Since a while exhaust gases are indeed in diesel engines is recycled to reduce the nitrogen oxides produced in a hot combustion.
Have I understood correctly, the exhaust gases are led into the cylinder, and the combustion at a lower temperature?
If so, why not just man injects less fuel in order to reduce the temperature? The exhaust gas recirculation is as far as I know at full load disabled?
The best answer
True, the combustion temperature is lowered thereby. See Wiki:
By supplying an inert gas, the generation of nitrogen oxides is lowered. Such an inert gas, for example waste gas, from which a small part is fed back into the combustion chamber. The rapid oxidation of fuel molecules is hindered by the presence of gas molecules. The temperature peaks and NOx emissions are therefore lowered. This effect is supported by the higher heat capacity of the main components of the exhaust carbon dioxide and water (in gaseous state).
For diesel engines, the power is determined by how much diesel is injected. If, as you suggested it, inject less diesel, the engine had less power.
Where should also be considered whether the combustion temperature really depends on the amount of diesel? To my knowledge, the exhaust gas temperature is higher, the more oxygen is involved in the combustion. That would be contrary to your suggestion.