System and method for protecting an engine from condensation at intake

摘要

An engine protection system and methods for preventing intake condensation are disclosed. In a system and various of the methods, an exhaust gas recirculation (EGR) valve is positioned within an EGR passage fluidly connecting an engine exhaust stream and an engine intake stream, while a waste heat recovery (WHR) system is used to recover heat from the EGR stream. An engine control unit (ECU) is coupled to various sensors and valves to divert working fluid from the WHR system from cooling the EGR exhaust flow below a level which favors production of condensation in the engine intake system. The ECU operates to divert working fluid flow when sensors indicate characteristics of either the exhaust flow or the intake stream which might lead to heavy condensation. A three-way valve is also used to divert the working fluid to a variable expansion valve fluidly coupled to the three-way valve in response to a signal from one of the sensors to prevent damage to the system turbine.

主权项

1. An engine protection system for preventing intake condensation, the system comprising:
an exhaust gas recirculation (EGR) valve positioned within an EGR passage fluidly connecting an engine exhaust stream and an engine intake stream; a super heater fluidly coupled by an inlet and an outlet to the EGR passage after the EGR valve; a boiler fluidly coupled by an inlet to the super heater and by an outlet to the EGR passage; a first temperature sensor for determining a temperature of the engine intake stream; a waste heat recovery (WHR) system for recovering heat from an EGR stream passing through the EGR passage, the WHR system comprising: a fluid loop including a fluid pump continuously circulating a working fluid from an outlet end of the pump to an inlet end of the pump, wherein the loop passes into and out of the boiler and then into and out of the super heater; a condenser coupled to the fluid loop; a turbine coupled to the fluid loop; a recuperator coupled to the fluid loop; a three-way valve coupled to the fluid loop to a position after the super heater and before the turbine; a bypass valve coupled to the fluid loop for diverting the working fluid away from the boiler and the super heater; and a controller electronically coupled to the first temperature sensor, the three-way valve and the bypass valve, wherein the controller opens the bypass valve in response to a temperature signal from the first temperature sensor, and wherein; the controller diverts the working fluid to a variable expansion valve fluidly coupled to the three-way valve in response to a temperature signal from the first temperature sensor.