CONDENSATION COEFFICIENT AND WETNESS THERMAL LOSSES OF WET STEAM FLOW AT LOW PRESSURES | ||
| ERJ. Engineering Research Journal | ||
| Article 7, Volume 24, Issue 2, April 2001, Pages 113-133 PDF (579.31 K) | ||
| Document Type: Original Article | ||
| DOI: 10.21608/erjm.2001.71022 | ||
| Author | ||
| N.H. MAHMOUD | ||
| Dept. of Mech. Power Engng., Menoufia University, Shebin El-Kom, Egypt | ||
| Abstract | ||
| Condensation coefficient of wet steam flow at low pressures has been evaluated theoretically. It was found from the theoretical results th&t wet steam condensation coefficient depends upon: the pressure at ~ilson point, vapour supercooling, droplet sue, evaporation coeffkieht' and .4 index of isentropic expansion. Available data on the condensation coefficient of wet steam flow through nozzles are found to be dependent on the pressure values of both initial flow conditions and Wilson point. A comparison has been conducted between the present values of the condensation coefficient and that reported and required to minimize the difference between the predicted and measured pressure distributions in wet steam flow through nozzles. The agreement in the comparison is good. In order to verify the model, another comparison between a measured pressure distribution and a predicted one through a nozzle based on selected values for the condensation and evaporation coefficients is also carried out. 'The quality of agreement in this comparison is good. Moreover, entropy increase due to the irreversibility of heat and mass transfer proceses in wet steam has been estimated numerically. The numerical results show that increasing the condensation coefficient, droplet size and expansion rate as well as decreasing the evaporation coefficient tends to increase the wetness thermal losses during wet steam flow. | ||
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