To construct the model, all the components of the system are interconnected of appropriate manner in the Trnsys program, as shows in the Fig.2. Table 1 shows the main parameters used in each Trnsys component. The working pressure required in the RO system is calculated for seawater with a salinity of 36000 ppm. The meteorological data corresponds to the city of Almeria in the south of the Mediterranean coast of Spain. The solar plant uses a trough collector SEGS LS-2 modelled as implemented in the Trnsys program. The plant has an area of 1000 m2 of solar collectors with the tracking axis oriented in the North-South direction. In [19] the results for the steam Rankine cycle using a different orientation can be found for comparison.

The Trnsys unit Type 66, allows the user to call an EES file, receive data from Trnsys component: Flow Rate Solar Field (Fs) and Outlet temperature Solar Field (To) and pass its output data to other

Tmsys component: Inlet Temperature Solar Field (Ti), turbine power (Wt) and exchanged heat in the evaporator and condenser, (Qv, Qpre), as represented by Fig. 3(b). The model developed in EES program, consists basically in material and energy balance equations as well as thermodynamic properties, using n-pentane as working fluid. Fig 3(c) shows the main components of the ORC: preheater, evaporator, recuperator, turbine, pump and condenser.

Fig. 3. (a) Main components of Trnsys used in the Solar ORC simulation. (b) Component Type 66. (c)

ORC cycle diagram.