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H2NG (hydrogen-natural gas mixtures) effects on energy performances of a condensing micro-CHP (combined heat and power) for residential applications: An expeditious assessment of water condensation and experimental analysis

Lo Basso, Gianluigi, de Santoli, Livio, Albo, Angelo, Nastasi, Benedetto
Energy 2015 v.84 pp. 397-418
condensation (phase transition), energy conservation, fuel cells, greenhouse gas emissions, greenhouse gases, heat recovery, hydrogen, internal combustion engines, natural gas, primary energy, temperature, water content
In order to accomplish significant primary energy saving and GHG (greenhouse gas) emissions reduction, CHP (combined heat and power) technology can be adopted largely for industrial and civil sectors. Waiting for the cutting-edge appliances (i.e. Fuel Cell) wide deployment, ICEs (internal combustion engines) fuelled with an environmentally-friendly fuel, such as H2NG (hydrogen-natural gas mixtures) could represent the bridge technology towards the forthcoming pure hydrogen economy. This paper deals with the results of an experimental campaign carried out on a Single Cylinder ICE, fuelled with NG (natural gas) and H2NG @ 15% vol. In detail, energy performances were assessed at rated and partial loads. From data analysis, it emerged that the electrical efficiency increased up to 2.28%, at the expense of the heat recovery one, having added hydrogen. Additionally, due to the higher water content in exhaust gas when H2NG is burned, it was investigated on how heat recovery efficiency has been affected by condensing operating conditions. Finally, to estimate this benefit, an expeditious procedure was developed building three maps for H2NG blends condensing properties from 0% up to 30% vol. of H2. Their outputs provided the condensation efficiency value and the absolute gain of heat recovery one with varying exhaust gas temperatures and hydrogen fraction in the mixture.