Transient volumetric heat transfer coefficient prediction of a three-phase direct contact condenser

Abstract

An experimental investigation for the time dependent volumetric heat transfer coefficient of the bubbles type, three-phase direct contact condenser has been carried out utilising a short column (70 cm in total height and 4 cm inner diameter). A 47 cm active height was chosen with five different mass flow rate ratios and three different initial dispersed phase temperatures. Vapour pentane and constant temperature tap water as dispersed and continuous phases were implemented. The results showed that the volumetric heat transfer coefficient decreases with increased time until it almost reaches its steady state conditions. A sharp decrease in the volumetric heat transfer coefficient was found at the beginning of the operation and, diminished over a short time interval. Furthermore, a positive effect of the mass flow rate ratios on the volumetric heat transfer coefficient was noted and this was more pronounced at the beginning of the operation. On the other hand, the volumetric heat transfer coefficient decreased with an increase in the continuous phase mass flow rate and there was no considerable effect of the initial dispersed phase temperatures, which confirms that latent heat transfer is dominant in the process. List of symbolsA Cross-section area (m 2 ) C pc Specific heat of continuous phase (kJ/kg°C) hfg Latent heat of condensation (kJ/kg) _ m Mass flow rate (kg/s) Q Heat transfer rate (kW) t Time (s) T Temperature (°C) u Velocity (m/s) V Column volume (m 3 ) Z Axial height (m)Greek symbols q Density (kg/m 3 ) D Difference (-)

Transient analysis of the steam‐water direct contact condensation in the packed column

“…And some research results showed that the efficient energy recovery can be enhanced by utilizing the direct contact condenser. [13] The direct contact condenser has many advantages compared with surface heat exchanger, such as simpler structure, lower investment cost, higher heat transfer rate, and less corrosion and fouling. Thus, direct contact condensers are also applied for industrial applications commonly.…”

A new model for the drag coefficient of a swarm of condensing vapour–liquid bubbles in a third immiscible liquid phase

“…Sideman and Hirsch, 1965;Isenberg and Sideman, 1970;Jacobs and Major, 1982;Higeta et al, 1983;Raina et al, 1984;Lerner et al, 1987;Wanchoo, 1993;Mori, 2002 andKalman, 2003) and bubble trains (Sideman and Moalem, 1974;Letan, 1990 andKalman, 2006). More recently, Mahood et al (2014aMahood et al ( , 2014bMahood et al ( , 2015aMahood et al ( , 2015b studied, experimentally and theoretically, the direct contact condensation of a swarm of two-phase bubbles in a three-phase condenser.…”

Experimental measurements and theoretical prediction for the volumetric heat transfer coefficient of a three-phase direct contact condenser

“…Although this study is not representative of a real three-phase direct contact condenser, it has improved the general understanding of the condensation of a swarm of two phase bubbles in an immiscible liquid. More recently, Mahood et al [17][18][19][20] have undertaken a research programme concerned with the investigation of a bubble type threephase direct contact condenser. Different parameters, which have an effect on the characteristic behaviour of a three-phase direct contact condenser have been investigated experimentally and theoretically.…”