Water Production by Condensation of Wet Air

It is now assumed that climate warming is effective and noticeable. It not only leads to a lack of water that is increasing in desert areas, but it must be kept in mind that the inhabitants of the villages located in the geographical areas whose access to water is difficult, make binding efforts to gain access to water. This article proposes to present the possibility of obtaining water by the condensation of the water vapors of the air by applying the thermodynamic processes of the humid air as well as those of the refrigerating installations. In fact, atmospheric air contains suspended water vapors. When this steam cools below its rose point, there is condensation if water vapors and liquid water or ice appears. It was obtained a quantity of condensed vapors in a refrigeration facility. This amount is directly proportional to the refrigeration power whose efficiency can be improved by the use of photovoltaic energy given the reduced financial cost of this energy. This seems to be a hope among the possible solutions to be considered for the resolution of the water issue.


Introduction
Today, at least that is forecast by the experts in terms of forecasting, it is now clear that the global warming in progress is increasing and that a third of humanity is in a situation of water stress [1] [2] [3] [4] [5]. For villagers in geographical areas with difficult access to water, water supply is difficult and requests physical effort [6] [7] [8] [9]. However, a solution is possible by condensing the water vapor from the air. In fact, the atmospheric air contains in suspension water vapor, it is often in the state of superheated steam. When at a given temperature Ѳ, humid air contains the maximum mass of water vapor that it can Modern Mechanical Engineering contain per kilogram of dry air, the air is said to be saturated [2] [3] [4]. In these particular conditions, the vapor pressure of the water in the air at the same value as the saturation vapor pressure of the water at the same temperature Ѳ. This is the pressure that water vapor would take in equilibrium with liquid water or ice.
Determination of the characteristics and processes that occur can be achieved by the thermodynamics of moist air using the psychometric diagram [10] [11]. Our study is carried out for tow climates, namely: the tropical climate and the desert climate ( Figure 1). In contact with the evaporator whose temperature is very low, the moist air exchange heat because the temperature gradient, this results in a change in the phase of the water in the air. It goes from gaseous state to the liquid state, in other words, it condenses. This condensation can be forced, it is a forced convection if the circulation of air is carried out in a mechanic way, or natural way if the heat exchange is caused by the gradient of density. Note that the amount of condensed water depends not only on the climate in which the process occurs, but also on the speed with the air passes through the evaporator.
This amount of water is directly proportional to the speed of air. The installation of Figure 4 represents a natural convection occurring in a tropical climate. On the evaporator, the water vapor of the air turns into ice, thanks to a system of regulation that stops for some time the electrical power of. During this moment, this ice turns into a liquid that flows by gravitation into the recipient. Water production is about 2 litres per 24 hours ( Figure 6 and Figure 7).      Figure 5 shows the process of water production in the psychometric diagram whose ordinates represent the moisture contents r (kg/kg as ) and the abscissa, the temperatures. In this figure, point 1 is the representative state of unsaturated humid air characterized by a temperature θ = 35˚C and hygrometry φ = 65% for the tropical climate and a humidity of φ = 35% for the climate desert. The progressive cooling of this air with a constant moisture content occurs along a horizontal line which, at a certain temperature θ R = 27˚C for the tropical climate and θ R = 17˚C for the desert climate, meets the saturation curve φ = 100%. This temperature θ R is called the dew temperature or dew point, it is the saturation point of the water vapor of the air. If the temperature is reduced below the dew point, the evolution of saturated humid air then follows the saturation curve φ = 100%. The value of the content decreases, there is consequently condensation of water vapor, or the ice appearance when temperatures are very low in Figure 6 and Figure 7. The amount of condensed water per kilogram of dry air shall be equal to the difference between the moisture content at the dew point and the water content at the temperature of Ѳ = 0˚C [12] [13] [14]. Given that the compressor power is directly proportional to the cooling capacity of the evaporator, it is possible to calculate coefficient of refrigeration performance, the air flow rate and therefore the flow of condensed water [15] [16].

Coefficient of Refrigeration Performance
The performance coefficient of the installation C.O.P. is the ratio of refrigeration production Q 0 by the electrical power consumed P. It is calculated by the relationship:   (1)

Calculation of the Air Flow of the Installation
The air flow D air passing through the evaporator is cooled in state (1) With: x 1 : absolute humidity of the air at state Ѳ 1 (kg/kg a ); x 2 : absolute humidity of the air at state Ѳ 2 (kg/kg a ).

Results and Discussion
The purpose of this project is to produce water in areas where access to water is difficult. Table 1, Table 2 clearly indicate for the same power and the same ambient temperature, contrary to tropical climates, the production of water in desert climates is lower, namely: D water = 0.124 kg/h for the tropical zone respectively D water = 0.08 kg/h and for the desert area. This is mainly due to the difference in hygrometry between tropical and desert climates picture 1. This is not the case for the desert areas located at the seaside or the ocean which benefit from a very good hygrometry and high absolute humidity [3] [4]. However, it is possible to improve the flow of water by improving the convection and the conduction of the evaporator by improving the heat exchange coefficient k and increasing the surface and the air flow of the evaporator, in other words by increasing the cooling capacity of the installation, especially since in the desert climate this flow rate is higher than that of the tropical climate due to the lower enthalpy difference [3] [5]. In the desert areas, the temperature drops during the night, even if very early in the morning, the relative humidity varies positively for a very short time. However, this variation in temperature does not significantly influence the moisture content and therefore does not influence the flow of water produced by the installation [9] [10]. In order to improve the performance coefficient of the air condensation water production system, it would be