A heating system includes at least one electric heater disposed within the fluid flow system. A control device includes a microprocessor and is configured to determine a temperature of the at least one electric heater based on a model and at least one input from the fluid flow system. The control device is configured to provide power to the at least one electric heater based on the temperature of the at least one electric heater.

Provided is a CO.sub.2 recovery device of an internal combustion engine capable of efficiently recovering CO.sub.2 emitted from an internal combustion engine or CO.sub.2 in the air, and of efficiently synthesizing methane using CO.sub.2. A CO.sub.2 recovery device of an internal combustion engine includes a CO.sub.2 capturing material disposed at a through channel of gas including CO.sub.2 to capture CO.sub.2 in the gas, and methanation catalyst to let CO.sub.2 desorbed from the CO.sub.2 capturing material react with H.sub.2 obtained from a H.sub.2 supply source to generate methane. The CO.sub.2 recovery device has a function to raise temperature of the CO.sub.2 capturing material using heat generated from the internal combustion engine to desorb CO.sub.2.

When the NSR temperature Tnsr is in a warming-up temperature range equal to or higher than the activation start temperature of the NSR catalyst and lower than the activation completion temperature of the NSR catalyst, a control apparatus according to the present invention controls the quantity of fuel supplied to the NSR catalyst by a fuel supply device such that the air-fuel ratio of the exhaust gas flowing into the NSR catalyst while the rich spike process is performed is lower when the NSR temperature Tnsr is lower than a specific temperature Tthr than when the NSR temperature Tnsr is equal to or higher than the specific temperature Tthr.

An exhaust gas purification apparatus for an internal combustion engine comprises an ammonia supplier which includes a storage unit configured to store a precursor of ammonia or ammonia (reducing agent or the like), and a controller programmed to carry out output restriction control as such control that an output of the internal combustion engine is restricted to be not more than a predetermined output such that a NOx purification rate brought about by the storage reduction NOx catalyst is within an allowable range if an amount of the reducing agent or the like stored in the storage unit is less than a predetermined storage amount.

A condensed water treatment device for an internal combustion engine is provided. The condensed water treatment device may include a condensed water tank, a condensed water supply device, and a condensed-water generation quantity controlling device. The condensed water treatment device may further include a computer. The computer by executing a computer program may function as a storage-water-quantity decrease controlling device and a storage-water-quantity increase controlling device.

During execution of a first purification process of fluctuating a hydrocarbon concentration in exhaust gas flowing into a first catalyst with an amplitude within a prescribed range at a time interval within a prescribed range, when a switch request to a second purification process of purifying NOx in a second catalyst by adding urea water into the exhaust gas is generated, the switch to the second purification process is prohibited on the condition that a current NOx purification rate (a first purification rate R1) is higher than a purification rate (a second purification rate R2) on the assumption that the second purification process is executed, and an HC poisoning recovery stand-by process of reducing an additive amount of hydrocarbon per once in the first purification process is executed so as to reduce a slip amount of hydrocarbon into the downstream of the first catalyst.

In an internal combustion engine, an exhaust purification catalyst (13), hydrocarbon feed valve (15) and particulate filter (14) are arranged in an exhaust passage. If temperature increasing control should be performed when a first NO.sub.X purification method is performed, injection of hydrocarbons for the first NO.sub.X purification method is performed with a predetermined period and injection of hydrocarbons for temperature increasing control is performed in a time period when injection of hydrocarbons for the first NO.sub.X purification method is not performed, the first NO.sub.X purification method being configured to purify NO.sub.X which is contained in the exhaust gas by injecting hydrocarbons from the hydrocarbon feed valve with the predetermined period, the temperature increasing control being configured to increase a temperature of the particulate filter to remove particulate matters trapped on the particulate filter. An amount of injection of hydrocarbons for temperature increasing control when an actual temperature of the particulate filter is low is set larger than that when the actual temperature of the particulate filter is high.

An exhaust system comprising: a NOx storage catalyst; an electric heating element; and a NOx reduction catalyst wherein the heating element is located downstream of the NOx storage catalyst.

Provided is a method for accurately diagnosing a degree of degradation of an oxidation catalyst. A target gas detecting element configured to output an electromotive force corresponding to a concentration of a target gas is provided downstream of a catalyst in an exhaust path of an internal combustion engine. A sum of change amounts of an electromotive force in a time-variable profile thereof after the introduction of a gas atmosphere for diagnosis into the catalyst is set as a diagnosis index value. The gas atmosphere has been intentionally created in the engine and includes a target gas having a concentration higher than the concentration of a target gas during a steady operation state of the engine. The index value is then compared with a threshold corresponding to the temperature of the catalyst to diagnosis whether degradation exceeding an acceptable degree has occurred in the catalyst.

Provided is a method for accurately diagnosing a degree of degradation of an oxidation catalyst. A target gas detecting element configured to output an electromotive force corresponding to a concentration of a target gas is provided downstream of a catalyst in an exhaust path of an internal combustion engine. A maximum change amount of an electromotive force after the introduction of a gas atmosphere for diagnosis into the catalyst is set as a diagnosis index value. The gas atmosphere has been intentionally created in the engine and includes a target gas having a concentration higher than the concentration of a target gas in a steady operation state of the engine. The index value is then compared with a threshold corresponding to the temperature of the catalyst to diagnosis whether degradation exceeding an acceptable degree has occurred in the catalyst.