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Aerothermodynamically Re-Design of an Air-Cool Heat Exchanger Fin Configuration Utilized for Cooling the Lubricating Oil of a Gas Turbine Unit Benefiting from Numerical Simulation

Kargarian, Abbas | 2018

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 50798 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Darbandi, Masoud
  7. Abstract:
  8. The lubricating oil is commonly used to cool down the moving parts of turbine gas systems. In many applications, this oil is cooled down using a recirculating water circuit. The water is then cooled down using an air-cooled heat exchanger. Any deficiency in aerothermodynamic design of such heat exchanger would result in high temperature of gas turbine moving parts such as bearings. Obviously, this mal-performance has adverse effect on the lifetime of these parts and their maintanence aspects. Since the good performance of air-cooled heat exchanger has numerous advantages for the performance of related gas turbine unit, it is mandatory to design these heat exchangers in minimum sizes and weights; albeit, with the highest guaranteed efficiencies. This is why such heat exchangers are designed and used in compact-type and they are equipped with numerous long continuous plate fins. In this research, the purpose is to aerothermodynamically re-design the basic configuration of a compact heat exchanger, which is utilized in a gas turbine unit. The main objective is to improve the thermal performance of this heat exchanger without enlarging its size and with no increase in its weight. This study is carried out using the CFD simulations. The research is conducted in three parts as follows: 1) the complete heat exchanger is modeled as a collection of several small heat exchangers, where each heat exchanger is restricted to a finite space between two consequent fins. Then, the numerical simulation is used to obtain the thermal and hydrodynamic performances of these spaces considering different inlet water temperatures. 2) Collecting the data from all the fins in step 1, a new aero-thermodynamic model is developed to simulate the full heat exchanger configuration. The simulation is performed using MATLAB domain. The simulation calculates the pressure drop and temperature distribution within the entire heat exchanger. 3) The third part is to investigate the effect of structural parameters of heat exchanger on its performance; in particular, the impact of the distance between the fins, the material of fins, and the influence of turbulators on the overall performance of heat exchanger. Eventually, the heat exchanger structure is redesigned aero-thermodynamically to improve the performance and reliability of the related gas turbine
  9. Keywords:
  10. Matlab Software ; Fins ; Gas Turbines ; Numerical Simulation ; Air-Cooled Heat Exchanger ; Fin-Tube Plate ; Redesign Heat Exchanger ; Computational Heat Transfer ; Oil Cooling

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