In day today's relevance, it is mandatory to device the usage of diesel in an economic way. In present scenario, the very low combustion efficiency of CI engine leads to poor performance of engine and produces emission due to incomplete combustion. Study of research papers is focused on the improvement in efficiency of the engine and reduction in emissions by comparing different techniques and using various blends. Engine manufacturers are compelled to incorporate different type of techniques to reduce emissions especially NOx and particulate matters from the engine. This paper mainly deals with the application of Exhaust Gas Recirculation (EGR) technique and use of various alternative fuels for reduction of oxides of nitrogen (NOx) emissions from diesel. High combustion temperature leads to formation of NOx and this paper indicates that EGR is an attractive method to reduce combustion temperature. EGR temperature plays an important role while admitting higher percentage of EGR in the engine. When the higher ratios of EGR are applied then cooled EGR can be advantageous. Some other emissions like CO & HC are also found to be reduced using different types of blends such as biodiesel and additives which are also known as cetane improvers.

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