A method for producing work from heat including mixing a first working fluid F1 vapor with a second working fluid F2 vapor to form a third working fluid F3; atomizing and/or vaporizing a liquid into the third working fluid F3 to define a saturated working fluid; and expanding the saturated working fluid to perform useful work. A high pressure F1(2) portion of the first working fluid F1 may be expanded prior to the mixing step while the F2 vapor is compressed prior to the mixing step. The steps of compressing the F2 vapor and expanding the high pressure F1(2) portion of the first working fluid F1 may be carried out by an integral compressor and expander assembly (204/209). The integral compressor and expander assembly (204/209) may be positioned within a combined mixer assembly (300) with an internal mixing chamber (206) and outlets (375, 351) of both the compressor (204) and expander (209) are directed toward the mixing chamber 206.