Condenser staging and circuiting for a micro combined heat and power system

Abstract

A micro combined heat and power system includes at least a heat source, an expander, a pump, a staged, counterflow condenser and a conduit for transporting a working fluid. The heat source can be, for example, a burner, while the expander is preferably a scroll expander. The heat source superheats the working fluid, which is preferably an organic working fluid. The superheated organic working fluid passes through the expander, which is coupled to a generator to produce electricity. After the working fluid is expanded, its gives up at least a portion of its excess heat first to the condenser. By placing the condenser in a counterflow arrangement, the fluid receiving the heat from the condensing working fluid can be of a higher temperature, thus allowing more system variation in the heat to power output ratio. The fluid receiving heat from the condenser may include circulating air, water or related fluid to provide space heat or domestic hot water.

We claim:  
     
         1 . A cogeneration system comprising: 
 a heat source;    a working fluid circuit comprising: 
 conduit configured to transport an organic working fluid through said working fluid circuit, at least a portion of said conduit disposed adjacent said heat source such that said organic working fluid disposed in said portion of said conduit is superheated during operation of said heat source;  
 an expander in fluid communication with said conduit such that said organic working fluid received therefrom remains superheated after expansion in said expander;  
 a condenser in fluid communication with said expander, said condenser configured such that a circulating fluid medium passing therethrough is in counterflow relationship to said organic working fluid; and  
 a pump configured to circulate said organic working fluid through at least said conduit, expander and condenser; and  
   at least one energy conversion circuit operatively responsive to said working fluid circuit such that upon operation of said cogeneration system, said at least one energy conversion circuit is configured to provide useable energy.    
     
     
         2 . A cogeneration system according to  claim 1 , wherein said condenser is a flat plate condenser.  
     
     
         3 . A cogeneration system according to  claim 1 , wherein said condenser is a shell-and-tube condenser.  
     
     
         4 . A cogeneration system according to  claim 3 , wherein the shell of said shell-and-tube condenser is in fluid communication with said working fluid circuit, and the tube is configured to be in fluid communication with said circulating fluid medium.  
     
     
         5 . A cogeneration system according to  claim 1 , wherein said at least one energy conversion circuit comprises: 
 a generator coupled to said expander to produce electricity; and a circulating fluid medium in thermal communication with said condenser such that at least a portion of the heat given up by said organic working fluid in said condenser provides increased thermal content to said circulating fluid medium.    
     
     
         6 . A cogeneration system according to  claim 5 , wherein said expander is a scroll expander.  
     
     
         7 . A cogeneration system according to  claim 5 , wherein said circulating fluid medium is configured to transport a space heating fluid.  
     
     
         8 . A cogeneration system according to  claim 7 , wherein said space heating fluid is water.  
     
     
         9 . A cogeneration system according to  claim 7 , wherein said space heating fluid is forced air.  
     
     
         10 . A cogeneration system according to  claim 5 , wherein said circulating fluid medium is configured to transport domestic hot water.  
     
     
         11 . A cogeneration system according to  claim 1 , wherein said heat source is a burner.  
     
     
         12 . A Rankine cycle cogeneration system comprising: 
 an organic working fluid;    an evaporator capable of superheating said organic working fluid, said evaporator comprising: 
 a burner; and  
 conduit adjacently spaced relative to said burner such that during burner operation heat transferred therefrom is sufficient to superheat said organic working fluid disposed in said conduit;  
   a substantially closed-loop working fluid circuit in thermal communication with said burner, said substantially closed-loop working fluid circuit configured to transport said organic working fluid therethrough, said substantially closed-loop working fluid circuit comprising: 
 an expander in fluid communication with said conduit such that said organic working fluid received therefrom remains superheated after expansion in said expander;  
 a condenser in fluid communication with said expander;  
 a pump configured to circulate said organic working fluid through at least said conduit, expander and condenser; and  
   at least one energy conversion circuit comprising: 
 a generator coupled to said expander to produce electricity; and  
 a circulating fluid medium configured to pass through said condenser in counterflow thermal communication with said organic working fluid such that at least a portion of the heat given up by said organic working fluid in said condenser provides increased thermal content to said circulating fluid medium.  
   
     
     
         13 . A dwelling configured to provide at least a portion of the heat and power needs of occupants therein, said dwelling comprising: 
 a plurality of walls defining at least one room therebetween;    a roof situated above said plurality of walls;    at least one ingress/egress to facilitate passage into and out of said dwelling; and    a cogeneration system in heat and power communication with said at least one room, said cogeneration system comprising: 
 a heat source;  
 a working fluid circuit comprising: 
 conduit configured to transport an organic working fluid through said working fluid circuit, at least a portion of said conduit disposed adjacent said heat source such that said organic working fluid disposed in said portion of said conduit disposed adjacent said heat source is superheated during operation of said heat source;  
 an expander in fluid communication with said conduit such that said organic working fluid received therefrom remains superheated after expansion in said expander;  
 a condenser in fluid communication with said expander, said condenser comprising: 
 a first loop configured to convey said organic working fluid therethrough; and  
 a second loop in counterflow thermal communication with said first loop; and  
 
 a pump configured to circulate said organic working fluid through at least said conduit, expander and condenser;  
 
 a generator responsive to said expander to provide electricity; and  
 a circulating fluid medium coupled to said second loop, said circulating fluid medium configured to provide at least space heat or domestic hot water to said dwelling.  
   
     
     
         14 . A dwelling according to  claim 13 , further comprising a controller responsive to occupant input.  
     
     
         15 . A dwelling according to  claim 14 , wherein said controller responsive to occupant input is a thermostat.  
     
     
         16 . A dwelling according to  claim 13 , wherein said circulating fluid medium is configured to provide both space heat and domestic hot water to said dwelling.  
     
     
         17 . A micro combined heat and power system comprising: 
 an electric production subsystem comprising: 
 an organic working fluid;  
 a burner for superheating said organic working fluid;  
 a scroll expander configured to receive and expand said organic working fluid in a superheated state;  
 a generator operatively coupled to said scroll expander to produce electricity;  
 a condenser in fluid communication with said scroll expander, said condenser comprising: 
 a first loop configured to convey said organic working fluid therethrough; and  
 a second loop in counterflow thermal communication with said first loop; and  
 
 a pump to circulate said organic working fluid through said electricity generating loop; and  
   a heat production subsystem including a circulating fluid medium coupled to said second loop, said circulating fluid medium configured to provide at least space heat or domestic hot water to said dwelling.    
     
     
         18 . A method of producing heat and electrical power from a cogeneration device, the method comprising the steps of: 
 providing a heat source;    configuring a first circuit to transport an organic working fluid adjacent said heat source;    superheating said organic working fluid;    expanding said superheated organic working fluid to generate electricity;    exchanging at least a portion of the excess heat from said organic working fluid that has passed through said expander in a condenser with a circulating fluid medium such that after passing through said condenser, said organic working fluid is no longer in a superheated state, said condenser comprising a first loop configured to convey said organic working fluid therethrough, and a second loop in counterflow thermal communication with said first loop such that said second loop is in fluid communication with said circulating fluid medium; and    returning said organic working fluid such that it is adjacent said heat source.    
     
     
         19 . A method according to  claim 18 , wherein said circulating fluid medium is configured to transport a space heating fluid.  
     
     
         20 . A method according to  claim 19 , wherein said space heating fluid is water.  
     
     
         21 . A method according to  claim 18 , wherein said space heating fluid is forced air.  
     
     
         22 . A method according to  claim 18 , wherein said circulating fluid medium is configured to transport domestic hot water.  
     
     
         23 . A method according to  claim 18 , wherein said circulating fluid medium is configured to transport both space heat and domestic hot water.