Effects of Heater Orientations on the Natural Circulation and Heat Transfer in a Supercritical CO2 Rectangular Loop

Chen, Lin; Zhang, Xin Rong; Jiang, Bin

doi:10.1115/1.4025543

Cited by 43 publications

(4 citation statements)

References 37 publications

(159 reference statements)

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“…Also, it is visible in the figure that the time to arrive at the steady state changes for each configuration. Similar behaviors were experimentally observed by Vijayan et al [26] and Chen et al [27]. They found experimentally that for HHHC and HHVC, the time to start the circulation is higher than the time to start the flow with vertical heaters, in which cases the flows start when the heating power is provided.…”

Section: Fluid Velocity Profilesupporting

confidence: 86%

Thermal performance investigation of a mini natural circulation loop for solar PV panel or electronic cooling simulated by lattice Boltzmann method

Bocanegra¹,

Marchitto²,

Misale³

2022

Int. J. EQ

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The natural circulation loop (NCL) consists of a thermal-hydraulic system that convoys thermal energy from a heat source to a heat sink without a pump. Applications of those loops can be found in solar energy, geothermal, nuclear reactors, and electronic cooling. The lattice Boltzmann method is a numerical method that can simulate thermal-fluid dynamics, using a mesoscopic approach based on the Boltzmann equation for the density function. A square NCL model with fixed temperatures at the heater and heat sink sections was developed in a bi-dimensional lattice with double distribution dynamics, one distribution for the hydrodynamic field and the other for the thermal field. The different cooler-heater configurations (vertical or horizontal) were investigated. We found that by positioning the source or sink vertically, the flow direction can be controlled. In contrast, in a loop with symmetric horizontal heater -horizontal cooler configuration where both fluid directions are equally probable. The effectiveness of the loop was studied by calculating the heat sink temperature gradient. The lower value was obtained for the horizontal heater horizontal cooler orientation (0.71) and the higher value for the vertical heater vertical cooler configuration with an increment of 34%; simultaneously, the flow rate (Reynolds number) was reduced by 47%.

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Section: Fluid Velocity Profilesupporting

confidence: 86%

Thermal performance investigation of a mini natural circulation loop for solar PV panel or electronic cooling simulated by lattice Boltzmann method

Bocanegra¹,

Marchitto²,

Misale³

2022

Int. J. EQ

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show abstract

“…By considering the different combinations of the heater and cooler orientations (horizontal heater horizontal condenser, horizontal heater vertical condenser, vertical heater vertical condenser and vertical heater horizontal condenser) Chen 14 numerically investigated the performance and stability of supercritical NCL (SCNCL). Similarly, Archana et al 15 developed 1 D numerical model to study the flow transient characteristics of SCNCL with CO 2 as loop fluid.…”

Section: Introductionmentioning

confidence: 99%

“…The steady state characteristics of the NCLs have been studied for different orientations is available in the open literature. 14,15,17 However, the loop fluid is either single phase or supercritical. Studies on the NCL filled with two phase mixtures in the riser section and single phase in the downcomer section with different possible orientations of heater and condenser are rare or not found in the open literature.…”

Section: Introductionmentioning

confidence: 99%

Effect of heater and condenser orientations on fluid flow behaviour in a two-phase natural circulation loop

Sudheer¹,

Kumar

Balasubramanian

2021

Proceedings of the Institution of Mechanical Engineers, Part E:

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A Numerical investigation on the influence of heater and condenser orientation and its location on steady state performance of a Two Phase Natural Circulation Loop (TPNCL) is presented. In the present study, four possible orientations are considered in TPNCL namely, Vertical Heater and Vertical Condenser (VHVC), Vertical Heater and Horizontal Condenser (VHHC), Horizontal Heater and Horizontal Condenser (HHHC) and Horizontal Heater and Vertical Condenser (HHVC). An in house MATLAB code is developed to solve the systems of equations. Homogeneous equilibrium model (HEM) is used in two phase regions. It is observed that steady state mass flow rate of the loop is significantly influenced by the developed pressure gradient in the riser and downcomer sections, as well as available vapour quality in the riser section. Moreover, it is also noticed that condenser position and orientation significantly effects the thermo-hydraulic characteristic of loop compared with heater orientation.

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“…Nemati et al [11] and Peeters [12] studied the turbulent attenuation and the effect of thermal boundary conditions on the development of turbulent pipe flows with fluids at the inlet Reynolds numbers of 360 and 8000. Chen [13] numerically studied the heat transfer and various convection structures of CO2 flow in microchannels. Cao [14] studied the convective flow and heat transfer characteristics of supercritical CO2 through natural circulation in a uniform diameter rectangular loop.…”

Section: Introductionmentioning

confidence: 99%

Experimental and Numerical Investigation of Convective Heat Transfer of Supercritical Carbon Dioxide at Low Mass Fluxes

Lei

Zhang

et al. 2017

Applied Sciences

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Featured Application: Supercritical carbon dioxide Brayton cycle, geothermal system, nuclear reactor.Abstract: Significant differences in the heat transfer behaviors of supercritical carbon dioxide in a heated channel have been observed at different mass fluxes. At low mass fluxes, a unique heat transfer characteristic is accompanied by a monotonously smooth temperature variation without any temperature peak, even though the ratio of heat flux to mass flux (q/G) is high. In this study, experimental and numerical investigations explore the hidden mechanism of the peculiar heat transfer characteristics of supercritical carbon dioxide at low mass fluxes in vertically upward tubes with inside diameters (ID) of 5 mm. The range of operating conditions examined within the study include a mass flux (G) between 0-200 kg/m 2 s, and a heat flux (q) of up to 120 kW/m 2 . The parametric effects within these experimental conditions were analyzed on the basis of the obtained heat transfer data. Furthermore, a qualitative modeling force analysis and quantitative numerical simulation of vertical flow at low mass flux reveal the heat transfer mechanism for these temperature profiles. In addition, the distribution of flow parameters and thermo-physical properties (such as shear stress, density, and specific heat) in the near-wall region were also studied. It is found that the heat transfer behavior of supercritical CO 2 at low mass flux is similar to "film boiling" at subcritical pressure, where "vapor-like" fluid occupies the sublayer region. Due to reduced buoyancy, the fluid does not cause enough mixing/instability to bring it to the bulk flow.

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Effects of Heater Orientations on the Natural Circulation and Heat Transfer in a Supercritical CO2 Rectangular Loop

Cited by 43 publications

References 37 publications

Thermal performance investigation of a mini natural circulation loop for solar PV panel or electronic cooling simulated by lattice Boltzmann method

Thermal performance investigation of a mini natural circulation loop for solar PV panel or electronic cooling simulated by lattice Boltzmann method

Effect of heater and condenser orientations on fluid flow behaviour in a two-phase natural circulation loop

Experimental and Numerical Investigation of Convective Heat Transfer of Supercritical Carbon Dioxide at Low Mass Fluxes

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