The contact heating model (FDC series) operates by placing the material directly onto shelves or trays. A heat‑transfer medium, such as hot water or silicone oil—circulates inside the shelves, transferring heat to the material through direct contact. This is essentially conduction heat transfer. Its advantages include stable heat delivery, mature process technology, and reliable control. However, as the shelves are made of 304 stainless steel, the thermal conductivity is relatively low. Additionally, the system requires a medium circulation structure, which makes the overall equipment more complex and results in higher initial investment.
The radiation‑heating model (FDR series), on the other hand, transfers heat to the surface and interior of the material in a non‑contact manner through radiant energy—this is radiation heat transfer. The heat enters the material primarily by radiation. The FDR series uses aluminum alloy shelves, which offer higher thermal conductivity and faster thermal response. As a result, the system is more energy‑efficient, has higher thermal efficiency, and features a simpler structure. It also adapts better to irregularly shaped materials and, under standard tray loading conditions, achieves more uniform temperature distribution with higher PLC control precision.
In summary, KEMOLO's FDR series, with its high‑thermal‑conductivity aluminum alloy shelves and radiation‑based heating, generally delivers better energy efficiency and a more favorable cost‑performance ratio for the food freeze‑drying industry. The FDC series, by contrast, represents a more traditional contact‑based industrial solution, offering robust stability but at the cost of higher energy consumption.
