Abstract:
A waste heat recovery (WHR) system and method for regulating exhaust gas recirculation (EGR) cooling is described. More particularly, a Rankine cycle WHR system and method is described, including an arrangement to improve the precision of EGR cooling for engine efficiency improvement and thermal management.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application is a continuation of U.S. patent application Ser. No. 13/355,339, filed on Jan. 20, 2012, which claims the benefit of priority to U.S. Provisional Patent Application No. 61/434,532, filed on Jan. 20, 2011, each of which is hereby incorporated by reference in its entirety for all purposes. 
     
    
     TECHNICAL FIELD 
       [0002]    This disclosure relates to a waste heat recovery (WHR) system and method for regulating exhaust gas recirculation (EGR) cooling and thus temperature control, and more particularly, to a Rankine cycle WHR system and method, including an arrangement to improve the precision of EGR cooling for engine efficiency improvement and thermal management. 
       BACKGROUND 
       [0003]    Increasing the efficiency of internal combustion engines is critical to meet customer expectations and an array of government-mandated regulations. Internal combustion engines generate significant amounts of heat that heat exchangers eventually transfer to the air surrounding the internal combustion engine. Waste heat recovery systems use some of this significant source of heat to improve the efficiency of an internal combustion engine. Waste heat recovery systems may offer additional benefit to an engine beyond converting waste heat to energy or work. 
       SUMMARY 
       [0004]    This disclosure provides an internal combustion engine comprising an exhaust gas recirculation (EGR) system containing an EGR gas and a waste heat recovery (WHR) system adapted to provide cooling to the EGR gas. The WHR system includes a WHR circuit, a fluid containment portion, a feed pump, at least one heat exchanger, an energy conversion portion, and an EGR temperature control circuit connected to the WHR circuit. The feed pump is operable to pump a working fluid from the containment portion through the WHR circuit. The at least one heat exchanger is positioned downstream from the feed pump and is operable to convert the working fluid from a liquid to a high-pressure vapor by transferring heat from the EGR gas to the working fluid. The energy conversion portion is positioned between the heat exchanger and the containment portion. A thermal control unit is positioned along the EGR temperature control circuit to cool the EGR gas and a pressure reduction device is positioned along the EGR temperature control circuit upstream of the thermal control unit to reduce the pressure of the working fluid sufficient to create a phase change of the working fluid. 
         [0005]    This disclosure also provides an internal combustion engine comprising an EGR system containing an EGR gas and a WHR system. The EGR system includes at least one heat exchanger and a thermal control unit positioned downstream from the at least one heat exchanger. The WHR system is adapted to provide a working fluid from a containment portion into a WHR circuit and a parallel EGR temperature control circuit. The WHR circuit includes a feed pump, the at least one heat exchanger, and an energy conversion portion. The at least one heat exchanger is adapted to provide cooling to the EGR gas and to change the phase of the working fluid from a liquid to a high-pressure vapor. The EGR temperature control circuit includes the thermal control unit and the thermal control unit is positioned along the EGR temperature control circuit to cool the EGR gas. 
         [0006]    This disclosure also provides an internal combustion engine comprising an EGR system containing an EGR gas, a WHR system, at least one sensor and a control system. The EGR system includes at least one heat exchanger and a thermal control unit positioned downstream from the at least one heat exchanger. The WHR system is adapted to provide cooling to the EGR gas. The WHR system includes a WHR circuit, a fluid containment portion, a feed pump, the at least one heat exchanger, an energy conversion portion, a thermal control unit, and a compressor. The feed pump is operable to pump a working fluid from the containment portion through the WHR circuit. The at least one heat exchanger is positioned downstream from the feed pump and is operable to convert the working fluid from a liquid to a high-pressure vapor by transferring heat from the EGR gas to the working fluid. The energy conversion portion is positioned between the at least one heat exchanger and the containment portion. The thermal control unit is connected to the WHR circuit and is positioned along the EGR temperature control circuit to cool the EGR gas. The compressor is positioned along the EGR temperature control circuit to pump working fluid from the thermal control unit. The at least one sensor is positioned along at least one of the EGR system and the WHR circuit. The at least one sensor is adapted to generate an output signal. The control system is adapted to receive the output signal and to generate a control signal based on the output signal to control the speed of at least one of the feed pump and the compressor. 
         [0007]    Advantages and features of the embodiments of this disclosure will become more apparent from the following detailed description of exemplary embodiments when viewed in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a schematic of a conventional internal combustion engine incorporating an exhaust gas recirculation (EGR) system. 
           [0009]      FIG. 2  is a schematic of an exemplary embodiment of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0010]    Referring to  FIG. 1 , shown therein is a conventional internal combustion engine  10 . Engine  10  may include an engine body or block  12 , an engine cooling circuit  14 , an air intake system  16 , an exhaust system  18 , an EGR system  20 , and a refrigeration circuit  22 . 
         [0011]    Engine body or block  12  may include an intake manifold  24  and an exhaust manifold  26 . Engine body  12  provides an engine output  28 , which may be a shaft or other mechanism (not shown) that drives a vehicle, generator, or other device that is able to make use of the output of engine body  12 . 
         [0012]    Engine cooling circuit  14  may include a radiator  30  and a fluid pump  32 . Engine cooling circuit  14  extends from engine block  12  to radiator  30  and back to engine block  12 . Cooling fluid pump  32  is adapted to circulate a cooling fluid and may be positioned along cooling circuit  14  between radiator  30  and engine body  12  in a location that is downstream from radiator  30 . A fan  34  may be positioned adjacent to radiator  30  to provide air for heat removal from radiator  30 . A mechanical output of engine block  12  may drive cooling fluid pump  32 , which moves cooling fluid through engine cooling circuit  14 . Cooling fluid pump  32  pushes cooling fluid downstream into engine block  12 . The cooling fluid then flows from engine block  12  to radiator  30 , where a cooling mechanism, such as fan  34 , reduces the temperature of the cooling fluid. The cooling fluid then flows downstream to pump  32  to complete the circuit. 
         [0013]    Air intake system  16  extends from an air source  44  to intake manifold  24  and may include a turbocharger  36 , a charge air cooler  38 , and an EGR mixer  40 . Turbocharger  36  includes a compressor  42 . Charge air cooler  38  is positioned along air intake system  16  downstream from compressor  42 . Between charge air cooler  38  and intake manifold  24  is EGR mixer  40 . The rotation of compressor  42 , caused by the action of exhaust system  18 , described in more detail hereinbelow, compresses air from air source  44 . The action of compressor  42  heats the air, which may require cooling before entering intake manifold  24 . Charge air cooler  38  receives the compressed air and cools it before the compressed air flows downstream to EGR mixer  40 . From EGR mixer  40 , the compressed air enters intake manifold  24 . 
         [0014]    Exhaust system  18  may include a turbocharger turbine  46  and an exhaust outlet  48 . High-pressure exhaust gas from exhaust manifold  26  flows downstream to enter turbine  46 , causing turbine  46  to rotate. The exhaust gas, at reduced pressure after passing through turbine  46 , flows to exhaust outlet  48 . Exhaust outlet  48  may connect to various conventional elements and systems, such as aftertreatment devices and an exhaust pipe or exhaust stack (not shown). Turbine  46  connects to compressor  42  by way of a connection  50 . Thus, the rotation of turbine  46  causes compressor  42  to rotate. 
         [0015]    EGR system  20  extends from exhaust manifold  26  to air intake system  16  and may include an EGR cooler  52 , an EGR valve  54 , an evaporator  56 , and EGR mixer  40 , previously described. EGR cooler  52  is positioned along EGR system  20  downstream from exhaust manifold  26 . Evaporator  56  is positioned along EGR system  20  downstream from EGR cooler  52  and upstream from EGR mixer  40 . EGR valve  54  may be positioned between EGR cooler  52  and evaporator  56 . High-pressure exhaust gas flows from exhaust manifold  26  to EGR cooler  52 , which decreases the temperature of the EGR gas. From EGR cooler  52 , the exhaust gas flows downstream to evaporator  56 , which is also part of refrigeration circuit  22 , as will be described further hereinbelow. Evaporator  56  provides additional cooling to the EGR gas flowing through EGR system  20 . The EGR gas then flows downstream to EGR mixer  40 , where the EGR gas mixes with air from intake system  16  prior to entry of the air and EGR gas mixture into intake manifold  24 . 
         [0016]    Refrigeration circuit  22  includes a thermal expansion valve (TXV)  58 , evaporator  56 , a compressor  60 , and a condenser  62 . Refrigeration circuit  22  connects evaporator  56  to condenser  62 . Positioned along refrigeration circuit  22  is compressor  60 , which is between evaporator  56  and condenser  62  and downstream from evaporator  56 . Downstream from condenser  62  and upstream from evaporator  56  is valve  58 . Compressor  60  serves to pump a refrigerant through refrigeration circuit  22 . As refrigerant flows into evaporator  56 , the heat from the EGR gas flowing through evaporator  56 , described hereinabove, causes the refrigerant to vaporize. The action of compressor  60  causes the vaporized refrigerant to flow downstream to condenser  62 , where fan  34  or other cooling mechanisms cool the refrigerant, causing it to condense to form a liquid. The refrigerant then flows back to evaporator  56 , regulated by the action of valve  58 , thus completing the refrigeration circuit. Compressor  60  may also be regulated to control the rate of refrigerant flow through circuit  22 . The benefit of the ability to adjust the temperature of the EGR gas is that increased cooling of EGR gas may lead to lower emissions of NOx from engine  10 . 
         [0017]    While the conventional system of  FIG. 1  works to cool EGR gas, it does so either by adding a dedicated refrigeration circuit  22  to the engine or by using an existing refrigerant system, such as a vehicle&#39;s air conditioning refrigerant system. In either case, refrigeration circuit  22  causes a reduction in the efficiency of internal combustion engine  10 . 
         [0018]    Referring now to  FIG. 2 , an exemplary embodiment of the present disclosure is described. Elements in the exemplary embodiment having the same number as the convention embodiment described in  FIG. 1  work as described hereinabove are discussed again only as necessary for clarity. 
         [0019]    The exemplary embodiment is shown in conjunction with an internal combustion engine  110 . Internal combustion engine  110  may include engine body or block  12 , engine cooling circuit  14 , air intake system  16 , exhaust system  18 , an EGR system  120 , a waste heat recovery system (WHR)  63 , and a control system  74 . Engine body  12 , engine cooling circuit  14 , air intake system  16 , and exhaust system  18  are described hereinabove. 
         [0020]    EGR system  120  includes an EGR circuit  121  extending from exhaust manifold  26  to connect to air intake system  16 . EGR system  120  may include a superheater  65 , a boiler  66 , an EGR valve  68 , an EGR thermal control unit (TCU)  70 , and EGR mixer  40 . EGR system  120  terminates at EGR mixer  40 , where EGR system  120  interfaces with air intake system  16 . Superheater  65  and boiler  66  may be positioned along EGR system  120  between exhaust manifold  26  and EGR mixer  40  to cool the EGR gas as described hereinbelow. While superheater  65  and boiler  66  are shown as two separate heat exchanger units, they may be a single integrated unit with two sections. In another embodiment, only one single heat exchanger may be used. EGR valve  68  and TCU  70  may be positioned along EGR system  120  between boiler  66  and EGR mixer  40  to further selectively and variably cool the EGR gas thereby controlling EGR temperature as described hereinbelow. A temperature sensor  72  may be located along EGR system  120  between TCU  70  and EGR mixer  40 . 
         [0021]    WHR system  63  may include a WHR circuit  64 , a working fluid cooling and containment portion (FCCP)  76 , a filter and dryer  78 , a feed pump  80 , a check valve  82 , a recuperator  84 , boiler  66 , superheater  65 , and an energy conversion portion  86 . FCCP  76  may include a condenser, a reservoir and a sub-cooler. The functions of these devices may be performed by a single unit or by a combination of separate units. 
         [0022]    Positioned along a first fluid path of WHR circuit  64  downstream of FCCP  76  is feed pump  80 . Filter and dryer  78  may be positioned along WHR circuit  64  between FCCP  76  and feed pump  80 . Positioned along WHR circuit  64  downstream from feed pump  80  are recuperator  84 , boiler  66 , and superheater  65 . Because of the function of recuperator  84 , described in more detail hereinbelow, recuperator  84  is located in two places along WHR circuit  64 . The first location is between feed pump  80  and boiler  66 . The second location is between superheater  65  and FCCP  76 . Energy conversion portion  86  is located along WHR circuit  64  downstream from superheater  65  and upstream from recuperator  84 . Check valve  82  may be located between feed pump  80  and recuperator  84 . A recuperator bypass  92  may provide a path around recuperator  84  that connects feed pump  80  with boiler  66 . The structure and function of the recuperator and the recuperator bypass is discussed in detail in U.S. Pat. No. 7,997,076 issued Aug. 16, 2011, the entire contents of which are hereby incorporated by reference. The connection of recuperator  84  to FCCP  76  completes WHR circuit  64 . 
         [0023]    Energy conversion portion  86  is capable of producing additional work or transferring energy to another device or system. For example, energy conversion portion  86  may be a turbine, piston, scroll, screw, or other type of expander device that moves, e.g., rotates, as a result of expanding working fluid vapor to provide additional work, which can be fed into the engine&#39;s driveline, for example, a driveline or engine output  128  of internal combustion engine  110  by way of a coupling mechanism  94 , to supplement the engine&#39;s power either mechanically or electrically (e.g., by turning a generator), or it can be used to drive a generator and power electrical devices, parasitics or a storage battery (not shown). Alternatively, energy conversion portion  86  can be used to transfer energy from one system to another system (e.g., to transfer heat energy from WHR system  63  to a fluid for a heating system). One type of energy conversion portion  86  is described in more detail in U.S. patent application Ser. No. 13/347,322, filed Jan. 10, 2012, the entire contents of which is hereby incorporated by reference. 
         [0024]    WHR system  63  further includes an EGR temperature control circuit  96  positioned along WHR circuit  64  in parallel with feed pump  80 , at least one heat exchanger  65 / 66 , and energy conversion portion  86 . Specifically, EGR temperature control circuit  96  is connected to WHR circuit  64  at a position downstream from FCCP  76  to thereby receive working fluid from WHR circuit  64 , and further connected to WHR circuit  64  upstream of FCCP  76  to return or deliver working fluid to WHR circuit  64  for delivery to FCCP  76  without flowing through feed pump  80 , at least one heat exchanger  65 / 66 , and energy conversion portion  86 . The connection of circuit  96  to circuit  64  downstream of FCCP  76  may be upstream of feed pump  80 , while the upstream connection of circuit  96  to circuit  64  may be along circuit  64  downstream of recuperator  84 . WHR system  63  includes a pressure reduction device  90  and may further include a compressor  88  positioned along circuit  96 . Pressure reduction device  90  may be a simple orifice or an expansion valve operable to cause a pressure drop in the fluid flow across the orifice or valve sufficient to cause the working fluid to change phase from a liquid to a gas. Pressure reduction device  90  may be positioned along circuit  96  upstream from TCU  70 . Compressor  88  may be positioned along circuit  96  downstream from TCU  70  to pull the gaseous working fluid from TCU  70  and direct it into working fluid circuit  64 . Instead of compressor  88 , circuit  96  may be connected to circuit  64  downstream of feed pump  80  so that higher pressure working fluid in forced into and through circuit  96  and TCU  70 . But, in this case, the evaporation temperature of the working fluid would be limited to that associated with the FCCP pressure. Using the compressor allows for an even lower pressure to be drawn in TCU  70 , allowing cooling at temperatures below that attained in the FCCP. Thus, as described hereinbelow, at least a portion of the cool working fluid (liquid phase) flowing from FCCP  76  can be selectively and variably directed through TCU  70  and then returned to FCCP  76  to control the temperature of EGR gas in EGR circuit  121  before it mixes with intake air and returns to the engine body  12 . 
         [0025]    As shown in  FIG. 2 , an EGR gas under high pressure flows downstream along EGR system  120  to superheater  65  and then to boiler  66 . The EGR gas is cooled as it passes through superheater  65  and boiler  66 . However, the primary purpose of superheater  65  and boiler  66 , which will be described in more detail hereinbelow, is related to the function of WHR system  63  rather than cooling the EGR gas. Thus, cooling of the EGR gas may be insufficient for optimal efficiency and NOx emission control in internal combustion engine  110 . TCU  70 , which is downstream along EGR system  120  from EGR valve  68  and from boiler  66 , provides cooling of EGR gas flow as its only function. Thus, as will be described in more detail hereinbelow, TCU  70  is able to controllably adjust the temperature of the EGR gas independent of the waste heat recovery function of WHR system  63 . The EGR gas, now cooled to an optimal temperature by TCU  70 , flows to EGR mixer  40 , where it joins airflow in air intake system  16 . 
         [0026]    WHR system  63 , containing a working fluid, is a Rankine cycle waste heat recovery system or an organic Rankine cycle system if the working fluid is an organic high molecular mass fluid with a liquid-vapor phase change that is lower than the water-steam phase change. Examples of Rankine cycle working fluids, organic and inorganic, include Genetron® R-245fa from Honeywell, Therminol®, Dowtherm J™ from Dow Chemical Co., Fluorinol® from American Nickeloid, toluene, dodecane, isododecane, methylundecane, neopentane, neopentane, octane, water/methanol mixtures, or steam. While the system described below may be a Rankine cycle or an organic Rankine cycle, it also presents an opportunity with respect to the EGR system. 
         [0027]    FCCP  76  may perform multiple functions including a condenser function, a cooling or sub-cooling function, and a receiver or reservoir function. Feed pump  80  pulls liquid working fluid from FCCP  76  through filter dryer  78 , which serves to remove contaminants from the liquid working fluid. Feed pump  80  then moves the liquid working fluid downstream along WHR circuit  64  through a check valve  82  that prevents reverse flow of the liquid working fluid. The liquid working fluid may then pass through recuperator  84  to receive a first heat transfer from vaporized working fluid, which is received from energy conversion portion  86 . In cases where the liquid working fluid is warm or the vaporized working fluid requires less cooling, recuperator bypass valve  92  may divert some or all liquid working fluid around recuperator  84 . Bypass valve  92  may be a proportional valve that permits a portion of the liquid working fluid to bypass recuperator  84 . Alternatively, bypass valve  92  may be modulated to open and close to adjust the amount of liquid working fluid entering recuperator  84 . 
         [0028]    Downstream from recuperator  84  is boiler  66 , which transfers heat from EGR gas to the liquid working fluid, which causes the liquid working fluid to boil or vaporize. The liquid working fluid then flows to superheater  65 , which increases the heat content of the vaporized working fluid and evaporates any liquid working fluid that remains. The vaporized working fluid is at high pressure, which flows along WHR circuit  64  to energy conversion portion  86 , which has been previously described. As the vaporized working fluid passes through energy conversion portion  86 , the temperature and pressure of the vaporized working fluid decreases. The vaporized working fluid flows downstream to recuperator  84 , where, as previously described, some of the heat energy transfers to the liquid working fluid flowing into recuperator  84  from feed pump  80 . The vaporized working fluid then travels to FCCP  76 , where the vaporized working fluid is condensed to a liquid, cooled to the extent necessary to maintain the function of WHR system  63 , and stored until the liquid working fluid travels through WHR circuit  64  again. 
         [0029]    Temperature control circuit  96  forms a fluid branch that operates in parallel to the above-described path. Liquid working fluid flows into temperature control circuit and then vaporizes. The vapor is then moved downstream to FCCP  76  by the action of compressor  88 . Thus, if compressor  88  is off, pressure builds in TCU  70  and working fluid does not flow through temperature control circuit  96 . When compressor  88  is on, liquid working fluid flows through valve  90 , which may be a thermal expansion valve, into TCU  70 . Because the EGR gas flow through TCU  70  has a temperature greater than the phase change temperature of the liquid working fluid, TCU  70  functions to reduce the temperature of the EGR gas while vaporizing the liquid working fluid. Compressor  88  then moves the vaporized working fluid back into the flow path that extends from recuperator  84  to FCCP  76 . 
         [0030]    Control system  74  may include a control module  98  and a wiring harness  100 . Control module  98 , which may be a single processor, a distributed processor, an electronic equivalent of a processor, or any combination of the aforementioned elements, as well as software, electronic storage, fixed lookup tables and the like, is connected to certain components of internal combustion engine  110  by wire harness  100 , though such connection may be by other means, including a wireless system. 
         [0031]    Control module  98  may connect to and send control signals to EGR valve  68 , FCCP  76 , feed pump  80 , valve  90 , and bypass valve  92 . Control module  98  may also connect to and receive signals from engine body  12 , temperature sensor  72 , a temperature and pressure sensor  102 , a temperature sensor  104 , a temperature sensor  106 , and a NOx sensor  108 . Control module  98  may receive signals from other sensors positioned throughout internal combustion engine  110  that serve to adjust the performance of EGR system  120  and WHR circuit  64 . Temperature sensor  102  may be positioned along WHR circuit  64  upstream from feed pump  80 . Temperature sensor  104  may be positioned along WHR circuit  64  between recuperator  84  and boiler  66 . Temperature sensor  106  may be positioned along WHR circuit  64  downstream from energy conversion portion  86 . NOx sensor  108  may be positioned along exhaust system  18 . 
         [0032]    Control system  74  may serve to control EGR system  120  by first receiving signals from engine body  12 , temperature sensor  72 , and NOx sensor  108 . Engine body  12  may indicate a need to change the temperature of the EGR gas flow into engine body  12  based on, for example, a change in engine operating conditions, such as engine load, or a detected or anticipated change in NOx emissions. Control system  74  may respond by increasing or decreasing EGR flow by adjusting EGR valve  68  to open or close, depending on the signal from engine body  12  and the temperature signal from temperature sensor  72 . Control system  74  may also adjust the speed of compressor  88  to increase or decrease the flow of working fluid through TCU  70  to adjust the temperature of the EGR gas flowing through TCU  70 . While valve  90  may be a fixed orifice, it may also be adjustable so that as compressor  88  operates, the pressure within TCU  70  may be adjusted, which would thus permit cooling of the EGR gas at different temperature levels since the phase-change temperature of the working fluid varies with pressure. By decreasing the compressor flow rate the pressure in TCU  70  is permitted to build, which increases the phase change temperature and provides less cooling for higher EGR temperature. Conversely, increasing the speed of compressor  88  reduces the pressure in TCU  70  and decreases the phase change temperature, which increases cooling of the EGR gas. Valve  90  may also be adjusted to modify the pressure within TCU  70 . For example, increased flow through valve  90  may increase pressure in TCU  70 , assuming the speed of compressor  88  remains fixed, which increases the phase change temperature and decreases cooling of the EGR gas. Conversely, reducing flow through valve  90  decreases the pressure, which decreases the phase change temperature and increases cooling of the EGR gas. 
         [0033]    Control system  74  may use NOx sensor  108  to control the function of temperature control circuit. More specifically, if NOx sensor  108  indicates a rising level of NOx, control system  74  may respond by increasing the flow of working fluid through TCU  70  by increasing the speed of compressor  88  and/or closing valve  90 , thus increasing cooling of the EGR gas. 
         [0034]    Control system  74  may control other aspects of WHR circuit  64 . For example, a signal received from temperature and pressure sensor  102  may indicate that sub-cooling of the liquid working fluid needs modified to increase the cavitation margin of feed pump  80 . Control system  74  may send a control signal to FCCP  76  to adjust sub-cooling, or the speed of feed pump  80  may be adjusted. Temperature sensor  104  may send a signal indicating a need for more heating or less heating of the working fluid as it flows through recuperator  84 . Control system  74  may then adjust bypass valve  92  to change the amount of heating provided to the working fluid by recuperator  84 . Temperature sensor  106  may indicate a need to adjust the superheat temperature of the working fluid, which may be accomplished by adjusting the flow of EGR gas through the EGR circuit, if the engine condition permits such adjustment, or by adjusting the speed of feed pump  80  and bypass valve  92  to increase or decrease heat transferred to the liquid working fluid prior to the liquid working fluid entering boiler  66 . 
         [0035]    As will be understood from the foregoing description, TCU  70  provides a significant benefit to the function of internal combustion engine  110 . The liquid working fluid routed through temperature control circuit  96  proceeds directly from FCCP  76  to TCU  70  and then back to FCCP  76 . Thus, the cooling provided to the EGR gas flow by TCU  70  is independent of the working fluid flow through the portion of the WHR system  63  that passes through energy conversion portion  86 , which permits more precise cooling of the EGR gas flow. Thus, TCU  70  permits using WHR system  63  for two separate waste heat recovery system functions while permitting both to operate independent of each other, that being the energy recovered from energy conversion portion  86  and the precise temperature control of the EGR gas flow by TCU  70 . 
         [0036]    While various embodiments of the disclosure have been shown and described, it is understood that these embodiments are not limited thereto. The embodiments may be changed, modified and further applied by those skilled in the art. Therefore, these embodiments are not limited to the detail shown and described previously, but also include all such changes and modifications.