Patent Publication Number: US-9835145-B1

Title: Thermal energy recovery systems

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. provisional application No. 61/551,359, filed Oct. 25, 2012 and entitled THERMAL ENERGY RECOVERY SYSTEMS, which provisional application is incorporated by reference herein in its entirety. 
    
    
     FIELD OF THE INVENTION 
     Illustrative embodiments of the disclosure generally relate to systems which exploit thermal energy for various purposes. More particularly, illustrative embodiments of the disclosure relate to thermal energy recovery systems which render thermal energy available for a variety of purposes. 
     BACKGROUND OF THE INVENTION 
     Thermal energy is useful in a variety of applications such as heating and cooking. In some applications, it may be desirable to exploit thermal energy which is obtained from a readily-available thermal energy source for various purposes. 
     Accordingly, thermal energy recovery systems which render thermal energy available for a variety of purposes may be desirable for some applications. 
     SUMMARY OF THE INVENTION 
     Illustrative embodiments of the disclosure are generally directed to thermal energy recovery systems. An illustrative embodiment of the thermal energy recovery system includes a piston assembly including a primary cylinder adapted to receive vapor and/or hot liquid in such a state or condition as to become vapor; first and second secondary cylinders extending from opposite ends of the primary cylinder; a primary piston disposed for displacement in the primary cylinder; first and second secondary pistons disposed for displacement in the first and second secondary cylinders, respectively; and a piston connecting member connecting the first and second secondary pistons to the primary piston. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Illustrative embodiments of the disclosure will now be described, by way of example, with reference to the accompanying drawings, in which: 
         FIG. 1  is a block diagram of an illustrative embodiment of a thermal energy recovery system; 
         FIG. 2  is a block diagram of an alternative illustrative embodiment of the thermal energy recovery system; 
         FIG. 3  is a block diagram of an illustrative embodiment of a solar-powered air-conditioning system; and 
         FIG. 4  is a block diagram of an illustrative embodiment of a vehicle propulsion system. 
     
    
    
     DETAILED DESCRIPTION 
     The following detailed description is merely exemplary in nature and is not intended to limit the described embodiments or the application and uses of the described embodiments. As used herein, the word “exemplary” or “illustrative” means “serving as an example, instance, or illustration.” Any implementation described herein as “exemplary” or “illustrative” is not necessarily to be construed as preferred or advantageous over other implementations. All of the implementations described below are exemplary implementations provided to enable persons skilled in the art to practice the disclosure and are not intended to limit the scope of the appended claims. Moreover, the illustrative embodiments described herein are not exhaustive and embodiments or implementations other than those which are described herein and which fall within the scope of the appended claims are possible. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description. 
     Referring initially to  FIG. 1  of the drawings, an illustrative embodiment of a thermal energy recovery system is generally indicated by reference numeral  1 . The thermal energy recovery system  1  may include a boiler  2  which in some embodiments may be adapted to form vapor  40  from a liquid  42 . In other embodiments, the boiler  2  may be adapted to receive vapor  40  from a vapor source (not illustrated). A piston assembly  6  may include a primary cylinder  7  which may have a generally elongated, cylindrical configuration and secondary cylinders  8 ,  8   a  which may extend from opposite ends of the primary cylinder  7 . Cylinder inlet valves  10 ,  10   a  may be provided at opposite ends of the primary cylinder  7 . Alternatively, a liquid injection system can be used in conjunction with or in place of inlet valves. The cylinder inlet valves  10 ,  10   a  may be disposed in fluid communication with the boiler  2  through boiler outlet conduits  3 . Cylinder outlet valves  12 ,  12   a  may be provided at opposite ends of the primary cylinder  7 . The cylinder outlet valves  12 ,  12   a  may be disposed generally in opposite or diametrically-opposed relationship to the cylinder inlet valves  10 ,  10   a , respectively. 
     A primary piston  16  may sealingly engage the interior surface of the primary cylinder  7 . The primary piston  16  may be adapted for slidable displacement between the opposite ends of the primary cylinder  7 . A secondary piston  17  may sealingly and slidably engage the interior surface of the secondary cylinder  8 . A secondary piston  17   a  may sealingly and slidably engage the interior surface of the secondary cylinder  8   a . Piston connecting members  18 ,  18   a  may connect the primary piston  16  to the secondary pistons  17  and  17   a , respectively. 
     A condenser  24  may be disposed in fluid communication with the cylinder outlet valves  12 ,  12   a  on the primary cylinder  7  of the piston assembly  6  through an exhaust manifold  20 . The boiler  2  may be disposed in fluid communication with the condenser  24  through a boiler return conduit  26 . 
     The secondary cylinder  8  may be fitted with an inlet check valve  13  and an outlet check valve  14 . In like manner, the secondary cylinder  8   a  may be fitted with an inlet check valve  13   a  and an outlet check valve  14   a . A pressure tank  32  may be disposed in fluid communication with the outlet check valve  14  through a pressure conduit  30  and with the outlet check valve  14   a  through a pressure conduit  30   a . A turbine/motor  34  may be disposed in fluid communication with the pressure tank  32  through a turbine/motor inlet conduit  33 . The turbine/motor  34  may be used to perform work in any of a variety of applications. A fluid reservoir  36  may be disposed in fluid communication with the turbine/motor  34  through a turbine outlet conduit  35 . The inlet check valve  13  of the secondary cylinder  8  may be disposed in fluid communication with the fluid reservoir  36  through a working fluid return conduit  31 . The inlet check valve  13   a  of the secondary cylinder  8   a  may be disposed in fluid communication with the fluid reservoir  36  through a working fluid return conduit  31   a.    
     In exemplary operation of the thermal energy recovery system  1 , a working fluid  44  is contained in the secondary cylinders  8 ,  8   a  of the piston assembly  6 . In some applications, the working fluid  44  may be a liquid. In some applications, the working fluid  44  may be a gas. The boiler  2  heats the water or other liquid  42  which subsequently becomes vapor  40  or alternatively, receives the vapor  40  from a vapor source (not illustrated). The cylinder inlet valve and/or liquid injection system  10  and the cylinder outlet valve  12   a  are opened whereas the cylinder inlet valve  10   a  and the cylinder outlet valve  12  are closed. Accordingly, the vapor  40  and/or evaporative liquid enters the primary cylinder  7  through the cylinder inlet valve and/or liquid injection system  10  such that the vapor  40  applies differential pressure against the primary piston  16 , causing movement of the piston  16  in the primary cylinder  7  to the right in  FIG. 1 . In that the vapor  40  on the exhaust side of the primary piston  16  passes through the exhaust manifold  20  to the condenser  24  and is condensed therein, the pressure differential applied to the primary piston  16  is enhanced, allowing for expansion of the working vapor  40  potentially to less than atmospheric pressure. This feature may allow for maximum expansion of the working vapor  40 , resulting in increased operational efficiency. This action causes the primary piston  16  to exert pressure against the secondary piston  17   a  through the piston connecting member  18   a . Consequently, the piston connecting member  18   a  pushes the secondary piston  17   a  in the secondary cylinder  8   a  to the right in  FIG. 1 . The secondary piston  17   a  displaces the working fluid  44  from the secondary cylinder  8   a  through the outlet check valve  14   a  and the pressure conduit  30   a , respectively, into and through the pressure tank  32 . The pressurized working fluid  44  exits the pressure tank  32  through the turbine inlet conduit  33  and flows through and rotates the turbine/motor  34 . The working fluid  44  leaves the turbine/motor  34  through the turbine outlet conduit  35  and enters the fluid reservoir  36 . From the fluid reservoir  36 , the working fluid return conduit  31   a  returns the working fluid  44  to the secondary cylinder  8  through the working fluid return conduit  31  and the inlet check valve  13 , respectively, due to the drop in pressure in the secondary cylinder  8  caused by refraction of the secondary piston  17 . 
     The differential or ratio of the pressure which is applied by the vapor  40  against the primary piston  16  to the pressure which is applied by the secondary piston  17   a  against the working fluid  44  is directly proportional to the square of the radius of the primary piston  16  and the secondary piston  17   a . The pressure which the secondary piston  17   a  exerts against the working fluid  44  is equal to the pressure which the vapor  40  exerts against the primary piston  16  times the area of the primary piston  16  divided by the area of the secondary piston  17   a . For example and without limitation, in embodiments in which the diameter of the primary piston  16  is 10 inches and the diameter of the secondary piston  17   a  is 1 inch, the area of the primary piston  16  (A=πr 2 ) is 78.5 in 2  less the area of the piston connecting member  18   a . The area of the secondary piston  17   a  is 0.785 in 2 . Therefore, a pressure of 10 lbs/in 2  applied to the primary piston  16  yields a pressure of 1,000 PSI developed by the secondary piston  17   a  (a ratio of 100:1). Piston sizes (primary versus secondary) can be designed so as to optimize working fluid pressures and maximize thermal efficiency. 
     As it moves to the right in  FIG. 1 , the primary piston  16  forces vapor  40  from the primary cylinder  7  through the open cylinder outlet valve  12   a . The exhaust manifold  20  distributes the vapor  40  into the condenser  24 , where the vapor  40  is condensed into the liquid  42 . As the vapor  40  condenses, its pressure is reduced, resulting in lower vapor pressure on the exhaust side of the primary piston  16 . This, in turn, increases the differential pressure on the primary piston  16 . The boiler return conduit  26  returns the liquid  42  to the boiler  2  and the process is repeated. In the subsequent power cycle of the piston assembly  6 , the cylinder inlet valve and/or liquid injection system  10   a  and the cylinder outlet valve  12  may open while the cylinder inlet valve  10  and the cylinder outlet valve  12   a  may be closed. Vapor  40  from the boiler  2  forces the primary piston  16  to the left in  FIG. 1  such that the secondary piston  17  expels the working fluid  44  from the secondary cylinder  8  and through the pressure conduit  30 , the pressure tank  32 , the turbine inlet conduit  33 , the turbine/motor  34 , the turbine outlet conduit  35  and the fluid reservoir  36 , respectively. From the fluid reservoir  36 , the working fluid return conduit  31  returns the working fluid  44  to the secondary cylinder  8   a  through the working fluid return conduit  31   a  and the inlet check valve  13   a , respectively, due to the drop in pressure in the secondary cylinder  8   a  caused by retraction of the secondary piston  17   a . Accordingly, as it reciprocates in the primary cylinder  7 , the primary piston  16  alternately actuates the secondary piston  17  and the secondary piston  17   a  to maintain a continuous flow of working fluid  44  through the turbine/motor  34 . In some applications, the rotating turbine/motor  34  may be used to perform some type of work (such as augmenting a drive train on a vehicle or generating electrical power, for example and without limitation). In other applications, the turbine/motor  34  may operate to compress gas according to the knowledge of those skilled in the art. 
     Referring next to  FIG. 2  of the drawings, an alternative illustrative embodiment of the thermal energy recovery system is generally indicated by reference numeral  101 . In  FIG. 2 , components which are analogous to the corresponding components of the thermal energy recovery system  1  in  FIG. 1  are designated by the same numerals in the 101-199 series. The thermal energy recovery system  101  may include a boiler  102 . The boiler  102  may be an exhaust boiler, a solar thermal array, a dedicated boiler or a geothermal source, for example and without limitation. A primary cylinder  7  ( FIG. 1 ) of a piston assembly  106  may be disposed in fluid communication with the boiler  102  through a boiler outlet conduit  103 . A condenser  124  may be disposed in fluid communication with the primary cylinder  7  of the piston assembly  106  through an exhaust manifold  120 . The boiler  102  may be disposed in fluid communication with the condenser  124  through a boiler return conduit  126 . 
     A working fluid surge reservoir  146  may be disposed in fluid communication with a first secondary cylinder  8  ( FIG. 1 ) of the piston assembly  106  through a pressure conduit  130 . A turbine/motor  134  may be disposed in fluid communication with the working fluid surge reservoir  146  through a turbine inlet conduit  133 . A working fluid return reservoir  148  may be disposed in fluid communication with the turbine/motor  134  through a turbine outlet conduit  135 . A second secondary cylinder  8   a  of the piston assembly  106  may be disposed in fluid communication with the working fluid/return reservoir  148  through a working fluid return conduit  131 . 
     In exemplary operation of the thermal energy recovery system  101 , the boiler  102  heats a liquid which subsequently becomes vapor  140  or receives the vapor  140  from a separate vapor source (not illustrated). The vapor  140  flows from the boiler  102  through the boiler outlet conduit  103  into the piston assembly  106 , which functions as was heretofore described with respect to the piston assembly  6  of the thermal energy recovery system  1  in  FIG. 1 . The vapor  140  flows to the condenser  124  through the exhaust manifold  120  and is condensed to form the liquid  140  in the condenser  124 . The liquid  140  returns to the boiler  102  through the boiler return conduit  126 . 
     Responsive to operation of the piston assembly  106 , pressurized working fluid  144  flows through the pressure conduit  130  into the working fluid surge reservoir  146 . From the working fluid surge reservoir  146 , the working fluid  144  flows through the turbine inlet conduit  133  and the turbine/motor  134 , respectively, rotating the turbine/motor  134 . The working fluid  144  flows from the turbine/motor  134  through the turbine outlet conduit  135  and into the working fluid return reservoir  148 . Finally, the working fluid return conduit  131  returns the working fluid  144  to the piston assembly  106 . 
     Referring next to  FIG. 3  of the drawings, an illustrative embodiment of a solar-powered air conditioning system is generally indicated by reference numeral  201 . In  FIG. 3 , components which are analogous to the corresponding components of the thermal energy recovery system  1  in  FIG. 1  are designated by the same numerals in the 201-299 series. The solar-powered air conditioning system  201  may include a thermal energy collector  252 . A collector outlet conduit  253  and a collector return conduit  254  may be disposed in fluid communication with each other and in thermally-conductive contact with the thermal energy collector  252 . A hot liquid storage tank  258  may be disposed in fluid communication with the collector outlet conduit  253 . A cold liquid storage tank  260  may be disposed in fluid communication with the collector return conduit  254 . The primary cylinder  7  ( FIG. 1 ) of a piston assembly  206  may be disposed in fluid communication with the hot liquid storage tank  258  through a storage tank outlet conduit  262 . 
     A condenser  224  may be disposed in fluid communication with the primary cylinder  7  of the piston assembly  206  through an exhaust manifold  220 . The cold liquid storage tank  260  may be disposed in fluid communication with the condenser  224  through a storage tank return conduit  263 . 
     A radiator  270  may be disposed in fluid communication with a first secondary cylinder  8  ( FIG. 3 ) of the piston assembly  206  through an assembly outlet conduit  266 . A refrigerant storage tank  272  may be disposed in fluid communication with the radiator  270  through a radiator outlet conduit  271 . An evaporator  274  may be disposed in fluid communication with the refrigerant storage tank  272  through a refrigerant outlet conduit  273 . The second secondary cylinder  8   a  ( FIG. 1 ) of the piston assembly  206  may be disposed in fluid communication with the evaporator  274  through an assembly return conduit  275 . 
     In exemplary operation of the solar-powered air conditioning system  201 , thermal energy  286  emitted by the Sun  284  heats the thermal energy collector  252 . Liquid  242  which flows through the thermal energy collector  252  is heated to produce hot liquid  240 , which flows through the collector outlet conduit  253  to the hot liquid storage tank  258 . The hot liquid  240  flows from the hot liquid storage tank  258  through the storage tank outlet conduit  262  to the piston assembly  206 , where the liquid becomes vapor  240  actuates the piston assembly  206  as was heretofore described with respect to the piston assembly  6  in  FIG. 1 . From the piston assembly  206 , the vapor  240  flows through the exhaust manifold  220  to the condenser  224 , where the vapor  240  is condensed into liquid  242 . The liquid  242  returns to the cold liquid storage tank  260  through the storage tank return conduit  263 . Subsequently, the liquid  242  flows to the thermal energy collector  252  through the collector return conduit  254 , and the process is repeated. 
     Responsive to flow of the vapor  240  into the piston assembly  206 , the piston assembly  206  forces refrigerant gas  244  through the assembly outlet conduit  266  to the radiator  270 . In the radiator  270 , flowing air absorbs heat from the refrigerant gas  244 , which then in a cooled state flows through the radiator outlet conduit  271  to the refrigerant storage tank  272 . The refrigerant gas  244  flows through the refrigerant outlet conduit  273  to the evaporator  274 , where the refrigerant gas  244  absorbs heat from flowing air and cools the air. The air which is cooled by the refrigerant gas  244  in the evaporator  274  may be distributed into an enclosed or partially enclosed space such as rooms (not illustrated) of a home or other building through ductwork or the like to cool the building typically in the same manner as a conventional air conditioning system. The refrigerant gas  244  returns to the piston assembly  206  through the assembly return conduit  275  and the process is repeated. 
     Referring next to  FIG. 4  of the drawings, an illustrative embodiment of a propulsion system for road and rail vehicles is generally indicated by reference numeral  301 . In  FIG. 4 , components which are analogous to the corresponding components of the thermal energy recovery system  1  in  FIG. 1  are designated by the same numerals in the 301-399 series. The propulsion system  301  may include a motor  388  which in some applications may be the primary mover of a road or rail vehicle. In some embodiments, the motor  388  may include an internal combustion engine. A boiler  302  may be disposed in thermal contact with the motor  388  or with exhaust gas  302   a  from the motor  388 . 
     The primary cylinder  7  ( FIG. 1 ) of a piston assembly  306  may be disposed in fluid communication with the boiler  302  through a boiler outlet conduit  303 . A condenser  324  may be disposed in fluid communication with the primary cylinder  7  of the piston assembly  306  through an exhaust manifold  320 . The boiler  302  may be disposed in fluid communication with the condenser  324  through a boiler return conduit  326 . 
     A pressurized air or other gaseous medium storage tank  332  may be disposed in fluid communication with a first secondary cylinder  8  ( FIG. 1 ) of the piston assembly  306  through a pressure conduit  330 . A turbine/motor  334  may be disposed in fluid communication with the pressurized air or gaseous medium storage tank  332  through a turbine inlet conduit  333 . In some applications, the turbine/motor  334  may drivingly engage a vehicle drive train (not illustrated) of the road or rail vehicle to augment the driving power of the motor  388 . The turbine/motor  334  may additionally be coupled to the braking system (not illustrated) of the road or rail vehicle for regenerative braking purposes according to the knowledge of those skilled in the art. In some embodiments, an external air compressor  392  may be disposed in fluid communication with the turbine inlet conduit  333  between the pressurized air storage tank  332  and the turbine/motor  334 . 
     In exemplary operation of the propulsion system  301 , the motor  388  may be operated as the primary mover of the road or rail vehicle. Exhaust gases  302   a  from the motor  388  heats the boiler  302  such that liquid  342  in the boiler  302  is heated and subsequently becomes vapor  340 . The vapor  340  flows through the boiler outlet conduit  303  to the piston assembly  306 , which is operated in a manner similar to that heretofore described with respect to the piston assembly  6  in  FIG. 1 . From the piston assembly  306 , the vapor  340  flows through the exhaust manifold  320  to the condenser  324 , where the vapor  340  is condensed into liquid  342 . The liquid  342  returns to the boiler  302  through the boiler return conduit  326  and the process is repeated. 
     Responsive to flow of the vapor  340  into the piston assembly  306 , the piston assembly  306  compresses and forces air or gaseous medium  343  through the pressure conduit  330  to the pressurized air storage tank  332 . The compressed gas  343  flows from the pressurized gas storage tank  332  through the turbine inlet conduit  333  to the turbine/motor  334  and drives the turbine/motor  334 . In some applications, the turbine/motor  334  may drive the vehicle drive train (not illustrated) of the road or rail vehicle to augment the driving power of the motor  388 . In some applications, the turbine/motor  334  may be reversible to provide regenerative braking capability according to the knowledge of those skilled in the art. In some applications, such as under circumstances in which the motor  388  is not being operated, for example, the external gas compressor  392  may be operated to force compressed gas  393  to the turbine/motor  334  through the turbine inlet conduit  333 . 
     While exemplary embodiments of the disclosure have been described above, it will be recognized and understood that various modifications can be made in the disclosure and the appended claims are intended to cover all such modifications which may fall within the spirit and scope of the disclosure.