I think for a "titanothermal" system, you use the right density hydrocarbon as the working fluid in the "boiler", and 3-D print the components out of H2O :-)
Except water ice isn't a very good heat conductor, so the evaporator / condenser might have to be something else. Ice could be used for other parts, though.
Except water ice isn't a very good heat conductor, so the evaporator / condenser might have to be something else. Ice could be used for other parts, though.