Rida SN Mahmudah, Restu Widiatmono, Denny Darmawan
The choice of working fluid plays a crucial role in determining the thermal performance of heat exchangers, especially in high-temperature energy systems such as those used in nuclear power plants. This study evaluates and compares the thermal performance of four candidate fluids - water, molten salt, lead-bismuth eutectic (LBE), and FLiBe - in a shell-and-tube heat exchanger configuration. Transient conjugate heat transfer simulations were conducted using OpenFOAM v12 for each fluid at four different mass flow rates (0.01, 0.05, 0.25, and 0.5 kg/s), while maintaining a fixed temperature difference between the shell and tube inlets. Results indicate that water exhibits the highest heat transfer rate due to its large specific heat capacity. However, its effectiveness tends to decrease with increasing mass flow rate. LBE, benefiting from high thermal conductivity, demonstrates superior heat transfer effectiveness at low flow conditions, whereas FLiBe offers a consistent balance between heat transfer rate and efficiency across all flow regimes. These findings highlight the trade-offs between energy transmission and utilization: higher heat transfer rates do not necessarily correspond to higher thermal effectiveness. The study assumes constant fluid properties and excludes pressure drop considerations, which are acknowledged as limitations and open opportunities for future investigation. © Published under licence by IOP Publishing Ltd.
Physics Study Program, Universitas Negeri Yogyakarta, Sleman, Indonesia
