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A Quasi-Three-Dimensional Multiscale Model for Two-Phase Simulation of Multi-Stream Plate-Fin Heat Exchangers

Niroomand, Reza | 2020

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 53303 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Saeedi, Mohammad Hassan; Kazemzadeh Hannani, Siamak; Mafi, Mostafa
  7. Abstract:
  8. The present thesis aimed to develop a thermal-hydraulic model for simulation of multi-stream plate-fin heat exchangers. In this study, a multi-scale point of view was employed for three-dimensional simulation of multi-stream plate-fin heat exchangers. This is a cost-effective method that reflects the effects of complex phenomena at the micro-scale in the macro-scale model. In this model, fluid and solid matrix temperature distributions were obtained in the three-dimensional space, considering conduction heat transfer through separating plates, side plates, cap plates, and transverse conduction through fins. The modular form of the model has facilitated layer-by-layer simulation of parallel and cross flow heat exchangers. This model was successfully validated using numerical and experimental case studies. The results showed that the total simulation time is decreased by 94.6% for a two-phase six-stream heat exchanger with 40 repeating unit cells. Moreover, the average of the heat transfer rate per unit cell in the heat exchanger with 15 unit cells was 88.4% more than a heat exchanger with 1 unit cell. Thermal simulation of the cross-flow heat exchanger showed that the average of the heat exchange between streams is reduced by 9.1% compared to the counter-current flow configuration ones. The developed code was also employed to evaluate the effect of inlet mass flow deviation, maldistribution of inlet fluids, and stacking patterns on the thermal performance of the heat exchanger
  9. Keywords:
  10. Two Phase Flow ; Multiscale Modeling ; Plate-Fine Heat Exchange ; Multi Stream Heat Exchanger (MHEX) ; Quasi Three Dimentional Modeling ; Thermohydraulic Model

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