In this work we describe a high level Matlab-Simulink model of a sensor system for vapor trace detection of different molecules in the air using array of differently functionalized capacitive sensors and extremely sensitive integrated electronic detection system. The model includes the adsorption/desorption process of differently modified sensors and high-level model of a low noise analog signal processing electronics. The proposed model makes possible to study the interactions, selectivity and sensitivity of the sensor system efficiently and forms the basis for the design of different modules of the sensor system, including pattern recognition algorithms. In this way, the design process has been shortened. A demonstrator measurements show promising detection limit of 3ppt of TNT in 1 Hz band which is close to the simulation results.