Effect of packing density on performance of charcoal-nitrogen adsorption cryocoolers

This paper presents the development and validation of a computational scheme for an analysis of activated charcoal-nitrogen adsorption cryocoolers. Using this procedure a comparative analysis of four samples of charcoal is carried out. It is shown that the specific power (SP) of the cryocooler is governed by the packing density achievable in addition to the charcoal adsorption characteristics, cycle operating pressures and temperatures. A 77 K cryocooler with an SP of the order of 400 W W-1 can be achieved with a charcoal packing density of about 1 g cm(-3) for several available charcoals. The analysis shows that Fluka and BCGI specimens can yield promising results under the present technologically realizable conditions. (C) 1997 Elsevier Science Ltd.