The Daegu metro station fire on 18 February 2003 was a tragic accident that claimed 192 lives in South Korea. The fire was set by an arsonist in a stopped train at the Daegu metro station, and spread to another train arriving at the station on the opposite track. The present numerical study aims to reproduce the Daegu metro station fire using a transient 3-D CFD simulation with detailed geometry of the station and tunnels in order to understand the behavior of the smoke and heat responsible for human losses in such accidents. The actual motion of the arriving train was also considered by using a moving mesh technique, and the fire development and CO gas generation were modeled with the enthalpy and scalar source terms. The evolutions of the temperature and CO gas distributions in the station were obtained in detail from the present simulation. The heat and CO concentrations at some critical locations (such as staircases) were shown and discussed in detail. The results of the present numerical study could provide useful data for future emergency plans of metro stations in case of fire.

Haeinsa temple is famous for over 80 000 wooden printing blocks of Buddhist scriptures called Tripitaka Koreana and its storage halls, both of which have been registered as the world cultural heritages by UNESCO. The objective of the present paper is to investigate the ventilation flow in the storage halls of Tripitaka Koreana in the case of building rearrangement in Haeinsa temple. Three-dimensional flow simulations were performed with the detailed geometry of all buildings in the temple. The slatted windows on walls of the storage halls and Tripitaka Koreana stored in the shelves inside the storage halls were modeled in detail to predict reliable ventilation performance. A tree canopy model was also adopted to take into account of the effect of the forest surrounding the temple. Wind velocities as inlet boundary condition were imposed from meteorological statistical data. The numerical results were obtained for the effects of the wind direction, wind speed and tree canopy model on the ventilation performance of the storage halls. It was shown from the numerical results that the ventilation flow distribution at the storage halls in the case of building rearrangement would not be significantly altered compared to that before rearrangement.

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Abstract. This paper describes numerical methodologies of the flow and heat transfer analysis in heat exchangers of various types. Heat exchangers considered in the present study include a louver fin radiator for a vehicle, a shell and tube heat exchanger for HVAC and plate heat exchangers with patterns of herringbone and of dimple used in waste heat recovery. For the analysis of the louver fin radiator, a 3-D Semi-microscopic Heat Exchange (SHE) method was used. SHE was characterized by conjugated heat transfer analysis for the domain which consists of water in a tube, tube wall, the region where passes through the louver fin and ambient air. It is shown that both the air flow in louver fin area and the water flow inside the cooling water passages are successfully predicted along with the heat transfer characteristics. A conjugate heat transfer analysis in a shell and tube heat exchanger was also performed. For the analysis of entire shell side of the heat exchanger, geometric features such as tubes, baffles, inlet and outlet were modeled in detail. It is shown from the analysis that a design modification for better flow distribution and thus for better performance can be proposed. Finally an analysis method for the conjugate heat transfer between hot flow-separating plate-cold flow of a plate heat exchanger was proposed. By using periodic boundary conditions for the repeating sections and appropriate inlet and outlet boundary conditions, the heat transfer in a plate heat exchanger with patterns of herringbone and of dimple was successfully analyzed. Comparisons of the present numerical results are in a good agreement with available experiment data.

A numerical analysis was conducted to investigate the flow and heat transfer in a large plate heat exchanger. For the purpose of investigation on the whole flow field inside a large plate heat exchanger, the microscopic method by using actual geometry is not practical since it requires huge computational resources. In the present study, a semi-microscopic method by using a porous media approach has been adopted in order to predict the overall flow and heat transfer performance for the large plate heat exchanger. The pressure drop and heat transfer characteristics of the flow passages inside the heat exchanger was obtained first from the microscopic simulation for the flow inside passages and heat transfer through the plates by using the detailed geometry of one representative repeating section of the heat transfer plate. These results were used as characteristics of the porous media replacing the complex flow passages to simulate the large plate heat exchanger as a whole. The overall performance predicted from the semi-microscopic method agrees well with available experimental data. The numerical method in the present study can be applicable to the different types of large heat exchangers that have complex geometry in order to predict the overall performance.