hrvatski

Analiza efikasnosti hibridnog sustava s gorivnim člancima na prirodni plin u Dalmaciji

Increasing energy consumption, lack of fossil fuels, the global warming issues, as well as increased public concern for environmental protection have led to fast progress of alternative energy sources and decentralized energy systems. Currently most interesting technology for simultaneous production of heat and power is cogeneration technology (mCHP) with fuel cells. Conventional heat and power systems for household supply are consisted of two different and separated processes of energy flow, while in mCHP system there is only one process of heat and power production. Generated 'waste heat' is used to follow thermal load of the building and to significantly increase fuel consumption efficiency. In the fuel cell chemical energy of the fuel is directly and continuously converted into electricity. Generated heat from PEMFC is also used in cogeneration for space heating or domestic hot water (DHW) preparation. The hydrogen needed to power fuel cells (PEMFC) is produced from natural gas in a special device called reformer. The existing infrastructure of natural gas with a high efficiency reformation contributes to faster market placement of fuel cells during the technology transition period. The energy system for heating/cooling purposes and domestic hot water preparing in the Mediterranean environment (Split) is presented in this paper. Proton exchange fuel cells (PEMFC), electric heat pump (HP), solar thermal collector (STC) and thermal storage tank (TS) are the main parts of the modeling system. Three heat sources are involved in DHW preparation, depending on availability. During the hours with sufficient amount of solar energy, the energy is converted into heat by solar thermal collector and which then is storage in TS. In the summer cooling season, electric heat pump can be used to maintain the internal project temperature of the house, with simultaneous DHW preparing. Specifically, the absorbed heat from the air flowing through isolated housing is used to heat water for TS. A fan provides air flow that flows through evaporator where the air is cooled to 10° C, while the DHW can be heated to a maximum of 50°C. PEMFC produces electricity needed to power the heat pump compressor, while at the same time the generated waste heat and heat generated due to PEMFC cooling are also used to power the TS. The heat stored in the TS is taken by the system during the hours when mentioned devices produce less energy than required by a household. In this paper, a thermodynamic analysis of energy conversion processes between different energy sources is presented with the objective of optimizing heat production process. Maximum efficiency in varying modes is achieved. An oversized system results in a large amount of unused waste heat. Frequent and sudden load changes in incorrectly modeled and poorly regulated system cause mCHP units to turn on and off a large number of times in short intervals, which drastically increases maintenance costs. Since the technology of mCHP system with fuel cell is in a range of advanced research phase, through pilot demonstration phase (Germany) to early commercial phase (Japan), it is necessary to continue the investment in research and development, to maximize reformer efficiency, increase the durability of fuel cells and with application of new technologies and materials reduce the price of equipment.

reformer, PEM gorivni članak, kogeneracija, spremnik topline

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