Heat transfer to supercritical fluids flowing in channels—empirical correlations (survey)

Pioro, Igor; Khartabil, Hussam F.; Duffey, Romney B.

doi:10.1016/j.nucengdes.2003.10.010

Cited by 391 publications

(166 citation statements)

References 21 publications

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“…A large number of experimental campaigns have been performed studying supercritical heat transfer, resulting in a large set of correlations, see e.g. [11]- [12] for reviews. However, when compared to experimental data, these correlations often show a very large scatter.…”

Section: Introductionmentioning

confidence: 99%

Experimental study of the coupled thermo-hydraulic–neutronic stability of a natural circulation HPLWR

T’Joen

Rohde

2012

Nuclear Engineering and Design

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The HPLWR (High Performance Light Water Reactor) is the European concept design for a SCWR (SuperCritical Water Reactor). This unique reactor design consists of a three pass core with intermediate mixing plena. As the supercritical water passes through the core, it experiences a significant density reduction. This large change in density could be used as the driving force for natural circulation of the coolant, adding an inherent safety feature to this concept design. The idea of natural circulation has been explored in the past for boiling water reactors (BWR). From those studies, it is known that the different feedback mechanisms can trigger flow instabilities. These can be purely thermo-hydraulic (driven by the friction -mass flow rate or gravity -mass flow rate feedback of the system), or they can be coupled thermo-hydraulic -neutronic (driven by the coupling between friction, mass flow rate and power production). The goal of this study is to explore the stability of a natural circulation HPLWR considering the thermo-hydraulic -neutronic feedback. This was done through a unique experimental facility, DeLight, which is a scaled model of the HPLWR using Freon R23 as a scaling fluid. An artificial neutronic feedback was incorporated into the system based on the average measured density. To model the heat transfer dynamics in the rods, a simple first order model was used with a fixed time constant of 6 seconds. The results include the measurements of the varying decay ratio (DR) and frequency over a wide range of operating conditions. A clear instability zone was found within the stability plane, which seems to be similar to that of a BWR. Experimental data on the stability of a supercritical loop is rare in open literature, and these data could serve as an important benchmark tool for existing codes and models.

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Section: Introductionmentioning

confidence: 99%

Experimental study of the coupled thermo-hydraulic–neutronic stability of a natural circulation HPLWR

T’Joen

Rohde

2012

Nuclear Engineering and Design

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“…The calculated heat flux from the measurements is in the range of 5 kW/m 2 -9 kW/m 2 which is significantly lower than the critical heat flux [22,23]. At high (critical) heat fluxes deteriorated heat transfer occurs, which is not likely to arise in these testing conditions.…”

Section: Heat Transfer Coefficientmentioning

confidence: 99%

Experimental Assessment of a Helical Coil Heat Exchanger Operating at Subcritical and Supercritical Conditions in a Small-Scale Solar Organic Rankine Cycle

et al. 2017

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Abstract:In this study, the performance of a helical coil heat exchanger operating at subcritical and supercritical conditions is analysed. The counter-current heat exchanger was specially designed to operate at a maximal pressure and temperature of 42 bar and 200 • C, respectively. The small-scale solar organic Rankine cycle (ORC) installation has a net power output of 3 kWe. The first tests were done in a laboratory where an electrical heater was used instead of the concentrated photovoltaic/thermal (CPV/T) collectors. The inlet heating fluid temperature of the water was 95 • C. The effects of different parameters on the heat transfer rate in the heat exchanger were investigated. Particularly, the performance analysis was elaborated considering the changes of the mass flow rate of the working fluid (R-404A) in the range of 0.20-0.33 kg/s and the inlet pressure varying from 18 bar up to 41 bar. Hence, the variation of the heat flux was in the range of 5-9 kW/m 2 . The results show that the working fluid's mass flow rate has significant influence on the heat transfer rate rather than the operational pressure. Furthermore, from the comparison between the experimental results with the heat transfer correlations from the literature, the experimental results fall within the uncertainty range for the supercritical analysis but there is a deviation of the investigated subcritical correlations.

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“…Recently developed cryogenic energy storage technology uses liquid air/nitrogen as both energy storage carrier and heat transfer fluid [1,2]. However, SCN2 has the great advantages of enhanced heat transfer properties namely heat transfer coefficient and thermal conductivity, which greatly impacts the specific heat capacity.…”

Section: Extended Abstractmentioning

confidence: 99%

Investigation on Heat Transfer Behaviour of Supercritical Nitrogen

Negoescu¹,

Li²,

Al‐Duri³

et al. 2016

World Congress on Mechanical, Chemical, and Material Engineering

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Extended AbstractA fluid above its critical temperature and pressure (Pc, Tc) is called supercritical (SCF) under which conditions the distinction between liquid and gas phases no longer exists. Due to the varied intra-molecular bonds, SCFs possess unique thermodynamic properties that are significantly different from their ambient state leading to different behavioural profiles and opening up a wide range of applications especially in the domains of energy production, environment protection and green processes. They become green solvents for extraction, particle production and superior reaction media for a wide range of catalytic and non-catalytic reactions. The products of SCF-mediated processes are of highly improved quality (in terms of purity and production efficiency), and process economic feasibility.Supercritical nitrogen (SCN2) is frequently used in in energy-related chemical engineering technologies such as air separation. Recently developed cryogenic energy storage technology uses liquid air/nitrogen as both energy storage carrier and heat transfer fluid [1,2]. However, SCN2 has the great advantages of enhanced heat transfer properties namely heat transfer coefficient and thermal conductivity, which greatly impacts the specific heat capacity.As nitrogen transfers from subcritical (compressed) to supercritical state, it experiences extreme variation of the above thermodynamic properties, creating highly rapid impact on the system behaviour. The objective of this study is to assess the influence of key parameters (heat flux, mass flux) on the heat transfer behaviour in supercritical nitrogen in the large specific heat region by employing the k-ε turbulence model. More specifically this work represents a qualitative analysis of the heat transfer coefficient trend in supercritical nitrogen flowing vertically up in a 2 mm diameter tube, at a working pressure of 3.6 MPa, for mass fluxes 300, 600, 900 kg/(m2s), and heat flux from 11450 to 120000 W/m2.The simulations are conducted in 2D axis-symmetric, steady state, using the pressure-based solver in ANSYS Fluent.The results obtained highlight the heat transfer deterioration with increasing heat flux, while the Dittus-Boelter correlation for the Nu number is used as reference.For all mass and heat fluxes investigated the heat transfer coefficient trend shows a sharp increase with bulk temperature, reaching a peak near the pseudo-critical point after which there is a significant drop in values. Moreover, the magnitude of the heat transfer coefficient in the large specific region is proportional to the mass flow rate.The well-known Dittus-Boelter correlation over predicts the values around the pseudo-critical point where the extreme variation of thermo-physical properties becomes important.

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Heat transfer to supercritical fluids flowing in channels—empirical correlations (survey)

Cited by 391 publications

References 21 publications

Experimental study of the coupled thermo-hydraulic–neutronic stability of a natural circulation HPLWR

Experimental study of the coupled thermo-hydraulic–neutronic stability of a natural circulation HPLWR

Experimental Assessment of a Helical Coil Heat Exchanger Operating at Subcritical and Supercritical Conditions in a Small-Scale Solar Organic Rankine Cycle

Investigation on Heat Transfer Behaviour of Supercritical Nitrogen

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