The reciprocating-mechanism driven heat loop (RMDHL) is a novel two-phase heat transfer device that could find many important applications in energy systems and electronic cooling. However, the previous RMDHL is based on a solenoid driver that may have difficulty in handling a large amount of heat transfer rate over a long distance due to the driver's inability to provide a large displacement volume. To overcome this difficulty, a bellows-type RMDHL demonstration model has been designed, fabricated, and tested. The results show that the bellows-type RMDHL has successfully overcome the weakness of the solenoid driver and may be employed for applications involving large heat transfer rates and over a large surface area. Another advantage of the bellows-type RMDHL is its potential to maintain an exceedingly uniform temperature over a relatively large surface. Additionally, the power consumption of the bellows driver was less than 5W when the power input to the cold plate was up to 600W, resulting in the ratio of driver's power input to the heat input to the cold plate being less than 1%, which represents a tenfold improvement over the solenoid-based RMDHL. All these technical improvements over the previous RMDHL have demonstrated significant progresses towards a refined RMDHL system for energy and electronics cooling applications. Copyright (c) 2012 John Wiley & Sons, Ltd.