Thermal Balance Method for EGR Rate Determination Usable for Real Engine with Uncooled EGR System

The presented work deals with an accurate method for the EGR (Exhaust Gas Recirculation) rate determination, which is suitable for the real combustion engines equipped with the uncooled EGR system. A Thermal Balance method (further T.B.) has been proposed for this purpose. It uses differences between EGR (hot gas) and fresh charging air temperatures as a base for the EGR mass fraction determination. This method has been developed and tested on a real engine in authors' laboratory and verified using the well known CO₂ method. As it is known that this method is inherently not accurate, the paper deals with a possibility how to improve the method. Measured differences between results from both methods T.B. and CO₂ are within 8% in the measured operating range.