The absorption chiller model is a static “black box” model (see Figure6), in which experimental COP and chilling power are used to predict the chiller response at different boundary conditions. The chiller main parameters are: specific heat of oil (Cp0il), specific heat of chilled water (Cpch), auxiliary power for pumps and fans operation (Paux) and minimum refrigerant outlet temperature (Tset). The chiller inputs are: oil mass flow rate (moil), oil inlet temperature (Toili), ambient temperature (Tamb), chilled water mass flow rate (mch), chilled water inlet temperature (Tchi). The main outputs are oil outlet temperature (Toil, o) and the chilled water outlet temperature (Tch, o), from

which driving heat rate (Q0ii), chilling power (Qch), rejected heat (Qamb) and chiller coefficient of performance (COP) are easily calculated. For a detailed description see [7].

Fig. 5. Chilling power (fraction of nominal value)
variation with ambient temperature and oil inlet
temperature for: oil flow rate 3500 l/h, chilled water
inlet temperature 0 °C, chilled water flow rate 2500l/h

chiller
black box
model

Fig. 6. Absorption chiller black box model.

Fig8. Capsule charge phase