M. Gurevich

Surface temperature measurement of a heated capillary tube by means of an infrared technique

We describe a method to measure the surface temperature of small-size devices by means of an infrared technique. The method is based on adjusting the temperature of the background to a level equal to the measured temperature of the object surface. The proposed method of infrared measurement was applied to investigate the average and local heat transfer coefficient in a small tube of inner diameter of 1.07 mm in laminar flow, in the range of Reynolds numbers 10 < Re < 400. It was shown that the heat transfer coefficient is much lower in the region of Reynolds numbers 10 < Re < 100 than that predicted theoretically for laminar flow in tubes of larger diameter.

Heat transfer to two-phase flow in inclined tubes

Abstract Experiments were performed to study the flow regimes and heat transfer in air–water flow in 8° inclined tubes of inner diameter of 49.2 and 25 mm. The flow regimes were investigated by using high-speed video technique and conductive tomography. The thermal patterns on the heated wall and local heat transfer coefficients were obtained by infrared thermography. Under the conditions studied, disturbance waves of different forms were observed. The analysis of the behavior of the heat transfer coefficients, together with flow visualization and conductive tomography showed that dryout took place in the open annular flow regimes with motionless or slowly moving droplets. Even under these conditions, the heat transfer coefficient is about 10 times higher than that for single-phase airflow.

Subcooled boiling of surfactant solutions

Abstract Boiling heat transfer from horizontal stainless steel tubes, submerged in subcooled surfactant solutions of various concentrations, was studied experimentally. The kinetic of boiling (bubble nucleation, growth and departure) was investigated by high-speed video recording in combination with Infrared Thermography. The specific features of boiling of surfactant solutions were revealed. It was found that the subcooled nucleate boiling of surfactant could not be described by a single curve, in contrast to water. A boiling hysteresis was found for degraded solutions. This phenomenon may be related to formation of a surfactant monolayer, which results in damping of an interfacial motion.

Boiling in capillary tubes

We present here a theoretical and experimental study of two-phase flow in a heated capillary tube. The flow parameters of a single-phase liquid, two-phase liquid-vapor, and single-phase vapor were analyzed in the frame of a one-dimensional model. The pressure, temperature and vapor quality measurements were carried out in a pipe of 1.0 mm inner diameter at various values of heat fluxes and mass flow rates and compared with theoretical predictions. The evolution of the bubble volume was studied both theoretically and experimentally. Using infrared technique, the temperature distribution on the heated tube surface was studied for various flow regimes. � 2003 Elsevier Ltd. All rights reserved.

Effect of particle motion on the wall’s thermal structure and on heat transfer

Abstract Experiments with spherical particles sliding and rolling in cocurrent and counter-current directions over a heated wall have been conducted to study the mechanism of heat transfer in a turbulent flow carrying coarse particles. The detailed distribution of the local temperature and heat transfer coefficient in the vicinity of moving coarse particles was obtained. Results of experiments show the effect of the particle motion and rotation on the temperature distribution of the heated wall and on the heat transfer in the turbulent boundary layer.