Thermal performance analysis of flat heat pipe with graded mini-grooves wick

Highlights: • A novel graded-grooves wick design was put forward for flat heat pipe. • An accurate mathematical model is established for mini-grooves flat heat pipe. • Effective thermal conductivity of proposed heat pipe is increased by 12.4%. • Local wick size & vapor chamber volume have great effects on thermal performance. • Grooves wick in slope type is suggested for practical application. Thermal management of micro electronic devices is one of the major issues for electronics application. Mini-grooves flat heat pipe is suitable to be used for small space electronics rapid cooling due to its high thermal conductivity, simple structure and good temperature uniformity. In this paper, an axial fluid flow and heat transfer mathematical model of mini-grooves flat heat pipe in steady state is built to study the axial distributions of key parameters such as pressure, velocity and wall temperature. As the wick structure plays an important role in the mini-grooves flat heat pipe heat transfer enhancement, the influence of mini-grooves size and wall with grooves along the axial direction on the heat transfer coefficient of mini-grooves flat heat pipe is studied. It is found that aiming at designing the optimum mini-grooves flat heat pipe, the local wick needs to be close to in saturated state, and the vapor chamber needs to be large. In this way, a novel graded-grooves wick design is put forward for flat heat pipe, which can increase the effective thermal conductivity coefficient by 12.4% with heat transfer rate 5.0 W. And the grooves wick in slope type with simple fabrication accords with practical application.