High‐flux heat transfer characteristics of pure ethylene glycol in axial and swirl flow

Abstract

Oak Ridge National Laboratory, O a k Ridge, TennesseeMeasurements were made of heat transfer rates and peak heat flux for atmospheric-pressure pool boiling, and of adiabatic and diabatic friction factors, nonboiling and local-boiling heat transfer rates, and burnout heat fluxes for both axial-and twisted-tape swirl-flow forced convection of pure ethylene glycol. Test sections were electrically heated copper, 347 stainless steel, and A-nickel tubes.Both In order to gain a more complete understanding of the influence of physical properties o n swirl-flow heat transfer, which has been studied at Oak Ridge National Laboratory with water as coolant ( l ) , a swirl-flow study of ethylene glycol was initiated.The program was broadened to finally encompass the pool boiling, forcedconvection nonboiling and local boiling, and burnout characteristics of ethylene glycol in both axial and swirl flow. A few tests were made under cooling conditions. The present paper is a summary of t h i s investigation. EXPERIMENTAL SYSTEMThe system used was basically the same as that used for the water studies ( I ) . Moyno and turbine pumps were used singly or together to pump the glycol through horizontal copper or 347 stainless steel test sections, resistance heated by 60 cycle/sec. a.c. current. The glycol was contained in a mixed overhead holdup drum which could be steam heated or water cooled with internal coils. A cooler tube, which folIowed the heater tube in some tests, was externally jacketed to form an annular flow passage for longitudinal flow of cooling water; &gauge (3-mil-diam. ) chromel/alumel thermocouples were embedded in the cooler tube wall. An upstream calming section longer than 40 diam. was used in all axial-flow tests.Swirl flow was generated with thin (15 mil thick) twisted tapes, onto which the tubes were drawn, as described in reference 1.Burnout tests were concluded by physical destruction of the test section (usually near the flow exit). Burnout was attained by slowly increasing the heat flux at essentially constant velocity, pressure, and inlet glycol temperature.The pool boiler, which measured nominally 6 by 6 by 9 in. deep, was A fully detailed description of this work will be given in 811 Oak Ridge National Laboratory report of the same title issued in 1963.be generally applicable to a large variety of similar to that used by Averin(2). The horizontal heater tube was saver soldered across two insulated copper end plates which served as electrodes; the bottom and sides were made of welded stainlesssteel plate. Thermocouples (chromel/ alumel in all tests) were laced inside the heater tube and longitu&ial traverses made under heating conditions to determine the location of the isothermal zone. External silver voltage leads and the four internal thermocouples were then located within this zone. PHYSICAL PROPERTIESThree anal ses of the glycol in the loop were made luring the tests; the composition ranged from 99.6 to 99.8 wt. % glycol (balance water). Values for specific heat, liquid density, latent heat of vapori...

Conductive sub-layer of twisted-tape-induced swirl-flow heat transfer in vertical circular tubes with various twisted-tape inserts

“…The constants,  k ,   ,  t , C 1e , C 2e , C 3e , and C  that appear in Eqs. (23) to (25), (34), (36) and (38) take the values given in Table 1.…”