# Review of Dew Point Evaporative Cooling Technology for Air Conditioning Applications
## 4 Dew Point Evaporative Coolers Research
### Modelling the DPIEC Performance  
There are number of studies focused on DPIEC performance development using different methods, such as analytical, numerical, and statistical. A summary can be found in Table 3, which provides information about the experimental model validation in mentioned study (see Yes or No in Table 3). For example, [PERSON] et al. [21] presented an analytical solution for minimalization of pressure drop in IEC. It was underlined that the pressure drop should be considered in a pre-design stage of IEC systems. They conducted numerical simulations which showed the increase of total power consumption with a fin height increment. [PERSON] et al. [22] analyzed counter-flow DPIEC considering water film parallel (configuration A) and counter (configuration B) flow distribution referring to the supply airflow. They developed a two-dimensional computational fluid dynamics model which was validated with experimental data. They found out that configuration B has greater cooling effectiveness and lower product temperature than configuration A. The thickness of a heat and mass exchanger wick material equals 0.25 mm and a layer of the natural fibrous wick is pasted on the surface of a polymer sheet. The material must absorb water continuously to cover the plate fully with the water film. [PERSON] et al. [23] developed a mathematical model of DPIEC which was validated against experimental data (with a maximum discrepancy of \(\pm\)7.0%), captured using the DPIEC unit in which natural fiber cellulose was used as a wet channel material. At the fundamental level they examined the convective heat and mass transfer process of the DPEC, establishing the ranges of the Nusselt number and Sherwood number. In 2018, [PERSON] et al. [24] presented the review of different methods of M-Cycle evaporative coolers modeling. The methods of evaluating DPIEC performance were divided into few groups, such as: analytical, numerical, statistical, and experimental approaches. This publication concluded that only the Chen model considered the phenomenon of condensation in evaporative exchangers. Nevertheless, in recent years, scientists presented some new approaches and developed models, taking this phenomenon into account, as evidenced by the following studies. \begin{table}
\begin{tabular}{c c c} \hline
**Novelty of Technology** & **Performance** & **Reference** \\ \hline Different IEC geometry and flow arrangement & \(\varepsilon^{tWB}\)= 53\% & [PERSON] [9] \\ \hline Super-performance hydrophilic material layer & \(\varepsilon^{tWB}\)= 114\%, & \\  & \(\varepsilon^{tDP}\)= 75\% & [PERSON] et al. [10] \\ \hline Presence of condensation in cross-flow exchanger & \(\varepsilon^{tWB}\)= 64.5\% & [PERSON] et al. [11] \\ \hline Different water spraying configurations & \(\varepsilon^{tWB}\)= 76\% & [PERSON] et al. [12] \\ \hline Exchangers made of polystyrene and nylon fiber & \(\varepsilon^{tDP}\)= 78.4\% & [PERSON] et al. [13] \\ \hline Analyzed different materials for DPIEC & - & [PERSON] et al. [14] \\ \hline Water-absorbing experiment & - & [PERSON] [15] \\ \hline Analyzed different cooling pads & - & [PERSON] et al. [16], [PERSON] et al. [17], \\  & & [PERSON] [19] \\ \hline \end{tabular}
\end{table} 
Table 2: Experiments including development of dew point indirect evaporative coolers (DPIEC) structure development. [PERSON] and [PERSON] [25] performed a numerical and experimental study of counterflow dew point evaporative cooler. They presented two heat and mass transfer models (1D and 3D). Both models match the experimental results with 10% and 8.5% accuracy. In this experiment, the dew point evaporative cooler is made of plastic, but in the working channels, the wicking paper was attached to the wall and its thickness equaled 0.15 mm. They also established the regression models for prediction the DPIEC performance using a numerical model validated against experimental data before [26]. [PERSON] et al. [27] developed a new method of counter-flow DPIEC performance prediction.