Numerical analysis of a single loop nitrogen pulsating heat pipe

Abstract A novel two-dimensional CFD model for a cryogenic pulsating heat pipe (PHP) has been developed using ANSYS Fluent. The PHP is a two-channel single loop with an inner and outer diameter of 1.8 mm and 3.16 mm, respectively. Nitrogen is the working fluid, and the tube structure material is stainless steel. The total length of the PHP is 120 mm, with each of the three sections equal to 40 mm. The volume of fluid (VOF) model has been chosen as the multi-phase Eulerian model, and the Lee model as the phase interaction model. A user-defined function (UDF) code is written to solve the mass transfer between the two phases and the corresponding heat transfer due to evaporation and condensation. The CFD model helps to understand the transient behaviour of temperature and the evolution of flow patterns with time. Furthermore, an experimental setup of a single-loop PHP has been constructed with stainless steel as the tube material with similar capillary dimensions as stated above. The condenser section of the PHP is housed inside a tubular container filled with liquid nitrogen. The entire PHP assembly is insulated using a LN2 pool to prevent any heat leakage.