5. Conclusions In this work a bottom up approach to modelling energy demand in mechanical recycling was used. The novel approach involves exploiting the mechanics of machining and specific energy modelling and extrapolating the mathematical models to predict energy demand in mechanical recycling of different composite panel thicknesses at a range of processing rates. This approach lays the foundation for considering processing conditions in defining resource footprint Specific conclusions are as follows:
The specific cutting energy for CFRP in mechanical recycling by a milling process has been modelled to be o.218 J/mms and this gives an upper unit process energy of 2.03 MJ/kg based on size reduction by industrial feed hopper milling at 10 kg/hr reducing to 0.27 MJ/kg at 150 kg/hr processing rate. This is a represen- tative range for environmental analysis in LCA
Mechanical recycling at higher throughput and at industrial scale processing is much more energy efficient.
The unit energy for composite manufacturing processes is higher than that of mechanical recycling and significantly lower than the embodied energy of virgin carbon fibres.
Specifically, this work has shown that mechanical recycling through a milling process can be environmentally beneficial. because the unit process energy for mechanical recycling(2.03-0.27 MJ/kg) is significantly lower than the embodied energy of virgin carbon fibre(183-286 MJ/kg). 5.1 Further work and recommendations