Analysis of the effects of heat sink temperature on single-phase natural circulation loops behaviour

Devia, Francesco; Misale, Mario

doi:10.1016/j.ijthermalsci.2012.03.006

Cited by 43 publications

(8 citation statements)

References 10 publications

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“…Several researchers have studied the influence of operating conditions on the transient/steady‐state behavior of NCL. For example, the effect of different heat sink temperatures on the transient and stability behavior of horizontal heating horizontal cooling SPNCL was explored numerically and experimentally by Devia and misale 13 . The influence of the nature of input power excitations on the dynamic characteristics of a rectangular‐shaped NCL has been explored by Rao et al 14 and Basu et al 15 Marchitto and Misale 16 conducted an experimental investigation to assess the flow and heat transfer characteristics of the two parallel‐connected SPNCL for different operating conditions.…”

Section: Introductionmentioning

confidence: 99%

Steady‐state and transient hydrothermal analyses of single‐phase natural circulation loop using water‐based tri‐hybrid nanofluids

2021

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Transient and steady-state characteristics of the natural circulation loop are studied using various water-based tri-hybrid (different nature and shaped nanoparticles) nanofluids. Effects of input power, loop inclination and loop aspect ratio on the mass flow rate, effectiveness, and entropy generation rate are studied. Results disclose that tri-hybrid nanofluids reduce the oscillation and attain steady state faster than water. Effectiveness increases and entropy generation rate decreases by using trihybrid nanofluids. Nanoparticle shape has found a significant impact. Al 2 O 3 + Cu + CNT/water shows the best performance. The mass flow rate increases with input power, loop aspect ratio, whereas, reduces with loop inclination. Effectiveness decreases and then increases with input power, whereas increases with loop inclination and decreases with loop aspect ratio. Entropy generation upsurges with input power and loop inclination, whereas decreases with loop aspect ratio. Loop aspect ratio of 1.5 to 3 is found suitable for better performance.

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Section: Introductionmentioning

confidence: 99%

Steady‐state and transient hydrothermal analyses of single‐phase natural circulation loop using water‐based tri‐hybrid nanofluids

2021

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“…The first studies were carried out by Keller [1] and Welander [2]. More recently Chen [3], Vijayan et al [4][5], Misale et al [6], Devia and Misale [7], Misale [8] and Swapnalee and Vijayan [9] developed theoretical analyses in order to focus the influence of the loop geometrical characteristics on the natural circulation instabilities.…”

Section: Introductionmentioning

confidence: 99%

Experiments on parallel connected loops in single phase natural circulation: preliminary results

Marchitto¹,

Misale²

2018

MMEP

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Natural circulation is the most important heat removal mechanism for passive protection systems in a lot of industrial applications, such as nuclear power plants, solar energy systems, reboilers and cooling of electronic systems. The aim of the present work is to investigate the flow and heat transfer characteristics of parallel loops, connected in the lower heated sections, in single-phase natural circulation. The test facility was composed by 2 vertical circuits connected in parallel; each of them was rectangular in geometry, the aspect ratio (defined as the height to width ratio) was 1.63, with circular copper tube of 4 mm (I.D.). An upper cold heat exchanger provided the heat sink, while the heat source at the bottom was a power supply system. Several calibrated thermocouples (T-type) placed in the fluid along the vertical tubes allowed the evaluation of the hot and cold legs average fluid temperature differences. Tests were carried out imposing 3 different heat sink temperatures (10, 20, 30°C); for each of these temperatures the power supply at the lower heater was increased from 20 to 90 W. The fluid investigated was distillate water. The experimental results have been analysed in terms of thermal performance of the single or connected loops. Collected data have also been compared with Vijaiyan's correlation.

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“…The effect of heat transfer in the pipeline on the mass flow rate parameters during natural circulation has been studied by several researchers [13][14][15][16][17][18].…”

Section: Introduction mentioning

confidence: 99%

“…Vijayan et al [17] examined the stability of the natural circulation of the single-phase rectangular loop for various orientations of heater and cooler. Then, Devia et al [15] conducted studies to evaluate the mass and heat flow to determine the flow stability in the loop with no variations in the heater and cooler. Meanwhile, Jiang and Shoji [19] and Guo et al [20] conducted the study on the cooling system performance with several parameters such as the diameter, length, and angle of inclination.…”

Section: Introduction mentioning

confidence: 99%

An Experimental Analysis on Nusselt Number of Natural Circulation Flow in Transient Condition Based on the Height Differences between Heater and Cooler

et al. 2018

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A better understanding on the phenomenon of natural circulation flow for cooling systems is necessary prior to improving the safety of nuclear power plant, not only in normal operation but also in accident conditions. One way to understand this phenomenon is by analyzing the Nusselt number in various geometrical dimensions through experimentation. The purpose of this study is to understand natural circulation phenomenon in transient condition by varying height differences between heater and cooler. To achieve this purpose, an experiment apparatus called NC-Queen was developed and arranged to enable three variations of height differences between heater and cooler, i.e., 1.4 m, 1.0 m, and 0.3 m. It is made of a stainless steel tube with a diameter of 1 inch, arranged in rectangular shape 6.4 m in length, and uses water as coolant. The initial temperature of the heater was set at 90 °C. The Nusselt number was obtained by calculating the flow rate as a function of transient temperature. The results confirm that height differences affect thermal properties and flow region based kinetics characteristics of water. In initial condition, decreasing height difference from 1.4 m to 1.0 m resulted in flow rate reduction of 16.7 %, while decreasing height difference from 1.4 m to 0.3 m resulted in a 39.1 % flow rate reduction. In final condition, the flow rate reductions were 75 % and 82.6 %, respectively. Meanwhile, in initial condition, the Nusselt number for height difference reduction from 1.4 m to 1.0 m and from 1.4 m to 0.3 m decreased by 30.5 % and 74.6 %, respectively, while for final condition, the Nusselt number decreased by 11.9 % and 67.4 %, respectively. The new constants in relationship between Nusselt number and the height difference are a = 20.06 and b = 0.56. The dominance of turbulent flow provides a good safety margin with indications of the large amount of heat released.

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Analysis of the effects of heat sink temperature on single-phase natural circulation loops behaviour

Cited by 43 publications

References 10 publications

Steady‐state and transient hydrothermal analyses of single‐phase natural circulation loop using water‐based tri‐hybrid nanofluids

Steady‐state and transient hydrothermal analyses of single‐phase natural circulation loop using water‐based tri‐hybrid nanofluids

Experiments on parallel connected loops in single phase natural circulation: preliminary results

An Experimental Analysis on Nusselt Number of Natural Circulation Flow in Transient Condition Based on the Height Differences between Heater and Cooler

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