Heat transfer from a rod bundle under natural circulation conditions

Technical Report · Sat Mar 01 04:00:00 EST 1986

OSTI ID:6063100

Hallinan, K P; Viskanta, R

A rectangular natural circulation loop with heat exchangers in the vertical legs was used to obtain heat transfer and fluid friction data from a tube bundle under natural circulation conditions. A 21 rod bundle arranged in a square array with a pitch-to-diameter ratio of 1.33 was used as the test heat exchanger. Deionized water at atmospheric pressure was used as the working fluid in the loop. Natural circulation resulted from the density difference of the fluid within the loop between the two vertical legs of the loop. Steady-state and transient experiments were performed. Based on the steady-state data obtained, empirical correlations for fluid friction and heat transfer of the circulating fluid flowing through the tube bundle were developed. The pressure drop in the loop was found to depend on the Reynolds number. Friction factor relations for laminar forced flow through tube bundles were found to accurately model fluid friction of the circulating fluid through the test bundle. Empirical correlations for the average Nusselt number were developed for both parrallel-flow and counter-flow arrangements of the test heat exchanger. The placement of grid spacers on the test bundle was found to have little effect on the total flow resistance of the circulating fluid, while enhancing the average heat transfer from 5% to 15%, depending on the thermal and flow conditions. The dynamic response of the circulating fluid and of the loop structural components was predicted from a one-dimensional model. The model equations were solved numerically using a finite-difference method. Local temperatures and flow rates of the circulating fluid were predicted for three step changes in the heating rate (start-up, step increase and step decrease). Good correspondence was obtained between the predicted and measured local temperatures and the time to reach steady-state conditions. 31 refs., 18 figs.

• Research Organization: Purdue Univ., Lafayette, IN (USA). School of Mechanical Engineering
• OSTI ID: 6063100
• Report Number(s): NUREG/CR-4556; ON: TI86901126
• Country of Publication: United States
• Language: English

Related Subjects

22 GENERAL STUDIES OF NUCLEAR REACTORS
220200 -- Nuclear Reactor Technology-- Components & Accessories
42 ENGINEERING
420400* -- Engineering-- Heat Transfer & Fluid Flow
CONVECTION
ENERGY TRANSFER
HEAT EXCHANGERS
HEAT TRANSFER
MASS TRANSFER
MATHEMATICAL MODELS
NATURAL CONVECTION
ROD BUNDLES
STEADY-STATE CONDITIONS
TESTING
TRANSIENTS