Forced-convection heat transfer in a spherical-annulus heat exchanger

Conference · Wed Apr 01 04:00:00 EST 1981

OSTI ID:6802781

Tuft, D B; Brandt, H

Results are presented of a combined numerical and experimental study of steady forced-convection heat transfer in a spherical annulus heat exchanger with 50/sup 0/C heated water flowing in an annulus formed by an insulated outer sphere and a 0/sup 0/C cooled inner sphere. The inner sphere radius is 139.7 mm, the outer sphere radius is 168.3 mm and the radius ratio is 1.2. In the analytical portion, results of numerical calculations of laminar incompressible fluid flow and heat transfer in a spherical annulus are presented. The full transient axisymmetric Navier-Stokes equations in spherical coordinates are solved by an explicit finite-difference solution technique. Steady solutions are obtained by allowing the transient solution to achieve steady state: temperature and heat-flux rate distributions are presented for gap Reynolds numbers from 4.4 to 440. In the experimental portion, measurements of inner sphere heat-flux rate distribution, flow separation angle, annulus fluid temperatures and total heat transfer are made for gap Reynolds numbers from 41 to 1086. The angle of separation along the inner sphere is found to vary as a function of Reynolds number. Measured total Nusselt numbers agree with results reported in the literature to within 2.0% at a gap Reynolds number of 974 and 26.0% at a gap Reynolds number of 66. It is believed that the numerical analysis is the first solution of the full laminar Navier-Stokes equations for forced-convection heat transfer in a spherical annulus. The computations predict the experimental trends and qualitative aspects of the flow and heat transfer while underpredicting heat-flux rates by a factor of two or more. Also, this is the first experimental study of spherical annulus convective heat transfer in which inner sphere heat-flux distribution has been measured. In addition, this is the first experimental study in which separation angle has been measured by other than visual methods and found to vary as a function of Reynolds number.

• Research Organization: Lawrence Livermore National Lab., CA (USA); California Univ., Davis (USA). Dept. of Mechanical Engineering
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 6802781
• Report Number(s): UCRL-85833; CONF-811101-30; ON: DE82019109
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
420200* -- Engineering-- Facilities
Equipment
& Techniques
420400 -- Engineering-- Heat Transfer & Fluid Flow
ANNULAR SPACE
CONFIGURATION
CONVECTION
DATA
DIFFERENTIAL EQUATIONS
EQUATIONS
EXPERIMENTAL DATA
FLUID FLOW
FORCED CONVECTION
HEAT EXCHANGERS
HYDROGEN COMPOUNDS
INFORMATION
LAMINAR FLOW
NAVIER-STOKES EQUATIONS
NUMERICAL DATA
NUMERICAL SOLUTION
NUSSELT NUMBER
OXYGEN COMPOUNDS
PARTIAL DIFFERENTIAL EQUATIONS
REYNOLDS NUMBER
SPACE
SPHERICAL CONFIGURATION
WATER