Evaporative Cooling System Research Articles

Experimental Study on the Performance of a Dew-Point Evaporative Cooling System with a Nanoporous Membrane

In this paper, a plate counter-flow dew-point evaporative cooling system was designed with a nanoporous membrane covered on the surface of the wet channel for enhancement of heat and mass transfer. First, the operating principle of this device and theoretical analysis of nanoporous membrane evaporation were discussed in detail. Then, the impacts of several operating parameters on cooling performance, mainly including inlet air temperature, humidity, velocity, and the effect of utilizing the membrane, were investigated in trials. It was found that the cooling performance can be improved by using membrane significantly. In the dry channel, the maximum temperature decrease can reach 12.5 °C. At a high inlet air temperature, the product air can be dropped to a lower temperature, contributing to a more significant heat transfer process. Lower humidity, on the other hand, resulted in a reduced product air temperature and a lower cooling efficiency. Under the condition of 50% humidity, the wet-bulb efficiency and dew-point efficiency were 1.09 and 0.79, respectively. With the inlet air velocity increasing from 1.5 m/s to 2 m/s, the outlet air temperature would rise, and the wet-bulb efficiency and dew-point efficiency would decrease. To achieve better cooling performance, inlet air velocity ought to be limited to a low speed.

Efeito do pré-resfriamento da água aplicada em placas porosas de sistemas de resfriamento evaporativo

ABSTRACT: This study assessed the ways the thermal environment is influenced by pre-cooling the water employed in wetting the porous plates present in the evaporative cooling systems (ECS). The experiment was performed using two physical models constructed on a distorted and reduced scale, which simulated closed agricultural facilities equipped with ECS made up of porous cellulose panels. In one physical model, the plates were made wet using chilled water (ECScw), while in the other they were moistened using natural water, at environment temperature (ECSnw). Both inside the physical models and outside, in the external environment, the air dry-bulb temperature (tdb), black globe temperature (tbg) and air relative humidity (RH) were measured, at 10 sec intervals. Later, the environmental indices, ECSnw cooling effectiveness and ECScw performance factor were assessed. When the porous ECS plates were thoroughly wet using pre-cooled water, lowering of the thermal variables and comfort indices was seen to be greater than when wetting the plates was done using water at room temperature. An empirical equation was proposed to determine the cooling performance factor applied to the ECScw related to water temperature, tdb and air wet-bulb temperature.

Designing, Modelling and Experimental Investigation of Direct Evaporative Cooling System Coupled With Commercial Desiccant Dehumidifier

Abstract With the increasing demand of clean and energy-efficient air conditioning systems, evaporative air cooling technique is gaining significant attention owing to less energy consumption and environmentally safe technology in comparison with conventional refrigerant-based air conditioners. In this study, commercial desiccant dehumidifier is coupled with experimentally developed direct evaporative cooling (DEC) system to first dehumidify the air and then pass it through DEC to achieve human thermal comfort level defined by ASHRAE standards. Under the climatic conditions of Islamabad, Pakistan, multiple experiments were carried out at different temperatures, flowrate, and relative humidity of air during November, when air temperature and relative humidity were in the range of 25–30 °C and 40–60%, respectively. To analyze the system performance under summer ambient conditions, indoor temperature was increased by 8–10 °C and relative humidity by 15–25% in laboratory. Experimental analysis showed that the system can provide human comfort level for a range of temperature 29–39.7 °C and relative humidity of 65–80% at flowrate of 180 m3/h. To achieve thermal comfort at higher humidity level, DEC is coupled with commercial desiccant dehumidifier. However, due to desiccant regeneration by an electric heater in the dehumidifier, the overall power consumption of the whole system increases up to 1.95 kW. Two well-known indices coefficient of performance (CoP) and energy efficiency ratio (EER) are used to analyze the system performance. Experimental analysis revealed that CoP decreases with the increasing specific humidity of air, decreasing ambient temperature, and flowrate.

Study of synergy between photovoltaic, thermoelectric and direct evaporative cooling system for improved performance

In case of photovoltaic (PV) most of the solar energy gets dissipated in the form of heat into the PV module. In the current context, efforts are made to improve the efficiency by utilizing this dissipated heat. One of the ways is to use low temperature thermoelectric (TE), based on the Seebeck effect, along with the PV cell. The mathematical model studied for performance evaluation, using ANSYS software, was based on cascaded hybrid Photovoltaic-Thermoelectric-Direct Evaporative Cooling System (PV-TE-EC) combinations, i.e. PV-EC (without TE), PV-TE-EC, PV-2TE-EC (two cascaded layers of TE sandwiched between PV and EC) and PV-3TE-EC (module with three cascaded TE layers) modules. Also, the effect of solar concentration ratio, temperature coefficient and wind speed was investigated. At concentration ratio 7, the resultant efficiencies of PV-TE-EC, PV-2TE-EC and PV-3TE-EC were higher than PV (15.71%) by 2.15, 4.87 and 6.54% respectively. It has been proposed that this efficiency can be further increased by using low temperature coefficient PV (0.34–0.38%/⁰C), radiation focusing unit with concentration ratio 3 to 7 and keeping the complete PV-3TE-EC setup at the lower wind speed location (≤1 m/s). This combination of parameters will allow the PV-3TE-EC hybrid system to demonstrate nearly constant efficiency throughout the day.

Performance Evaluation of Truck Equipped with the Evaporative Cooling System during Transportation of Vegetable

The research describes the development of an evaporative cooling system in a non-refrigerated truck for the short-term storage of vegetables during transportation. The system comprises an evaporative cooler, storage unit, power supply, control panel, and real-time data monitoring for temperature and relative humidity. Computational fluid dynamic (CFD) simulation was conducted to investigate the temperature and airflow distributions in the evaporative-cooled storage unit for five different configurations of air inlet and outlet. The configuration of one air inlet (front — lower left) and two air outlets (top — front and back centre) of the storage unit was shown to provide optimum temperature and airflow distributions and hence, was applied in the system modification. The functionality and performance of the modified system were then evaluated in terms of the cooling profile of the storage units and leafy vegetable quality for the fresh market. Three storage treatments for the selected vegetable were investigated, i.e., evaporative-cooled truck (T1), canvas truck (T2), and cold truck (T3) during a five-hour journey from Cameron Highlands to Serdang. The average temperature inside the storage units was T3 < T1 < T2. Evaporative-cooled truck exhibited an average temperature reduction (DT) of 10°C from the ambient condition. It also demonstrated a relative humidity of >90%, which was in agreement with the recommended relative humidity for leafy vegetable storage. Post-five-hour storage treatments, vegetable stored under T1 exhibited the least weight loss as compared to T2 and T3. The results indicated that the evaporative cooling system manages to preserve vegetable quality soon after harvesting, hence the potential to reduce postharvest loss during transportation.

Performance Analysis of Gas Turbine Inlet Air Cooling Plant with Hybrid Indirect Evaporative Cooling and Absorption Chiller System

To generate electricity, Gas Turbine Power Plants are extensively used around the world but their efficiency is negatively affected on hot days by ambient air temperatures. efficiency and output power will decrease by 2% and 12.5% respectively at ambient temperature 40°C due to lower air density and the resulting increase in compressor specific work. 
 Ordinarily, cooling down the intake air of the gas turbine is facilitated by employing a variety of Turbine Inlet Air cooling Systems (TIACSs), depending on the plant’s immediate weather conditions. This paper studies a new hybrid cooling method, combined cooling systems (IECS + Absorption Chiller), used for a 157 MW gas power plant located in Asalouyeh in southern Iran. The Performance and Thermo-Economic analysis revealed that the annual power output can be 62,090 MW, the net income generated by the increased electricity sales can be $ 3,670,000 for a 60% period of the year while Payback Period is found to be 1.56 years.

PENERAPAN WIRELESS COMUNICATION HC-05 PADA MODEL KENDALI ECOSYSTEM (EVAPORATIVE COOLER SYSTEM)

Abstract The interconnectedness of the times includes all aspects, one of which is the temperature of the earth which is getting warmer, the annual prediction of increasing by 1 ° to 1.5 ° Celsius. In addition, there are technological updates with ideas that are a daily necessity. Evaporative Cooler is a conventional air conditioner throughout the world with various types and types, DEC (Direct evaporative Cooler), for example works by converting sensible heat into latent heat, whose main circuit consists of an electric motor, swing cooler motor and 24V DC water pump, a actuator module used in the implementation of this system. The idea that came up was that not many people paid attention to the system its use. This research will apply one of the wireless communication, namely the Bluetooth HC-05 Module in the control model design using ECOSYSTEM (Evaporative Cooler System) where the input is integrated with an artificial application installed on a smartphone with Bluetooth devices in it with the android operating system so that it can communicate between systems. Focusing on the communication performance applied by the HC-05 with a 2.4GHz frequency as a receiver or sender of commands with a range of signal distances that can be given, equipped with an Arduino UNO ATMega328 microcontroller for core system controllers. Over-the-air communication model that does not require other media devices in the process of working. Measurement of the performance of the signal coverage is proven horizontally and vertically, intended because there is a difference in the capture power of the transceiver and receiver signals as well as the conditions when bluetooth is controlled, it is connected and not yet connected. In the test, bluetooth only captures two conditions when it is working, when it is still affordable, bluetooth will connect and remain connected with a delay of not more than 0.02 seconds or not connected at all when the range is getting farther.

Experimental Investigation of Solar based Liquid Desiccant Indirect Evaporative Cooling system

ABSTRACT Air conditioning by using vapor compression cycle is the most commonly used system although its operating energy cost is significantly high. Liquid desiccant dehumidifier with Indirect Evaporative Cooling (IEC) is another alternative suitable for hot and humid climatic conditions. The system works in two parts. In liquid desiccant dehumidifier section, moisture from humid air is removed and such air is passed through Indirect Evaporative Cooling system where air is cooled. An attempt was made to set up an experimental module with Scheffler solar concentrator to provide thermal energy for evaporation of liquid desiccant while a new type of polymer plate exchanger was used in evaporative cooling section instead of commonly used metal heat exchanger. The experimentation was carried using CaCl2 desiccant with varying flow rates between 2 and 4 l/min in dehumidifier section and reduction of relative humidity by 4 to 9% was achieved. As desiccant flow rate was increased, it resulted into higher carry over losses. Experimentally, it was found that for a flow rate of 3 l/min, the carry over losses are minimum. For this flow rate of desiccant, secondary-to-primary-air ratio of 0.8, water flow rate of 11 l/min, and air cooling by 4.7°C were achieved. Maximum wet bulb and dew point effectiveness were found to be 0.61 and 0.42, respectively, for secondary-to-primary-air ratio of 0.8. It could be concluded that a polymer plate heat exchanger-based system could be considered as efficient system than metal plate heat exchanger systems, because longer life, lighter weight, and low operating cost are the characteristics of polymers.

Artificial Intelligence for the Prediction of the Thermal Performance of Evaporative Cooling Systems

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.

Analysis of the Performance of a Passive Downdraught Evaporative Cooling System Driven by Solar Chimneys in a Residential Building by Using an Experimentally Validated TRNSYS Model

Natural ventilation, combined with a passive cooling system, can provide significant energy savings in the refrigeration of indoor spaces. The performance of these systems is highly dependent on outdoor climatic conditions. The objective of this study was to analyse the feasibility of a passive, downdraught, evaporative cooling system driven by solar chimneys in different climatic zones by using an experimentally validated simulation tool. This tool combined a ventilation model and a thermal model of the dwelling in which an empirical model of a direct evaporative system made of plastic mesh was implemented. For experimental validation of the combined model, sensors were installed in the dwelling and calibrated in the laboratory. The combined model was applied to Spanish and European cities with different climates. In the simulation, values of cooling energy per volume of air ranging between 0.53 Wh/m3 and 0.79 Wh/m3 were obtained for Alicante (hot climate with moderate humidity) and Madrid (hot and dry climate), respectively. In these locations, medium and high applicability was obtained, respectively, in comparison with Burgos (cold climate with moderate humidity) and Bilbao (cold and humid climate), which were low. The evaluation of the reference building in each location allowed establishing a classification in terms of performance, comfort and applicability for each climate.

Heat and Mass Transfer in Open Evaporative Cooling System Using Various Types of Fills In Oil Industry

This research work is to study the performance of evaporative cooling system using new type of packing with different shapes (saddle, counter current wavy, and triangular splash) and materials (glass, thermoplastic, and resistance wood) of packing for an air –water cooling system . The basis of the installation is the evaporative cooling system,1.75 m height and 40 x 40 cm outside cross section. The fluids in this system are air which moving from the bottom to the top of cooling system (mass flow rates ranging between 0.07 and 0.18 kg/s) and the water which are moving from top to bottom of cooling evaporator ((mass flow rates ranging between 0.11 and 0.27kg/s)). The inlet water temperatures ranging
 between 35 and 55oC .The packing heights were changed during the research in order to get the temperature profile and the relation of these temperatures with the other variables in the cooling system, the packing heights ranging between 35 to 140 cm. The overall volumetric heat and mass transfer coefficients and tower characteristics, were predicted as a function of the fluids flow rates.
 A computer program used to solve and find the relation between the variables in the system and the functions (overall volumetric heat and mass transfer coefficients, number of transfer coefficient, the temperature variation along the tower).
 
 
 The results show that :
 1-At maximum air mass flow and
 minimum water mass flow, the
 mass transfer coefficients would
 be on the maximum value and
 vice-versa.
 2- The thermoplastic packing was
 much more efficient than glass
 and wood by efficiency about 12
 to 18 %. ,also the results showed
 that The triangular packing was
 much more efficient than wavy
 and glass by efficiency about 5 to
 11 %.
 3-The temperatures distribution
 were not constant in all layers; the temperatures distribution in the first layer were not very well, this happened because the distribution of water in the packing surface was just know happened, while in the other layers the temperature distrib-ution and profile were so good.

Design and Energy Analysis of a Solar Desiccant Evaporative Cooling System with Built-In Daily Energy Storage

Heat storage with thermochemical (TC) materials is a promising technology for solar energy storage. In this paper, a solar-driven desiccant evaporative cooling (DEC) system for air-conditioning is proposed, which converts solar heat energy into cooling with built-in daily storage. The system utilises thermochemical heat storage along with the DEC technology in a unique way. Magnesium Chloride (MgCl2·6H2O) has been used, which serves as both a desiccant and a thermochemical heat storage medium. The system has been designed for the subtropical climate of Lahore, Pakistan, for a bedroom with 8 h of cooling requirements during the night. MATLAB has been employed for modelling the system. The simulation results show that 57 kg of magnesium chloride is sufficient to meet 98.8% of cooling demand for the entire month of July at an elevated cooling requirement. It was found that the cooling output of the system increased with increasing heat exchanger effectiveness. The heat exchangers’ effectiveness was increased from 0.7 to 0.8, with the solar fraction increased from 70.4% to 82.44%. The cooled air supplied to the building meets the fresh air requirements for proper ventilation.

Research on Resistance Characteristics of the Self-circulating Evaporative Cooling System for Traction Transformer

Compared with the tradition cooling technology, the evaporative cooling technology has the advantage of energy-saving, safety and reliability. So a self-circulating evaporative cooling structure was proposed. The narrow flow channels were designed between disk-type windings. The evaporative coolant flows in the narrow flow channels and takes away the heat loss through phase transition. In this paper the resistance characteristics of the system were studied through experiment based on the 900kVA transformer prototype.

Experimental Investigation of Thermal Performance of Aluminum Foil Coated with Polyester in a Direct Evaporative Cooling System

An experimental study was carried out for an evaporative cooling system in order to investigate the effect of using an aluminum pad coated with fabric polyester. In the present work, it was considered to use a new different type of cooling medium and test its performance during the change in the wet-bulb temperature and dry-bulb temperature of the supply air outside of the pad, the relative humidity of the supply air, the amount of air supplied (300-600) CFM and also the change of the amount of circulated water (1.75, 2.5, 4.5) liter per minute. A decrease in the WBT of the air was obtained, whereas the WBT of the air entering the pad was 26.5 . In contrast, the WBT of the outside air had reached 23 even though evaporative cooling is an adiabatic process which makes the WBT of the air that comes out of the pad is equal to the entering air WBT. The decrease in DBT is by changing the amount of air and water passing through the aluminum pad, whereas the DBT of the air entering the pad was 45 , while the DBT of the outside air had reached 29 . Also, an essential thing was obtained as this rise in the relative humidity of the air is very small 57%RH compared to the conventional pads, and this gives a positive impression as the air supplied from this pad has less moisture and its ability to carry moisture is much higher than that of air supplied from other pads. This gives a positive impression because the air supplied from this pad has lower humidity and its ability to hold moisture much higher than the air supplied from other traditional pads.

Numerical Investigation of a Novel Plate-Fin Indirect Evaporative Cooling System Considering Condensation

An indirect evaporative cooling system combining with thermoelectric cooling technology (i.e., TIEC system) is proposed, in which a counter-flow plate-fin indirect evaporative cooler is inserted with thermoelectric cooling (i.e., TEC) modules. In hot and humid climate, condensation may occur on the dry channel surface of the cooler. For the TIEC system, with the aid of TEC technology, the surface temperature of the dry channel can be much lower than that of a traditional indirect evaporative cooler, thus, the condensation from the primary air is more likely to take place. A numerical model of this novel TIEC system is developed with specifically taking condensation from primary air into account. Detailed performance analysis of the TIEC system is carried out. Analytical results found that the condensation from primary air reduces the dew point effectiveness by up to 45.0% by weakening the sensible heat transfer but increases the coefficient of performance by up to 62.2% by increasing the latent heat transfer, under given conditions. The effects of main operating conditions, such as the electrical current I and number n of TEC modules, inlet temperature Tp,i, humidity ratio RHp and velocity Vp of the primary air, and the mass flow rate ratio x of secondary to primary air, are investigated under non-condensation and condensation states. It is shown that condensate is more easily produced under higher I, n, Tp,i, RHp, x and lower Vp.

An Overview of Different Indirect and Semi-Indirect Evaporative Cooling System for Study Potency of Nanopore Skinless Bamboo as An Evaporative Cooling New Porous Material

The high energy consumption of compressor based cooling system has prompted the researchers to study and develop non-compressor based cooling system that less energy consumption, less environment damaging but still has high enough cooling performances. Indirect and semi indirect evaporative cooling system is the feasible non-compressor based cooling systems that can reach the cooling performance required. This two evaporative cooling system has some different in construction, porous material used, airflow scheme and secondary air cooling method used for various applications. This paper would report the cooling performances achieved by those two cooling system in terms of cooling efficiency, cooling capacity, wet bulb effectiveness, dew point effectiveness, and temperature drop. Porous material used in indirect and semi-indirect evaporative cooling would be highlighted in terms of their type, size, thickness and any other feature. The introduction of nanopore skinless bamboo potency as a new porous material for either indirect or semi-indirect evaporative cooling would be described. In the future study of nanopore skinless bamboo, a surface morphology and several hygrothermal test including sorption, water vapor transmission, thermal conductivity test would be applied, before it utilize as a new porous material for direct or semi indirect evaporative cooling.

CFD Analysis of Earth Air Heat Exchanger (EAHE) for Storage System Using With Evaporative Cooling System

CFD Analysis of Earth Air Heat Exchanger (EAHE) for Storage System Using With Evaporative Cooling System

Research on the Temperature Distribution of the Hollow Conductors in the Self-circulating Evaporative Inner Cooling System for High Power Rectifier Equipment

In the evaporative inner cooling system for high power rectifier equipment, the thyristor and quick fuse are both cooled double-sided via hollow conductors. Different from the previous study on the system with single structure, the self-circulating system for high power rectifier equipment has composite structure. Then the system with composite structure may show different heat transfer characteristics. So in this paper, the temperature distribution of the horizontal and vertical hollow conductors in the self-circulating system was studied through theoretical analysis and simulation.

Thermodynamic Process Simulation and Evaluation on Surface-Mounted Evaporative Cooling System

The change of exergy has a direct impact on the circulation head of the surface-mounted evaporative cooling system that relies on the change of vapor-liquid density for circulating cooling. In this paper, the circulation system of the surface-mounted evaporative cooling system is taken as the research object. Based on the second law of thermodynamics, an exergy analysis model of main equipment is established to analyze and evaluate the characteristics of exergy change of the system. The research results show that under different thermal loads, the exergy efficiency is less than 70%, the exergy loss in the liquid box is relatively large, and the main irreversible exergy loss in liquid box occurs in the vapor-liquid boiling process, which will restrict the cooling capacity of the system. This study provides a theoretical basis for further optimizing the flow heat transfer process of the surface-mounted evaporative cooling system.

Performance Assessment of Solar Cooling Systems with Energy Storage

The paper presents a complete solar cooling comparison. A detailed model of a tertiary sector building has been evaluated in three locations (Riyadh, Abu Dhabi, and Palermo) and coupled with four solar cooling systems: two solar thermal cooling systems (Li-Br absorption chiller and adsorption chiller), a solar Desiccant Evaporative Cooling system and a solar electric cooling (Photovoltaic coupled with Compression chiller). A multi-variable optimization procedure selects the optimal size of each component. The results show that the solar cooling system based on absorption chiller satisfied the cooling demand regardless of the site location whilst the performance of the Desiccant Evaporative Cooling system is dramatically affected by ambient conditions. The electric solar cooling option shows the best overall efficiency and appears a costeffective solution despite the high cost of the storage system.