Design and develop a mixture thermostat that regulates EGR cooler temperature in commercial vehicles to compliance with Euro-7 norm

One of the most important causes of air pollution is the release of polluting gases (NOx) from internal combustion engines to the environment. The emission standards, which have been continuously developed in recent years, have forced engine manufacturers to focus on this issue. Engine manufacturers have developed new systems used in vehicles in order to reduce exhaust emission values and nitrogen oxide (NOx) ratio. The most important of these systems is the Exhaust Gas Recirculation (EGR) system. The purpose of the EGR system is to reduce the emission of unburned NOx gas discharged from the exhaust. The EGR cooler is one of the subsystems in the EGR system. The purpose of the EGR cooler is to reduce the temperature of the gas coming from the exhaust so that the gas reaches the most efficient combustion temperature before it enters the cylinder. According to the calculations made by the engine manufacturers, it was revealed that the cold water inlet temperature of the EGR Cooler should be kept constant at the specified temperature. In this study, the design and development of a mixing thermostat to be included in the system in order to fulfill this requirement and keep the performance of the EGR cooler at the best level has been examined. In this the temperature of the coolant entering the exchanger must be kept at 65 ° C in order to operate the EGR cooler at the most efficient point. To accomplish this, a mixing thermostat is placed at the cold water inlet of the heat exchanger, so that the thermostat will ensure that the temperature at the outlet of the mixing thermostat is 65 ° C, regardless of the engine water temperature. In this study, Catia V5 software was used for 3D designs, and Computational Fluid Dynamics (CFD) software Ansys CFX module was used for design optimizations. Prototype samples were produced for the final design and functional tests were carried out in test benches. The results of the numerical and experimental studies were evaluated.