1.1. Goals

The just described experience demonstrates that a deep attention has to be paid in planning SHC-CHP systems from three points of view: layout, control strategy and machine sizes. The present research work proposes a first layout with a specific control strategy and a procedure for sizing such a plant with the main goal to avoid issues like the above mentioned. The selected plant configuration is then simulated in TRNSYS along one year to analyse the off-design behaviour of the single components, their interaction and the performance of the overall system.

1.2. Major hypothesis

The selected layout and the sizing procedure have been applied supposing the EURAC building to be the final user. In this regard, data derived from the installed monitoring system have been used. These data correspond to the building heating and cooling demand monitored since November 2005 to

October 2006 (Fig. 3.). To simulate the power load, the temperatures of the stream being delivered to the building and returning from it have been assumed constant, both in winter and in summer, according to the selected distribution system (DS). Thus, the demanded power has been translated in a “demanded mass flow” at constant temperature gaps. So, during the simulations, the “demanded mass flow” at the assumed return temperature gets elaborated by the designed facility. Under the mentioned hypothesis, checking that what is produced by the facility matches what is required by the building means ensuring that the “demanded mass flow” gets distributed at the assumed delivery temperature.