Supercritical Natural Circulation Loop

2017 ◽  
pp. 188-214
Author(s):  
Dipankar Narayan Basu ◽  
Milan Krishna Singha Sarkar
Keyword(s):  
Nuclear Reactors ◽  
Natural Circulation ◽  
Point Of View ◽  
Circulation Loop ◽  
Working Fluid ◽  
Operating Parameters ◽  
System Behavior ◽  
Natural Circulation Loop ◽  
Stability Point ◽  
Future Direction

Supercritical natural circulation loop is a compelling technology for cooling of modern nuclear reactors, which promises enhanced thermalhydraulic performance in a simple design. Being a new concept, related knowledge base is relatively thin and involves several conflicting theories and controversies. Present chapter summarizes the observation till date, starting from the very fundamentals. The phenomenon of natural circulation and suitability of supercritical medium as working fluid are discussed in details. Different methods of analyses, including analytical, simple 1-D numerical and multidimensional computational codes, as well as experimental, are elucidated. A comprehensive discussion is presented about the effect of various geometric and operating parameters on the system behavior, from both thermalhydraulic and stability point of view. Finally, a few recommendations are included about the operation of such loops and future direction of research.

Supercritical Natural Circulation Loop

2021 ◽  
pp. 338-369
Author(s):  
Tanuj Srivastava ◽  
Pranab Sutradhar ◽  
Milan Krishna Singha Sarkar ◽  
Dipankar Narayan Basu
Keyword(s):  
Nuclear Reactors ◽  
Natural Circulation ◽  
Point Of View ◽  
Circulation Loop ◽  
Working Fluid ◽  
System Behavior ◽  
Steady State Condition ◽  
Natural Circulation Loop ◽  
Stability Point ◽  
Future Direction

Supercritical natural circulation loop is a compelling technology for cooling of modern nuclear reactors, which promises enhanced thermal-hydraulic performance in a simple design. Being a new concept, related knowledge base is relatively thin and involves several conflicting theories and controversies. The chapter summarizes the observation till date, starting from the very fundamentals. The phenomenon of natural circulation under steady state condition and suitability of supercritical medium as working fluid are discussed in detail. Different methods of analyses, including analytical, simple 1-d numerical, and multidimensional computational codes, as well as experimental, are elucidated. A comprehensive discussion is presented about the effect of various geometric and operating parameters on the system behavior, from both thermal-hydraulic and stability point of view. Finally, a few recommendations are included about the operation of such loops and future direction of research.

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.

Steady-State Performance of a Rectangular Natural Circulation Loop With Differentially Heated Parallel Channels

2015 ◽  
Vol 8 (1) ◽  
Author(s):  
Shubhankar Chakraborty ◽  
Prasanta Kr. Das
Keyword(s):  
Steady State ◽  
Phase Change ◽  
Energy Transport ◽  
Natural Circulation ◽  
Circulation Loop ◽  
Circulation Rate ◽  
Working Fluid ◽  
Two Phase ◽  
State Behavior ◽  
Natural Circulation Loop

Natural circulation loop (NCL) transfers thermal energy without using any external power. As with phase change, one can expect a higher rate of heat transfer and a greater change in density, NCL with a phase change of the circulating fluid is a more effective energy transfer device. Though in many of the practical NCLs there are multiple heating risers, the characteristics of NCLs with parallel boiling risers have not been investigated in detail. In the present work, the steady-state behavior of a two-phase NCL with two parallel boiling risers for water as the working fluid has been investigated. Emphasis has been given to the performance of the loop when the risers are differentially heated. Effect of different parameters on the loop circulation rate and energy transport for both equally and differentially heated conditions has been thoroughly examined and compared to the performance of a single-riser loop under equivalent working condition.

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