Improving efficiency and renewables utilization by hybrid heating plants for industrial buildings

In this paper, a typical industrial building was modelled using a dynamic simulation software in three very different climatic zones in Italy. On the basis of the thermal loads, a hybrid condensing radiant tubes heating system was modelled. The radiant tubes system was coupled to an air heating system with terminals placed in the building fed by two heat sources: one deriving from the condensation of the exhausted of the radiant tubes, and the other by a heat pump with external air heat source. The energy performance of the hybrid heating system was evaluated by optimizing the nominal power of the heat pump, the bivalent temperature in alternative bivalent operation (the system gives priority to the heat pump, which switches off when the outside air temperature drops below the bivalent temperature and the radiant tubes turn on), and the peak power of the photovoltaic system on the roof of the building. This analysis was performed taking into account the variation in heat pump performance with the outside air temperature. The optimal configuration of the hybrid heating system (minimizing the annual amount of total non-renewable primary energy and maximizing the non-renewable primary energy ratio) was then compared to some more traditional heating systems for industrial buildings to evaluate the energy advantages of this innovative solution.