Theoretical study in Single-Phase Forced-Convection Heat Transfer Characteristics for Narrow Annuli Fuel Coolant Channels

The heat transfer characteristics of downflow in the single-phase forced-convection will be investigated theoretically with narrow vertical annuli sub-channels (WWR-M2 channel) using THMOD2 code. The main objective for this study is to investigate in turbulent flow region the applicability of existing heat transfer equations (i.e. Dittus-Boelter, Colburn, and so on) in the narrow vertical annuli channel, which is modelling and simulating sub-channel of 3 mm spacing (gap) and 600 mm in active length in the fuel elements for thermal hydraulic analysis tasks of the WWR-M2 research reactor or any other type. As a result, it was revealed that by use of equivalent hydraulic diameter, existing correlations are applicable to a WWR-M2 channel as narrow as 3 mm in gap for turbulent flow though the precision and Reynolds number are different among the heat transfer correlations. The New heat transfer equation for sub-channels of WWR-M2 channel heated from one side or both sides will be proposed