| Title |
An experimental investigation of the effect of airflow heating and humidification on a water droplet’s thermal state and phase changes / |
| Authors |
Puida, E ; Miliauskas, G ; Poškas, R ; Poškas, P ; Paukštaitis, L |
| ISBN |
9781775922162 |
| Full Text |
|
| Is Part of |
ATE HEFAT 2021: 15th international conference on heat transfer, fluid mechanics and thermodynamics, virtual conference, 26-28 July 2021: proceedings.. [S.l.] : HEFAT, 2021. p. 224-229.. ISBN 9781775922162 |
| Abstract [eng] |
This experimental investigation highlights the influence of the temperature and humidity of gas flow on water droplet phase changes for the effectiveness of technologies designed to recover heat from exhaust wet flue gas. The experiments were carried out in an original experimental rig where a water droplet hanged on a thermocouple in the atmospheric pressure airflow of 21ºC, which was then heated to the temperature of 112–114ºC and humidified to different levels. The airflow was humidified by vapor from a water evaporator. The vapor flow was defined by weighting the vapor generator. In the experimental rig, the humidity of the flowing air was defined by the volume and mass fractions of water vapor calculated based on the flows of heated atmospheric air and additionally supplied water vapor. Thermal images of the heating droplet were taken every second measuring the temperature of the water covering the thermocouple ball. A variation diagram of the droplet equivalent diameter was compiled by image recognition code analysing the photos of synchronous filming (25 frames per second). The droplet equivalent diameter was defined as the diameter of a sphere whose volume equals to the volume of the droplet covering the ball. The results of the experiment demonstrated the substantial influence of additional air humidification on the intensity of transfer processes in droplets in transitional as well as equilibrium evaporation regimes. Furthermore, additional humidification also significantly influences the variation of the droplet’s thermal state. The temperature of equilibrium evaporation is also affected by air humidification, but the initial temperature of water is influential only in the transitional phase change regime. The results confirmed that transitional regimes could be defined qualitatively using dimensionless parameters expressed through the ratio of the dew point temperature with the droplet equilibrium evaporation temperature and the initial droplet water t0 temperature. |
| Published |
[S.l.] : HEFAT, 2021 |
| Type |
Conference paper |
| Language |
English |
| Publication date |
2021 |
