Rethinking spray drying for full electrification by process adaptation

Spray drying is a cornerstone of dairy manufacturing, yet its high energy demand and carbon footprint require transformative solutions. Electrification using high temperature heat pumps (HTHPs) offers strong potential, but existing studies mainly optimize heat pump configurations while treating spray drying processes as fixed boundary conditions, limiting system-level performance. This study rethinks spray drying for full electrification by proposing a system-level framework that simultaneously adapts process parameters and HTHP integration. The framework establishes thermodynamic coupling between the multiple HTHPs and key components including the drying chamber, fluidizers, desiccant wheels, and heat exchanger network, and captures interactions among production, efficiency, and economic performance. Using skimmed milk powder production as a case study, the model reveals that coordinated adjustments of airflow, feed rate, and fluidizer humidity can significantly lower the required drying temperature to 152.4 °C, achieving a coefficient of performance of 3.3, a levelized heat cost of 25.69 €/MWh, and a specific energy consumption of 0.36 kWh/kg. Exergy analysis further clarifies internal loss mechanisms and energy recovery opportunities. By shifting from heat pump optimization to holistic process redesign, this work introduces a new pathway for fully electrified spray drying and provides a practical decision-support framework for balancing production, efficiency, and economic viability in cleaner dairy manufacturing.