A MATHEMATICAL MODEL FOR DIRECT EVAPORATIVE COOLING AIR CONDITIONING 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.

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Thermal analysis of a direct evaporative cooling system enhancement with desiccant dehumidification for vehicular air conditioning

Applied Thermal Engineering ◽

10.1016/j.applthermaleng.2015.12.059 ◽

2016 ◽

Vol 98 ◽

pp. 1273-1285 ◽

Cited By ~ 18

Author(s):

Ali Alahmer

Keyword(s):

Thermal Analysis ◽

Air Conditioning ◽

Cooling System ◽

Evaporative Cooling ◽

Direct Evaporative Cooling ◽

Evaporative Cooling System

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Energy - Saving Potential of Evaporative Cooling System for Building Application - A Review

International Journal for Research in Engineering Application & Management ◽

10.35291/2454-9150.2020.0247 ◽

2020 ◽

pp. 14-17

Keyword(s):

Air Conditioning ◽

Cooling System ◽

Evaporative Cooling ◽

Cooling Systems ◽

Energy Saving Potential ◽

The Earth ◽

Direct Evaporative Cooling ◽

Evaporative Cooling System ◽

Air Conditioning Systems ◽

Vapour Compression

The function of air conditioning systems has seen impressive development over the most recent couple of decades everywhere throughout the world, particularly in commercial buildings in ensuring the occupant thermal comfort. All the same, it is followed to have bad effects on the earth as well as increased power consumption in buildings. Hence, there has been extensive research to recognize options, in contrast to conventional vapour compression air conditioning systems. This account intends to review the ongoing improvements concerning evaporative cooling advancements that might give adequate cooling comfort, reduce environmental impact and lower energy consumption in buildings. Researches have done as on date in evaporative cooling systems centre predominantly around mainly on drawing down the dry bulb temperature of the incoming air. The theoretical efficiency of 100% can be achieved when the room dry bulb temperature is equal to the wet-bulb temperature of the outside atmospheric air. A wide literature review has been carried out and mapped out the best evaporative cooling systems. The review covers direct evaporative cooling, indirect evaporative cooling, and combined direct-indirect cooling systems.

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Experimental Investigation of a Direct Evaporative Cooling System for Year-Round Thermal Management with Solar-Assisted Dryer

International Journal of Photoenergy ◽

10.1155/2020/6698904 ◽

2020 ◽

Vol 2020 ◽

pp. 1-24

Author(s):

Sujatha Abaranji ◽

Karthik Panchabikesan ◽

Velraj Ramalingam

Keyword(s):

Experimental Investigation ◽

Energy Consumption ◽

Thermal Management ◽

Energy Efficient ◽

Cooling System ◽

Evaporative Cooling ◽

Water Evaporation ◽

Direct Evaporative Cooling ◽

Evaporative Cooling System ◽

Building Cooling

Building cooling is achieved by the extensive use of air conditioners. These mechanically driven devices provide thermal comfort by deteriorating the environment with increased energy consumption. To alleviate environmental degradation, the need for energy-efficient and eco-friendly systems for building cooling becomes essential. Evaporative cooling, a typical passive cooling technique, could meet the energy demand and global climatic issues. In conventional direct evaporative cooling, the sensible cooling of air is achieved by continuous water circulation over the cooling pad. Despite its simple operation, the problem of the pad material and water stagnation in the sump limits its usage. Moreover, the continuous pump operation increases the electrical energy consumption. In the present work, a porous material is used as the water storage medium eliminating the pump and sump. An experimental investigation is performed on the developed setup, and experiments are conducted for three different RH conditions (low, medium, and high) to assess the porous material’s ability as a cooling medium. Cooling capacity, effectiveness, and water evaporation rate are determined to evaluate the direct evaporative cooling system’s performance. The material that replaces the pump and sump is vermicompost due to its excellent water retention characteristics. There is no necessity to change material each time. However, the vermicompost is regenerated at the end of the experiment using a solar dryer. The passing of hot air over the vermicompost also avoids mould spores’ transmission, if any, present through the air. The results show that vermicompost produces an average temperature drop of 9.5°C during low RH conditions. Besides, vermicompost helps with the energy savings of 21.7% by eliminating the pump. Hence, vermicompost could be an alternate energy-efficient material to replace the pad-pump-sump of the conventional evaporative cooling system. Further, if this direct evaporative cooling system is integrated with solar-assisted drying of vermicompost, it is possible to provide a clean and sustainable indoor environment. This system could pave the way for year-round thermal management of building cooling applications with environmental safety.

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Feasibility of Reducing Electricity Consumption of Air Conditioning Equipment by Condenser Direct Evaporative Cooling Technology. Example of Case Study in Dubai

Atmosphere ◽

10.3390/atmos12091205 ◽

2021 ◽

Vol 12 (9) ◽

pp. 1205

Author(s):

Anatolijs Borodinecs ◽

Kristina Lebedeva ◽

Aleksejs Prozuments ◽

Arturs Brahmanis ◽

Aldis Grekis ◽

...

Keyword(s):

Air Conditioning ◽

Cooling System ◽

Evaporative Cooling ◽

Electricity Consumption ◽

Air Cooling ◽

Additional Energy ◽

Direct Evaporative Cooling ◽

Evaporative Cooling System ◽

Cooling Technology

The use of air conditioning technology is accompanied by an increase in electricity consumption, which is linked to an intensification of fossil fuel extraction. This in turn calls for developing cooling solutions of higher energy efficiency. The aim of this study is to examine energy consumption reduction of direct evaporative cooling technology for generating cool air in hot-dry climate regions. At the initial stage, already-installed air cooling equipment with a direct evaporative cooling system was studied for the creation of two regression models of electricity consumption representing the “on” and “off” sequences. Water consumption for system operation was taken into consideration. In the following stage, inlet water temperature dependence for pre-cooling purposes for the direct evaporative cooling system was studied. A mathematical model was developed and the subsequent calculations suggested that there is no need to pre-cool water before it enters the system and therefore consume additional energy. Practical application of this study is evaluated based on the case study in Dubai. The results of this study present significant energy saving potential for system operations of the direct evaporative cooling system of approximately 122 MWh per year. The return on investment for the equipment with direct evaporative cooling in case of an office building in Dubai featuring a hot desert climate is around 4.2 years. The purpose of this study is to examine the potential advantage of air cooling equipment with direct evaporative cooling technology compared to cooling equipment without this technology. The results provide the expediency of conducting further research in this area, in particular with regards to analyzing various materials for the adiabatic precooling pads, as well as the possibility of using a newly developed metal precooling pad.

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