Boiling-Curve Measurements From a Controlled Heat-Transfer Process

Abstract

Feedback has been introduced around a boiling heat-transfer process in such a way that stable operation of the process has been obtained in all boiling regions including the transition region, in which, as is well known, the process itself is unstable. This system makes it possible to obtain much new information concerning both the steady-state and dynamic characteristics of boiling heat-transfer processes. Pool-boiling data which were obtained by the use of this system are presented. Accurate measurements of heater voltage and current were obtained by a new technique involving the use of digital instruments. These data are presented in the form of plotted experimental points in the nucleate, transition, and film boiling regions. The new measurement technique is described. Values of n in the equation q/As = CTdn are determined for all three boiling regions, where q = Btu/hr, As is heater surface area, and Td is temperature difference between heater surface and ambient liquid. The ambient liquid is distilled water maintained at saturation temperature under atmospheric pressure.

Investigation of pressure drops and heat transfer coefficients for loss of coolant evaluation. Quarterly progress report for period ending December 30, 1973

“…The data of Peterson et show a peak q" at substantially lower values of (6) ATsat• (See Fig.9) The value of ATsat at which the peak q" occurs seems to depend on flow rate here. The data obtained in the present investigation, which was obtained at a substantially lower G than that used by f .…”

“…The agreement appears to be reasonable. However, the data (6) of in terms of q" vs. AT It is seen that all of this data shows a sat peak q" at a AT of about 150 'F. The data of Ellion behave simil-…”

Snares of Pool Boiling Research: Puiting Our History to Use

“…But their artful manipulation of the electric supply was done with. a sophisticated feedback control system that controlled the temperature of the wire (a system developed by Peterson and Zaalouk (1971)) and their temperatures were obtained by measuring the resistance of the wire. Sakurai and Shiatsu' s transition boiling data formed a hysteresis loop within the already multiple-valued boiling curve.…”

Apparatus for investigating boiling phenomena in a fibrous porous medium

“…Water level in the cell is controlled simply by interfacing a capacitive proximity switch with a normallyopen solenoid valve to meter flow of heated make-up water, and does not interact with the other components of the control system.The Surface Temnerature Control SystemThe temperature of the boiling surface of the copper heating block is one of the controlled variables for the boiling experiment. Since minimal instabilities are encountered in this boiling study, adequate control is maintained throughout the experiment with a standard PID controller, rather than the complex systems needed for control of classical pool boiling studies that utilize surface temperature as the control variable[12][13][14][15].As previously mentioned, the temperature of the heater surface is calculated from the readings of three thermocouples positioned within the heater block in proximity to the boiling surface. To facilitate control of surface temperature, the control software interfaces with the data A schematic of the interface between the data acquisition and process control systems.acquisition system and the temperature controller.…”