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 wound around the mixing pipe: with power levels up to 4.5 kW it accelerates urea-water solution (DEF/UWS) vaporization, enables early ammonia (NH3) availability and minimizes solid deposit formation when exhaust temperatures are marginal. Tests performed on an FPT XC13 six-cylinder engine with a dual-dosing ATS reveal that localized electrical heating reduces the SCR light-off temperature by roughly 20 deg C, achieves DeNOx efficiencies above 90% at 150–200 deg C, eliminates deposits for pipe surface temperatures >200 deg C, and meets engineering targets for cold-start emissions. Back pressure remains comparable to a non-heated baseline, validating the integration concept. The results position the heated UVM as a promising strategy to satisfy stringent NOx regulations such as Euro7.