Experimental Evaluation of an Electrically Heated Urea Vapor Module (UVM) for Improved SCR System Performance under Transient and Off-Road Operating Conditions

This paper presents an experimental study on an electrically heated Urea Vapor Module (UVM) designed to enhance the low-temperature performance of Selective Catalytic Reduction (SCR) systems. The UVM integrates a resistive heating element (up to 4.5 kW) wound around the mixing pipe to accelerate urea-water solution (UWS) vaporization, enable early ammonia (NH₃) availability, and minimize deposit formation under critical low-load conditions. Testing was performed on an FPT XC13 engine equipped with an alpha1 aftertreatment system (ATS). Results demonstrate that the heated UVM reduces SCR light-off temperature by ~20 °C, significantly improves DeNOx efficiency below 210 °C, and prevents deposit accumulation when pipe surface temperatures exceed 200 °C. These findings confirm that localized electrical heating of the UVM is a promising approach to meet stringent future NOx regulations such as Euro VII and California 2027.