0
Research Papers: Natural and Mixed Convection

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

[+] Author and Article Information
Lin Chen, Bin Jiang

Department of Energy
and Resources Engineering,
College of Engineering,
Peking University,
Beijing 100871, China

Xin-Rong Zhang

Department of Energy
and Resources Engineering,
College of Engineering,
Peking University,
Beijing 100871, China
Beijing Key Laboratory for
Solid Waste Utilization and Management,
Peking University,
Beijing 100871, China

1Corresponding author.

Contributed by the Heat Transfer Division of ASME for publication in the JOURNAL OF HEAT TRANSFER. Manuscript received December 23, 2012; final manuscript received August 24, 2013; published online March 6, 2014. Assoc. Editor: Bruce L. Drolen.

J. Heat Transfer 136(5), 052501 (Mar 06, 2014) (12 pages) Paper No: HT-12-1672; doi: 10.1115/1.4025543 History: Received December 23, 2012; Revised August 24, 2013

Supercritical fluid based heat transfer loop (NCL) has become a hot topic in energy conversion systems. In such systems, supercritical natural convection stability and heat transfer conditions are crucial for design and safe operation. In the present study, numerical simulations were performed to investigate the influences of heater orientations on the performance of supercritical CO2 based circulation loops. The numerical model is based on Navier-Stokes equations with supercritical turbulence effects considered. It is found that the heat source location has significant influence on the flow pattern and system heat transfer. Vertical heating cases are found stable in a wide range of heat flux conditions due to the changes of buoyancy force torques across the NCLs, while horizontal heating cases show transition heat flux and oscillations are still seen. However, the influence of heat source location is less significant on the heat transfer characteristics. The effect of cooler heat transfer is found of special importance for the heat transfer and system stability behaviors. The NCL flow and heat transfer correlations are also compared in this study, and it is recommended that more numerical and experimental studies be made in the future.

FIGURES IN THIS ARTICLE
<>
Copyright © 2014 by ASME
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Fig. 1

Thermal physical properties of supercritical CO2 fluid at 7.5 MPa, 8.0 Mpa, 9.0 MPa, and 10.0 MPa. (a) Density; (b) specific heat; (c) thermal conductivity; and (d) viscosity.

Grahic Jump Location
Fig. 2

Schematic of the NCL model studied. (a) Down middle heating; (b) down left heating; (c) left middle heating; and (d) left down heating.

Grahic Jump Location
Fig. 3

The variation of the mass flow rate with time (heat flux: 60,000 W/m2)

Grahic Jump Location
Fig. 4

The variation of the mass flow rate with time (Heat flux: 6000 W/m2)

Grahic Jump Location
Fig. 5

The variation of the mass flow rate with time (heat flux: 600 W/m2)

Grahic Jump Location
Fig. 6

Temperature differences across the heater and cooler under different orientations and heat flux conditions. (a) 600 W/m2 heat flux at the heater; (b) 6000 W/m2 heat flux at the heater; and (c) 60,000 W/m2 heat flux at the heater.

Grahic Jump Location
Fig. 7

The average Nusselt number of heat sinks of loops with flow time for different heat source locations (heat flux: 60,000 W/m2)

Grahic Jump Location
Fig. 8

The average Nusselt number of heat sinks of loops with flow time for different heat source locations (heat flux: 6000 W/m2)

Grahic Jump Location
Fig. 9

The average Nusselt numbers of heat sinks of loops with flow time different heat source orientations (heat flux: 600 W/m2)

Grahic Jump Location
Fig. 10

Thermal conductivity of CO2 fluid at representative cross planes in the mid of heater and cooler. (a) Mid of heater and (b) mid of cooler.

Grahic Jump Location
Fig. 11

Correlated plots for Reynolds number and modified Grashof number of steady supercritical flow cases

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In