scholarly journals A Study on Thermal Effectiveness of Multi-Stages Evaporative Air Cooling

2020 ◽  
Vol 8 (2) ◽  
pp. 1-14
Author(s):  
Alaa R. Al-Badri ◽  
Zahraa Mohsin Farhan
Keyword(s):  
Air Temperature ◽  
System Performance ◽  
Air Conditioning ◽  
Evaporative Cooling ◽  
Experimental Tests ◽  
Weather Conditions ◽  
Air Cooling ◽  
Air Velocity ◽  
Cooling Systems ◽  
Continuous Increase

The air conditioning system performance is significantly affected by temperature rise which causes continuous increase in electricity consumption and pollution problems to environment. Evaporative cooling systems are characterized by their low energy consumption so that they represent successful potential alternatives to traditional vapor compression air conditioning systems. This study investigates the performance of multi-stages evaporative cooling systems experimentally and theoretically. The experimental set-up is mainly composed of two parts: indirect unit to decrease the air temperature and direct unit to moisturize the air. The system is installed and equipped with temperatures, humidity, and air velocity sensors. The experimental tests were run continuously to monitor the system performance at various weather conditions between  to  in June and July months. A mathematical model for the system components was developed and implemented in the Engineering Equation Solver (EES) program to simulate the performance of multi-stages evaporative cooling systems. The results showed that the heat flux  increases with the increase in the Reynolds number Re of inlet air, velocity fraction  extracted air for sensible cooling, air temperature at the product-in , air velocity at the product-in , and the adiabatic efficiency . But, it is decreasing with increasing the spacing between the heat exchanger plates  and the relative humidity at the product-in . Optimum performance was obtained with very small space between plates which was bout 5mm. Good agreement have been shown between experimental and predicted data, where the  results. Uncertainty of experimental data was within the range 4.14 to 6.15.

Systematic Assessment of Combustion Turbine Inlet Air-Cooling Techniques

2005 ◽  
Vol 127 (1) ◽  
pp. 159-169 ◽  
Author(s):  
Abdalla M. Al-Amiri ◽  
Montaser M. Zamzam
Keyword(s):  
Air Temperature ◽  
Evaporative Cooling ◽  
Heat Rate ◽  
Climatic Conditions ◽  
Coefficient Of Performance ◽  
Air Cooling ◽  
Cooling Systems ◽  
Turbine Inlet ◽  
Wide Range ◽  
The Impact

The current study is centered on assessing the benefits of incorporating combustion turbine inlet air-cooling systems into a reference combustion turbine plant, which is based on a simple cycle under base load mode. Actual climatic conditions of a selected site were examined thoroughly to identify the different governing weather patterns. The main performance characteristics of both refrigerative and evaporative cooling systems were explored by examining the effect of several parameters including inlet air temperature, airflow-to-turbine output ratio, coefficient of performance (for refrigerative cooling systems), and evaporative degree hours (for evaporative cooling systems). The impact of these parameters was presented against the annual gross energy increase, average heat rate reduction, cooling load requirements and net power increase. Finally, a feasibility design chart was constructed to outline the economic returns of employing a refrigerative cooling unit against different prescribed inlet air temperature values using a wide range of combustion turbine mass flow rates.

Use of a membrane module for semi-direct air evaporative cooling

2019 ◽  
Vol 29 (10) ◽  
pp. 1346-1358 ◽  
Author(s):  
Sebastian Englart
Keyword(s):  
Moisture Content ◽  
Relative Error ◽  
Air Temperature ◽  
Evaporative Cooling ◽  
Cross Flow ◽  
Membrane Module ◽  
Transfer Model ◽  
Air Cooling ◽  
Heating Efficiency ◽  
Circulating Water

This study discusses the use of a membrane module for semi-direct evaporative air cooling. A cross-flow membrane module was used to carry out this air treatment process. For such a flow, it was proposed to describe and solve the heat and mass transfer model as a one-dimensional problem. The mathematical model was used to determine the moisture content and air temperature at the outlet from the module and the temperature of the circulating water. Results obtained using the proposed model are in good agreement with the experimental data. The relative error for the air temperature at the module outlet did not exceed 0.5%. For the moisture content, the relative error did not exceed 4%. For the circulating water temperature, the relative error did not exceed 0.6%. This paper also discusses the heating efficiency of the evaporative cooling process. Methods for determining the unit cooling indicator and the energy efficiency ratio are also proposed.

scholarly journals Performance Characteristics of Solid-Desiccant Evaporative Cooling Systems

Energies ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2574 ◽  
Author(s):  
Ramadas Narayanan ◽  
Edward Halawa ◽  
Sanjeev Jain
Keyword(s):  
Air Conditioning ◽  
Natural Ventilation ◽  
Waste Heat ◽  
Numerical Study ◽  
Evaporative Cooling ◽  
Peak Load ◽  
Dew Point ◽  
Low Grade ◽  
Subtropical Climate ◽  
Cooling Systems

Air conditioning accounts for up to 50% of energy use in buildings. Increased air-conditioning-system installations not only increase total energy consumption but also raise peak load demand. Desiccant evaporative cooling systems use low-grade thermal energy, such as solar energy and waste heat, instead of electricity to provide thermal comfort. This system can potentially lead to significant energy saving, reduction in carbon emissions, and it has a low dew-point operation and large capacity range. Their light weight, simplicity of design, and close-to-atmospheric operation make them easy to maintain. This paper evaluates the applicability of this technology to the climatic conditions of Brisbane, Queensland, Australia, specifically for the residential sector. Given the subtropical climate of Brisbane, where humidity levels are not excessively high during cooling periods, the numerical study shows that such a system can be a potential alternative to conventional compression-based air-conditioning systems. Nevertheless, the installation of such a system in Brisbane’s climate zone requires careful design, proper selection of components, and a cheap heat source for regeneration. The paper also discusses the economy-cycle options for this system in such a climate and compares its effectiveness to natural ventilation.

scholarly journals Calculation of Water Evaporative Cooling Systems in Animal Husbandry

2020 ◽  
pp. 35-38
Author(s):  
N.N. Novikov ◽  
Keyword(s):  
Air Conditioning ◽  
Evaporation Rate ◽  
Evaporative Cooling ◽  
Animal Husbandry ◽  
Water Evaporation ◽  
Cooling Systems ◽  
Temperature And Humidity ◽  
Hot Weather ◽  
Livestock Building ◽  
Air Exchange

A method for calculating the parameters of the microclimate in a livestock building using water-evaporative air conditioning is described. It makes it possible to choose a rational temperature and humidity conditions for a room in hot weather, calculate the required air exchange, water evaporation rate and select the appropriate equipment.

The Use of Ejector Refrigeration Systems for Turbine Inlet Air Cooling: A Thermodynamic and CFD Study

2007 ◽  
Author(s):  
Hany A. Al-Ansary
Keyword(s):  
Power Consumption ◽  
Power Output ◽  
Waste Heat ◽  
Evaporative Cooling ◽  
Published Data ◽  
Air Cooling ◽  
Refrigeration System ◽  
Compressor Blades ◽  
Cooling Systems ◽  
Turbine Inlet

Cooling turbine inlet air is a proven method of increasing turbine power output, especially during peak summer demand. It is estimated that turbine power output can increase by as much as 0.7% for every 1°C drop in inlet air temperature. Two inlet air cooling systems are widely used: evaporative cooling systems and chiller systems. Evaporative cooling is economical and uncomplicated, but its efficiency can significantly drop if the relative humidity is high. There is also a potential for excessive wear of compressor blades if water droplets are carried into the compressor section. On the other hand, chiller systems have the advantage of being independent of humidity and do not have the potential to cause damage to compressor blades. However, chiller systems consume power and cause a larger pressure drop than evaporative coolers. In this work, the possibility of using an ejector refrigeration system to cool turbine inlet air is explored. These systems are low-maintenance, fluid-driven, heat-operated devices that can use part of the turbine exhaust flow as the heat source for running the cycle. These systems require only pump power to feed liquid refrigerant to the vapor generator, making the power consumption potentially lower than conventional chiller systems. Using thermodynamic analysis, this paper compares the performance of ejector refrigeration systems with that of chiller systems based primarily on their power consumption. Performance characteristics for the ejector system are obtained through a CFD model that uses a real-gas model for R-134a. Published data on the performance of a commercial gas turbine is also considered. The power consumption of ejector refrigeration systems is found to be significantly smaller than that of vapor compression systems, with savings ranging from 19% to 80%. Power consumption is also found to be small compared to the boost in turbine power that is obtained. The percentage of waste heat needed to operate the ejector refrigeration system is found to be generally less than 25%.

scholarly journals A MATHEMATICAL MODEL FOR DIRECT EVAPORATIVE COOLING AIR CONDITIONING SYSTEM

2003 ◽  
Vol 2 (2) ◽  
Author(s):  
J. R. Camargo ◽  
C. D. Ebinuma ◽  
S. Cardoso
Keyword(s):  
Mathematical Model ◽  
Air Conditioning ◽  
Cooling System ◽  
Convective Heat Transfer Coefficient ◽  
Evaporative Cooling ◽  
Experimental Tests ◽  
Water Evaporation ◽  
Human Thermal Comfort ◽  
Direct Evaporative Cooling ◽  
Evaporative Cooling System

Air conditioning systems are responsible for increasing men's work efficiency as well for his comfort, mainly in the warm periods of the year. Currently, the most used system is the mechanical vapor compression system. However, in many cases, evaporative cooling system can be an economical alternative to replace the conventional system, under several conditions, or as a pre-cooler in the conventional systems. It leads to a reduction in the operational cost, comparing with systems using only mechanical refrigeration. Evaporative cooling operates using induced processes of heat and mass transfer, where water and air are the working fluids. It consists in water evaporation, induced by the passage of an air flow, thus decreasing the air temperature. This paper presents the basic principles of the evaporative cooling process for human thermal comfort, the principles of operation for the direct evaporative cooling system and the mathematical development of the equations of thermal exchanges, allowing the determination of the effectiveness of saturation. It also presents some results of experimental tests in a direct evaporative cooler that take place in the Air Conditioning Laboratory at the University of Taubaté Mechanical Engineering Department, and the experimental results are used to determinate the convective heat transfer coefficient and to compare with the mathematical model.

scholarly journals Performance Enhancement of Split Air Conditioner During Evaporative Cooling Application

2021 ◽  
Vol 86 (2) ◽  
pp. 147-156
Author(s):  
Rahmat Iman Mainil ◽  
Ahmad Wisnu Sulaiman ◽  
Afdhal Kurniawan Mainil ◽  
Azridjal Aziz
Keyword(s):  
Air Temperature ◽  
Flow Rate ◽  
Air Conditioning ◽  
Evaporative Cooling ◽  
Water Flow Rate ◽  
Coefficient Of Performance ◽  
Air Conditioner ◽  
Discharge Water ◽  
Cooling Module ◽  
The Impact

The increase of condenser temperature and pressure in air-conditioning leads to decreased cooling capacity and the increase of power consumption. Evaporative cooling could improve the thermal performance of the system. In this study, the evaporative cooling module was installed before the condenser to reduce the inlet air temperature to the condenser unit. The impact of condenser air temperature on the air conditioning system's overall performance was determined by varying the cooling pad discharge water flowrate of 880, 1040, and 1200 mL/min. The cooling load of 2000 W was employed in this experiment. The obtained results were compared with the air conditioning without an evaporative cooling module. It shows that the coefficient of performance (COP) increases with the increase of discharge water flow rate. The highest COP obtained is 7.09 at the flow rate of 1200 mL/min. The compressor work reduces about 6.57 % as compared with the air conditioner without evaporative cooling application. Besides, the COP increases by 12. 95 % at the highest flow rate.

scholarly journals Passive evaporative cooling through water-filled bricks: a preliminary investigation

2021 ◽  
Vol 2069 (1) ◽  
pp. 012123
Author(s):  
A Tejero-González ◽  
F Nocera ◽  
V Costanzo ◽  
E Velasco-Gómez
Keyword(s):  
Energy Efficient ◽  
Air Conditioning ◽  
Current Knowledge ◽  
Preliminary Investigation ◽  
Evaporative Cooling ◽  
Passive Cooling ◽  
Air Velocity ◽  
Direct Evaporative Cooling ◽  
Geometric Arrangements ◽  
Hollow Bricks

Abstract Direct evaporative cooling is widely known to be an energy efficient air-conditioning option for arid and semi-arid climates. However, care must be taken on humidity ranges achieved indoors. Existing literature presents several options for integrating evaporative cooling within buildings for passive cooling applications. This work aims at expanding the current knowledge by focusing on the use of water-filled hollow bricks to implement evaporative cooling of air in contact with the brick’s surfaces. A prototype is built and experimentally characterized under controlled air velocity, air temperature and relative humidity conditions. Results on the psychrometric conditions achieved under different geometric arrangements (i.e., with one, two or three rows of four bricks each) are presented and discussed. Insights on likely building integration of the system for passive cooling purposes in farms and agriculture applications are eventually given.

Theoretical analysis of heat and mass transfer processes in an evaporative cooling system with zeolite desiccant powered by solar energy

2018 ◽  
Author(s):  
◽  
Amged Al Ezzi
Keyword(s):  
Water Vapor ◽  
Flat Plate ◽  
Air Temperature ◽  
Air Conditioning ◽  
Cooling System ◽  
Evaporative Cooling ◽  
Air Conditioning System ◽  
Coating Method ◽  
Evaporative Cooler ◽  
Desiccant Material

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] Concerns about energy sources depletion and environmental pollution issues have been raised and is a top priority of the global community. Refrigeration machines have been received the major of attention because of their energy consumption and pollution. Different from traditional cooling strategies, desiccant cooling technology (DCT) has been emergent as a promising alternative giving the fact that the economic-ecological air conditioning system is not restricted to hot and dry climates only. In the current experimental study, an advancement solar assisted desiccant cooling system (SADCS) is presented. The advantage is to use only a fraction of the energy of typical compressor-based cooling systems. The advancements have taken place into the dehumidification, evaporator, and regeneration sections. The role of appropriate choosing of the desiccant material type on the adsorption process has been presented, and a Faujasite (FAU) 13X zeolite is utilized in the dehumidification stage. A novel monolayer coating method has conducted. The new coating method has insured no external water vapor condensation ruins the desiccant material during relative humidity working range (20-97) %. Moreover, the new coating method allows to increase the performance of the adsorption and desorption processes, respectively. By giving the coming air stream the ability to pass through and surround the zeolite beads, accessibility to adsorb and desorb water vapor molecules is easier as more rooms are available. That clearly has been stated as 6450 g of zeolite holds 684 g of water in full saturation status within 37 minutes and regenerates by less than 120 [degree]C air temperature within 66 minutes. In the evaporative cooling section, an effective small compact evaporative cooler (CEC) system dealing only with product flow is introduced. The new CEC is utilized direct and indirect evaporation of water mechanisms combined in cross channels to cool air. Dropping air temperature by (5-7) [degree]C has recorded without desiccant stage. Supplying the required regeneration energy from a green energy source was essential in this study. For this purpose, an innovative flat plate double-mesh air solar collector has designed and carried out. In the new collector, a double copper mesh frames were fixing within a double Plexiglas covers flat plate collector. Experimental results show a good consistent with the mathematical model. With an average 0.71 solar fraction and 80 [degree]C exit air temperature, the collector presents 0.73 as thermal efficiency. As the improvements of the desiccant air-conditioning system turns out globally recognized by the progress in different research outcomes, designs, setting up and evaluation methods, it is expected that the system will be one of the most important alternative systems for the maintenance of human's environment comfort and air quality when considering the reduced dependence on conventional energy usage. Present work and results provide a reference data sets related to real adsorption dehumidification process and show that the advancement SADCS has a great potential in the future of the evaporative cooler systems.

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