Method for improving low-temperature SCR (Selective Catalytic Reduction) efficiency

The invention discloses a method for improving low-temperature SCR (Selective Catalytic Reduction) efficiency, which belongs to the technical field of engine post-treatment, and comprises the following steps: heating a urea solution stored in a urea tank to a set temperature according to working conditions, pumping out the urea solution through a urea pump, and transmitting the urea solution to a urea nozzle mounted on an SCR catalyst at a set pressure. The urea solution heating logic comprises the following steps that S1, when an engine is in a power-on state, the urea temperature of a urea solution stored in a urea tank is obtained in real time, and the exhaust temperature of the engine is obtained in real time; s2, if the urea temperature is lower than the lower limit of the urea temperature threshold value and the exhaust temperature is lower than the lower limit of the exhaust temperature threshold value, executing the step S3; otherwise, executing the step S4; s3, heating the urea solution stored in the