Turboexpansion reversible heat pump cycle

Abstract

A working fluid circulates through a heat pump cycle in a first direction. Heat is transferred from a first environment to a working fluid. The working fluid is pressurized by a compressor. Heat is transferred from the working fluid to a second environment different from the first environment. A first portion of the working fluid is flowed through a throttle valve. A second portion of the working fluid is flowed to a turbine wheel of a flow-through electric generator. Electrical power is generated by the generator in response to the second portion of the working fluid flowing across the turbine wheel. The working fluid can circulate through the heat pump cycle in a second direction opposite the first direction. Regardless of whether the working fluid flows through the heat pump cycle in the first or second directions, impellers of the generator rotate in the same direction.

What is claimed is: 
     
         1 . A heat pump system comprising:
 a first heat exchanger configured to exchange heat between a working fluid and a first environment in which the first heat exchanger is disposed;   a compressor in fluid communication with the first heat exchanger, the compressor configured to pressurize the working fluid;   a second heat exchanger in fluid communication with the compressor, the second heat exchanger configured to exchange heat between the working fluid and a second environment in which the second heat exchanger is disposed, the second environment being different from the first environment;   a first flowline connecting the first heat exchanger and the second heat exchanger, the first flowline configured to flow the working fluid;   a throttle valve installed on the first flowline, the throttle valve defining an adjustable flow restriction configured to reduce a pressure of a first portion of the working fluid as the first portion of the working fluid flows through the throttle valve;   a second flowline connecting the first heat exchanger and the second heat exchanger around the throttle valve, the second flowline providing an alternative flow path for a second portion of the working fluid to bypass the throttle valve; and   a flow-through electric generator installed on the second flowline, the flow-through electric generator comprising:
 a turbine wheel configured to receive the second portion of the working fluid and rotate in response to expansion of the second portion of the working fluid flowing into an inlet of the turbine wheel and out of an outlet of the turbine wheel; 
 a rotor coupled to the turbine wheel and configured to rotate with the turbine wheel; and 
 a stator, wherein the flow-through electric generator is configured to generate electrical power upon rotation of the rotor within the stator. 
   
     
     
         2 . The system of  claim 1 , wherein the second flowline branches from and reconnects to the first flowline around the throttle valve. 
     
     
         3 . The system of  claim 2 , further comprising:
 a first reversible valve switchable between a first position and a second position, wherein the first reversible valve is in fluid communication with the first heat exchanger, the second heat exchanger, and the compressor; and   a second reversible valve installed on the second flowline, wherein the second reversible valve is switchable between a third position and a fourth position, wherein the second reversible valve is in fluid communication with the first heat exchanger, the second heat exchanger, and the flow-through electric generator, wherein when the first reversible valve is in the first position and the second reversible valve is in the third position, flow of the working fluid is directed through the first heat exchanger, the second heat exchanger, and the throttle valve in a first direction, wherein when the first reversible valve is in the second position and the second reversible valve is in the fourth position, flow of the working fluid is directed through the first heat exchanger, the second heat exchanger, and the throttle valve in a second direction opposite the first direction.   
     
     
         4 . The system of  claim 3 , wherein the rotor of the flow-through electric generator is coupled to an impeller of the compressor, and the impeller of the compressor coupled to the rotor of the flow-through electric generator is configured to rotate with the rotor of the flow-through electric generator for pressurizing the working fluid. 
     
     
         5 . The system of  claim 3 , wherein the flow-through electric generator is electrically connected to the compressor and is configured to provide at least a portion of the generated electrical power to the compressor for pressurizing the working fluid. 
     
     
         6 . The system of  claim 5 , further comprising a power electronics system electrically connected to an electrical output of the flow-through electric generator and electrically connected to the compressor, wherein the power electronics system is configured to receive the generated electrical power from the flow-through electric generator and convert the received electrical power to specified power characteristics for delivery to the compressor for pressurizing the working fluid. 
     
     
         7 . The system of  claim 3 , wherein a first outlet temperature of the first portion of the working fluid exiting the throttle valve is greater than a second outlet temperature of the second portion of the working fluid exiting the flow-through electric generator. 
     
     
         8 . The system of  claim 7 , wherein the flow-through electric generator further comprises a hermetically sealed housing enclosing the turbine wheel, wherein the rotor and the stator are hermetically sealed inline in the second flowline flowing the second portion of the working fluid, such that the second portion of the working fluid flows across the turbine wheel and the stator, and the rotor comprises a permanent magnet rotor. 
     
     
         9 . A method of operating a heat pump cycle, the method comprising:
 circulating a working fluid through the heat pump cycle in a first direction, wherein circulating the working fluid through the heat pump cycle in the first direction comprises:
 transferring heat, by a first heat exchanger, from a first environment in which the first heat exchanger is disposed to the working fluid, thereby causing at least a portion of the working fluid to vaporize; 
 pressurizing, by a compressor, the working fluid received from the first heat exchanger; 
 transferring heat, by a second heat exchanger, from the working fluid to a second, different environment in which the second heat exchanger is disposed, thereby causing at least a portion of the working fluid to condense; 
 flowing a first portion of the working fluid from the second heat exchanger through a throttle valve, thereby reducing a pressure of the first portion of the working fluid; 
 flowing a second portion of the working fluid from the second heat exchanger to a turbine wheel of a flow-through electric generator; 
 generating electrical power, by the flow-through electric generator, in response to the second portion of the working fluid flowing across the turbine wheel; and 
 flowing the first portion of the working fluid from the throttle valve to the first heat exchanger and flowing the second portion of the working fluid from the flow-through electric generator to the first heat exchanger. 
   
     
     
         10 . The method of  claim 9 , wherein a rotor of the flow-through electric generator is coupled to an impeller of the compressor, wherein flowing the second portion of the working fluid to the turbine wheel causes rotation of the rotor of the flow-through electric generator and co-rotation of the impeller of the compressor that is coupled to the rotor of the flow-through electric generator, thereby imparting at least a portion of work to the compressor for pressurizing the working fluid. 
     
     
         11 . The method of  claim 9 , wherein the flow-through electric generator is electrically connected to the compressor, and the method further comprises providing at least a portion of the generated electrical power to the compressor for pressurizing the working fluid. 
     
     
         12 . The method of  claim 11 , wherein a first outlet temperature of the first portion of the working fluid exiting the throttle valve is greater than a second outlet temperature of the second portion of the working fluid exiting the flow-through electric generator. 
     
     
         13 . The method of  claim 12 , wherein the heat pump cycle comprises:
 a first reversible valve switchable between a first position and a second position, wherein the first reversible valve is in fluid communication with the first heat exchanger, the second heat exchanger, and the compressor; and   a second reversible valve switchable between a third position and a fourth position, wherein the second reversible valve is in fluid communication with the first heat exchanger, the second heat exchanger, and the flow-through electric generator, wherein the working fluid is circulated through the heat pump cycle in the first direction while the first reversible valve is in the first position and the second reversible valve is in the third position, and the method further comprises switching the first reversible valve to the second position and switching the second reversible valve to the fourth position, thereby circulating the working fluid through the heat pump cycle in a second direction, different from the first direction.   
     
     
         14 . The method of  claim 13 , wherein circulating the working fluid through the heat pump cycle in the second direction comprises:
 transferring heat, by the second heat exchanger, from the second environment to the working fluid, thereby causing at least a portion of the working fluid to vaporize;   pressurizing, by the compressor, the working fluid received from the second heat exchanger;   transferring heat, by the first heat exchanger, from the working fluid to the first environment, thereby causing at least a portion of the working fluid to condense;   flowing the first portion of the working fluid from the first heat exchanger through the throttle valve, thereby reducing the pressure of the first portion of the working fluid;   flowing the second portion of the working fluid from the first heat exchanger to the turbine wheel of the flow-through electric generator;   continuing to generate electrical power, by the flow-through electric generator, in response to the second portion of the working fluid flowing across the turbine wheel; and   flowing the first portion of the working fluid from the throttle valve to the second heat exchanger and flowing the second portion of the working fluid from the flow-through electric generator to the second heat exchanger.   
     
     
         15 . The method of  claim 14 , further comprising switching the first reversible valve from the second position to the first position and switching the second reversible valve from the fourth position to the third position to switch from circulating the working fluid through the heat pump cycle in the second direction to circulating the working fluid through the heat pump cycle in the first direction, wherein the compressor rotates in the same direction regardless of whether the first reversible valve is energized or de-energized, wherein the turbine wheel of the flow-through electric generator rotates in the same direction regardless of whether the second reversible valve is energized or de-energized. 
     
     
         16 . The method of  claim 15 , wherein the flow-through electric generator further comprises a stator and a hermetically sealed housing enclosing the turbine wheel, wherein the stator and the rotor are hermetically sealed inline in a flowline flowing the second portion of the working fluid, such that the second portion of the working fluid flows across the turbine wheel and the stator. 
     
     
         17 . The method of  claim 16 , wherein the rotor comprises a permanent magnet rotor. 
     
     
         18 . A heat pump system comprising:
 a first heat exchanger configured to exchange heat between a working fluid and a first environment in which the first heat exchanger is disposed;   a compressor configured to pressurize the working fluid;   a second heat exchanger configured to exchange heat between the working fluid and a second environment in which the second heat exchanger is disposed, the second environment being different from the first environment;   a throttle valve configured to reduce a pressure of a first portion of the working fluid as the first portion of the working fluid flows through the throttle valve; and   a flow-through turboexpander generator configured to receive a second portion of the working fluid and generate electrical power in response to expansion of the second portion of the working fluid flowing through the flow-through turboexpander generator, wherein the flow-through turboexpander generator comprises a stator, a turbine wheel, a rotor coupled to the turbine wheel, and a hermetically sealed housing enclosing a turbine wheel, wherein the stator and the rotor are hermetically sealed inline in a flowline flowing the second portion of the working fluid, such that the second portion of the working fluid flows across the turbine wheel and the stator, wherein the rotor comprises a permanent magnet rotor.   
     
     
         19 . The heat pump system of  claim 18 , further comprising:
 a first reversible valve switchable between a first position and a second position, wherein the first reversible valve is in fluid communication with the first heat exchanger, the second heat exchanger, and the compressor; and   a second reversible valve installed on the second flowline, wherein the second reversible valve is switchable between a third position and a fourth position, wherein the second reversible valve is in fluid communication with the first heat exchanger, the second heat exchanger, and the flow-through electric generator, wherein when the first reversible valve is in the first position and the second reversible valve is in the third position, flow of the working fluid is directed through the first heat exchanger, the second heat exchanger, and the throttle valve in a first direction, wherein when the first reversible valve is in the second position and the second reversible valve is in the fourth position, flow of the working fluid is directed through the first heat exchanger, the second heat exchanger, and the throttle valve in a second direction opposite the first direction.   
     
     
         20 . The heat pump system of  claim 19 , wherein the flow-through turboexpander generator is electrically connected to the compressor and is configured to provide at least a portion of the generated electrical power to the compressor for pressurizing the working fluid.