Variable pressure power cycle and control system
AssigneeW. K. Technology, Inc.
InventorFred L. Goldsberry
Life of this patent
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Abstract
A variable pressure power cycle and control system that is adjustable to a variable heat source is disclosed. The power cycle adjusts itself to the heat source so that a minimal temperature difference is maintained between the heat source fluid and the power cycle working fluid, thereby substantially matching the thermodynamic envelope of the power cycle to the thermodynamic envelope of the heat source. Adjustments are made by sensing the inlet temperature of the heat source fluid and then setting a superheated vapor temperature and pressure to achieve a minimum temperature difference between the heat source fluid and the working fluid.
Claims29
A method of generating power using a Rankine cycle with a turbine, a working fluid, and including a heating phase within a variable thermodynamic envelope that substantially fills a thermodynamic envelope defined by a variable temperature heat source fluid and a heat sink, comprising adjusting the temperature and pressure of the working fluid at the turbine inlet in response to changes in the inlet temperature of the heat source to maintain a minimum temperature difference between the heat source fluid and the working fluid during the heating phase of the cycle.
A method of controlling a variable pressure supercritical Rankine power cycle utilizing a turbine, a condenser, a feed pump and a working fluid and including a heating phase comprising the steps of:
- a. sensing the inlet temperature of a heat source liquid;
- b. based on the heat source liquid inlet temperature and the working fluid and turbine utilized, selecting a superheated vapor point for the working fluid defining an isobaric pressure curve for the working fluid over the heating phase of the cycle, the isobaric pressure curve having a temperature substantially approaching the temperature of the heat source liquid at a point along the heating phase of the cycle;
- c. setting the back pressure immediately upstream of the turbine inlet to the pressure selected for the superheated vapor point for the working fluid;
- d. sensing the temperature of the working fluid at the superheated vapor point;
- and
- e. regulating the flow rate of the working fluid through the heating phase of the cycle so that the temperature of the working fluid at the superheated vapor point is maintained.
An apparatus for controlling a variable pressure supercritical Rankine power cycle utilizing a turbine, a condenser, a feed pump, and a working fluid and including a heating phase comprising:
- a. means for sensing the inlet temperature of the heat source liquid;
- b. means for selecting a superheated vapor point for the working fluid based on the heat source liquid inlet temperature and the working fluid and turbine utilized, the superheated vapor point defining an isobaric pressure curve for the working fluid over the heating phase of the cycle having a temperature substantially approaching the temperature of the heat source liquid at a point along the heating phase of the cycle;
- c. means for setting the back pressure immediately upstream of the turbine inlet to the pressure selected for the superheated vapor point for the working fluid;
- d. means for sensing the temperature of the working fluid at the superheated vapor point;
- and
- e. means for regulating the flow rate of the working fluid through the heating phase of the cycle so that the temperature of the working fluid at the superheated vapor point is maintained.
A method of converting heat from a variable liquid heat source to mechanical energy using a turbine, a condenser, a pump, a heat exchanger, and a working fluid to generate a supercritical Rankine cycle, the method comprising:
- a. selecting a working fluid having a critical temperature less than the temperature of the heat source liquid;
- b. vaporizing the working fluid isobarically by passing the working fluid in heat exchange with the liquid heat source at a supercritical pressure which maintains the working fluid at a preselected minimum temperature differential below the temperature of the heat source liquid during heat exchange;
- c. expanding the vaporized working fluid to generate mechanical energy;
- d. condensing and cooling the expanded working fluid;
- e. raising the pressure of the condensed and cooled working fluid;
- and
- f. repeating the cycle of steps (b) through (e).
Dependencies are inferred from the claim text.