A Comparative Study of the Oil-Free Centrifugal Water Chillers with the Flooded or Falling Film Evaporator—A Case Study

Kuo-Shu Hung, Jenn-Chyi Chung, Chung-Che Liu, Jun-Jie Lin and Chi-Chuan Wang
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Kuo-Shu Hung: Green Energy & Environment Research Laboratories, Industrial Technology Research Institute, Chutung 310, Taiwan
Jenn-Chyi Chung: Green Energy & Environment Research Laboratories, Industrial Technology Research Institute, Chutung 310, Taiwan
Chung-Che Liu: Green Energy & Environment Research Laboratories, Industrial Technology Research Institute, Chutung 310, Taiwan
Jun-Jie Lin: Green Energy & Environment Research Laboratories, Industrial Technology Research Institute, Chutung 310, Taiwan
Chi-Chuan Wang: Department of Mechanical Engineering, National Chiao Tung University, Hsinchu 300, Taiwan

Energies, 2019, vol. 12, issue 13, 1-11

Abstract: A comparative study regarding the performance of real-scale oil-free centrifugal chillers having the flooded evaporator or falling film evaporator was conducted in this study. The nominal capacity for the test chillers was around 200~230 USRT (US refrigeration ton) (703~809 kW). The compressors of the two chillers were identical and R-134a was used as the working fluid. Both evaporators employed the same enhanced tubes (GEWA-B) to fulfill phase change. Tests were conducted in full, 75%, 50%, and 25% loading. Test results indicate that both chillers contained a comparable system performance with an integrated part-load value of around 8.62~8.63. The overall heat transfer coefficient for the flooded evaporator was appreciably higher (20~40%) than the falling film evaporator. This is because the falling film flowrate was below the threshold value and the heat transfer was dominated by evaporation mode. Yet, the heat transfer performance for the falling film evaporator was further jeopardized due to starvation of the film flowrate (partial dry-out), especially in the middle or bottom of the tube bundle. This phenomenon became even more pronounced at partial loading (25%), whereas the flooded evaporator did not reveal such a performance dip at partial loading.

Keywords: oil-free centrifugal chiller; flooded evaporator; falling film evaporator; heat transfer (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2019
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