**Solar Air-Conditioning Systems**

**Solar Air-Conditioning Systems**

Emna Aridhi, Hmida Bemri and Abdelkader Mami Additional information is available at the end of the chapter

Emna Aridhi, Hmida Bemri and Abdelkader Mami

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/intechopen.72189

#### **Abstract**

The chapter presents the recent studies focusing on optimizing the efficiency of air-conditioning (AC) systems using solar energy. For this purpose, several advanced AC plants (absorption, adsorption, and desiccant) are designed. Their technology and components are described in this chapter. It also discusses the energy intake of the solar energy use in airconditioning, especially in rural regions where the electricity shortage is frequent, as well as the reduction of the energy costs and the pollution rate. A comparison between solar AC systems and traditional AC systems at the level of the designs, costs, and effectiveness is made at the end of the chapter.

DOI: 10.5772/intechopen.72189

**Keywords:** solar energy, air-conditioning systems, energy savings, absorption systems, desiccant systems, adsorption systems

## **1. Introduction**

In recent years, the demand for comfort has been accentuated due to the earth's changing climate. Therefore, the use of air-conditioning systems is increased, which leads to higher costs and consumption of energy. It also significantly contributes to the global warming. For instance, in the United States, air conditioners use about 6% of the entire electricity produced, at an annual cost of about \$ 29 billion to homeowners. Consequently, roughly 117 million metric tons of CO<sup>2</sup> , per year, are released into the atmosphere. On the other hand, 40% of energy consumption and 36% of CO2 emissions in the EU are caused by buildings, according to United Nations Environment Programme (UNEP). As a result, an increasing interest has been concentrated on the design of modern sustainable AC systems powered by renewables, especially the solar energy that is a universally inexhaustible natural and clean resource [1]. Hence, it can offer a reduction of the consumption, the demand, and the costs of energy, without decreasing the desired comfort. These systems allow converting the solar thermal energy (in the form of

Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons

heat) into conditioned air and sometimes chilling storage water. They are outstandingly used in residential and other sectors (offices, hotels, restaurants, storage warehouses, schools, hospitals, etc.) [2], what makes them classified among the most energy consumers.

Several research studies around the world aimed to design various modern solar-powered plants with energy storage. They allow minimizing the environmental effects and satisfying the energy demand [4, 8, 9]. We find single-stage or double-stage absorption systems with and without crystallization [4]. The single-stage systems are equipped with two heat exchangers and two or three storage tanks. However, the double-stage systems are different from the preview systems by adding the two pairs of absorber/generator and evaporator/condenser. In addition, the crystallization process occurs that the refrigerant undergoes three-phase transformation (solid: usually crystallized salt, liquid, and vapor) [4]. Furthermore, these plants and their performance are closely linked to the climatic conditions (especially solar irradiance) of the regions where they are installed. For instance, Mediterranean countries are characterized by a hot climate, which encourages the use of solar air-conditioning systems [5]. In fact, Tunisia widely invests in solar energy that this country is characterized by a sunny climate over long periods of the year [10]. In this reference, an absorption solar installation

consists of a water-lithium bromide absorption chiller having a capacity of 11 kW, a flat-plate

The simulation results showed that the COP reached 0.725 for a cooling capacity of 16.5 kW as long as the heat source temperature increases, which causes the growth of the heat transfer between the system exchangers and then the quantity of heat distributed in the surroundings [11]. Moreover, another study analyzed the energy performance of a solar air-conditioning office building that maximum monthly consumes about 380 kWh [12]. It consists of insulating the walls and cooling the roof. Hence, it allows reaching an energy saving of 46 and 80% in winter and summer, respectively, as well as, reducing the cooling load from 14.09 to 8.68 kW. In the same framework, the studies [13, 14] aimed to improve the efficiency of a solar

chiller associated with a cooling tower, a backup heater, two tanks for storage and drain-back storage, and a set of fan coils installed in the building to be cooled [14]. The synoptic scheme presenting the main components of the proposed cooling system is illustrated in **Figure 2**,

installation equipped with parabolic solar collectors (having an area of 39 m2

**Figure 2.** Synoptic schema of the solar cooling system using parabolic collectors.

to minimize the energy consumption during the summer. It

, and a hot water storage tank having a volume of 0.8 m<sup>3</sup>

.

5

), an absorption

Solar Air-Conditioning Systems

http://dx.doi.org/10.5772/intechopen.72189

is applied to a room of 150 m2

according to Ref. [14].

solar collector having an area of 30 m2

The present chapter reviews recent studies focusing on three technologies of solar AC systems: absorption, adsorption, and desiccant systems.
