5,126 research outputs found
THEORETICAL AND EXPERIMENTAL ANALYSIS OF A VAPOR-COMPRESSION REFRIGERATION CYCLE WITH A HEAT EXCHANGER BETWEEN THE SUCTION AND LIQUID LINES
Vapor-compression refrigeration systems require a significant amount of electrical energy. Therefore, there is a need for finding efficient ways of operating this equipment, reducing their energy consumption. The use of heat exchangers between the suction line and the liquid line can produce a better performance of the thermodynamic cycle, as well as reduce it. The present work aims at an experimental analysis of the suction/liquid heat exchanger present in a freezer running with refrigerant fluid R-134a. Three different scenarios were used in order to evaluate the thermal performance of the refrigeration cycle. The first scenario was the conventional freezer set up to collect the required data for further comparison. Moreover, the second and third scenarios were introduced with a 20 cm and 40 cm suction/liquid heat exchanger, respectively, into the system. From the experiments, it was observed that the heat exchange does not significantly affect the coefficient of performance (COP) of the freezer. It was concluded from this work that the best scenario analyzed was the 20 cm suction/liquid heat exchanger where most of the thermodynamic properties were improved, one of them being the isentropic efficiency
Pragas do eucalipto introduzidas no Brasil.
Sessão de Painéis
Osteodistrofias en el perro y en el gato : diagnóstico diferencial
El presente trabajo intenta hacer un protocolo del diagnóstico de las osteodistrofias según las diferentes publicaciones revisadas, así como por la propia experiencia de los autores.In this present work I am traying to do a protocol of the diagnosis of the osteodistrophies according to the different revised publications as well as the personal experience of the authors
Critical behaviour of the compactified theory
We investigate the critical behaviour of the -component Euclidean model at leading order in -expansion. We consider it in
three situations: confined between two parallel planes a distance apart
from one another, confined to an infinitely long cylinder having a square
cross-section of area and to a cubic box of volume . Taking the mass
term in the form , we retrieve Ginzburg-Landau
models which are supposed to describe samples of a material undergoing a phase
transition, respectively in the form of a film, a wire and of a grain, whose
bulk transition temperature () is known. We obtain equations for the
critical temperature as functions of (film), (wire), (grain) and of
, and determine the limiting sizes sustaining the transition.Comment: 12 pages, no figure
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