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Abstract

By means of the synthetic diagram method (Romaniszyn 1970) populations of benthic Polychaeta at the depth ranging from 15 to 250 m of the Admiralty Bay (South Shetland Islands) were analysed. During the summer season of 1979/80 three replicate subsamples were taken at 18 stations situated along 3 crosssections using the Van Veen grab of a catching area of 0.09 m2 ; 61 benthic taxa of Polychaeta were recorded in these samples. The characteristics of particular assemblages are presented together with their tendency to change as a result of substrate quality, depth and position in the study area. Considerable affinity between the fauna of Polychaeta in the shallowest part of the bay and the composition and structure of polychaete assemblages occurring at Arthur Harbor (Anvers Island), which were described by Richardson and Hedgpeth (1977) was recorded.
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Abstract

The paper presents four 1-dimensional models of thermal resistance of walls in a heat exchanger with rectangular minichannels. The first model is the simplest one, with a single wall separating two fluids. The second model of the so called equivalent wall takes into account total volume of intermediate walls between layers of minichannels and of side walls of minichannels. The next two more complicated models take separately into account thermal resistance of these walls. In these two models side walls are treated as fins. The results of models comparison are presented. It is shown that thermal resistance may be neglected for metal walls but it should be taken into account for the walls made of plastics. For the case of non-neglected wall thermal resistance the optimum wall thickness was derived. Minichannel heat exchangers made of plastic are larger than those built of metal, but are significantly cheaper. It makes possible to use of such exchangers in inexpensive microscale ORC installations.
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