Доступ предоставлен для: Guest

ISSN Online: 2377-424X

ISBN Print: 0-89116-559-2

International Heat Transfer Conference 8
August, 17-22, 1986, San Francisco, USA

THE DITHER-TECHNIQUE FOR STEADY-STATE TRANSITION BOILING MEASUREMENTS

Get access (open in a dialog) DOI: 10.1615/IHTC8.2580
pages 501-506

Аннотация

A simple control system for electrically heated test sections is presented allowing for steady-state temperature controlled experiments in the transition region. Due to the static nonlinearity caused by the electrical heater and the ON-OFF controller used, the closed loop behavior of the system undergoes high amplitude limit cycle oscillations in the mean wall temperature if transition boiling experiments are carried out. By injection of a high frequency sine wave signal (dither) with properly chosen amplitude and frequency the system behaves similar to a proportional controller and such oscillations vanish. The reliability of this method is tested by experiments with refrigerant R114 flowing upward in a vertical nickel tube with 14 mm inside diameter and 1 mm wall thickness. The tube is surrounded by an indirectly heated copper shell divided into several independently controlled sections.