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The present study reports the development of a deep learning artificial intelligence (AI) model for predicting the thermal performance of evaporative cooling systems, which are widely used for thermal comfort in different applications. The existing, conventional methods for the analysis of evaporation-assisted cooling systems rely on experimental, mathematical, and empirical approaches in order to determine their thermal performance, which limits their applications in diverse and ambient spatiotemporal conditions. The objective of this research was to predict the thermal performance of three evaporation-assisted air-conditioning systems—direct, indirect, and Maisotsenko evaporative cooling systems—by using an AI approach. For this purpose, a deep learning algorithm was developed and lumped hyperparameters were initially chosen. A correlation analysis was performed prior to the development of the AI model in order to identify the input features that could be the most influential for the prediction efficiency. The deep learning algorithm was then optimized to increase the learning rate and predictive accuracy with respect to experimental data by tuning the hyperparameters, such as by manipulating the activation functions, the number of hidden layers, and the neurons in each layer by incorporating optimizers, including Adam and RMsprop. The results confirmed the applicability of the method with an overall value of R2 = 0.987 between the input data and ground-truth data, showing that the most competent model could predict the designated output features (Toutdb, wout, and Eoutair). The suggested method is straightforward and was found to be practical in the evaluation of the thermal performance of deployed air conditioning systems under different conditions. The results supported the hypothesis that the proposed deep learning AI algorithm has the potential to explore the feasibility of the three evaporative cooling systems in dynamic ambient conditions for various agricultural and livestock applications.

Evaporative cooling technology (ECT) has been deemed as an alternative to the conventional vapor-compression air conditioning system for dry climates in recent years due to its simple structure and low operating cost. Generally speaking, the ECT includes two types of different technologies, direct evaporative cooling (DEC) and indirect evaporative cooling (IEC). Both technologies can theoretically reduce the air temperature to the wet-bulb temperature of outdoor air. The major difference between these two technologies is that DEC will introduce extra moisture to the supply air while IEC will not. The enhanced IEC, Maisotsenko-cycle (M-cyle) IEC, can even bring down the air temperature to the dew point temperature. The ECT integrated with solid desiccant systems, i.e., solid desiccant-assisted evaporative cooling technologies (SDECT), could make the technology applicable to a wider range of weather conditions, e.g., weather with high humidity. In this paper, the recent development of various evaporative cooling technologies (ECT), solid desiccant material and the integration of these two technologies, the SDECT, were thoroughly reviewed with respect to their configuration, optimization and desiccant unit improvement. Furthermore, modeling techniques for simulating SDECT with their pros and cons were also reviewed. Potential opportunities and research recommendations were indicated, which include improving the structure and material of M-cycle IEC, developing novel desiccant material and optimizing configuration, water consumption rate and operation strategy of SDECT system. This review paper indicated that the SDECT system could be a potential replacement for the conventional vapor-compressed cooling system and could be applied in hot and humid environments with proper arrangements.

Evaporative cooling, an eco-friendly and energy-efficient technique, mitigates the environmental damage caused by mechanically driven air-conditioners. Recent studies have shown that rotating humidifiers are useful for large space cooling applications due to their higher efficiency. Despite the benefits, it leads to an increase in the electrical energy consumption. Vermicompost, an excellent water storage medium, replaces the pad of conventional air coolers, thereby eliminating the pump used for water circulation and the motor used in centrifugal humidifiers. However, the amount of water storage depends on the mass of the vermicompost. The supplied water should produce continuous cooling if the vermicompost is completely soaked and operated. If all the water evaporates over a period, vermicompost may dry, necessitating additional water supply. Hence, the need arises to study the influence of the mass of vermicompost and the water supply method on the performance of vermicompost-based direct evaporative cooling systems. The present study proposes to experiment with three different masses and two modes of water supply: initial and continuous. Experimental results showed that the system produced an average effectiveness of 82 % using '500 g' and '1000 g' of vermicompost through the continuous water supply, while the effectiveness augments to 85 % using '1500 g' of vermicompost with only the initial water supply. The studies reveal that a lower mass of vermicompost with a continuous water supply is preferable for cooling in small spaces. A higher mass of vermicompost with an initial water supply is helpful for large spaces like greenhouses and livestock buildings. Hence, the present system is energy-efficient, showing an energy savings of 69.43% by neglecting the pump and motor, as in centrifugal humidifiers. Moreover, it is eco-friendly as it eliminates the pump and sump that lead to the transmission of diseases like dengue and malaria caused by insect breeding in the sump.

Direct evaporative coolers are energy-efficient, economic solutions to supplying cooling demand for space conditioning. Since their potential strongly depends on air hygrothermal conditions, they are traditionally used in dry and hot climates, though they can be used in many applications and climates. This work proposes a new direct evaporative cooling system with a fabric-based pad. Its design enables maximum wetted surface with minimum pressure drop. Its performance has been experimentally characterized in terms of saturation efficiency, air humidification, pressure drop, and level of particles, based on a full factorial Design of Experiments. Factors studied are air dry bulb temperature, specific humidity, and airflow. Saturation efficiencies obtained for a 25 cm pad are above the values achieved by other alternative evaporative cooling (EC) pads proposed in the literature, with lower pressure drops.

As the cooling requirement and the energy prices are increasing rapidly across the world, the need to develop highly efficient cooling equipment is rising as well. Adiabatic cooling employs evaporation to pre-cool the air flowing through a closed-loop coil. This study examines various adiabatic evaporative cooling pads in terms of their pre-cooling potential and advantages over currently available technological solutions through isolating three cross-sectional metal cooling pad shapes (W, Z and Z1). The results of the study suggest that the correlation between Δt↓ and RH↑ is somewhat close in all three cases; however, a slightly higher temperature drop is observed when using a W-shaped metal sheet. Pressure drop variability was negligible under current cooling pad configurations and experimental boundary conditions. Further studies focusing on measurement continuity, longevity and boundary conditions’ variability are recommended.

A review is conducted about the application of the evaporative cooling technology in thermal power plants. Different case studies are considered, namely, evaporative air conditioners, evaporative cooling in direct air-cooled systems, gas turbine inlet cooling, wet cooling towers, and hybrid cooling towers with a crosswind effect. Some effort is provided to describe the advantages related to direct evaporative cooling when it is applied in thermal power plants and illustrate the research gaps, which have not been filled yet. In particular, typical case studies are intentionally used to compare the cooling performances when direct evaporative cooling is implemented in different types of cooling towers, including the natural draft wet cooling tower (NDWCT) and the pre-cooled natural draft dry cooling tower (NDDCT). It is shown that the NDWCT provides the best cooling performance in terms of power station cooling, followed by the pre-cooled NDDCT, and the NDDCT; moreover, the evaporative pre-cooling is able to enhance the cooling performance of NDDCT. Besides, on a yearly basis, better NDDCT cooling performances can be obtained by means of a spray-based pre-cooling approach with respect to wet media pre-cooling. Therefore, the use of nozzle spray is suggested for improvement in the performance of indirect/direct air-cooling systems with controlled water consumption.

One of the most important parts of direct evaporative cooling systems is the cooling pad. Pads vary in materials and construction features. The parameters studied in the performance of the pads are air speed, pad thickness, geometrical characteristics, and its configuration and the provided water flow rate. The performance of the pads is usually determined through saturation efficiency, pressure drop, temperature drop and humidity increase in the treated air, evaporation and water consumption, cooling capacity, coefficient of performance, and heat and mass transfer coefficients. Since the geometry and how to place the pad in the evaporative cooling system is one of the most important issues related to the performance of such systems, the present work experimentally investigates the amount of cooling and evaporation of the direct evaporative cooling system under 5 different angles of placement of the cellulose pad in relation to the vertical position. It includes angles of 0∘, 5∘, 10∘, 15∘, and 20∘ in 5 different air speeds, 2 different inlet water flow rates, 2 inlet air temperatures, and 2 different inlet water temperatures. Results show that the lowest output temperature, highest air relative humidity, highest coefficient of performance (about 12% more than 0∘), highest saturation efficiency, and highest evaporation rate are obtained in the case of a 15∘ of cooling pad placement angle.

Air conditioners (ACs) are more commonly used nowadays in residential and commercial buildings to achieve thermal comfort in the summer season. Due to the high outside temperature, condenser pressure was highest and ultimately resulted in high electricity consumption. One of the ways to reduce the energy consumption of AC systems and increase cooling capacity is by reducing air temperature entering the condenser by using the evaporative cooling principle. This article presents an experimental and theoretical investigation of improving the performance of the conventional air conditioning unit supported by a direct evaporative cooling system to increase the cooling capacity and reduce the consumption of power in hot and dry climates. A window-type AC unit was implemented in the experiment where the AC system is modulated to provide a wide range of various weather conditions. The results show that using evaporative cooling assist enhanced the system to overcome the many challenges by which the refrigeration capacity was increased in the range of 10–20%. Also, the results show a decrease in outlet temperature by 6–10°C, and the power consumption was reduced by about 3%. MATLAB program was used to analyze different data that were obtained. The input parameters for this program are the inlet conditions such as the weather conditions of the located city, namely the outdoor dry temperature and the outdoor relative humidity. The effectiveness and cooling capacity were calculated based on the frontal air velocity and the inlet air temperature. A comparison between the experimental and theoretical work showed a good agreement, as the relative difference is less than 9%.

Considering the energy-saving advantages of the direct evaporative cooler (DEC) compared to the traditional air conditioning system (TAC), this study aims to indicate its ability to improve the thermal comfort and the indoor air quality of the bus compared to the bus air-conditioned by the traditional compressor system. Taking a bus in Lanzhou as the object, the numerical model and method were first verified by an experimental method. Then, numerical analyses were simultaneously carried out in both bus models, which were air-conditioned by TAC and DEC, respectively. The results showed that the thermal comfort of the bus air-conditioned by DEC is more satisfactory, and the indoor air quality is better. Additionally, the bus air-conditioned by DEC achieves a 43.7% improvement in the temperature efficiency and a 31.3% improvement in the ventilation efficiency compared to the bus air-conditioned by TAC. The conclusion will provide valuable insights into the application of DEC in buses in dry regions.

In this study, saturation efficiency and pressure drop, two critical parameters for the direct evaporative cooling phenomenon, were numerically investigated and optimized. For this purpose, the direct evaporative cooling process was simulated at inlet air velocities in the range of 1–3 m/s on different thicknesses of CELdek 7090 evaporative cooling pad from 100 to 300 mm. The mathematical model of pressure drop and saturation efficiency was developed by analyzing variance at R -squared values of 99.53% and 99.99%, respectively. Finally, the non-dominated sorting genetic algorithm II (NSGA-II) was applied to minimize the pressure drop while maximizing the saturation efficiency simultaneously. The results indicate that applying mathematical models makes it possible to predict the saturation efficiency and pressure drop of direct evaporative cooling systems with a 4% and 7.9% deviation, respectively. It can also be concluded that the pad thickness effect is more significant on the saturation efficiency than on the pressure drop. On the other hand, the inlet velocity has a greater impact on the pressure drop. NSGA-II optimization demonstrated that, regardless of the pad thickness, optimal saturation efficiency and pressure drop were obtained at the inlet air velocity of 1 m/s. Accordingly, when using direct evaporative cooling systems, efficiency and pressure drop can be optimized whenever the fan is set at a low speed. Depending on the researchers’ and designers’ goals, the findings of this research can be used in the design of direct evaporative cooling systems for different applications to achieve maximal saturation efficiency at the minimum possible energy consumption.