Patent ID: 8839620

Claim:
An engine waste heat recovery system comprising: an engine configured to reject heat to a working fluid; a heat exchanger configured to receive the working fluid; first and second stages respectively including first and second vane assemblies each having a hub supporting vanes radially movable relative to its hub, the first stage including a high pressure chamber and a first intermediate pressure chamber, and the second stage including a second intermediate pressure chamber and a low pressure chamber, the high pressure chamber configured to receive the working fluid from the heat exchanger, the first and second intermediate pressure chambers fluidly coupled to one another, the first vane assembly configured to rotate from the high pressure chamber to the first intermediate pressure chamber with the second vane assembly configured to rotate from the second intermediate pressure chamber to the low pressure chamber; and a balance valve operable to balance flow through the first stage and the second stage by selectively increasing or decreasing flow of the working fluid to the second intermediate pressure chamber.