Project: A Finless Freezer


Planning / Implementation / Main components

Grasso GmbH Refrigeration Technology


Ammonia (NH3)

System start-up


The expense of running a freezer is determined not only by the refrigeration output, but also by the cost of cleaning the facility. For this reason, Grasso partnered with Matal S. A. to develop a finless heat transmitter that is being put through its paces in a freezer as part of an ammonia/carbon dioxide cascade plant.


Usually heat transmitters have fins that increase the evaporator's surface. However, this also facilitates the deposition of microorganisms and makes the facility harder to clean. Thus, there is demand for finless alternatives offering the same level of efficiency in the foods industry.


The heart of the prototype is a spiral chiller equipped with a finless evaporator. The evaporator is tested by cooling 8,000 regular ice-packs from ambient temperature to -37 degrees Celsius in 30 minutes. The refrigeration energy is furnished by an ammonia/carbon dioxide cascade: ammonia for the high-temperature cycle, carbon dioxide for the low-temperature cycle. The advantage: only 40 kilograms of ammonia are used, and remain confined to the central machine room while the freezer is supplied with carbon dioxide.

Technical data:


Type of facility

Cascade system



Refrigerant charge

40 kg

Secondary refrigerant


Refrigerating capacity

250 kW

Main components

Spiral chiller, finless evaporator

Special features / Comments

To minimize on-site assembly time, the cascade was delivered as a compact, ready-made condensing unit.


Grasso GmbH Refrigeration Technology
Thomas Spänich
Holzhauser Strasse 165
D-13509 Berlin

Phone: +49 (0)30 435 92-721
Fax: +49 (0)30 435 92-799