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The energy balance in the feed zone of grooved barrel single screw extruders is important for design and operation of such extruders. Experimental investigations with different bulk materials were undertaken to obtain further insight into the energy balance of the feed zone. The energy balance considers the enthalpy change resulting from temperature and density increase as a result of screw drive power and heat flow in the barrel. Experimental results show a decreasing solid bed temperature for decreasing residence times. In addition, with a reduced gap in the throttle with constant throughput, the pressure increases resulting into various deformation mechanisms of solid particles. The energy required for the deformation of solid particles into a solid bed elevates the specific screw drive power and heat generation. It is shown that the compression behavior of bulk materials is temperature-dependent and influences the energy balance in the feed zone. [ABSTRACT FROM AUTHOR]