Thermal energy retrieval system for internal combustion engines

Abstract

A thermal energy retrieval system in which waste heat generated by an internal combustion engine is used to evaporate an organic working fluid in an evaporator. The evaporated working fluid is passed through a turbine to generate mechanical or electrical power which could be used to supplement the work done by the internal combustion engine. A unitary control valve is disposed between a feed pump and the evaporator to automatically regulate the flow of working fluid to the evaporator in accordance with the sensed temperature of the working fluid at its exit from the evaporator. This ensures the optimization of the thermodynamic efficiency of the system, which in turn leads to the provision of a more compact system useful as an add-on to motive mounted engines.

1 . A compact thermal energy retrieval system for an internal combustion engine, comprising a refrigerant circulated in a closed cycle, an evaporator for heating said refrigerant from a liquid state to a high pressure vapor by means of heat generated by the internal combustion engine, an expander/turbine unit through which said vapor is passed to develop power, and a condenser to cool and condense said vapor emanating from said turbine to a condensed fluid before being re-circulated through said evaporator; and a control unit for controlling the operation of said thermal energy retrieval system, said control unit including a temperature sensor mounted in said closed cycle for sensing a temperature of said refrigerant substantially at said evaporator and providing a first output signal as a function of the temperature of the refrigerant, and a fluid flow regulator incrementally adjusting a mass flow rate of circulation of said refrigerant through said evaporator in accordance with said output signal.  
     
     
         2 . A system as defined in  claim 1 , wherein said fluid flow regulator includes a feed pump and a control valve, and wherein a clutch is provided to selectively connect and disconnect said feed pump and a driving source, said clutch being operatively connected to said control unit to disconnect said feed pump from said driving source when a negative power output is computed by said control unit.  
     
     
         3 . A system as defined in  claim 2 , wherein said control unit further includes a first flow rate meter for providing a second output signal as a function of the flow rate of the working fluid passing through said evaporator, and wherein disconnection of said feed pump from said driving source is governed by a function of said first and second output signals.  
     
     
         4 . A system as defined in  claim 2 , wherein said evaporator has inlet and outlet ports for allowing a recuperated waste heat fluid emanating from the internal combustion engine to be circulated through said evaporator, and wherein said control unit further includes a second flow rate meter for providing a third output signal as a function of the flow rate of the recuperated waste heat fluids, and second and third temperature sensors for providing fourth and fifth output signals as functions of the temperature of the recuperated waste heat fluid at an entry and an exit of the internal combustion engine, and wherein re-connection of said feed pump with said driving source is governed by a function of said third, fourth and fifth output signals.  
     
     
         5 . A system as defined in  claim 1 , wherein said refrigerant is selected from a group consisting of: TER55 and TER64.  
     
     
         6 . A system as defined in  claim 2 , wherein said control valve includes first and second outlets adapted to be simultaneously partly closed by a valve member responsive to said control unit, said first outlet being in flow communication with said evaporator, whereas said second outlet is in flow communication with an overflow line for returning excess working fluid flow upstream of said control valve so that only a desired amount of refrigerant flows to the evaporator during engine operation.  
     
     
         7 . A system as defined in  claim 4 , wherein said control unit further includes a pair of valves for selectively allowing said recuperated waste heat fluid to flow through said evaporator, said valves being operatively connected to said control unit for blocking engine coolant flow to said evaporator once said feed pump has been disconnected from said driving source thereof.  
     
     
         8 . A system as defined in  claim 1 , wherein said expander/turbine unit and said condenser are connected in fluid flow communication via a tube, said tube being provided with fins to promote cooling of the refrigerant after expansion and reduce gas pressure thereof at entry to the condenser.  
     
     
         9 . A system as defined in  claim 1 , wherein said expander/turbine unit has an outlet and wherein said outlet leads to an expansion chamber to reduce flow velocity and gas pressure in said closed cycle between said expander/turbine unit and said condenser.  
     
     
         10 . A system as defined in  claim 1 , wherein said feed pump is adapted to be drivingly connected to a power-take-off of said internal combustion engine.  
     
     
         11 . A system as defined in  claim 10 , wherein said system has a power output adapted to be connected to the power-take-off of the internal combustion engine.  
     
     
         12 . A system as defined in  claim 1 , wherein said expander/turbine unit is surrounded by a jacket through which a coolant fluid is passed to cool said turbine.  
     
     
         13 . A system as defined in  claim 12 , wherein said jacket is integrated in said closed cycle, said coolant fluid being said refrigerant, and wherein said refrigerant is flowed from said jacket to said evaporator, thereby providing pre-heating of said refrigerant before entering into said evaporator, while at the same time removing heat from said expander/turbine unit.  
     
     
         14 . A system as defined in  claim 13 , wherein a turbo-alternator is coupled to said expander/turbine unit for converting mechanical energy developed by said expander/turbine unit into electricity, and wherein said turbo-alternator is also surrounded by said jacket.  
     
     
         15 . A system as defined in  claim 14 , wherein said expander/turbine unit has an output shaft, and wherein a turbo-gear reducer is coupled to said output shaft, said turbo-gear reducer being also surrounded by said jacket.  
     
     
         16 . A compact thermal energy retrieval system for an internal combustion engine, comprising a refrigerant circulated in a closed cycle, an evaporator for heating said refrigerant from a liquid state to a high pressure vapor by means of heat generated by the internal combustion engine, an expander/turbine unit through which said vapor is passed to develop power, and a condenser to cool and condense said vapor emanating from said turbine to a condensed fluid before being re-circulated through said evaporator; and a control unit for controlling the operation of said thermal energy retrieval system, wherein said expander/turbine unit is surrounded by a jacket through which a coolant fluid is passed to cool said expander/turbine unit.  
     
     
         17 . A system as defined in  claim 16 , wherein said jacket is integrated in said closed cycle, said coolant fluid being said refrigerant, and wherein said refrigerant is flowed from said jacket to said evaporator, thereby providing pre-heating of said refrigerant before entering into said evaporator, while at the same time removing heat from said expander/turbine unit.  
     
     
         18 . A system as defined in  claim 17 , wherein a turbo-alternator is coupled to said expander/turbine unit for converting mechanical energy developed by said expander/turbine unit into electricity, and wherein said turbo-alternator is also surrounded by said jacket.  
     
     
         19 . A system as defined in  claim 17 , wherein said expander/turbine unit has an output shaft, and wherein a turbo-gear reducer is coupled to said output shaft, said turbo-gear reducer being also surrounded by said jacket.  
     
     
         20 . A compact evaporator for heating a working fluid from a liquid state to a high pressure vapor, comprising a container, a heat exchanging panel spirally rolled within said container about a central axis thereof and defining an internal serpentine passage connected in flow communication with an inlet and an outlet for allowing a working fluid to flow through said serpentine passage, and inlet and outlet means for allowing a heat source fluid to flow through said container on an outside surface of said heat exchanging panel to transfer heat to the working fluid via said heat exchanging panel.  
     
     
         21 . A compact evaporator as defined in  claim 20 , wherein flow turbulators are distributed within said serpentine passage to promote heat exchange between the heat source fluid and the working fluid.  
     
     
         22 . A compact evaporator as defined in  claim 20 , wherein said heat exchanging panel is spirally rolled about an axially extending core, and wherein said serpentine passage is axially oriented within said container.  
     
     
         23 . A compact evaporator as defined in  claim 20 , wherein said turbulators include a plurality of semispherical bubbles uniformly distributed within said serpentine passage.