An Analytical and Experimental Heat Transfer Investigation of a Mother-Baby Plastic Granule Extruder Machine with Heat Recovery Integration

Abstract

This study presents an analytical and experimental heat transfer investigation of a mother-baby plastic granules extruder machine with the integration of a heat recovery structure. The analytical model was developed by considering conduction through the heater to the barrel surface, conduction across the barrel wall, convection between the barrel inner surface and the raw plastic, and additional heat generation due to shear and friction of the rotating screw. To validate the model, experimental trials were conducted on an LDPE processing extruder unit under two cases: (i) without heat recovery integration and (ii) with a CRC sheet-based heat recovery structure installed between the mother and baby units. A total of 48 temperature readings (8 readings per day for 3 consecutive days, in both cases) were collected to analyse the thermal response. The results showed close agreement between analytical predictions and experimental observations, with notable variations in temperature distribution across the barrel and plastic melt zones. The incorporation of the heat recovery structure demonstrated improved utilization of the rejected thermal energy, thereby confirming the effectiveness of the proposed design. This combined analytical–experimental approach provides a detailed understanding of the heat transfer processes in extrusion machines and highlights potential pathways for enhancing thermal performance and energy efficiency in plastic recycling operations.

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