(...) Since the thermal storage medium (thermal accumulator) is in direct contact with the thermal transfer arrangement, it has been found that significantly improved thermal transfer can be achieved than was possible with the known apparatus. In the known apparatus, thermal transfer between the thermal storage medium and the conduit of the thermal transfer arrangement occurs via the metal sheets containing the medium, by means of a frictional fit between these sheets and the conduit. It has now been found that this frictional fit may in many circumstances prevent satisfactory heat transfer between the two components.

http://www.patentopedia.us/beet_harvester/controlling_temper...
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beatriz_souza