Enthalpy and exergy analysis in the framework of a district scale energy balance
This report presents a study of an enthalpy and exergy analysis in the framework of a district scale energy balance. Energy demand (heating, cooling and lighting) for buildings represents more than 30 % of the total worlds energy use. Main eﬀorts have been made on increasing performances of new building envelop and on the use of low temperature processes in order to increase the exergy eﬃciency. On a district scale, diﬀerent temperature and energy ﬂow levels are present, meaning a great potential to make use of synergetic eﬀects by rationally managing energy ﬂow interactions between buildings as synergies by enhanced energy management and the usability of waste heat source. An optimisation of exergy ﬂows for the heating systems allows to identify the temperatures levels according to the energy demand, which helps to implement the best choice of available technologies. A number of connection cases will be described and studied to show the potential gain in terms of thermal and economical performances, where the thermal performances are deﬁned by both the energy and the exergy eﬃciency. This study shows an improvement of the thermal performances of connection cases where in all scenarios the heat losses are lower than the waste heat recovery. These gains on thermal performances may increase further by the integration of appropriate technologies such as heat pumps. The use of primary resource like gas can also be decreased.