Convection heat transfer of CO{sub 2} at supercritical pressures in a vertical mini tube at relatively low reynolds numbers

Journal Article · Mon Sep 15 04:00:00 EDT 2008 · Experimental Thermal and Fluid Science

DOI:https://doi.org/10.1016/J.EXPTHERMFLUSCI.2008.05.006· OSTI ID:21116053

Jiang, Pei-Xue; Zhang, Yu; Zhao, Chen-Ru; Shi, Run-Fu ^[1]

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1. Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Thermal Engineering, Tsinghua University, Beijing 100084 (China)

Convection heat transfer of CO{sub 2} at supercritical pressures in a 0.27 mm diameter vertical mini tube was investigated experimentally and numerically for upward and downward flows at relatively low inlet Reynolds numbers (2900 and 1900). The effects of inlet temperature, pressure, mass flow rate, heat flux, flow direction, buoyancy and flow acceleration on the convection heat transfer were investigated. For inlet Reynolds numbers less than 2.9 x 10{sup 3}, the local wall temperature varies non-linearly for both flow directions at high heat fluxes (113 kW/m{sup 2}). For the mini tube used in the current study, the buoyancy effect is normally low even when the heating is relatively strong, while the flow acceleration due to heating can strongly influence the turbulence and reduce the heat transfer for high heat fluxes. For relatively low Reynolds numbers (Re{sub in} {<=} 2.9 x 10{sup 3}) and the low heat flux (30.0 kW/m{sup 2}) the predicted values using the LB low Reynolds number correspond well with the measured data. However, for the high heat flux (113 kW/m{sup 2}), the predicted values do not correspond well with the measured data due to the influence of the flow acceleration on the turbulence. (author)

• OSTI ID: 21116053
• Journal Information: Experimental Thermal and Fluid Science, Journal Name: Experimental Thermal and Fluid Science Journal Issue: 8 Vol. 32; ISSN 0894-1777; ISSN ETFSEO
• Country of Publication: United States
• Language: English

Related Subjects

22 GENERAL STUDIES OF NUCLEAR REACTORS
42 ENGINEERING
ACCELERATION
AIR CONDITIONERS
Buoyancy
CARBON DIOXIDE
CONVECTION
FLOW RATE
Flow acceleration
HEAT EXCHANGERS
HEAT FLUX
HEAT PUMPS
HEATING
MASS
Minitubes
NONLINEAR PROBLEMS
PRESSURE DEPENDENCE
PRESSURE RANGE MEGA PA 01-10
REYNOLDS NUMBER
SIMULATION
SUPERCRITICAL STATE
Supercritical pressure
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0400-1000 K
TUBES
TURBULENCE
WALLS
WATER COOLED REACTORS