*2.4. System Modeling*

The TRNSYS library includes modules (TYPES) that represent the equipment commonly used in energy systems, modules for processing meteorological data, and modules for processing simulation results. The modular structure of TRNSYS gives grea<sup>t</sup> flexibility to analyze different types of energy systems. The representation of SACS in TRNSYS, described in the previous section, is illustrated in Figure 5. Table 4 provides information about the most important components of the system, the type of module that represents them, and provides some parameters of the basic design. Figure 5 and Table 4 do not include other components and flows of less importance. The period of simulation in TRNSYS was seven months (cooling season) from 1April 1 (2160 h) until the end of October (7296 h), with a step time simulation of one minute. Baghdad meteorological data was gained from TMY2.

**Figure 4.** Contribution of the various cooling load component.

**Figure 5.** Diagram of the TRNSYS model of the solar absorption cooling system (SACS).

Some of the simplifying assumptions used in the calculation are indicated below:


In developing the model, the recommendations by some authors who have simulated the behavior of solar absorption cooling systems with TRNSYS, or other applications, have been taken into account [19,31].

**Component Type TRNSYS Parameters (Base Design Values)** Solar Collector TYPE 71a Apricus ETC-30 (Table 3) Number of collectors (12) Inclination (30◦) Hot water tank TYPE 4a Volume (50 <sup>L</sup>/m<sup>2</sup> collector) Auxiliary boiler TYPE 6 E fficiency (90%) Absorption chiller TYPE 107 YAZAKI WFC SC10 (Table 5) Cooling tower TYPE 51b B.A.C. FXT-26 (Table 4) Weather data TYPE 109—TMY2 Location: Baghdad, Iraq Collector pump TYPE 3b Flow rate 50 (L/h)/m<sup>2</sup> of collector Collector pump control TYPE 2b Maximum accumulator temperature (90 ◦C) Minimum collector gain (5 ◦C) Pipe TYPE 31 Flow mixer TYPE 11h Building TYPE 56a

**Table 4.** List of the most important components of the TRNSYS model.
