# Review of Dew Point Evaporative Cooling Technology for Air Conditioning Applications
## 4 Dew Point Evaporative Coolers Research
### Modelling the DPIEC Performance
The method consists of the NTU (Number of Heat Transfer Units) model and two-dimensional computational fluid dynamic model, which both allow to capture the essential boundary conditions and further obtain the transfer coefficients. It simplifies computation and provides accurate data to find the optimum design of DPIEC. [PERSON] et al. [28] implemented the performance model of dew point cooler (DPC) with a guideless and corrugated Heat and Mass Exchanger (HMX) in whole building energy modeling. They predicted the system by simulating its operation in different climates. The authors presented the potential to optimize evaporative systems for various types of buildings located in different climatic conditions. [PERSON] et al. [29] applied the counter flow M-Cycle cooler in eight Arab Gulf cities for their specific weather conditions. They developed the mathematical model which was validated towards existing experimental data. For those regions, the required supply air parameters were calculated and compared to supply air parameters achieved by using a direct evaporative cooler and vapor-compression system. The main advantage of the M-Cycle unit was utilizing less electric energy than a vapor-compression system, for the same cooling capacity. However, it uses more water than direct evaporative cooler while the supply air parameters are more suitable to cover cooling loads. In recent years, several publications have been published on the modeling of exchangers, taking into account the condensation of water vapor from the product air. For example, the cross flow indirect evaporative cooler was modeled by [PERSON] et al. [30]. They developed a two-dimensional mathematical model for heat and mass transfer in the exchanger based on the condensation area ratio. The model is solved by the finite difference method using the MATLAB program. The influence of condensation area ratio on wet-bulb efficiency, \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Study Methods**} & **Experiment** & \multirow{2}{*}{**Novelty of Technology**} & **Performance** & \multirow{2}{*}{**Reference**} \\  & **(Y/N)** & & & **(Maximum)** & \\  & & & **Effectiveness** & \\ \hline Analytical & N & Different fin heights included & \(\epsilon^{tW}\)B\({}_{=}\) 120\% & [21] \\ \hline CFD & Y & Different water film distribution & \(\epsilon^{tW}\)B\({}_{=}\) 110\% & \multirow{2}{*}{[22]} \\  & & & \(\epsilon^{tD}\)P\({}_{=}\) 78\% & \\ \hline CFD & Y & \begin{tabular}{c} Nusselt number and Sherwood \\ number are examined \\ \end{tabular} & - & [23] \\ \hline Statistical & Y & Simple predicting the DPIEC performance & \(\epsilon^{tW}\)B\({}_{=}\) 120\% & [25] \\ \cline{3-5} NTU-Le-R method and & & & \(\epsilon^{tW}\)B\({}_{=}\) 118\% & [26] \\ CFD model & Y & \begin{tabular}{c} Presented a new method to precisely \\ obtain the transfer coefficient \\ \end{tabular} & - & [27] \\ \hline Statistical and building energy model & Y & \begin{tabular}{c} The detailed investigation of the \\ cooling systems within a building \\ context \\ \end{tabular} & \(\epsilon^{tW}\)B\({}_{=}\) 115\% & \multirow{2}{*}{[28]} \\  & & & \(\epsilon^{tD}\)P\({}_{=}\) 85\% & \\ \hline \(\varepsilon\)-NTU method & N & & \(\epsilon^{tW}\)B\({}_{=}\) 84\% & [30] \\ \hline \(\varepsilon\)-NTU method & Y & \
\begin{tabular}{c} The condensation phenomenon \\ included and analyzed \\ \end{tabular} & \(\epsilon^{tW}\)B\({}_{=}\) 84\% & [31] \\ \hline \(\varepsilon\)-NTU method & Y &
\begin{tabular}{c} \(\epsilon^{tW}\)B\({}_{=}\) 100\% \\ \(\epsilon^{tD}\)P\({}_{=}\) 96\% \\ \end{tabular} & [32] \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Modelling of the DPIEC performance. dehumidification rate, latent heat transfer, and sensible heat transfer of indirect evaporative cooling was analyzed by the authors. In 2018, there were two studies which compared counter-flow and cross flow IEC performance operating in conditions while condensation takes place. [PERSON] et al.