Natural gas engine and EGR second-stage cooling device thereof

Abstract

The invention discloses a natural gas engine and an EGR second-stage cooling device thereof for second-stage cooling of EGR waste gas. The natural gas engine comprises an EGR cooler and a vaporizer, wherein an input end of the EGR cooler is connected with an exhaust pipe of the EGR waste gas; the vaporizer comprises a cooling liquid vaporizing part and an EGR waste gas vaporizing part both for heat exchange with LNG; an inlet end of the EGR waste gas vaporizing part is connected with an output end of the EGR cooler; and an outlet end of the EGR waste gas vaporizing part is connected with an EGR mixer. Low-temperature natural gas is used for secondary cooling of the EGR waste gas cooled by the EGR cooler, so that the temperature of the EGR waste gas is lowered, the temperature of mixed gasformed by mixing with air after intercooling is reduced, the knocking problem caused by higher intake temperature is solved, and the reliability of the engine is improved; and as the natural gas can take away a lot of heat, the heat needing to be taken away by the cooling liquid is greatly reduced, the whole vehicle heat dissipation power demand is reduced, and the problem of difficult matching between a whole vehicle radiator and a fan is solved.

Description

technical field [0001] The invention relates to the technical field of power devices, in particular to a natural gas engine and an EGR secondary cooling device thereof. Background technique [0002] In high-temperature areas, the ambient temperature can reach more than 40 degrees Celsius. When a natural gas engine (LNG engine) operates at high load in a high-temperature environment, due to the high ambient temperature, the heat dissipation power of the intercooler decreases, and the intake air temperature after the intercooler is high. When the engine water temperature is high, the temperature of the EGR exhaust gas after cooling is also relatively high. After the intercooled air is mixed with the EGR exhaust gas, the temperature will rise further, and knocking will easily occur, which will affect the life of the engine. The EGR exhaust gas of a high-power natural gas engine has a high temperature and a large flow rate, but the required cooling temperature is low. This part ...

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Problems solved by technology

[0002] In high-temperature areas, the ambient temperature can reach more than 40 degrees Celsius. When a natural gas engine (LNG engine) operates at high load in a high-temperature environment, due to the high ambient temperature, the heat dissipation power of the intercooler decreases, and the intake air temperature after the intercooler is high. When the engine water temperature is high, the temperature of the EGR exhaust gas after cooling is also relatively high. After the intercooled air is mixed with the EGR exhaust gas, the temperature will rise further, and knocking will easily occur, which will affect the life of the engine.

The EGR exhaust gas of a high-power natural gas engine has a high temperature and a large flow rate, but the required cooling temperature is low. This part of the heat needs to be absorbed by the coolant and dissipated into the air through the radiator and fan of the water tank. The high ambient temperature reduces the heat dissipation of the water tank. The heat dissipation power of the radiator requires a larger radiator and fan to dissipate the heat and achieve the thermal balance of the vehicle. However, due to the layout space of the vehicle, it is difficult to match a large enough intercooler and fan

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