Theoretical and Experimental Study of Convective Condensation Inside a Circular Tube

Abstract

This paper presents a theoretical modeling and numerical and experimental investigations of the laminar convective condensation inside a circular smooth tube. The developed model includes the interaction between the surface tension, gravity, and shear stresses at the vapor-liquid interface and its cross influence on heat transfer. The influence of the gravity force, tube diameter, and temperature drop on the heat transfer at in-tube condensation of pure ethanol vapor is considered. The heat transfer coefficient as a function of the inclination angle of the condenser tube and the temperature drop between the vapor saturation and the wall temperatures is measured. A comparison of the experimental and numerical data is performed. The results of the numerical calculation are in good agreement with the experimental results. Numerical experiments have been carried out with the aim of predicting the time length of the transition to the steady-state regime after an abrupt change of the gravity level. It is shown that the transition time to the steady-state regime increases with an increase in the diameter of the condenser tube. The transition time to the steady-state regime under microgravity conditions is longer than that under normal gravity for a tube with a diameter larger than the value close to the capillary length of the working liquid.

The dynamics of a vapour bubble growth under the boiling of a subcooled liquid in low volumes

“…The shadow method has been used for investigation of the bubbles growth at the boiling process in small volumes at different temperatures of heating surfaces [25][26][27][28]. Schematic diagram of the experimental setup is shown in Fig.…”

Condensation heat transfer in microgravity conditions

“…In long channels (600 mm long) the flow is stratified under normal gravity and annular when gravity is ignored. Marchuk et al 38 Numerical Circular 1–5 mm ID channels with length from 100 to 200 mm Pure ethanol (99.8%) P sat = 440 mbar G = 1.66 kg m −2 s −1 Numerical simulations of laminar FWC inside a circular tube by means of a finite-element method Under microgravity the gravity force is weak and the surface tension forces decrease with the growth of the tube diameter. Marchuk and Kabov 67 Numerical Disk-shaped fin (61.25 mm radius of the disk) FC-72 T sat = 56.7 °C Δ T sat-wall = 5 K ṁ f = 0.012 kg min −1 Numerical simulations of FWC on disk-shaped fin considering capillary forces Due to the additional curvature of the disk-shaped fin, the condensate outflow is greater for the disk-shaped fin compared to a straight one.…”

Fin Shape Design for Stable Film-Wise Vapor Condensation in Microgravity

“…In works (Marchuk et al 2013;Marchuk 2015), a threedimensional film vapor condensation model on curved surfaces was developed, taking into account mass forces, surface tension, and friction on the surface of the condensate film. An evolutionary equation for the condensate film thickness was obtained.…”