Avaliação de um sistema de refrigeração por adsorção para produção de gelo, operando diferentes tipos de ciclo com baixas temperaturas de geração. / Evaluation of a system of refrigeration for adsorção for ice production, operating different types of cycle with low temperatures of generation.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2004

RESUMO

The goal of this project was to design and built a prototype of an adsorption refrigeration system for ice production with cycle operation flexibility. The prototype was to be powered by different energy sources. To reach this goal, the properties and characteristics of some adsorbents and adsorbates were compared and ammonia was chosen as adsorbate and carbon was chosen as adsorbent. Their thermodynamic equilibrium was characterized. The data of this characterization was used to access the parameters of the Dubinin-Astakhov equation, which can be used to estimate the refrigerant uptake variation in the carbon, during the adsorption refrigeration cycle. The next step was to model the heat transfer and the desorption/adsorption process in an adsorption refrigeration system that could operate different kind of refrigeration cycle. The model was numerically solved considering different operation and reactor design conditions. The results of the experiments with the model indicated that the use of the cycle in double stage with vapour recovery can produce higher C.O.P. and specific net cooling power than the utilization of the other cycles if the generation temperature is bellow 80-85 °C. If the generation temperature is above this level, the utilization of the vapour recovery cycle can produce higher C.O.P. and specific net cooling power. To conclude the project, a prototype of adsorption refrigeration with similar characteristics to the modelled one was built and instrumented. This system is powered by heat transfer fluid vapour generated in a boiler or in flat plate solar collector. The result of the experiments indicated the same trend of the simulation results. When the boiler was used to vaporize the heat transfer fluid, the prototype produced about 48 kg of ice per day, operating under the cycle in double stage with vapour recovery and generating temperature of 85°C. Considering that the flat plate solar collector vaporizes the heat transfer fluid during the daytime and the boiler, during the nigh time, it could be produced until 31,4 kg of ice per day. In this case, the amount of ice produced during the daytime would be until 6,7 kg.

ASSUNTO(S)

modelagem instrumentation refrigeração alternative energies refrigeration adsorção modelling energia - fontes alternativas adsorption

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