Estudo da viabilidade da utilização do calor proveniente da reação de oxidação de cavacos de usinagem em um sistema de refrigeração tipo DAR

Abstract

Nowadays, high levels of pollution and strong cost reduction policy in companies, allied to the forecast of fossil fuels exhaustion (non-renewable) such as gasoline, natural gas, diesel and coal, encourages researches related to renewable energy use, cogeneration and energy reuse in manufacturing environments, through the exploitation of energy waste from industrial processes to use in a heat exchanger or regenerator, for example. The most common processes are the production of electricity and thermal energy (heat or cold) from the use of natural gas or biomass. Alongside this stage of shift in thinking, in a agricultural equipment company, located in Curitiba, Brazil, was discovered energy waste from the heat released by exothermic chemical reaction of oxidation of machining chips, which are stored then sold to a metallurgical industry. It was found that within a period of 48 hours, the oxidation of the chips reached peaks up to 90 °C This Paper Work aimed at C. exploring the feasibility of using heat from the oxidation reaction of machining chips in a Diffusion Absorption Refrigerator (DAR) system, which has the main feature of requiring only a source of heat for its operation, presenting no moving parts or mechanisms for movement of working fluids, that are: water, ammonia and hydrogen gas. The existing literature was studied, in order to understand the functioning of this refrigerator cycle details. Convenient control volumes were developed for the DAR system based on a model with commercial flow of ammonia at approximately 100 grams per hour, and fed by a constant temperature thermal source, which is the oxidation reaction of machining chips. Thus it was determined equations of energy and mass balances for the volume control software implementing them in the ESS software, for the purpose of solving the equations systems to determine the COP, cooling capacity and the heat lost in the condenser. The results have proved that it is possible to use the available heat source to produce refrigeration. Since the cooling capacity obtained is relatively small, 31.66 W, it was not possible to use this type of refrigerator in applications that require extremely low temperatures, such as the contraction of parts for assembly by interference, where there is need to reach -20°C.