A study on a potential of a small thermosyphon solar organic Rankine cycle system for
generating power under a concept of thermosyphon to generate pressure head in fluid without pump
was undertaken. R134a was the working liquid which boiled in a 2 m2 flat plate solar collector. The
vapor expanded through an expander which was modified from a scroll compressor of automobile airconditioner
and a mechanical work was generated. After that the vapor condensed completely in the
condenser of which the height was 3 m from the solar collector and the condensed liquid entered the
solar collector to restart the new cycle. The results on a clear sky day showed that the maximum
mechanical power was about 161.6 W and the maximum cycle efficiency was around 18%.