Apparatus, systems, and methods for low grade waste heat management

Abstract

The present invention relates to apparatus, systems, and methods of managing large quantities of low-grade waste heat energy by generating excess electrical power via an ORC process driven by the removal and recovery of waste heat under favorable operating conditions, and utilizing the same apparatus to provide waste heat removal via a refrigeration process that consumes electrical power when environmental conditions do not permit operation in the ORC mode. The mode of operation of the system is principally determined by the thermal energy of the waste heat stream and the availability, or lack thereof, of adequate cooling resources. Such resources are often subject to local environmental conditions, particularly ambient temperature which varies on a diurnal and annual basis.

What is claimed is: 
     
         1 . A power generation system comprising:
 A. a closed loop circuit comprising a working fluid circulating in a single direction from a first heat exchanger to a first positive displacement machine, and then to a second heat exchanger, and then to a second positive displacement machine, and then to said first heat exchanger;   
       wherein (i) said first positive displacement machine is capable of generating mechanical power via expansion of said working fluid in said first positive displacement machine when the pressure in the first heat exchanger is the highest pressure in the system, and (ii) said second positive displacement machine is capable of generating mechanical power via expansion of said working fluid in said second positive displacement machine when the pressure at the second heat exchanger is the highest pressure in the system. 
     
     
         2 . The system of  claim 1  further comprising a first motor/generator in mechanical power communication with said first positive displacement machine and a second motor/generator in mechanical power communication with said first positive displacement machine, wherein each of said first and second motor/generators are capable of generating electric power from said received mechanical power. 
     
     
         3 . The system of  claim 2  wherein (i) said first motor/generator consumes electric power to pressurize the system via said first positive displacement machine whenever said second motor/generator is generating electric power, and (ii) said second motor/generator consumes electric power to pressurize the system via said second positive displacement machine whenever said first positive displacement machine is generating electric power. 
     
     
         4 . The system of  claim 1  wherein said working fluid comprises a mixture of an organic refrigerant and a lubricant. 
     
     
         5 . The system of  claim 4  further comprising a lubrication pump to provide said mixture directly to either or both of said positive displacement machines. 
     
     
         6 . The system of  claim 1  wherein at least one of either of said first and second positive displacement machines is a screw-type expander, a screw pump, a centrifugal pump, a scroll expander, a turbine, a gerotor, a gear pump, a cavity pump, a piston pump, or a plunger pump. 
     
     
         7 . The system of  claim 1  wherein either or both of said first and second positive displacement machines comprise a variable frequency drive control system. 
     
     
         8 . The system of  claim 1  further configured to reverse the direction of working fluid flow through either or both of said first and second positive displacement machine(s) by interchanging the working fluid connections to the input and output ports of said machine(s) without altering the direction of working fluid flow in the remainder of the system. 
     
     
         9 . The system of  claim 1  further comprising a heat energy source in thermal communication with either or both of said first and second heat exchanger(s). 
     
     
         10 . The system of  claim 6  wherein said source of heat energy comprises at least one of any of an automotive manufacturing facility, a food processing facility, an oil or natural gas processing facility, or a computer data center. 
     
     
         11 . A method of generating power using a closed loop working fluid circuit, the method comprising:
 A. circulating a working fluid in a single direction from a first heat exchanger to a first positive displacement machine, and then to a second heat exchanger, and then to a second positive displacement machine, and then to said first heat exchanger;   B. generating mechanical power via expansion of said working fluid in said first positive displacement machine when heat energy provided to said working fluid via said first heat exchanger causes the highest pressure in the system to exist at said first heat exchanger; and   C. generating mechanical power via expansion of said working fluid in said second positive displacement machine when heat energy provided to said working fluid via said second heat exchanger causes the highest pressure in the system to exist at said second heat exchanger.   
     
     
         12 . The method of  claim 11  comprising an additional step of generating electric power from said mechanical power via first and second motor/generators in mechanical power communication with said first and second positive displacement machines, respectively. 
     
     
         13 . The method of  claim 12  comprising the additional steps of (i) consuming electric power by said first motor/generator to pressurize the system via said first positive displacement machine whenever said second positive displacement machine is generating electric power, and (ii) consuming electric power by said second motor/generator to pressurize the system via said second positive displacement machine whenever said first positive displacement machine is generating electric power. 
     
     
         14 . The method of  claim 11  wherein said working fluid comprises a mixture of an organic refrigerant and a lubricant. 
     
     
         15 . The method of  claim 11  wherein at least one of either of said first and second positive displacement machines is a screw-type expander, a screw pump, a centrifugal pump, a scroll expander, a turbine, a gerotor, a gear pumps, a cavity pump, a piston pump, or a plunger pump. 
     
     
         16 . The method of  claim 11  further comprising steps of manually, automatically, or manually and automatically adjusting the volume index (Vi) of said first positive displacement machine, said second positive displacement machine, or said first positive displacement machine and said second positive displacement machine. 
     
     
         17 . The method of  claim 11  further comprising steps of manually, automatically, or manually and automatically adjusting the speed of said first positive displacement machine, said second positive displacement machine, or said first positive displacement machine and said second positive displacement machine. 
     
     
         18 . The method of  claim 11  further comprising steps of (i) condensing said working fluid in said first heat exchanger whenever the highest pressure in the system exists at said second heat exchanger, and (ii) condensing said working fluid in said second heat exchanger whenever the highest pressure in the system exists at said first heat exchanger. 
     
     
         19 . The method of  claim 11  comprising an additional step of interchanging the working fluid connections to the input and output ports of either or both of said first or second positive displacement machine(s) to reverse the working fluid flow direction only through said machine(s) without altering the direction of working fluid flow in the remainder of the system. 
     
     
         20 . The method of  claim 11  further comprising a step of communicating heat energy to said first heat exchanger, to said second heat exchanger, or to said first and second heat exchangers from at least one of any of an automotive manufacturing facility, a food processing facility, an oil or natural gas processing facility, or a computer data center.