Improving heat transfer and eliminating Geyser boiling in loop thermosyphons: Model and experimentation

•A new design of a loop thermosyphon was presented and tested.•Geyser Boiling occurrence was eliminating in the loop thermosyphons with flat evaporators.•The used of wick structures on a vertical internal wall of flat evaporator eliminates Geyser Boiling.•Mathematical model was developed to predict loop thermosyphon thermal behavior.