APPLICATION OF PSEUDO-THREE-DIMENSIONAL HEAT EXCHANGER
MODEL IN THE ONE-DIMENSIONAL SIMULATION OF THE VEHICLE
COOLING SYSTEM UNDER THE FTP-72 DRIVING SCHEDULE |
Jagun Koo 1, Huiju Yang 2, Yongkil Cha 2, Sangseok Yu 3 |
1CAE Team, Doowon Climate Control 2CAE Team, Hanon Systems 3Department of Mechanical Engineering, Chungnam National University |
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ABSTRACT |
In designing the heat exchanger model, the existing epsilon-number of transfer units (NTU) method cannot
reflect factors inside the heat exchanger, such as the local flow rate changes. Furthermore, it is difficult to apply a
three-dimensional model to a one-dimensional analysis since high computational power is required. In contrast, a
pseudo-three-dimensional heat exchanger model which has higher accuracy than the existing epsilon-NTU method and has
faster speed for application in one-dimensional analysis. However, pseudo-three-dimensional model has still improvements in
the simulation time as the mesh counts increase. In this study, the improved pseudo-three-dimensional heat exchanger model
was developed and integrated within a one-dimensional analysis loop capable of simulating vehicle driving and the cooling
system. The integrated model calculated the change in the energy consumption of the entire cooling system with the change
in the aspect ratio of the heat exchanger. Also, the optimal operation strategy of the cooling system, which incorporated a
proportional integral derivative controller of the three-way valve, was determined to reduce the parasitic losses. As a result,
parasitic loss of the cooling system decreased by 14.1 % as aspect ratio increased by 46 % under FTP-72 (UDDS) driving
schedule and simulation time was reduced 90.1 % while accuracy degrades only 2.7 %. |
Key Words:
Dymola, Modelica, Pseudo-three-dimensional heat exchanger model, Single-zone combustion analysis,
Staggered grid analysis, Three-way valve |
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