**3.2. Structures of reinforced concrete**

The characteristics of the reinforced concrete are as follows: it increases the rigidity and offers the possibility of completing the build later. The structure is formed per rigid knots and nondeformable edges. The disadvantages are low capacity acoustic and thermal insulation and high cost [6].


**Table 2.** Comparison of structures.

#### **3.3. Metallic structures**

These structures are metallic and are characterized by their low cost in comparison with structures of reinforced concrete, high resistance of the metallic structures due to their properties of the steel such as useful long life, ductility, tenacity, and high electrical conductivity. Their advantages are as follows: rapidity of assembly, great capacity of laminated, resistance to the fatigue, armor with diverse types of shaped and possible structural reutilization after dismounting. The disadvantages are as follows: corrosion, elastic bulge, and high cost in comparison with the structures of wood.

absorber; additionally, the system requires a solution pump and two valves, as shown in **Figure 5**. A quantity of heat (QGE) is added to the generator at a relatively high temperature (TGE) to vaporize the working fluid from the solution. The vaporized working fluid (1) goes to the condenser, where it is condensed into a saturated liquid, and the heat released from this condensation process (QCO) is discharged to the atmosphere at an intermediate temperature (TCO). The liquid leaving the condenser (2) passes through an expansion valve to reduce its pressure (3) and goes to the evaporator; as the saturation temperature of the refrigerant at lower pressure is much lower than room temperature (TEV), the refrigerant absorbs the heat of the room (QEV), and it vaporizes, producing the cooling effect. Then, the vapor generated (4) moves to the absorber where it is absorbed by the strong solution of absorbent coming from generator (7, 8), delivering heat (QAB), which is dissipated to the ambient to keep the absorption process at a desirable temperature (TAB). Finally, the mixture refrigerant/absorbent

Design and Construction for Hydroxides Based Air Conditioning System with Solar Collectors…

http://dx.doi.org/10.5772/intechopen.72188

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The cycle can be mathematically described by the following equations derived from mass and

*QGE* = *m*<sup>6</sup> *H*<sup>6</sup> − *m*<sup>1</sup> *H*<sup>1</sup> − *m*<sup>7</sup> *H*<sup>7</sup> (1)

*QCO* = *m*<sup>1</sup> *H*<sup>1</sup> − *m*<sup>2</sup> *H*<sup>2</sup> (2)

*QEV* = *m*<sup>4</sup> *H*<sup>4</sup> − *m*<sup>3</sup> *H*<sup>3</sup> (3)

*QAB* = *m*<sup>4</sup> *H*<sup>4</sup> + *m*<sup>8</sup> *H*<sup>8</sup> − *m*<sup>5</sup> *H*<sup>5</sup> (4)

The coefficient of performance (COP) is a parameter that is defined as the ratio of available useful energy to the total power supplied to the system. As the work from the pump solution,

These equations allow us to compute the system in order to simulate various operating condi-

The mixture refrigerant/absorbent is better known as working pair, and the performance of the cycle depends critically on it [11]. Generally, a suitable working pair should satisfy some requirements such as a high boiling point difference and a good miscibility between the components, chemically stable, nontoxic, environmental-friendly to mention a few [12, 13]. A wide variety of refrigerant/absorbent combinations have been suggested for absorption cooling systems [13], being the mixtures of water/LiBr and ammonia/water as the two most

is relatively small (about 1%) with respect to the heat supplied in the generator, and it is

*QGE* + *Wp*

(5)

is pumped (5, 6) to the generator to restart the cycle.

*COP* <sup>=</sup> \_\_\_\_\_\_\_ *QEV*

tions and determine which those that meet the requirements.

usually negligible for analysis purposes.

energy balances:

*Wp*

**4.1. Working pair**

**Table 2** shows the advantages and disadvantages of the structural materials.
