WO2015143272A1

WO2015143272A1 - Enhanced waste heat recovery system and method comprising an expander connected to a generator

Info

Publication number: WO2015143272A1
Application number: PCT/US2015/021670
Authority: WO
Inventors: Mark R.J. Versteyhe; Stijn Goossens
Original assignee: Dana Ltd
Current assignee: Dana Ltd
Priority date: 2014-03-20
Filing date: 2015-03-20
Publication date: 2015-09-24
Anticipated expiration: 2016-09-20

Abstract

A combined internal combustion engine and waste heat recovery system and method for facilitating driving engagement between the internal combustion engine and the waste heat recovery system is provided. The waste heat recovery system comprises a condenser, a pump, a heat exchanger, an expansion device, a generator, and an electrical load. The heat exchanger is in fluid communication with the pump and thermal communication with an exhaust of the internal combustion engine. The expansion device is in fluid communication with the heat exchanger and the condenser. The generator is in driving engagement with the expansion device. The electrical load is in electrical communication with the generator. In response to rotation of the expansion device, an electrical current generated by the generator is applied to the electrical load to increase an efficiency of the combined internal combustion engine and waste heat recovery system.

Description

TITLE

ENHANCED WASTE HEAT RECOVERY SYSTEM AND METHOD COMPRISING AN EXPANDER CONNECTED TO A GENERATOR

CLAIM OF PRIORITY

The present application claims the benefit of priority to U.S. Provisional Application No. 61/955,843 filed on March 20, 2014, which is incorporated herein in its entirety by reference.

FIELD OF THE INVENTION

The present invention relates to energy recovery systems and more specifically to waste heat recovery systems used with internal combustion engines.

BACKGROUND OF THE INVENTION

A conventional internal combustion engine typically has a limited brake thermal efficiency (BTE). Energy released during a combustion process utilized by the internal combustion engine is only partially converted to useful work. A large portion of the energy released during the combustion process is rejected as waste heat to an ambient environment of the internal combustion engine. The waste heat is typically dispersed to the ambient environment of the internal combustion engine through the use of a cooling system and an exhaust system of the internal combustion engine. Efficiencies of the internal combustion alone (not accounting for any power transmission losses) typically do not exceed about 50%.

An amount of energy that is rejected as waste heat to the ambient environment is proportional to an efficiency, and thus a fuel consumption, of the internal combustion engine. With increasing fuel costs and emission regulations becoming more and more stringent, new technologies to improve an efficiency of internal combustion engines are highly sought after. FIG. 1 illustrates an exemplary waste heat recovery (WHR) system 100 used with an internal combustion engine 102 that is known in the art. The WHR system 100 captures waste heat to generate additional power for the internal combustion engine 102. The WHR system 100 includes a heat exchanger 104, an expansion device 106, a condenser 108, and a feed pump 110. A working fluid is pumped through the WHR system 100 to convert waste heat to power at the expansion device 106. The working fluid is a 2-phase fluid or a mixture of such fluids fitting a temperature range of the waste heat flow from the internal combustion engine 102. The heat exchanger 104 captures the thermal energy in the waste heat from the internal combustion engine 102 to evaporate the working fluid. The vapors of the working fluid are then expanded in the expansion device 106 to generate additional useful work.

Typically, the expansion device 106 of the WHR system 100 is mechanically coupled to a crankshaft of the internal combustion engine 102 by a belt, a gear box, a continuously variable transmission or any other

mechanical system which is capable of supplying additional torque and power to a rotating shaft. The connection of the expansion device 106 to the crankshaft via these structures increases a complexity of the WHR system 100 and the internal combustion engine 102. Further, the connection encroaches on valuable space in the vehicle and makes retrofitting of the WHR system 100 to any internal combustion engine very difficult, if not impossible.

The connection between the expansion device 106 and the crankshaft of the internal combustion engine 102 can also limit the performance of the expansion device 106 and the WHR system 100. By adjusting a rotational speed of the expansion device 106, optimal performance of the WHR system 100 may be achieved. However, being able to change the rotational speed of the expansion device 106 typically results in a complex mechanical system or a system with a significant amount of additional energy losses. Adapting the rotational speed of the expansion device 106 may be accomplished through the use of a continuously variable transmission, but the continuously variable transmission is a complex and expensive device which can contribute to system losses. Consequently, the WHR system 100 may be designed to perform optimally at the normal operating point of the internal combustion engine 102 (for example, a normal engine speed and load), resulting in an optimal evaporation pressure and temperature in the heat exchanger 104 and an optimal mass flow for the working fluid. However, the internal combustion engine 102 should be expected to operate under highly dynamic conditions (for example, highly variable engine speed and load), which also result in dynamic operating conditions for the WHR system 100.

It can be appreciated that to maximize the power generated by the WHR system 100 a mass flow rate and/or an evaporation pressure and temperature of the working fluid have to be controlled appropriately. However, by

connecting the expansion device 106 directly with a belt or gear box to the crankshaft of the internal combustion engine 102, the expansion device 106 and the internal combustion engine 102 have a fixed speed ratio. Thus, the mass flow rate of the working fluid cannot be controlled independently from the speed of the internal combustion engine 102 when the expansion device 106 has a fixed displacement. This results in having an inappropriate evaporation pressure in the WHR system 100 (more particularly in the heat exchanger 104), which causes the WHR system 100 to convert energy less efficiently.

A similar rationale can be applied in cases of variable speed of the internal combustion engine 102 or other dynamic operation conditions typically encountered by the internal combustion engine 102 and the WHR system 100. In order to maximize a conversion efficiency of the WHR system 100, the mass flow rate of the working fluid and/or the heat exchanger 104 has to be controlled independently of the speed of the internal combustion engine 102. Such a control might be accomplished by decoupling the internal combustion engine 102 and the expansion device 106.

Consequently, it would be very advantageous to have a power output of the WHR system 100 not in the form a rotating, mechanical power output.

It would be advantageous to develop a waste heat recovery system for an internal combustion engine that increases an efficiency of the internal combustion engine, is compatible with existing internal combustion engine components, and does not require mechanical interlinking between the waste heat recovery system and the internal combustion engine.

SUMMARY OF THE INVENTION

Presently provided by the invention, a waste heat recovery system for an internal combustion engine that increases an efficiency of the internal combustion engine, is compatible with existing internal combustion engine components, and does not require mechanical interlinking between the waste heat recovery system and the internal combustion engine, has surprisingly been discovered.

In one embodiment, the present invention is directed to a combined internal combustion engine and waste heat recovery system. The waste heat recovery system comprises a condenser, a pump, a heat exchanger, an expansion device, a generator, and an electrical load. The pump is in fluid communication with the condenser. The heat exchanger is in fluid

communication with the pump and thermal communication with an exhaust of the internal combustion engine. The expansion device is in fluid

communication with the heat exchanger and the condenser. The generator is in driving engagement with the expansion device. The electrical load is in electrical communication with the generator. In response to rotation of the expansion device, an electrical current generated by the generator is applied to the electrical load to increase an efficiency of the combined internal combustion engine and waste heat recovery system.

In another embodiment, the present invention is directed to a method for facilitating driving engagement between an internal combustion engine and waste heat recovery system. The method comprises the steps of providing the internal combustion engine, providing the waste heat recovery system, vaporizing a working fluid using heat from exhaust gases of the internal combustion engine, driving the expansion device using the vaporized working fluid, generating an electrical current using the generator; and applying the electrical current to the electrical load to increase an efficiency of the combined internal combustion engine and waste heat recovery system. The waste heat recovery system comprises a condenser, a pump in fluid communication with the condenser, a heat exchanger in fluid communication with the pump and thermal communication with an exhaust of the internal combustion engine, an expansion device in fluid communication with the heat exchanger and the condenser, a generator in driving engagement with the expansion device, and an electrical load in electrical communication with the generator.

Various aspects of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The above, as well as other advantages of the present invention will become readily apparent to those skilled in the art from the following detailed description when considered in the light of the accompanying drawings in which:

FIG. 1 is a schematic illustration of a combined internal combustion engine and waste heat recovery system according to the prior art;

FIG. 2 is a schematic illustration of a combined internal combustion engine and waste heat recovery system according to an embodiment of the present invention;

FIG. 3 is a pressure versus volume diagram of an optimal cycle used with the waste heat recovery system shown in FIG. 2;

FIG. 4A is a pressure versus volume diagram of a thermodynamic cycle exhibiting under expansion losses; and

FIG. 4B is a pressure versus volume diagram of a thermodynamic cycle exhibiting over expansion losses.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

It is to be understood that the invention may assume various alternative orientations and step sequences, except where expressly specified to the contrary. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification are simply exemplary embodiments of the inventive concepts defined herein. Hence, specific dimensions, directions or other physical characteristics relating to the embodiments disclosed are not to be considered as limiting, unless expressly stated otherwise.

FIG. 2 illustrates an exemplary waste heat recovery (WHR) system 200 according to an embodiment of the invention, the WHR system 200 used with an internal combustion engine 202. The WHR system 200 captures waste heat from the internal combustion engine 202 to generate additional power. The WHR system 200 includes a heat exchanger 204, an expansion device 206 in driving engagement with a generator 208, a condenser 210, and a feed pump 212. A working fluid is pumped through the WHR system 200 to convert waste heat to power at the expansion device 206. The working fluid is a two-phase fluid or a mixture of such fluids fitting a temperature range of the waste heat flow from the internal combustion engine 202. The heat exchanger 204 captures the thermal energy in the waste heat from the internal combustion engine 202 to evaporate the working fluid. The vapors of the working fluid are then expanded in the expansion device 206 to generate additional useful work, which is converted to electricity using the generator 208. A power

management unit 214 is in electrical communication with the generator 208 and an electrical load 216 to manage current and voltage levels for the generator 208 and an electrical load 216.

The WHR system 200 may utilize the organic Rankine cycle; however, it is understood that other thermodynamic cycles may also be used with the WHR system 200. It is understood that the components of the WHR system 200 and a working fluid used may be adapted for use with other thermodynamic cycles. Typically, the internal combustion engine 202 is used as a power source for a vehicle (not shown); however, it is understood that the internal combustion engine 202 may be used in other applications, such as in stationary power generation applications.

The internal combustion engine 202 comprises a primary portion 218 and an engine output 220. The primary portion 218 is in thermal

communication with the heat exchanger 204 through an exhaust 222 of the primary portion 218; however, it is understood that the primary portion 218 may be in thermal communication with the heat exchanger 204 through a cooling system (not shown) or both the exhaust 222 and the cooling system of the primary portion 218. The primary portion 218 is in driving engagement with the engine output 220. The internal combustion engine 202 may be any type of internal combustion engine, and it is understood that the internal combustion engine 202 and the electrical load 216 may form a portion of driveline for a hybrid vehicle.

The primary portion 218 comprises at least an engine block; however, it is understood that the primary portion 218 may also include components typically used with an internal combustion engine, such as a plurality of valves, a plurality of pistons, at least one crankshaft, a plurality of connecting rods, a clutching device, a ratio adapting device, a fuel delivery system, an ignition system, and the cooling system. The engine output 220 is a mechanical component driven by the primary portion 218. The engine output 220 may be a vehicle driveline or a portion of a vehicle driveline, such as a driveshaft, a transmission, or a flywheel.

The WHR system 200 comprises the heat exchanger 204, the expansion device 206 in driving engagement with the generator 208, the condenser 210, the feed pump 212, and a plurality of fluid conduits 224. The feed pump 212 is in fluid communication with the heat exchanger 204 and the condenser 210. The expansion device 206 is in fluid communication with the condenser 210 and the heat exchanger 204. The WHR system 200 is a closed circuit, thermodynamic device that employs a liquid-vapor phase change to convert heat energy into motive power. It is understood that the WHR system 200 may include additional components not illustrated in FIG. 2, such as, but not limited to, a working fluid reservoir, a plurality of valves, and a plurality of sensors in communication with a control system. The plurality of fluid conduits 224 facilitate fluid communication to occur between each of the components 204, 206, 210, 212 and may comprise a plurality of preformed rigid tubes, flexible conduits, or conduits formed within a portion of each of the components 204, 206, 210, 212. The feed pump 212 transfers the working fluid used with the WHR system 200 from the condenser 210 to the heat exchanger 204 through a portion of the plurality of fluid conduits 224. The feed pump 212 is conventional and well known in the art. The feed pump 212 may be an electrically operated pump designed to transfer the working fluid in a liquid state. Alternately, it is understood that the feed pump 212 may be mechanically driven by a rotating component of the primary portion 218 or the expansion device 206.

The heat exchanger 204 facilitates thermal communication between the exhaust 222 and a portion of the plurality of fluid conduits 224. It is understood that the heat exchanger 204 may comprise a plurality of heat exchangers. The heat exchanger 204 is conventional and well known in the art, and may also be referred to as an evaporator. As the working fluid passes through a portion of the heat exchanger 204, the working fluid is heated and evaporated by energy imparted to the working fluid by the exhaust gases passing through the exhaust 222. As a result of the thermal communication between a portion of the plurality of fluid conduits 224 and the exhaust 222, the working fluid leaves the heat exchanger 204 in a gaseous state.

The expansion device 206 extracts work from the working fluid in the gaseous state. The expansion device 206 is a reciprocating piston expander. The expansion device 206 comprises at least one piston (not shown) in selective fluid communication with a portion of the plurality of fluid conduits 224 between the heat exchanger 204 and the condenser 210. The at least one piston is arranged to convert a reciprocating motion into a rotary motion using a crankshaft (not shown). In response to an opening of a valve (not shown), the working fluid in a gaseous state enters a cylinder one of the pistons is disposed in. A pressure of the working fluid in a gaseous state urges the piston, resulting in an expansion of the working fluid within the cylinder and a rotation of the crankshaft. Such expansion devices are well known in the art, and a full understanding of such devices is outside the scope of the invention described herein. An output 226 of the expansion device 206 is drivingly engaged with a rotor portion 228 of the generator 208. During operation of the WHR system 200, the working fluid leaving the heat exchanger 204 is expanded in the expansion device 206, imparting work to the rotor portion 228 of the generator 208. During expansion of the working fluid, the working fluid drives the expansion device 206 and the pressure and temperature of the working fluid are reduced. After exiting the expansion device 206, the working fluid continues within a portion of the plurality of fluid conduits 224 to the condenser 210.

The condenser 210 facilitates thermal communication between the working fluid in the gaseous state and an ambient environment of the WHR system 200. The condenser 210 is a heat exchanging device and is

conventional and well known in the art. The condenser 210 may be a liquid to air type heat exchanger or a liquid to liquid type heat exchanger. As the working fluid passes through a portion of the condenser 210, the working fluid is cooled as the energy within the working fluid is distributed by the condenser 210 to the ambient environment of the WHR system 200. The condenser 210 provides further cooling for the working fluid, in addition to the temperature drop that occurs as the working fluid passes through the expansion device 206. As a result of the thermal communication between the working fluid and the condenser 210, the working fluid condenses and leaves the condenser 210 in a liquid state. After passing through the condenser 210, the working fluid (now in a fully liquid state) flows to the working fluid reservoir (not shown) and is then pumped to an increased pressure by the feed pump 212 so that the cycle may be repeated.

The generator 208 converts mechanical energy applied by the

expansion device 206 to electrical energy. The generator 208 is directly driven by an output shaft of the expansion device 206. The generator 208 comprises the rotor portion 228 and a stator portion 230, and is well known in the art. The generator 208 is an alternating current generator, such as a single phase, 3 phase, or multi-phase generator; however, it is understood that that generator may be a direct current generator. The generator 208 is in electrical communication with and controlled by the power management unit 214.

Through control of the generator 208, a rotational speed of the expansion device 206 is controlled while ensuring the voltages and currents required by the electrical load 216 are provided.

The power management unit 214 is in electrical communication with the generator 208 and the electrical load 216. The power management unit 214 can include the necessary components required for operation of the generator 208, an alternating to direct current converter or any other configuration of electronic switches and corresponding control of them to facilitate control of the generator 208 and the electrical load 216. The power management unit 214 is in electrical communication and manages the current and voltage levels between the power management unit 214, the generator 208, and the electrical load 216. The power management unit 214 is able to control the current and field in the generator 208 as independently as possible from the power actually extracted from the expansion device 206 and/or an amount of mechanical power available from the expansion device 206. If the mechanical power available in the expansion device 206 is not matched with the power actually extracted from the expansion device 206, one of the expansion device 206 and the generator 208 will experience a speed change until a new equilibrium is reached. The power management unit 214 can thus be used to regulate an amount of electrical power extracted from the WHR system 200 so that the speed of the expansion device 206 is controlled so that the expansion device operates at an optimal operating condition.

The electrical load 216 is a device that uses and/or stores electrical energy. The electrical load 216 is in electrical communication with the power management unit 214. The electrical load 216 may comprise a plurality of energy storage devices, such as batteries. Electrical energy stored in the electrical load 216 can be delivered to the vehicle when the power

management unit 214 indicates more electrical power is needed. For example, if the power provided by the expansion device 206 is not sufficient for a given electrical load, the additional needed power can come from the electrical load 216, in the form of batteries, to assist the generator 208.

A hybrid vehicle, for example, is a type of vehicle that would use such a battery. In the case of a hybrid vehicle, power management unit 214 ensures that an output voltage is controlled to work in the suited operating range of the batteries that form the electrical load 216. Another example for the electrical load 216 is an electric motor drivingly engaged with a portion of a driveline of the vehicle. As non-limiting examples, the portion of the driveline of the vehicle may be a shaft of the internal combustion engine 202, a shaft of a power takeoff, or any other shaft. When the electrical load 216 is an electric motor, the electric motor can be directly fed with the energy created by the WHR system.

The electrical load in the system can also be a combination of many loads. An example of this would be for the load to comprise an electric motor that receives some portion of the load and batteries that comprise another portion of the load.

In use, the WHR system 200 paired with the internal combustion engine 202 increases an overall thermal efficiency of the internal combustion engine 202 and a vehicle the WHR system 200 and internal combustion engine 202 is incorporated in, and overcomes many problems common to conventional waste heat recovery systems. During operation of the WHR system 200, electricity generated by the generator 208 is distributed by the power management unit 214 to improve an efficiency of the vehicle incorporating the WHR system 200.

The WHR system 200 in driving engagement with the generator 208 allows controlling of the expansion device 206 in an optimal way. More specifically, by varying a rotational speed of the expansion device 206, the pressures and temperatures in the WHR system 200 can be controlled in an optimal way. This allows optimizing the efficiency of the total system, meaning a combination of the WHR system 200 and the combustion engine 202. This also allows the expansion device 206 to minimize energy losses due to under or over expansion in the cycle. Furthermore, driving engagement with the generator 208 brings an increased level of control over the expansion device 206, allowing the expansion device 206 to recover a significant amount of energy flowing through the exhaust gases.

The WHR system 200 captures a portion of a waste heat leaving the primary portion 218 present in the exhaust gases and converts the waste heat to useful work, and then electricity to increasing an overall thermal efficiency and a fuel efficiency of the internal combustion engine 202. The working fluid used with the WHR system 200 may be an organic fluid (which is used in both a liquid and a gaseous state, as described hereinabove). The working fluid is selected for a temperature range of the waste heat of the internal combustion engine 202. As non-limiting examples, the working fluid may be a refrigerant (such as R-22, R-123, R134a, or R245a), alcohol, butane, iso-butane, pentane, iso-pentane, hexane, iso-hexane, water, and any mixture thereof. Alternately, it is understood that the working fluid may be another type of fluid suitable for use in a waste heat recover system employing a thermodynamic cycle.

By not drivingly engaging the expansion device 206 with the internal combustion engine 202, the problems typically encountered with conventional waste heat recovery systems can be avoided, such as complex interoperability and a mechanical connection between the expansion device and the internal combustion engine.

By using the WHR system 200 paired with the internal combustion engine 202, the thermal energy contained in the exhaust gases can be captured and converted to useful work and then to electricity, which may be applied to a portion of the internal combustion engine 202 as additional torque, stored as electrical energy, or used by electrical devices associated with the vehicle including the WHR system 200.

An optimal cycle used with the WHR system 200 is represented in a pressure versus volume diagram shown in FIG. 3. The cycle starts at the top left in the diagram, at minimum volume and maximum pressure, P_su, which is representative of the pressure of the fluid at an output of the heat exchanger 204. The minimum volume may be the dead volume of the piston in the cylinder of the expansion device 206.

As the piston is moved backwards in the cylinder, a piston chamber inlet is open and a volume V_{s, exp} is aspired into the cylinder before the inlet is closed. When the inlet is closed, the working fluid vapor is expanded as the piston moves to its maximum volume. In an optimal cycle, at the end of the expansion phase, the pressure inside the cylinder, Ρ,η, is the same as the pressure in the output circuit, P_ex. It is understood that the expansion device 206 may be other types of devices besides a reciprocating piston expander, such as an axial turbine, a radial turbine, or a screw expander, for example.

In conventional waste heat recovery systems, it can be appreciated that to maximize the power generated by the waste heat recovery system, a mass flow rate and/or an evaporation pressure and temperature of the working fluid have to be controlled appropriately. However, by connecting the expansion device directly with a belt or gear box to the crankshaft of the internal combustion engine, the expansion device and the internal combustion engine have a fixed speed ratio. Thus, the mass flow rate of the working fluid cannot be controlled independently from the speed of the internal combustion engine when the expansion device has a fixed displacement. This results in having an inappropriate evaporation pressure in the conventional waste heat recovery system (more particularly in the heat exchanger), which causes the system to convert energy less efficiently.

An example of the above is described as follows. Consider a vehicle driving at constant speed. When a slope of the road increases, a load on the internal combustion engine also increases, resulting in higher fuel consumption. Accordingly, the conventional waste heat recovery system can recover more thermal energy from the exhaust gases: In order to optimize the waste heat recovery, the mass flow rate of the working fluid has to increase when operating the system at constant and optimal working conditions. As the internal combustion engine and the expansion device are operating at a constant speed, the mass flow rate cannot be altered over the expansion device, which would result in an increase of the boiler pressure. As the expansion device has a fixed displacement and expansion ratio, an increase of the inlet pressure at the expansion device will cause an increase of the under expansion losses and thus will lower a conversion efficiency of the system. Such a situation is depicted in FIG. 4A. FIG. 4B depicts the converse, known as over expansion losses.

Under expansion losses happen when the mass flow is not sufficient. In that case, the suction pressure, P_su+, increases and the expansion made in the piston cylinder is insufficient. Thus, the pressure at the end of the expansion is larger than the exhaust pressure and this pressure difference is lost when opening the exhaust.

On the contrary, over expansion losses happen in the case of a mass flow that is too large. This incorrect mass flow decreases the suction pressures, P_su-, and the pressure at the end of the expansion is thus too low. When opening the piston chamber at the exhaust pressure, some gas will reenter the piston chamber, creating losses.

A similar rationale can be applied in case of variable engine speed or other dynamic operation conditions of the internal combustion engine and the waste heat recovery system. To maximize the conversion efficiency of the waste heat recover system, the mass flow rate of the working fluid and/or the heat exchanger has to be controlled independently of the speed of the internal combustion engine. Such a control might be accomplished by decoupling the internal combustion engine and the expansion device, such as provided by the embodiment of the invention shown in FIG. 2.

The WHR system 200, which generates electricity instead of a rotational mechanical power, is advantageous over conventional waste heat recovery systems in many applications. As non-limiting examples, when the vehicle including the WHR system 200 is an electric hybrid vehicles or a vehicle which requires a high electric auxiliary load (like cooling trucks, for example), the WHR system 200 is advantageous. In these cases, directly connecting an output of the expansion device to the internal combustion engine leads to an unnecessary step in the energy conversion, resulting in some instances in a decrease in efficiency.

In accordance with the provisions of the patent statutes, the present invention has been described in what is considered to represent its preferred embodiments. However, it should be noted that the invention can be practiced otherwise than as specifically illustrated and described without departing from its spirit or scope.

Claims

What is claimed is:

1. A combined internal combustion engine and waste heat recovery system, comprising:

the internal combustion engine; and

the waste heat recovery system, comprising:

a condenser;

a pump in fluid communication with the condenser; a heat exchanger in fluid communication with the pump and thermal communication with an exhaust of the internal combustion engine;

an expansion device in fluid communication with the heat exchanger and the condenser;

a generator in driving engagement with the expansion device; and an electrical load in electrical communication with the generator, wherein in response to rotation of the expansion device, an electrical current generated by the generator is applied to the electrical load to increase an efficiency of the combined internal combustion engine and waste heat recovery system.

2. The combined internal combustion engine and waste heat recovery system according to claim 1 , wherein the waste heat recovery system utilizes a fluid to perform a themodynamic cycle.

3. The combined internal combustion engine and waste heat recovery system according to claim 2, wherein the fluid is a refrigerant.

4. The combined internal combustion engine and waste heat recovery system according to claim 2, wherein the thermodynamic cycle is the organic Rankine cycle.

5. The combined internal combustion engine and waste heat recovery system according to claim 1 , wherein the expansion device is in driving engagement with a rotor portion of the generator.

6. The combined internal combustion engine and waste heat recovery system according to claim 1 , further comprising a power management unit, the power management unit in electrical communication with the generator and the electrical load.

7. The combined internal combustion engine and waste heat recovery system according to claim 1 , wherein the electrical load is one of a plurality of batteries and an electric motor.

8. The combined internal combustion engine and waste heat recovery system according to claim 1 , wherein the power management unit controls a speed of the expansion device to regulate an amount of power extracted using the waste heat recovery system.

9. The combined internal combustion engine and waste heat recovery system according to claim 1 , wherein the power management unit manages the current and voltage levels between the power management unit, the generator, and the electrical load.

10. A method for facilitating driving engagement between an internal combustion engine and waste heat recovery system, comprising the steps of: providing the internal combustion engine;

providing the waste heat recovery system, comprising:

a condenser;

a pump in fluid communication with the condenser; a heat exchanger in fluid communication with the pump and thermal communication with an exhaust of the internal combustion engine; an expansion device in fluid communication with the heat exchanger and the condenser;

a generator in driving engagement with the expansion device; and an electrical load in electrical communication with the generator; vaporizing a working fluid using heat from exhaust gases of the internal combustion engine;

driving the expansion device using the vaporized working fluid;

generating an electrical current using the generator; and

applying the electrical current to the electrical load to increase an efficiency of the combined internal combustion engine and waste heat recovery system.

11. The method for facilitating driving engagement between an internal combustion engine and waste heat recovery system according to claim

10, wherein the waste heat recovery system utilizes a fluid to perform a themodynamic cycle.

12. The method for facilitating driving engagement between an internal combustion engine and waste heat recovery system according to claim

11 , wherein the fluid is a refrigerant.

13. The method for facilitating driving engagement between an internal combustion engine and waste heat recovery system according to claim 11 , wherein the thermodynamic cycle is the organic Rankine cycle.

14. The method for facilitating driving engagement between an internal combustion engine and waste heat recovery system according to claim 10, wherein the expansion device is in driving engagement with a rotor portion of the generator.

15. The method for facilitating driving engagement between an internal combustion engine and waste heat recovery system according to claim 10, further comprising a power management unit, the power management unit in electrical communication with the generator and the electrical load.

16. The method for facilitating driving engagement between an internal combustion engine and waste heat recovery system according to claim 10, wherein the electrical load is one of a plurality of batteries and an electric motor.

17. The method for facilitating driving engagement between an internal combustion engine and waste heat recovery system according to claim 10, further comprising the step of controlling a speed of the expansion device using the power management unit to regulate an amount of power extracted using the waste heat recovery system.

18. The method for facilitating driving engagement between an internal combustion engine and waste heat recovery system according to claim 10, further comprising the step of managing the current and voltage levels between the power management unit, the generator, and the electrical load using the power management unit.