Deionized water

used as working fluid

flows through a staggered array micro-cylinders-group with 3.5 mm width and 40 mm length

which are made of micro-cylinders with hydraulic diameter of 500 μm and heights of 500 μm

750 μm and 1000 μm.An experimental study is performed on the influence of heat flux on forced convective heat transfer in the micro-cylinders-group heated by an electricity heater.The flow rate and the temperature difference between the inlet and the outlet of micro-cylinder-group are measured and the Nusselt numbers are obtained over Reynolds numbers ranging from 100 to 1000.The experimental results indicate that heat flux has a significant effect on the convective heat transfer in the micro-cylinders-group.As the heat flux increases

the average temperature of the working fluid increases apparently

which decreases the Prandtl number

so that the convective heat transfer of the working fluid is weakened.On the other hand

the viscosity of the working fluid is lower at higher heat flux

which intensifies the molecular thermal motion and strengthens the flow disturbance

enhancing the heat transfer.As the heat flux increases at low Re

the adverse effects of the end-wall effect on convective heat transfer is weakened

and the temperature difference between the wall and the working fluid is increased

further enhancing the heat transfer.With the increase of Re

the influence of heat flux increment on the convective heat transfer decreases due to the weakness of end-wall effect.