Determination of Effect of Salt Content in Cooling Liquid on the Result of Cable Capacitance per Unit Length Measurement

Capacitance per unit length and related wave resistance refer to the main characteristics of a number of cable products, such as communication cables, control cables or radio-frequency cables. The capacitance per unit length value is regulated by the standards for appropriate types of cables. This study describes the technical implementation of the electrical method of measuring of the capacitance per unit length of the electric cable directly on the production line. It is shown that the change in specific electrical conductivity of water, which a capacitance transducer is dipped into, has a significant impact on the outcome of in-process control of cable capacitance per unit length. A method of offset from the impact of this measurement on the control results is suggested.

Simulation Study of Spiral Electrode Capacitance Sensor for Measuring Concentration of Gas-Solid Two-Phase Flow

Gas-sold two-phase flow is a typical and complex flow form in the natural world and the industrial process. The accurate measurement of the parameters is the key problem for improving the industry control quality and promoting enterprise economic benefit. Three-dimensional finite element simulation of spiral electrodes capacitance sensor was put up by ANSYS in this paper. The results from simulation show that spiral electrode capacitance sensor has an obvious advantage. The sensor has uniform sensing filled, and the capacitance value has nothing to do with flow pattern which is only related to solid concentration change. There is good linear correlation between capacitance value and solid concentration. Relationship graph between capacitance value and solid concentration was obtained by calculated. In addition, with the FEM the qualitative analyses to the effect of each structural parameter of the capacitance transducer on its capability were made. These can provide bases and supports for optimum design of this kind of sensors. Comparing with ECT, it is a simply and easy-implemented method of concentration measurement using spiral electrode capacitance sensor.

Capacitive Void Fraction Measurements and Probabilistic Flow Pattern Mapping of Horizontal Refrigerant Flow

A capacitive void fraction sensor was developed to study the dynamic behavior of refrigerant two-phase flows in horizontal macro-scale smooth tubes of evaporators used in air-conditioning and heat pump applications. A first prototype was successfully tested with air-water flow. The dielectric constant of liquid HFC refrigerants however is much smaller than the one of water, which results in much smaller capacitances to be measured. Therefore an improved version of the capacitance transducer was developed to make dynamic measurements of these HFC fluids possible. The sensor signal can be used for flow pattern detection and void fraction measurements of high pressure HFCs. A macro-scale test facility for two-phase flow and heat transfer studies of high pressure HFCs was designed and constructed. The adiabatic test section consists of a sight glass with high speed camera and the capacitive void fraction sensor. Two datasets of sensor signals were gathered using R410A and R134a respectively (G = 200–500kg/m2s and x from 0 to 1 in steps of 0.025 at Tsat = 15°C). To find more objectivity in flow pattern mapping, a signal analysis was performed. The average, the variance and a high frequency parameter were found suitable for flow regime classification into slug flow, intermittent flow and annular flow by using the fuzzy c-means clustering algorithm. A probabilistic flow pattern map is presented for the HFC data. These maps clearly quantify the width of the transition zones and can be applied for probabilistic heat transfer and/or pressure drop modeling.