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Abstract

In the paper presented are definitions of specific indicators of power which characterize the operation of the organic Rankine cycle (ORC) plant. These quantities have been presented as function of evaporation temperature for selected working fluids of ORC installation. In the paper presented also is the procedure for selection of working fluid with the view of obtaining maximum power. In the procedure of selection of working fluid the mentioned above indicators are of primary importance. In order to obtain maximum power there ought to be selected such working fluids which evaporate close to critical conditions. The value of this indicator increases when evaporation enthalpy decreases and it is known that the latent heat of evaporation decreases with temperature and reaches a value of zero at the critical point.
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Abstract

The process of cognitive aging in global sense can be characterised by changes of the fluid and crystallised intelligence. In the context of this explanation the basic question is which cognitive functions and regulatory mechanisms play the basic role of the determinants for cognitive aging. Probable, mechanism of associative memory play a central role in top-down direction of cognitive processing. This type of memory connect the resources/networks of long term memory with the current processing in working memory. Another set of mechanisms concerns with bottom-up direction based on procedural memory, which is fundamental for the functioning of the mind as whole (Tulving theory,1985). Unfortunately, our knowledge about associative memory and its relations to working and procedural memory is incomplete and unclear. The importance of associative memory are partly, empirically supported by classic research on decreasing the cognitive components of intelligence aging, since the fluid and crystallized intelligence where discovered (Horn, Cattell, 1967). Changes of the mind functioning and its cognitive growth/aging can be characterised as a complex chain from primary, biologically determined mind, through Piagetian and Vygotsky’s type of mind to relatively balanced mind.
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Abstract

The paper discusses the feasibility, effectiveness and validity of a gas turbine power plant, operated according to the Brayton comparative cycle in order to develop low-potential waste heat (160◦C) and convert it into electricity. Fourteen working fluids, mainly with organic origin have been examined. It can be concluded that low molecular weight working fluids allow to obtain higher power efficiency of Brayton cycle only if conversions without taking into account internal losses are considered. For the cycle that takes into account the compression conversion efficiency in the compressor and expansion in the gas turbine, the highest efficiency was obtained for the perfluoropentane working medium and other substances with relatively high molecular weight values. However, even for the cycle using internal heat recovery, the thermal efficiency of the Brayton cycle did not exceed 7%.The paper discusses the feasibility, effectiveness and validity of a gas turbine power plant, operated according to the Brayton comparative cycle in order to develop low-potential waste heat (160◦C) and convert it into electricity. Fourteen working fluids, mainly with organic origin have been examined. It can be concluded that low molecular weight working fluids allow to obtain higher power efficiency of Brayton cycle only if conversions without taking into account internal losses are considered. For the cycle that takes into account the compression conversion efficiency in the compressor and expansion in the gas turbine, the highest efficiency was obtained for the perfluoropentane working medium and other substances with relatively high molecular weight values. However, even for the cycle using internal heat recovery, the thermal efficiency of the Brayton cycle did not exceed 7%.
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