Electric heaters with the effect of self-regulation of fuel system temperature in diesel engines

BACKGROUND: Diesel internal combustion engines (ICE) are massively used as powerunits of automotive and tractor machinery, as they have high energy efficiency and reliability. It is very important to provide the fastest possible start-up for internal combustion engines and stable idling operation at ambient temperatures in the range from -40 to 0 °C, especially in the winter period of operation. One of the approaches connected with improvement of conditions of starting a diesel engine in cold season is application of electric heating system, including the use of heater materials based on composites with positive temperature resistance coefficient that allows adapting the heating system to minimum power consumption. Development of the design of the electric heating system for diesel engine fuel filters, the control system and the algorithm of its operation is a relevant technical task. AIM: Development of electro-heating polymer composites (EHPC) containing multilayer carbon nanotubes (MCNTs) for diesel engine fuel filters. METHODS: An elastic organosilicon compound was used as a polymer matrix, and MCNTs synthesized by ultrahigh frequency electromagnetic radiation (UHF method) by exposure to a mixture of ferrocene and graphite in a 1:1 ratio were used as an electrically conductive dispersed filler. The surface morphology of MCNTs was studied with a scanning electronic microscope at 5 kV. The temperature field was studied using the “Testo-875-1” thermal imager with an optical lens of 32 × 23°. RESULTS: The technical solution for heating the fuel filter of diesel engine by means of heating elements ensuring direct control and stabilization of the temperature mode in the process of diesel fuel thermoregulation is considered. Polarization of polymer matrix and tunneling of elementary charge in MCNTs lie in the basis of the process of electric heating of composite material at the electric current. Programmable parameters of the microcontroller were used for thermoregulation in the process of electric heating and sustaining the given temperature mode, which makes it possible to eliminate the decrease in the heating rate of EHPCs and to increase their energy efficiency in a wide range of temperatures of operation of the fuel supply equipment of an internal combustion engine. To form the software for the EHPCs control system, 5 operation modes including start-up, idling and modes under load (25, 50, 75% of the nominal value of the full load of the internal combustion engine) were used. CONCLUSION: The practical value of the study lies in the possibility of using the proposed electric heaters for controlled heating of fuel with a given temperature, which reduces the load on the battery and significantly expands the potential capabilities of electric heating technologies for automotive and tractor machinery.