Diesel Engine Aftertreatment Control Operation with Waste Heat Recovery

Abstract

A diesel engine exhaust gas aftertreatment system is described. The system may comprise a heat transfer device comprising a first side and a second side; a heater downstream of the first side of the heat transfer device, a filter downstream of the heater; and, an exhaust path downstream of the filter leading to the second side of the heat transfer device, wherein the exhaust path is isolated from an external surface of the filter to inhibit heat transfer from the heated exhaust gas exiting the filter to the external surface of the filter.

1 . A diesel engine exhaust gas aftertreatment system, comprising:
 a heat transfer device comprising a first side and a second side;   a heater downstream of the first side of the heat transfer device;   a filter downstream of the heater; and,   an exhaust path downstream of the filter leading to the second side of the heat transfer device, wherein the exhaust path is isolated from an external surface of the filter to inhibit heat transfer from the heated exhaust gas exiting the filter to the external surface of the filter.   
     
     
         2 . The system of  claim 1 , further comprising a heater control device to regulate operation of the heater responsive to a temperature and/or a pressure of the exhaust gas, where the heater control device is further responsive to an engine control unit. 
     
     
         3 . The system of  claim 2 , where the heater control device is further responsive to an engine condition received from the engine control unit, where the engine condition includes engine speed, air fuel ratio, fuel injection timing, and/or engine load. 
     
     
         4 . The system of  claim 1 , further comprising a catalyst coupled downstream of a third side of the heat transfer device. 
     
     
         5 . The system of  claim 1 , wherein the heat transfer device comprises a shell and tube heat exchanger. 
     
     
         6 . The system of  claim 1 , wherein substantially all of the exhaust gas entering the first side of the heat transfer device is conducted to the second side of the heat transfer device after being conducted through at least the heater, the filter, and the exhaust path. 
     
     
         7 . The system of  claim 6 , wherein the heater is a fuel-fired heater. 
     
     
         8 . The system of  claim 1 , wherein the heater is located directly upstream of the particulate filter, and where the heat transfer device is located directly downstream of the particulate filter. 
     
     
         9 . A method of operating a diesel engine exhaust gas aftertreatment system having a heat transfer device, a particulate filter, and a heater, comprising:
 during a first exhaust gas condition:
 conducting a first volume of exhaust gas through a first passage of the heat transfer device, operating the heater to elevate temperature of the first volume of exhaust gas exiting the heat transfer device, conducting the first volume of exhaust gas exiting the heater through the particulate filter, conducting the first volume of exhaust gas exiting the particulate filter through an exhaust passage to a second passage of the heat transfer device, wherein the exhaust passage is isolated from an external surface of the filter to inhibit heat transfer from the heated exhaust gas exiting the filter to the external surface of the filter, and heating a second volume of exhaust gas conducted from the engine to the first passage of the heat transfer device with energy transferred from the first volume of exhaust gas in the second passage of the heat transfer device; and 
   during a second exhaust gas condition:
 conducting a third volume of exhaust gas through the first passage of the heat transfer device, conducting the third volume of exhaust gas through the heater without operating the heater, conducting the third volume of exhaust gas exiting the heater through a particulate filter, conducting the third volume of exhaust gas exiting the particulate filter through the exhaust passage to the second passage of the heat transfer device, and cooling a fourth volume of exhaust gas conducted from the engine to the first passage of the heat transfer device via energy transferred to the third volume of exhaust gas in the second passage of the heat transfer device. 
   
     
     
         10 . The method of  claim 9 , further comprising controlling operation of the heater responsive to at least a temperature of the aftertreatment system. 
     
     
         11 . The method of  claim 10 , further comprising routing exhaust gas from the second passage to a catalyst, where operation of the heater is adjusted responsive to temperature of the catalyst. 
     
     
         12 . The method of  claim 11 , wherein the heater is further adjusted responsive to at least a pressure and an oxygen concentration of the exhaust gas. 
     
     
         13 . A diesel engine exhaust gas aftertreatment system, comprising:
 a heat transfer device comprising a first passageway and a second passageway, the first passageway between a first side and a second side of the device, the second side opposite the first side, the second passageway between a third side and a fourth side of the device, the fourth side opposite the third side;   a first exhaust path leading exhaust gas from the engine to the first side;   a second exhaust path leading exhaust gas from the second side to the third side, the second path including a heater, and a particulate filter coupled downstream of the heater;   a third exhaust path leading exhaust gas from the fourth side, the third path including a catalytic emission control device; and   a controller to operate the heater during a first mode where heat is transferred from exhaust gas in the second passageway to exhaust gas in the first passageway, and to deactivate the heater during a second mode where heat is transferred from exhaust gas in the first passageway to exhaust gas in the second passageway, where said controller transitions the system between the first mode and the second mode responsive to temperature of the catalytic emission control device.   
     
     
         14 . The system of  claim 13  wherein the controller further transitions the system among the first and second mode responsive to the temperature during regeneration of the particulate filter. 
     
     
         15 . The system of  claim 13  wherein the controller adjusts operation of the heater responsive engine operating conditions. 
     
     
         16 . The system of  claim 13 , wherein the heat transfer device comprises a shell and tube heat exchanger. 
     
     
         17 . The system of  claim 16 , wherein substantially all of the exhaust gas exiting the second side of the heat transfer device is conducted to the third side of the heat transfer device after being conducted through at least the heater and the particulate filter. 
     
     
         18 . The system of  claim 17 , wherein the heater is located directly upstream of the particulate filter, and where the heat transfer device is located directly downstream of the particulate filter.