Patent Application
20130160450
The present disclosure relates generally to Organic Rankine Cycle (ORC) systems and, more particularly, to a secondary cooling system therefor.
The Organic Rankine Cycle (ORC) is a vapor power cycle with an organic fluid refrigerant instead of water/steam as the working fluid. The working fluid is heated in an “evaporator/boiler” by a source of waste or low quality heat. The fluid starts as a liquid and ends up as a vapor. The high-pressure refrigerant vapor expands in the turbine to produce power. The low-pressure vapor exhausted from the turbine is condensed then sent back to the pump to restart the cycle.
The simple Rankine cycle used for power generation follows the process order: 1) Adiabatic pressure rise through a pump; 2) Isobaric heat addition in a preheater, evaporator and superheater; 3) Adiabatic expansion in a turbine; and 4) Isobaric heat rejection in a condenser, although other cycle modifications are possible such as the addition of a vapor-to-liquid recuperator.
ORC generators may be hermetic or non-hermetic. Non-hermetic generators do not share the working fluid environment and are typically cooled by air or water. Hermetic generators share and are cooled by refrigerant from the main cycle.
An Organic Rankine Cycle (ORC) system according to an exemplary aspect of the present disclosure includes a turbine driven by a working fluid and a generator driven by the turbine. The generator includes a rotor volume at sub-atmospheric pressure, the working fluid sprayed into said rotor volume.
An Organic Rankine Cycle (ORC) system according to an exemplary aspect of the present disclosure includes a secondary cooling flow circuit in communication with a rotor volume at sub-atmospheric pressure, said secondary cooling flow circuit sprays a working fluid into said rotor volume.
A method of operating an Organic Rankine Cycle (ORC) system according to an exemplary aspect of the present disclosure includes spraying a working fluid into a rotor volume at sub-atmospheric pressure.
Various features will become apparent to those skilled in the art from the following detailed description of the disclosed non-limiting embodiment. The drawings that accompany the detailed description can be briefly described as follows:
With reference to
A secondary cooling flow circuit 51 communicates a relatively small amount of the cooling fluid to the generator 22 to provide thermal management thereof. The secondary cooling flow circuit 51 generally includes a cold heat exchanger 52 to condense the working fluid and effectively pulls the working fluid out of the housing 40 through a main drain line 54. The secondary loop condenser 52 also receives cooling fluid. The main drain line 54 removes vapor and liquid working fluid from the housing 40 and generates a sub-atmospheric pressure within the rotor volume G.
Below the cold heat exchanger is a receiver tank 53 to accumulate liquid. A pump 56 pumps the condensed/cooled working fluid from the receiver tank 53 to a valve system that consists of a restriction valve 57, and a check valve 59. The valve 57 is varied to set the pressure at the pump exit. If the valve 57 is wide open then the pump exit pressure will be only slightly above the rotor cavity pressure and well below the primary system pressure. The check valve 59 will remain closed and no refrigerant will flow through line 261.
As valve 57 closes, the pump exit pressure rises until it exceeds the primary system pressure at 26 and refrigerant flows out of the secondary cooling loop 51 to the primary loop. This flow is necessary because flow leaks into the secondary cooling loop 51 through the seal 46 and must be removed or else loop 51 may eventually fill up with liquid working fluid. Valve 57 is thus used to control the amount of working fluid in circuit 51.
From Valve 57, the liquid working fluid flows into the stator cooling jacket to absorb heat from the stator 42 generated by joule heating, and the liquid working fluid is partially boiled.
The working fluid is then sprayed into the rotor volume G through a nozzle 58. It should be appreciated that one or more nozzles may be circumferentially arranged about the rotor 44. Since the working fluid received heat from the stator 42, the working fluid is now two-phase. A small pressure drop may be used at the nozzle to disperse the working fluid. As the working fluid is in a saturated environment within the housing 40, the working fluid will be at a temperature determined by its pressure. The working fluid passes between the rotor 44 and the stator 42 and further receives heat generated by windage and rotor internal losses when sprayed toward the rotor 44. The working fluid thereafter collects in the housing 40 and renters the main drain line 54.
With reference to
It should be understood that relative positional terms such as “forward,” “aft,” “upper,” “lower,” “above,” “below,” and the like are with reference to the normal operational attitude of the vehicle and should not be considered otherwise limiting.
It should be understood that like reference numerals identify corresponding or similar elements throughout the several drawings. It should also be understood that although a particular component arrangement is disclosed in the illustrated embodiment, other arrangements will benefit herefrom.
Although particular step sequences are shown, described, and claimed, it should be understood that steps may be performed in any order, separated or combined unless otherwise indicated and will still benefit from the present disclosure.
The foregoing description is exemplary rather than defined by the limitations within. Various non-limiting embodiments are disclosed herein, however, one of ordinary skill in the art would recognize that various modifications and variations in light of the above teachings will fall within the scope of the appended claims. It is therefore to be understood that within the scope of the appended claims, the disclosure may be practiced other than as specifically described. For that reason the appended claims should be studied to determine true scope and content.
