School of Mechanical Engineering Dvir Mendler
School of Mechanical Engineering Seminar
Wednesday, April 17, 2019 at 14:00
Wolfson Building of Mechanical Engineering, Room 206
Wind Effect on an Induced Flow Air Cooled Condenser
Dvir Mendler
M.Sc. student of Prof. Alexander Gelfgat
Air Cooled Condensers (ACC) are the largest and most expensive part of the thermoelectric power plant. The ACC role in the Organic Rankine Cycle (ORC) is crucial to the power plant power output since its performance sets the turbine back pressure. In this work an "induced flow ACC" will be investigated, which means the fans are located above the tubes bundle and intake air from it, then create a jet upwards. The ACC size can reach hundreds of meters length and ~10 meters width with height of 5-12 meters. This geometry specification demands the use of large ground areas which exposed to ambient conditions.
During normal measures of the power plant performance, a sudden decrease of power output appeared, this power output reduction was directly linked to wind velocity at the site. In addition to that, ACC fans showed large oscillations in power consumption and a rise of back pressure was noticed during winds. All the above connect the ACC performance to the reduction of power output, hence a computational experiment using CFD was planned to produce a complete picture of the physical phenomena.
Once the computational model was produced from ~10 million cells, a case was built with the main components characteristics as elaborated in this work. The analysis pointed to a decrease in fans flow rate during winds, that leads to a decrease of the effective heat exchanging area of the ACC bundle. This observation was validated by actual measurements of the fans flow rate. The analysis also showed unique flow pattern that was validated by smoke tests. Calculating the decrease of fans flow rate with the effective heat exchange area explains the decrease of power output.
A comprehensive study of the flow field using many analyzes to eliminate different theories, produced an explanation for the flow behavior causing this decrease in performance. The full theory behind this flow phenomena is given in the results and conclusion chapter of this work. In addition, a simple cost-effective solution is offered to reduce wind effect on ACC with minimal impact on normal operation.
