Thermodynamic cycle operating at low pressure using a radial turbine

A method to operate a thermodynamic cycle involving a working gas/fluid whereby the working gas/fluid passes from a hot, upstream side to a cold, downstream side of the thermodynamic cycle through a system comprising an inlet channel, an expansion machine operating at pressures below 10 bar maximum pressure, and an electricity generator operably coupled to the expansion machine so as to generate electricity, wherein the method comprises:

• employing a single stage radial turbine as the expansion machine;
• wherein the single stage radial turbine comprises a high pressure side, an inlet at the high pressure side coupled to the inlet channel, a low pressure side and rotating turbine blades arranged on an axle defining a Z direction, and
• wherein the single stage radial turbine is operated at a dimensionless speed in a range of 0.55-0.85;
• receiving heat from a heat source that is at least one of the following:
• geothermal heat, solar heat, industrial waste heat and heat from combustion processes, wherein the heat used has a temperature within a range of 60-120° C.;
• passing a working gas/fluid through the single stage radial turbine comprising at least one of CO2, solvent, amine, and water;
• partly or wholly removing condensing liquid in the single stage radial turbine away from the single stage radial turbine towards an absorption chamber by at least one of allowing the condensing liquid to escape downstream of the inlet channel, but upstream of the rotating turbine blades, and allowing the condensing liquid to escape upstream of the inlet channel;
• operating the single stage radial turbine at a ratio of pressures on the hot, upstream side versus the cold, downstream side of the thermodynamic cycle to be in a range of 6-9;
• and
• maintaining a pressure on a cold side of a thermodynamic process below 0.8 bar by providing cooling to the working gas/fluid on the cold side.