# Review of Dew Point Evaporative Cooling Technology for Air Conditioning Applications
## 5 Discussion and Summary  
The literature review showed different directions of research in dew point indirect evaporative cooling technology. Some system performance indicators, like dew point effectiveness and wet bulb effectiveness, reach maximum values that are similar in different studies. The maximum dew point efficiency is almost 100% for specific conditions and exchanger specific parameters (see Table 5). Therefore, there has been more and more work that focuses on improvement of energy consumption or the quality of water distribution methods in exchangers. There are a few experimental works listed in Table 1, in which  
Figure 6: Desiccant cooling system scheme with ambient air precooling. various exchanger geometries, water distribution systems, and materials are analyzed. The DPIEC wet bulb efficiency (e.g., \(\varepsilon^{\text{tWB}}=53\%\), \(\varepsilon^{\text{tWB}}=64.5\%\), \(\varepsilon^{tWB}=76\%\) presented in Table 2) of those devices is lower, hence these technologies need further improvements. Many numerical studies of evaporative exchangers for hot climates can be found in the literature (Table 5). Scientists have shown high DPIEC efficiency in hot climates. The electrical coefficient of performance (COPel) is an important indicator, which depends on the geometry of the exchanger and it reaches values equal to 60. The implementation of DPIEC in humid or moderate climates involves the expansion of the system, due to the necessity of latent loads assimilation in an additional device (e.g., desiccant wheel or vapor compression system). The least complicated way to use a dew point evaporative cooler is a hybrid system with a typical compressor system. In such systems, scientists have proved electricity savings resulting from such an operation. The amount of savings depends on the type of building and its location. For example, [PERSON] showed savings of 42-64% for hot and dry climates. [PERSON] showed savings of around 38% for a residential building for a warm and humid climate. [PERSON] and [PERSON] showed savings of 38% for the humid climate in which the office building is located. [PERSON] showed a saving of 65% for the air conditioning system of a commercial facility located in a temperate climate. Analyzes, simulations, and optimization of such systems aim to obtain the highest possible energy savings. In the case of usage of evaporative exchangers in sorption systems, an important indicator is the thermal COP or SCOP (seasonal COP), which defines the effectiveness of the system. Scientists are aiming to increase the COP without complicating the system structure. Currently, the systems achieve mean SCOP values of about 2.5, while the maximum instantaneous COP values are 4.5. Tables 5 and 6 present a summary of selected publications, in which the different climate conditions for system operation were considered. In recent years, most scientists perform numerical studies on the basis of models validated to the existing experimental data. It can also be seen that combined systems are analyzed rather for hot humid climates, hence it requires more advanced technology. This is due to the need for ambient air dehumidification, which cannot be achieved with only DPIEC application. Recent publications also confirm researchers' commitment in optimization of indirect evaporative cooler devices and hybrid systems (Table 4). The variety of proposed methods can be observed. Overall, research on indirect evaporative cooling is not slowing down, therefore this technology is becoming a more and more promising alternative cooling technology.