Outer Diameter ◽  
Natural Circulation Loop ◽  
Water Based

Experiments were conducted to investigate the heat transfer characteristics of water-based suspensions of phase change nanocapsules in a natural circulation loop with mini-channel heat sinks and heat sources. A total of 23 and 34 rectangular mini-channels, each with width 0.8 mm, depth 1.2 mm, length 50 mm and hydraulic diameter 0.96 mm, were evenly placed on the copper blocks as the heat source and heat sink, respectively. The adiabatic sections of the circulation loop were constructed using PMMA tubes with an outer diameter of 6 mm and an inner diameter of 4 mm, which were fabricated and assembled to construct a rectangular loop with a height of 630 mm and a width of 220 mm. Using a core material of n-eicosane and a shell of urea-formaldehyde resin, the phase change material nanocapsules of mean particle size 150 nm were fabricated successfully and then dispersed in pure water as the working fluid to form the water-based suspensions with mass fractions of the nanocapsules in the range 0.1–1 wt.%. The results clearly indicate that water-based suspensions of phase change nanocapsules can markedly enhance the heat transfer performance of the natural circulation loop considered.

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