Waste Heat Recovery System

Abstract

A waste heat recovery system may include a pump, first and second heat exchangers, an expander, and a valve. The first heat exchanger receives working fluid from the pump. The expander receives working fluid from the first heat exchanger and includes an output shaft that is powered by the flow of working fluid through the expander. The second heat exchanger may include a first fluid path and a second fluid path that is shorter than the first fluid path. The valve controls fluid flow through the first and second fluid paths. A sensor may measure a parameter of the working fluid that indicates whether the working fluid is in a gaseous state, a liquid state or a mixture of gas and liquid. A control module in communication with the sensor may control a position of the valve based on a value of the parameter measured by the sensor.

What is claimed is: 
     
         1 . A waste heat recovery system comprising:
 a pump;   a first heat exchanger disposed downstream of the pump and receiving working fluid from the pump;   an expander disposed downstream of the first heat exchanger and receiving working fluid from the first heat exchanger, the expander including an output shaft that is powered by the working fluid flowing through the expander;   a second heat exchanger disposed downstream of the expander and receiving working fluid from the expander, the second heat exchanger including a first inlet, a second inlet and an outlet, wherein a first fluid path through the second heat exchanger between the first inlet and the outlet has a first length, and wherein a second fluid path through the second heat exchanger between the second inlet and the outlet has a second length that is shorter than the first length; and   a valve disposed upstream of the outlet of the second heat exchanger and downstream of the expander and controlling fluid flow through the first and second inlets.   
     
     
         2 . The waste heat recovery system of  claim 1 , wherein working fluid in the first heat exchanger absorbs heat from a fluid separate from the working fluid, the fluid being selected from the group consisting of: engine exhaust gas, compressed air, and engine coolant. 
     
     
         3 . The waste heat recovery system of  claim 1 , wherein the valve is disposed upstream of the first and second inlets. 
     
     
         4 . The waste heat recovery system of  claim 1 , wherein the second fluid path includes only a portion of the first fluid path. 
     
     
         5 . The waste heat recovery system of  claim 1 , wherein the valve is movable between a first position in which working fluid is allowed to flow through the first inlet and is prevented from flowing through the second inlet, a second position in which working fluid is allowed to flow through the second inlet and is prevented from flowing through the first inlet, and a third position in which working fluid is allowed to flow through the first inlet and the second inlet. 
     
     
         6 . The waste heat recovery system of  claim 1 , further comprising a sensor disposed downstream of the second heat exchanger and upstream of the pump; and a control module in communication with the sensor and controlling operation of the valve based on data received from the sensor. 
     
     
         7 . The waste heat recovery system of  claim 6 , wherein the sensor is a temperature sensor, and wherein the control module controls the valve based on a comparison of data from the sensor and a predetermined temperature value indicative of full condensation of the working fluid exiting the outlet of the second heat exchanger. 
     
     
         8 . The waste heat recovery system of  claim 7 , wherein the first and second inlets and the outlet are formed in a vehicle panel disposed on an underbody of a vehicle such that heat from the working fluid within the second heat exchanger is transferred to air flowing between the underbody of the vehicle and a ground surface upon which the vehicle is situated. 
     
     
         9 . The waste heat recovery system of  claim 8 , wherein the vehicle panel includes a component selected from the group consisting of: a skid plate, a floor pan, a belly pan, and an under-floor aerodynamic panel. 
     
     
         10 . The waste heat recovery system of  claim 1 , wherein the second heat exchanger is integrally formed with a body panel of a vehicle. 
     
     
         11 . A waste heat recovery system comprising:
 a pump;   a first heat exchanger disposed downstream of the pump and receiving working fluid from the pump;   an expander disposed downstream of the first heat exchanger and receiving working fluid from the first heat exchanger, the expander including an output shaft that is powered by the working fluid flowing through the expander;   a second heat exchanger including a first fluid path having a first length and a second fluid path having a second length that is shorter than the first length;   a valve disposed downstream of the expander and controlling fluid flow through the first and second fluid paths;   a sensor disposed downstream of the first and second fluid paths and upstream of the pump, the sensor measuring a parameter of the working fluid indicating whether the working fluid is in a gaseous state, a liquid state or a mixture of gas and liquid; and   a control module in communication with the sensor and the valve and controlling a position of the valve based on a value of the parameter measured by the sensor.   
     
     
         12 . The waste heat recovery system of  claim 11 , wherein the valve is disposed within the second heat exchanger between an inlet of the second heat exchanger and an outlet of the second heat exchanger. 
     
     
         13 . The waste heat recovery system of  claim 11 , wherein the second heat exchanger includes first inlet, a second inlet and an outlet, wherein the first fluid path extends between the first inlet and the outlet, and wherein the second fluid path extends between the second inlet and the outlet. 
     
     
         14 . The waste heat recovery system of  claim 13 , wherein the valve is disposed upstream of the first and second inlets. 
     
     
         15 . The waste heat recovery system of  claim 14 , wherein the valve is movable between a first position in which working fluid is allowed to flow through the first inlet and is prevented from flowing through the second inlet, a second position in which working fluid is allowed to flow through the second inlet and is prevented from flowing through the first inlet, and a third position in which working fluid is allowed to flow through the first inlet and the second inlet. 
     
     
         16 . The waste heat recovery system of  claim 11 , wherein the sensor is a temperature sensor, and wherein the control module controls the valve based on a comparison of data from the sensor and a predetermined temperature value indicative of full condensation of the working fluid exiting the second heat exchanger. 
     
     
         17 . The waste heat recovery system of  claim 11 , wherein the first and second fluid paths are formed in a vehicle panel disposed on an underbody of a vehicle such that heat from the working fluid within the second heat exchanger is transferred to air flowing between the underbody of the vehicle and a ground surface upon which the vehicle is situated. 
     
     
         18 . The waste heat recovery system of  claim 17 , wherein the vehicle panel includes a component selected from the group consisting of: a skid plate, a floor pan, a belly pan, and an under-floor aerodynamic panel. 
     
     
         19 . The waste heat recovery system of  claim 11 , wherein the second heat exchanger is integrally formed with a body panel of a vehicle. 
     
     
         20 . A waste heat recovery system comprising:
 a pump;   a first heat exchanger disposed downstream of the pump and receiving working fluid from the pump;   an expander disposed downstream of the first heat exchanger and receiving working fluid from the first heat exchanger, the expander including an output shaft that is powered by the working fluid flowing through the expander;   a second heat exchanger disposed downstream of the expander and receiving working fluid from the expander, the second heat exchanger formed in a vehicle panel disposed on an underbody of a vehicle such that heat from the working fluid within the second heat exchanger is transferred to air flowing between the underbody of the vehicle and a ground surface upon which the vehicle is situated.   
     
     
         21 . The waste heat recovery system of  claim 20 , wherein the vehicle panel includes a component selected from the group consisting of: a skid plate, a floor pan, a belly pan, and an under-floor aerodynamic panel. 
     
     
         22 . The waste heat recovery system of  claim 20 , wherein the second heat exchanger includes a first inlet, a second inlet and an outlet, wherein a first fluid path through the second heat exchanger between the first inlet and the outlet has a first length, and wherein a second fluid path through the second heat exchanger between the second inlet and the outlet has a second length that is shorter than the first length. 
     
     
         23 . The waste heat recovery system of  claim 22 , further comprising a valve disposed upstream of the outlet of the second heat exchanger and downstream of the expander and controlling fluid flow through the first and second inlets. 
     
     
         24 . The waste heat recovery system of  claim 23 , wherein the valve is disposed upstream of the first and second inlets. 
     
     
         25 . The waste heat recovery system of  claim 24 , wherein the second fluid path includes only a portion of the first fluid path. 
     
     
         26 . The waste heat recovery system of  claim 25 , wherein the valve is movable between a first position in which working fluid is allowed to flow through the first inlet and is prevented from flowing through the second inlet, a second position in which working fluid is allowed to flow through the second inlet and is prevented from flowing through the first inlet, and a third position in which working fluid is allowed to flow through the first inlet and the second inlet. 
     
     
         27 . The waste heat recovery system of  claim 26 , further comprising a sensor disposed downstream of the second heat exchanger and upstream of the pump; and a control module in communication with the sensor and controlling operation of the valve based on data received from the sensor. 
     
     
         28 . The waste heat recovery system of  claim 27 , wherein the sensor is a temperature sensor, and wherein the control module controls the valve based on a comparison of data from the sensor and a predetermined temperature value indicative of full condensation of the working fluid exiting the outlet of the second heat exchanger.