Multi-module heat pump integration for fully electrified spray drying processes

High-temperature heat pumps (HTHPs) offer a transformative pathway to fully electrify spray drying, yet their deployment remains hindered by prohibitive heat costs, impractically high CO₂-HTHP operating pressures, and process-integration inefficiencies. To address these challenges, this study proposes a greenfield integration concept based on multiple modular HTHPs capable of supplying process heat up to ~240 °C from 15 °C ambient air, enabling efficient and scalable electrification across a wide range of milk powder production capacities. A multiphase approach was employed, comprising: (1) diagram based heat integration quality assessment for preliminary HTHP placements, (2) detailed process simulation and exergy analysis for identification and reduction of internal inefficiencies, and (3) techno-economic evaluation to confirm overall energy performance. Three heat exchanger network layouts with distinct HTHP operating temperatures were modeled, achieving total COP values of 2.20, 2.29, and 2.14, with corresponding second law efficiencies of 45.1%, 46.8%, and 43.8%. A key insight is that maximizing the COP of individual HTHPs does not ensure the highest overall process efficiency when multiple HTHPs are integrated. The parametric study evaluates the influence of process conditions, supplemental electric boiler capacity, and energy prices. Implementing process modifications instead of relying on fixed process parameters reduces the specific power consumption by 15%, from 0.415 kWh/kg to 0.354 kWh/kg.