**7. Economic evaluation**

**Parameter Ventilation Mode Recirculation Mode**

**Outdoor air Room supply air**

**Wet bulb Temperature (°C)**

April 30.14 13.19 21.10 17.31 9.81 15.19 May 33.21 14.27 22.05 18.74 9.91 16.70 June 39.54 15.71 24.69 18.52 10.11 15.88 July 41.51 20.55 28.97 17.44 10.23 14.10 August 37.28 20.39 27.94 18.32 10.45 15.23 September 37.01 23.52 29.50 18.51 10.12 16.90 October 34.34 15.53 24.47 17.43 9.55 15.77 November 28.71 16.34 23.50 18.54 9.23 15.13 December 23.53 12.94 18.88 18.16 8.88 15.01

**Dry bulb Temperature (°C)**

**Humidity Ratio (gv**

**/kga )** **Wet bulb Temperature (°C)**

**Humidity Ratio (gv**

**/kga )**

**Month Dry bulb** 

132 Sustainable Air Conditioning Systems

**Temperature (°C)**

**Table 1.** Climatic data and desired supply conditions.

**Figure 12.** Monthly variations of COP for ventilation cycle.

**Table 2.** Average performance parameters for desiccant cooling system operating on ventilation and circulation cycle.

Qcool (kW) 44.40 45.2 Qreg (kW) 99.58 128.21 COP 0.461 0.354 Regeneration temperature (°C) 120 120

> In this section, an overview of economic aspects related to desiccant cooling technology has been presented. The economic evaluation of desiccant cooling system has been carried out by different researchers. Abdel-Salam and Simon [15] evaluated a membrane based liquid desiccant cooling system for its enviro-economic aspects. They compared primary energy consumption of four different systems. The obtained results showed that the primary energy consumption and total life cycle cost of desiccant cooling system was lower than conventional system by 19 and 12%, respectively. Addition of energy recovery ventilator improved the difference by 32% for primary energy consumption and 21% for total life cycle cost. Li et al. [16] compared vapor compression cooling system and hybrid of desiccant system for energy and economic evaluation. The results indicated that replacing the conventional system with hybrid system would reduce the size from 28 to 19 kW leading to annual effective energy savings of nearly 6760 kWh. However, the payback period would be 7 years because of the added initial investment costs.

> The costs of system accessories will vary depending upon the required flow rates and cooling needs [9]. The sizing charts for fans and pumps are shown in **Figures 14** and **15**, respectively. It can be observed that cost of each accessory depends upon the required output. The small desiccant cooling systems have higher specific costs as compared to large units. A comparative analysis of system specific cost with respect to its size is presented in **Figure 16**. The specific installed system costs are 7300 EUR/kW for small-scale systems and in average 1900 EUR/kW for large-scale systems [17].

**8. Recent developments and future needs**

desorbed easily by providing heat input.

The performance and development of desiccant cooling systems strongly depends on the desiccant materials used. The thermo-physical properties of these materials affect the performance of the system significantly. The key parameter for the selection of a desiccant material is that it should have the ability to absorb and hold large amount of water vapor. It should be

Renewable and Sustainable Air Conditioning http://dx.doi.org/10.5772/intechopen.73166 135

The properties such as density, vapor pressure, etc. of different desiccant materials can be enhanced by mixing two or more materials together. The mixed desiccants are termed as composite desiccants. Many researchers have studied the properties of composite desiccant materials in order to study their effects on dehumidification performance of the system. **Table 3** provides a summary of some experimental studies on desiccant cooling systems and lists the regeneration temperature and desiccant material used [18–24]. The literature review showed that most of the experimental studies were conducted with silica gel at high regeneration temperatures. There is

Although, a number of developments have been made in desiccant cooling technology but a number of steps still needs to be addressed in order to make this technology more market

• Cost-effective, non-corrosive, and nontoxic liquid desiccant materials need to be developed. • The effectiveness of regenerator needs to be improved using several approaches including multiple-effect boilers and vapor compression distillation. Different alternative energy

• Surface enhancements or extended surfaces such as fins should be used to modify the de-

**Author Desiccant material used Regeneration** 

Jia et al. [18] Silica gel 60–120°C White et al. [19] Zeolite and polymers 50–80°C Enteria et al. [20] Silica gel 60–80°C

Angrisani et al. [22] Silica gel 60–70°C Enteria et al. [23] Silica gel, Titanium dioxide 60–80°C Wrobel et al. [24] Lithium Chloride 45–50°C

**temperature**

45–90°C

currently limited research conducted with desiccant wheel other than silica gel.

sign of dehumidifier and regenerator for better heat and mass transfer.

Eicker et al. [21] Lithium chloride, Titanium dioxide, silica gel, silica gel and

**Table 3.** Summary of literature for regeneration temperature and desiccant materials.

calcium chloride

accessible. Some of the future research and development needs are:

sources should be utilized for regeneration purpose.

**Figure 14.** Cost of fan [9].

**Figure 15.** Cost of pump [9].

**Figure 16.** Specific costs of thermal cooling systems. Source: Green Chiller.
