Desenvolvimento e avaliação de uma bomba de calor usada no condicionamento de ar para secagem de alimentos

AUTOR(ES)
FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

31/05/1993

RESUMO

A heat pump made up of a reciprocating compressor driven by a 1.1 kW electric motor, an air condenser, a dry expansion evaporator, filled with R22 refrigerant fluid and fully instrumented was circuited to a tray dryer. Ambient air was sucked through the evaporator, flowed outside the condenser and was blown into the dryer. The thermodynamic performance of the heat pump was evaluated through several tests, keeping the entrance air under constant conditions (temperature: 21, 25 and 30°C; relative humidity, φ: 40, 64 and 92%). The results indicated that the evaporation temperature, tev, is the most influencing parameter on process efficiency. Energy savings, when compared to a system that uses only electric resistances to over heat the air in order to produce the same drying potencial, was of the order of 40%, when humid air (φ >90%) and t ≤ 0°C were used. Values of the effective heating performance coefficient, COP, ranged from 1.7 to 2.1. An exergetic analysis pointed the motor-compressor as the element of the greatest exergy consumption. onion rings were used during drying tests in order to compare the results to data obtained from another dryer, identical to the first one, but using heated air coming from an electrical heater, both at 55°C. Drying curves confirmed the superior performance of the, heat pump system, allowing considerable process time reduction, implying on color maintenance (evaluated from spectrophotometrical analysis) and energy saving by amount of 15 to 35%, as compared to the second dryer. A computational program, for simulating the heat pump processes at steady state, using Fortran77 language, showed average deviations between 4.2 and 9.0% when compared to experimental results. The model was employed to analyze the influence of operational parameters on evaporation temperature values and on the system performance

ASSUNTO(S)

alimentos - desidratação bombas de calor secagem

ACESSO AO ARTIGO

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