Methods and systems are provided for using compression heating to heat a cylinder piston before cylinder combustion is resumed. Cylinder heating is achieved using combinations of slow unfueled engine rotation where the engine cylinders are heated via compression stroke heating, and slow compressor rotation where the cylinders are heated via compression heating. One or more intake or exhaust heaters may be concurrently operated to expedite cylinder heating.

A fuel oxygen conversion unit includes a contactor defining a liquid fuel inlet, a stripping gas inlet and a fuel/gas mixture outlet. The fuel oxygen conversion unit also includes a fuel/gas separator defining a fuel/gas mixture inlet in flow communication with the fuel/gas mixture outlet of the contactor, an axial direction, and a radial direction. The fuel/gas separator includes a separator assembly including a core including a gas-permeable section extending along the axial direction and defining a maximum diameter, the maximum diameter of the gas-permeable section being substantially constant along the axial direction; and a stationary casing, the fuel/gas separator defining a fuel/gas chamber in fluid communication with the fuel/gas mixture inlet at a location inward of the stationary casing and outward of the gas-permeable section of the separator assembly along the radial direction.

A fuel oxygen conversion unit includes a contactor defining a liquid fuel inlet, a stripping gas inlet and a fuel/gas mixture outlet. The fuel oxygen conversion unit also includes a fuel/gas separator defining a fuel/gas mixture inlet in flow communication with the fuel/gas mixture outlet of the contactor, an axial direction, and a radial direction. The fuel/gas separator includes a separator assembly including a core including a gas-permeable section extending along the axial direction and defining a maximum diameter, the maximum diameter of the gas-permeable section being substantially constant along the axial direction; and a stationary casing, the fuel/gas separator defining a fuel/gas chamber in fluid communication with the fuel/gas mixture inlet at a location inward of the stationary casing and outward of the gas-permeable section of the separator assembly along the radial direction.

A gas supply device is equipped with an oxygen enrichment membrane module, a pump portion, and an electronic control unit. The electronic control unit performs oxygen enrichment control for merging the air supplied to a first space from a second space through the oxygen enrichment membrane and containing a higher concentration of oxygen than an atmosphere with the atmosphere that has flowed into the first space and supplying the merged air and atmosphere to a combustion chamber of the cylinders by driving the pump portion, and nitrogen enrichment control for discharging air containing a higher concentration of oxygen than the atmosphere to the second space from the first space through the oxygen enrichment membrane, producing air containing a higher concentration of nitrogen than the atmosphere in the first space, and supplying the air containing the higher concentration of nitrogen to the combustion chamber by driving the pump portion.

A gas supply device is equipped with an oxygen enrichment membrane module, a pump portion, and an electronic control unit. The electronic control unit performs oxygen enrichment control for merging the air supplied to a first space from a second space through the oxygen enrichment membrane and containing a higher concentration of oxygen than an atmosphere with the atmosphere that has flowed into the first space and supplying the merged air and atmosphere to a combustion chamber of the cylinders by driving the pump portion, and nitrogen enrichment control for discharging air containing a higher concentration of oxygen than the atmosphere to the second space from the first space through the oxygen enrichment membrane, producing air containing a higher concentration of nitrogen than the atmosphere in the first space, and supplying the air containing the higher concentration of nitrogen to the combustion chamber by driving the pump portion.

A method and system for monitoring an exhaust gas sensor coupled in an engine exhaust is provided. In one example, the method determines an estimate of an exhaust gas oxygen sensor time constant according to a comparison of air/fuel ratios and a system time constant.

A method and system for monitoring an exhaust gas sensor coupled in an engine exhaust is provided. In one example, the method determines an estimate of an exhaust gas oxygen sensor time constant according to a comparison of air/fuel ratios and a system time constant.

A gas supply device is equipped with an oxygen enrichment membrane module, a pump portion, and an electronic control unit. The electronic control unit performs oxygen enrichment control for merging the air supplied to a first space from a second space through the oxygen enrichment membrane and containing a higher concentration of oxygen than an atmosphere with the atmosphere that has flowed into the first space and supplying the merged air and atmosphere to a combustion chamber of the cylinders by driving the pump portion, and nitrogen enrichment control for discharging air containing a higher concentration of oxygen than the atmosphere to the second space from the first space through the oxygen enrichment membrane, producing air containing a higher concentration of nitrogen than the atmosphere in the first space, and supplying the air containing the higher concentration of nitrogen to the combustion chamber by driving the pump portion.

A gas supply device is equipped with an oxygen enrichment membrane module, a pump portion, and an electronic control unit. The electronic control unit performs oxygen enrichment control for merging the air supplied to a first space from a second space through the oxygen enrichment membrane and containing a higher concentration of oxygen than an atmosphere with the atmosphere that has flowed into the first space and supplying the merged air and atmosphere to a combustion chamber of the cylinders by driving the pump portion, and nitrogen enrichment control for discharging air containing a higher concentration of oxygen than the atmosphere to the second space from the first space through the oxygen enrichment membrane, producing air containing a higher concentration of nitrogen than the atmosphere in the first space, and supplying the air containing the higher concentration of nitrogen to the combustion chamber by driving the pump portion.

A method and system for monitoring an exhaust gas sensor coupled in an engine exhaust is provided. In one example, the method determines an estimate of an exhaust gas oxygen sensor time constant according to a comparison of air/fuel ratios and a system time constant.