Investigation of the energy performance of multi-source integrated CHP systems for small-scale applications

Abstract

The work aims at analysing the performance of an innovative multi-source integrated energy system for small-scale combined heat and power (CHP) applications. The system is based on an organic Rankine cycle (ORC) coupled with a biodiesel internal combustion engine (ICE), a wind turbine (WT) and a photovoltaic system (PV). The engine exhaust gas provides energy to the bottoming ORC system, whereas the thermal energy of the ICE cooling and lubricating system is used for cogeneration purposes at low temperature. Both ORC and ICE systems operate in order to satisfy the thermal demand of a commercial centre. Wind and photovoltaic units work in parallel to increase the electric self-consumption rate. When the solar and/or wind sources are high, the biodiesel ICE-ORC can be switched-off or operated at partial load. A numerical thermodynamic model has been developed and a preliminary investigation has been performed to define the proper size of the system according to a thermal-driven strategy. An hourly energy balance has been carried on an annual basis. The analysis has been focused on a multi-variable optimisation and the proper trade-off between electric surplus and self-consumption has been found. The results reveal that the multi-source CHP system represents an efficient solution for smart-grid communities.