Study also shows that in india larger parts of the central and northern regions. Evaporative cooling an overview sciencedirect topics. Analysis and evaluation of a passive evaporative cool. When evaporative processes are used to cool an element of the building, which then acts as a heat sink, this is known as indirect evaporative cooling. Schiano 2004 mentioned that porous pottery and clay jars were used for cooling in a system called muscatese evaporative cooling system. During the last century evaporative cooling was reused for cooling in hot arid climates. The experiences presented in this paper were selected according to the most relevant passive solutions for buildings, in particular. Passive downdraught evaporative cooling request pdf. Evaporative cooling is the most economical concept for cooling of a building. Click download or read online button to get passive cooling of buildings book now. Request pdf passive downdraught evaporative cooling this is the second in a series of four papers that describe a 3year eufunded research project into the application of passive downdraught. Water can absorb a lot of heat without changing phases, allowing it to remove heat. Shading devices abstract passive design responds to local climate and site conditions in order to maximise the comfort and health of building users while minimising energy use. Passive cooling addresses all of the existing creative energyless means of keeping buildings cool.
One of the most interesting charts is the psychrometric chart with overlays that show the design strategies e. Combination of evaporative cooling and wind tower for passive cooling. Unlike passive heating, which draws on the sun, passive cooling relies on three natural heat sinks the sky, the atmosphere, and the earth to achieve temperature moderation. A cool tower is a perfect answer for cooling a renewable energy powered dwelling. International conference passive and low energy cooling. Passive radiative cooling below ambient air temperature under. Sources of passive cooling are more varied and complex than passive heating, which comes from a single, predictable source solar radiation.
Elmasry uae university, united arab emirates abstract ongoing development in many parts of the united arab emirates has consequences on the urban environment. Experience on passive cooling techniques for buildings. Passive downdraught evaporative cooling pdec is one of the proven alternatives to conventional cooling as its operation requires low amounts of energy with significant reduction in co2 emissions when compared with conventional airconditioners 2. Passive cooling technologies in buildings are a critical issue in that they enhance the. A passive evaporative cooling system by natural ventilation. However, active and passive cooling strategies have not been adequately examined in a. Passive cooling techniques are closely linked to the thermal comfort of the occupants, and it is possible to achieve this comfort by reducing the heat gains, thermal moderation and removing the internal heat. Refer to figure 5 for a schematic view of an indirect evaporative cooling section located upstream of a direct eac. Passive down draft evaporative cooling pdec systems, which have a certain type of evaporative devices such as porous medium and spray, have been developed and integrated with buildings in an attempt to improve the cooling capacity of wind towers. Passive cooling methods for energy efficient buildings. A more sophisticated approach was to take advantage of evaporative cooling by running water through the structure, as done in the alhambra castle.
Modern systems combine the evaporation effects with the movement of the cooled air. Evaporative cooling is based on the thermodynamics of evaporation of water, i. The systems design was based upon the humidifying capacity of an ultrasonic humidifier supplied by a quebec company, plastique frapa inc. Passive downdraught evaporative cooling pdec origin. Using passive cooling strategies to improve thermal. When warm, dry unsaturated air is pulled through a watersoaked pad, water is evaporated and is absorbed as water vapor into the air.
In 1905,200 btumin or 12,000btuh was established as 1 ton of refrigeration, and in 1902 a 400ton airconditioning system was installed in. Passive downdraught evaporative cooling applied to an. Air cooling systemsfor thermal comfort were built in the 1890s, but they did not find widespread use until the development of mechanical refrigeration in the early 1900s. While several different types of this particular system exist, pdec tower with spray was studied in that it is flexible, efficient, and prevalent.
This can happen naturally passive evaporative cooling or. When a body of water is placed in a hot and relatively dry space, the water evaporates into the air and increases humidity. Review of passive heatingcooling systems of buildings. In indirect evaporative cooling, evaporation occurs inside a heat exchanger and the water content of the cooled air remains unchanged. P193 passive cooling techniques for buildings asiepi wp7.
While several different types of this particular system exist, pdec tower with spray was studied in. An overview of passive cooling techniques in buildings. Pdf analysis and evaluation of a passive evaporative. Nov 05, 2016 passive cooling is a nonmechanical means of cooling homes, using an approach to building design that controls the heat entering the structure and encourages its dissipation. Santamouris 2007 evaporative cooling was used and commercialized in desert coolers since 1920.
Green material prospects for passive evaporative cooling. For passive heating cooling, combination of trombe wall, cool roof, and thermal insulation can achieve 46% and 80% of savings in winters and summers, respectively. For steam humidifiers, this energy typically comes from the electricity or gas being used to boil the water. The earliest methods of space cooling during dry season was discussed by bahadori in 1978 6 and the summary of the stateoftheart of passive cooling systems was provided by givoni in 1991 7.
Evaporative cooling has been applied in various forms for several centuries in different parts of the world, particularly in the middle east where various techniques have been employed over time to encourage air movement and cooling in buildings. It introduces an overview of pdec towers and existing models. In direct evaporative cooling, the water content of the cooled air increases because air is in contact with the evaporated water. The use of glazed facades in modern buildings has come with an increased operational cost due to the higher solar gain. Direct and indirect evaporative cooling strategies.
Passive cooling systems use nonmechanical methods to maintain a comfortable indoor temperature and are a key factor in mitigating the impact of buildings on the environment. Evaporative cooling differs from typical air conditioning systems, which use vaporcompression or absorption refrigeration cycles. The concept of evaporative cooling came from the sweating of our bodies. Integrating passive cooling techniques for sustainable. A number of studies have been carried out on the passive cooling of the outer surface of buildings for the purpose of conserving energy without.
Analysis and evaluation of a passive evaporative cool tower in conjunction with a solar chimney. Evaporative cooling practical action 3 any part of the country using locally available materials. To evaporate 1kg of water into an atmosphere, 680w of energy is required. Evaporative cooling applies to all processes in which the sensible heat in an air stream is exchanged for. The basic structure of the cooling chamber can be built from bricks and river sand, with a cover made from cane or other plant material and sacks or cloth.
Passive cooling an alternative to expensive cooling systems. Passive cooling and heating methods within buildings are studied a lot nowadays. Evaporative cooling is a process which takes advantage of the latent heat of evaporation of water to absorb sensible heat from the surrounding air with which it is in contact. The key to designing a passive building is to take best advantage of the local climate. Comfort cooling was obtained by ice or by chillers that used ice. Passive cooling refers to any technologies or design. Bipvt system for thermal heating and electricity production. Passive cooling techniques can reduce the peak cooling load in buildings, thus reducing the size of. Green material prospects for passive evaporative cooling systems. This paper discusses the development of a new module in energyplus that predicts the cooling performance of pdec towers with sprays.
These components are a modified form of wind towers. In order to extend the use of evaporative cooling, a downdraft evaporative cool tower was. Varying combinations of innovative envelope design, air movement, evaporative cooling, earthcoupled thermal mass, lifestyle choices and acclimatisation are required to provide adequate cooling comfort. Course contents evaporative coolers, often called swamp coolers, are cooling systems that use only water and a blower to circulate air. An evaporative cooler also swamp cooler, swamp box, desert cooler and wet air cooler is a device that cools air through the evaporation of water. The first is a brief overview of the processes of natural cooling and the design techniques that are.
It is a concept that reduces the need for energyintensive systems like airconditioning, focusing not only on the architectural design of the building, but also the. Koenigsbergers manual of tropical housing and building, part one. Passive cooling of buildings download ebook pdf, epub. Small droplets of pressurised water can be sprayed into the incoming ambient air at the top of a cooling tower. The air supplied into a conditioned room by the main supply fan is called the primary air stream. When combined with other passive design techniques, adequate thermal comfort might be achieved without air conditioning. Purushothama, in humidification and ventilation management. Direct evaporative cooling is advisable only where and when the wet bulb temperature. Evaporative cooling is a very powerful method of passive cooling that can easily compete with conventional air conditioners in consciously designed buildings santamouris and asimakopolous, 1996. A passive downdraft evaporative cooling pdec tower is a component that is designed to capture the wind at the top of a tower and cool the outdoor air using water evaporation.
The rate of evaporative cooling is a function of both humidity and air movement. This example is of the qaa of muhib addin ashshaf i almuwaqqi, iran a. Passive downdraught evaporative cooling can also be used in hot dry climates to improve the natural ventilation of buildings by encouraging the convection of air downwards. Pdf analysis and evaluation of a passive evaporative cool. This phase change requires energy, which is called latent heat of evaporation this is the energy required to change a substance from liquid phase to the gaseous one without temperature change. Introduction passive down draft evaporative cooling pdec is a representative term that is defined as a passive and low energy technique for cooling and ventilating spaces in hot, dry climates bowman et al. The only power required is for a small dc pump to circulate water over the cooler pads or a mister.
A passive downdraft evaporative cooling pdec tower is a component that is designed. Passive evaporative cooling is one of the most efficient and long recognized ways of inducing thermal comfort in predominantly hot and arid climates. Passive evaporative cool tower study asu stardust center. For passive heatingcooling, combination of trombe wall, cool roof, and thermal insulation can achieve 46% and 80% of savings in winters and summers, respectively. Passive downdraught evaporative cooling applied to an auditorium. Pdec, evaporative cooling, energy efficient, stack effect. Evaporative cooling is a passive technique 5 that is not only applicable to regions with multiple climatic situations, such as those with hot and dry climate, but also to regions with moderate climate 6. Passive radiative cooling below ambient air temperature. It does not require any blowers or fans to move the cool air. The first is a brief overview of the processes of natural cooling and the design techniques that are being put to use in practice today. In summary, evaporative cooling is the process of removing heat from a surface due to the evaporation of water. A simulation model is employed to design and evaluate. Advances in the application of passive downdraft evaporative.
Passive radiative cooling below ambient air temperature under direct sunlight aaswath p. This site is like a library, use search box in the widget to get ebook that you want. A study on passive cooling methods by evaporation and solar. Passive cooling is a key element of a larger strategy known as natural conditioning heating, cooling, ventilating and lighting a building naturally, that is, without mechanical or electronic. Evaporative cooling can also be passive and indirect, by providing a shaded water pond over an uninsulated roof. Pdf this paper introduces a new method waterretaining roof brick to reduce the energy cooling load in meeting peoples comfort demands in hot. Evaporative cooling uses the fact that water will absorb a relatively large amount of heat in order to evaporate.