Efficient Energy Conversion Contribution in Urban Area Transition Towards Smart Cities
The European cities transition towards smart city targets inevitably passes from the transformation of current urban areas that are generally far from this objective. Use of renewable sources could represent the ultimate goal of this transition, but, at present, it is necessary to be aware that the coverage rate of thermal and cooling energy needs of urban utilities is largely satisfied by natural gas network and electricity grid. This study considers the way to augment exploitation of an existing natural gas distribution network through efficient energy conversion systems able to manage energy needs in winter heating and summer cooling seasons. Based on a gas-fired cogeneration system, the proposed conversion system efficiently uses simultaneous production of electrical and thermal energy to power electrically powered heat pumps and heat-fed chillers/heat pumps, respectively. Devices efficiency conversion was based on averaged performance data of manufacturer’s catalogues or from literature. Natural refrigerant for electrical and thermal driven chiller/heat pumps was selected in order to cover a wide range (also high) of temperature level in heating mode at user side and to increase environmental sustainability due to use of this natural refrigerant. Absorber and jet pump cycle as heat-fed chillers/heat pump were considered. A geothermal source was imposed as external source. In this work, a numerical simulation on TRNSYS was performed to investigate the performance of the system in terms of primary energy consumption. Results show that energy conversion efficiencies of devices play a relevant role in global performance, both on heating and cooling mode. The heat-fed chillers/heat pumps can greatly contribute to make this configuration an efficient tool to increase thermal and cooling energy that a given natural gas distribution network can provide in an urban area. Moreover, this solution opens up new perspectives to spread solar cooling and heating technologies.
KeywordsHeat-fed chillers/heat pumps Energy efficiency Natural gas network Numerical simulation
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