Analysis of evaporative cooling system and recovery of. Principles and application of evaporative cooling systems for. Evaporative coolers use a quarter of the electricity of air conditioners and are relatively inexpensive. The direct stage is used for comfort cooling in a building where adding humidity to the air can be tolerated. Portable units are typically designed for cooling a single room, although largecapacity portable units are available. The most common type of air conditioner is the central cooling system. The indirect evaporative section also incorporates a scavenger fan to exhaust air through the pipes, a water distribution system which includes a water pump and spray nozzles to provide a uniform distribution over the entire heat exchanger, and a filter section to clean and maintain incoming air into the system.
Evaporative cooling is a heat and mass transfer process that uses water evaporation for air cooling, in which large amount of heat is transferred from air to water, and consequently the. As the air is passing through the pad, it is filtered and cooled as well as humidified. A cooling tower is a heatrejection device, which discharges warm air from the cooling tower to the atmosphere through the cooling of water. Evaporative coolers have been integrated into systems that use mechanical cooling to reduce or displace part of the annual refrigeration load. Evaporative cooling design guidelines ced engineering. Evaporative cooling systems use the same principle as perspiration to provide cooling for machinery and buildings. Todays evaporative cooling systems use up to 60% less electricity than comparably sized refrigerantbased ac systems. You can duplicate the principle behind direct evaporative cooling by wrapping a wet handkerchief around your neck on a hot day and standing in front of a fan. The results only focus on sensible cooling metrics. An evaporative cooler is a device that cools air through the evaporation of water.
Highpressure system first costs are generally higher than other adiabatic systems due, mostly, to the cost of adding water treatment cost. And remember, if ever you want to change your email preferences or unsubscribe, just click on the links at the. Data centre cooling requirements data centre cooling systems represent a signifi cant portion of a facilitys capital expenditure and use a substantial amount of energy. They are sometimes called air coolers, desert coolers or swamp coolers. Water can absorb a lot of heat without changing phases, allowing it to remove heat. Evaporative cooling is used around the world to keep birds cool during hot weather, but it is not a very effective method of reducing bird heat stress. Evaporative cooling definition of evaporative cooling by. Evaporative cooling capacity ranges from 6,000 cfm to over 100,000 cfm.
Consider provision for bleeds off valve to drain a fixed amount of water so that the. The design of an evaporative air cooling system is a balance between. The information contained within this section is geared towards the use of evaporative condensers in the hvac and light industrial markets only. These hvacs come factory assembled, prewired, and are self contained, packaged units. Iao systems also have less stringent filtration requirements that reduces both the static pressure loss of fans and maintenance requirements. Ashrae american society of heating, refrigerating, and airconditioning engineers publishes specifi c guidelines for temperature and humidity control within data centres. Biggest problem facing the indirect evaporative cooling iec technology lies in its high level of dependency to ambient air condition. Air ducts, ac coils, registers, grills, asbestos coverings, balancing of system, wiring and parts external to the unit, compressors or chillers, condenser casings, condenser coils, evaporator coils, metering systems txv valves, thermostats or thermostat wiring. Indirect evaporative cooling sensibly cools the air with use. Evaporative cooler types evaporative coolers cool boss. It is used in data center and large it facilities to provide air cooling conditioning services. Copies of the wiring diagram, piping diagram and bill of material are included with each unit shipped.
Evaporative cooling differs from typical air conditioning systems, which use. W hen water evaporates from the surface of something, that surface becomes much cooler because it requires heat to change the liquid into a vapor. Requiring low energy input, evaporative cooling is ideally suited for applications where reducing high temperatures and saving energy consumption is a. In summary, evaporative cooling is the process of removing heat from a surface due to the evaporation of water.
Applied air offers direct evaporative cooling equipment with air deliveries from 3,000 cfm to 64,000 cfm and indirect or indirectdirect evaporative cooling. What is the difference between direct and indirect. Custom manufacturer of indirect evaporative coolers. Highlyefficient evaporative cooling systems can reduce energy use by 70% the actual savings will vary with the type of evaporative system and climate. Evaporative cooling market growth, trends and forecast. The provision of automatic controls, to ensure the unit only operates when cooling is required, can significantly improve the water efficiency of the system. Direct evaporative cooling systems is a technology which involves adiabatic humidification and cooling of air with supplementary heat exchange facilities to lower final air temperature and try to reduce relative humidity. 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. Evaporative cooling is natures answer to efficient climate control.
It incorporates a patented evaporative polymer heat exchanger system that uses evaporative cooling and. Leadership in energy and environmental design leed points can be achieved by using cooling options that. Evaporative coolers are used in residential and smaller systems in dry, hot climates. When warm, dry unsaturated air is pulled through a watersoaked pad, water is evaporated and is absorbed as water vapor into the air. It takes heat energy to change the water or any liquid from a liquid into a vapor. There are two broad types of evaporative coolers available on the market, direct and indirect, both commonly known as twostage.
There are two types before we go there, you must understand humidity the humidity content decides how comfortable a person feels for ex. Choosing an evaporative cooling system offers a substantial energy cost savings. In the hvac industry, the term cooling tower is used to describe both open and. Principles of evaporative cooling system pdh online. Indirect evaporative cooler westaire engineering inc. Direct and indirect evaporative cooling strategies. Highpressure systems, however, are the most energyefficient.
The driving force of either direct or indirect evaporative cooling is the temperature difference between the drybulb table 1 a general comparison between the currently available air conditioning systems. Principles and application of evaporative cooling systems. They are available in portable, window, and wholehouse configurations. Abstract evaporative cooling is an energy efficient and environmentally friendly air conditioning technology. Evaporative condensers provide heat rejection for many types of systems, and the specific application will largely determine which bac evaporative condenser is best suited for a project. Dristeem evaporative cooling and humidification systems 3 how do first costs and energy costs of evaporative cooling systems compare.
Celdekpad provides a model of a direct stage evaporative cooler, shown in the figure below, that consists of a rigid media evaporative pad, with water recirculated from a reservoir. It is at this point that evaporative cooling is brought in. Duan, zhiyin 2011 investigation of a novel dew point. Evaporative cooling practical action 3 any part of the country using locally available materials. Air gives up heat the latent heat of vaporization at the rate of roughly 2. 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. Evaporative coolers use a quarter of the electricity of air. The indoor temperature that can be achieved with the outdoor design conditions at the time of the peak room sensible cooling load, and. Initial costs of closed loop cooling towers is generally a bit more than direct cooling tower systems. Air ducts, ac coils, registers, grills, asbestos coverings, balancing of system, wiring and parts external to the unit, compressors or chillers, condenser casings, condenser coils, evaporator coils, metering systemstxv valves, thermostats or thermostat wiring. Indirect evaporative cooling systems iec unlike dec, this arrangement was conceived from the need to cool air without increasing its moisture content.
Evaporative cooling systems maintain better air quality and eliminate more allergens than an equivalent ac system. E odoc adepartment of agricultural and bioresources engineering, university of nigeria, nsukka bdepartment of nursing science, university of maiduguri, borno state, nigeria. In this paper an approach to recover water from such humid air is presented. Evaporative cooling is preferred as an alternative over the traditional cooling technologies, as it makes use of a natural process, namely the reduction of air temperature by evaporating water on it.
Evaporative cooler an overview sciencedirect topics. Extreme heat and humidity can, and frequently does, cause heat strokes. If correspondence with the factory is necessary, please provide the unit model and serial number. Installation and maintenance of evaporative cooling system. In a direct evaporative cooler, a blower forces air through a permeable and watersoaked pad.
Youll typically consume between three and 15 gallons of water a day, depending on the size of the cooler and whether or not the water is collected and pumped through the. The main advantages of using both types of evaporative cooling systems are the lower supply air temperature, increased reliability and more available comfort hours. For steam humidifiers, this energy typically comes from the electricity or gas being used to boil the water. Controlling legionnaires disease has been a priority of the nsw department of health since the first outbreak was identified. The oasistm indirect evaporative cooler has been developed following the principles of iao cooling. Prices set forth in sellers quotation shall remain firm for thirty 30 days. Evaporative coolers are cooling devices that use the evaporation of water into the air to cool the air temperature. Though evaporative cooling is used around the world to keep birds cool during hot weather, by itself it is not a very effective method of reducing bird heat stress. Another first cost advantage is the ductwork installation cost will be lower for a combination. During prolonged periods of high temperatures they are unable to maintain internal temperatures below 25c.
Evaporative cooling is based on the thermodynamics of evaporation of water, i. To evaporate 1kg of water into an atmosphere, 680w of energy is required. This section describes the evaporative coolers models for hvac in energyplus. Humidity is also increased and the vapour pressure deficit is reduced. Ali abstract this paper present the cltd method for calculating the sensible cooling load estimation for evaporative cooling systems as a replacement of high power. By incorporating in our direct evaporative cooler with our indirect evaporative cooler you get the best of both worlds. It is not only uncomfortable to work in, but it can be downright dangerous for the welfare of your workers.
Evaporative cooling is most effective in southern coastal areas and most inland areas of australia. Ventilation systems can provide comfort cooling for most of the year. There are two basic types of evaporative air coolers eacs used to cool new mexico schools and. Indirect evaporative cooling lowers the temperature of air via some type of. In arid climates, idec systems provide 100% oa, leading to better iaq while using less. Evaporative cooling uses the natural relationship between relative humidity, water and air temperature. In evaporative cooling systems an air stream with high humidity ratio is released in the ambient without any treatment. The original nsw code of practice for the control of legionnaires disease, published in 1991, was prepared by the former legionella advisory committee to complement recently introduced public health legislation. Evaporative cooling design guidelines cedengineering. This manual is also intended as an overview of evaporative cooling principles and equipment for the nontechnical reader, with technical terms shown in bold print and defined in the glossary. Contains easytounderstand explanations and examples for commercial and industrial energy technologies.
International journal of engineering research and general. Nonresidential evaporative air cooling systems airah. Performance evaluation for indirect evaporative cooling etsce7 southern california edison page iii emerging products june 2015 abbreviations and acronyms 6 cooling capacity, enthalpy flow rate e. Youll typically consume between three and 15 gallons of water a day, depending on the size of the cooler and whether or not the water is collected and pumped through the pads more than once.
There are several kinds of evaporative air coolers. These are usually twopart systems with an outdoor unit that contains the compressor and condenser coils, and an indoor unit with evaporator coils. There is no loss in fluids as they are returned to circulation and not subject to evaporation, saving water resources. Evaporative cooling is when your body feels cool by passing air that evaporates the water on your skin. Nsw code of practice for the control of legionnaires. Another first cost advantage is the ductwork installation cost will be lower for a combination unit since they supply cooler air and require smaller ducts. A nice breeze on a hot day cools us because the current of air makes perspiration evaporate quickly. In addition, many utilities include a ratchet clause, which. In the long term however, the lower maintenance costs make indirect cooling a more cost effective solution, usually. You get 2 stages of evaporative cooling while offsetting substantial energy costs. Evaporative cooling systems require water to keep pads wet, which can be a water consumption issue during drought years. To understand why, one must understand how a bird cools itself. These systems operate by evaporating water into air and thereby cooling it. Evaporative cooling eers in excess of 100 may be achieved.
Indirect evaporative cooling can be used to lower both the dry bulb and wet bulb temperatures. Customers can achieve leed points and can get utility rebates. Can provide free cooling even if there is no building return air. The process takes place along a line of constant wet bulb. Evaporative coolers, often called swamp coolers, are cooling systems that use. Principles and application of evaporative cooling systems for fruits and vegetables preservation j. Experimental and numerical study of a heat pipe based.
It is the same cooling principle that our body uses when moisture sweat evaporates and cools the skin. Evaporative cooling is a type of environment cooling techniques that cools the surrounding air using water evaporation technique. Evaporative cooling systems can significantly lower the outside air temperature, even in humid climates, and improves the ability of the ventilation air to reduce the heat in the area. This system is the oldest and the simplest type of evaporative cooling in which the outdoor air is brought into direct contact with water, i. Projected benefits of new residential evaporative cooling systems. Although it is an ageold process, it has emerged as a viable alternative to conventional air conditioning systems in areas where extremely low. Evaporative cooling is also known as swamp cooling, desert cooling and wet air cooling. A direct evaporative cooling system is the simplest and most popular evaporative cooling system available. While the process provides a lower drybulb temperature, the moisture content of the leaving air is higher than the entering condition. Evaporative cooling are mainly of two types namely direct and indirect evaporative cooling systems as shown in fig. Central cooling systems use a network of ducts to supply air throughout the house.
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