Condensation in Tube Heat Exchanger

book

English

Heat transfer and fluid behavior in different heat exchanger configurations have been studied for over sixty years . More recently assisted by numerical simulations to describe the flow and heat transfer behavior, including Computational Fluid Dynamics approaches for the analysis . Boiling and condensation phenomena inside mini-channels have lots of applications: in heat sinks or power electronics, temperature control in the aerospace industry, refrigeration of fuel injection systems, boilers components in fuel cells, cooling the sections in contact with plasma in fusion reactors, condensing units of air conditioning equipment in cars, and so on. Flow boiling and flow condensation are often regarded as two opposite or symmetrical phenomena involving the change of phase. In both cases of phase change the annular flow structure seems to be mostly susceptible to common modeling. In the case of flow boiling in conventional channels one can expect that bubble nucleation renders the process of heat transfer not to have its counterpart in the condensation inside tubes. Similarly in as the case of inside tube condensation, where the collapse of bubbles forms continuous liquid, is the condensation specific phenomenon. Most of correct modeling of heat transfer in case of condensation inside channels relates the heat transfer coefficient to the friction coefficient, contrary to modeling in case of flow boiling. The effects of condensation during two-phase flow in the mini-channels heat exchanger are investigated for horizontal, vertical and inclined positions with different connection methods. This book examines some of these important effects of fluid condensation in the wavy micro-channels heat exchanger. In the individual chapters the cases are numerically solved, which occur in technical practice and their correct solution is necessary for the further action in connection with the design of the tube heat exchangers. The course of fluid temperatures, surface tension, heat flux, mass flux, quality vapour, surface roughness, friction factor, thermal and hydrodynamic behavior, gravitational orientation, position and connection are important parameters that significantly affect the heat transfer characteristics in the exchanger in phase changes of flowing fluids during condensation or evaporation. The important role play dimensionless numbers here (Nusselt number, Reynolds number, Prandtl number , Weber number, Bondy number, Boiling number ets.) whose experimental calculation or prediction on the basis of suitable correlation relations is a necessary part of calculation and design procedures.

Tube heat exchanger; condensation

KUBÍN, M.; HIRŠ, J.

1. 1. 2024

VUTIUM

Brno

978-80-214-6205-2

Condensation in Tube Heat Exchanger

VUTIUM

první

300