Avaliação da demanda, do consumo eletrico e do controle de temperatura para condicionamento de ambientes, usando sistemas de refrigeração com termoacumulação. / Evaluation of demand, electric consumption and control of temperature for environment conditioning, using refrigeration systems with thermal storage.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

The commercial and financial building together represent a great parcel of the consumption of electric energy in the commercial sector, about 24,6 % of the total. The environment conditioning systems and commercial refrigeration in these types of building are responsible for a great consumption of electric energy and demand, being in the band of 35 % through 40 % of the total consumption. The shifting of the demand of electric from peak periods to off-peak periods brings a reduction of costs for the consumers, due to the differentiated tariffs in these periods. Moreover, the concessionaire who supplies the energy can save in the investment of the generation and distribution, by the reduction of the demand in peak periods. The thermal-storage systems have as main objective the rationalization of the demand of electric, due to use of it in periods of the low demand, beyond the reduction of the initial investment. The accumulation of energy at low temperture can be made through banks of frozen water or ice banks, and these last ones have high capacity of storage at lower volumes, due to phase change. In this work it was used as thermal-storage system, the ice bank, for the thermal conditioning of five different environments with two strategies of operation: thermal-storage with total load and simultaneous load. For the control of the temperatures of the respective environments the conventional logics of control ("On-off" and PID) in the frozen water outflows were used in each "fan-coil". It was compared the differences of the types of controllers, related to the pointers of efficiencies, under disturbances in the load and set-point. Parallel, also it was evaluated the readiness of the refrigeration system to be comparative related to the energy consumption. It was evidenced that the PID logic of control was more efficient in relation to the "On-off" logic of control with band of 0,5 ºC for strategy of thermal-storage with simultaneous load, due to a more precise performance around the set-point. In the strategy of thermal-storage with total load the "On-off" controller with band of 0,2 ºC was more efficient than the PID controller, because the definite band was reduced. In relation to the thermal-storage strategies were observed that the strategy of thermal-storage with simultaneous load was better, in terms of the energy consumption, compared the strategy with total load, since the refrigeration system operated with higher temperatures of evaporation. But, using systems with and without thermal-storage, it was observed that it had a reduction of 33 % of the variables costs (demand and energy consumption) when making the thermal-storage, shown the viability of this system as the variables costs economy.

ASSUNTO(S)

refrigeração termoacumulação pid controllers temperature control controladores pid refrigeration thermal storage controle de temperatura

ACESSO AO ARTIGO

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