During evaporation, water molecules in the evaporative pad absorb heat from outdoor air as they change phase from liquid to vapor.Īs a result of evaporation, ECs lower the air temperature while simultaneously increasing the amount of water vapor in the air. As ambient air passes through the wet evaporative pads the water evaporates. The evaporative pad is kept moist during operation by an electric pump that sends water to distribution troughs at the top of the evaporative pads. ECs work by pulling hot, dry outdoor air across a wet evaporative pad typically made from aspen wood shavings, other natural fibers, or corrugated cellulose materials (Figure 1B). Indirect evaporative coolers are available, but rarely used in residences in dry climates due to the high efficiency and low cost of direct evaporative coolers.įor the purposes of this review, EC will refer to residential direct evaporative air coolers, also known as “drip coolers”, “desert coolers”, and “swamp coolers”. The cooled air is then blown indoors.ĭirect evaporative coolers are the simplest and most common type of EC used in residences in arid and semi‐arid climates. As water evaporates from the cooling pad into the air, sensible heat in the air is transferred to latent heat in the form of water vapor. (B) Cooling process involves pulling hot, dry outdoor air through a wetted evaporative pad. (A) Common roof mounted residential direct evaporative cooler used in Rocky Mountain States, U.S. in the late 1930s was a major factor in opening up the otherwise hostile summer climate of Arizona and neighboring states to population growth (Figure 1A). The advent of mass‐produced mechanical evaporative air coolers (ECs) in the Southwest U.S. An electric fan was then used to blow outdoor air across the wetted cloth into the home. In the early 1930s in the Southwest U.S., homemade evaporative coolers were fashioned by covering a wooden box with burlap or other cloth. As early as 1905, British soldiers' barracks in India were air conditioned by arranging tatties over fans to cool supply air coming into the building. Other historic examples include the practice in India of hanging “tatties”, wetted screens made from the roots of khus khus (cuscus) grass, over windward doorways and window openings during hot summer months,Īnd the introduction of water into wind towers in traditional Middle Eastern architecture.Įarly mechanical methods incorporated the use of fans to improve airflow across wetted media. settlers who covered wall openings with damp burlap. Similar approaches were used by Western U.S. In the Southwest U.S., Native Americans splashed water on the tops of arbors in hot weather, which may have cooled the shaded area under the arbor by as much as 10 degrees. Historically, there are several examples of passive evaporative cooling methods, which relied on natural airflow. This brings to light a gap in the literature on evaporative coolers, which is the lack of data on health effects associated with their use.Įvaporative cooling is one of the oldest and most energy efficient forms of air conditioning used in hot, dry climates. To our knowledge, this is the first review to summarize and evaluate studies on the influence that evaporative coolers have on the bioaerosol and microbiological profile of homes. We evaluate the effects of evaporative coolers on indoor bacterial endotoxins, fungal β‐(1 → 3)‐D‐glucans, dust mite antigens, residential microbial communities, and Legionella pneumophila. This review summarizes the current knowledge of bioaerosol and microbiological studies associated with evaporative coolers, focusing on harmful and potentially helpful outcomes from their use. There is also evidence that evaporative coolers can enable a diverse microbial environment that may confer early‐life immunological protection against the development of allergies and asthma or exacerbate these same hypersensitivities. Studies have shown residential evaporative coolers may pull outdoor air pollutants into the home or contribute to elevated levels of indoor bioaerosols that may be harmful to health. While evaporative coolers can help save energy, they also have the potential to influence human health. Evaporative cooling is an energy efficient form of air conditioning in dry climates that functions by pulling hot, dry outdoor air across a wet evaporative pad.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |