Typical closed loop cooling tower system is shown in figure 7. Cooling towers may either use the evaporation of water to remove process heat and cool the working fluid to near the wetbulb air temperature or, in the case of closed circuit dry cooling towers, rely solely on air to cool the working fluid to near. The main part of the installation is the cooling tower, hav. In this type of cooling tower, the working fluid is channelled through tubes which collects the ambient heat and then this heat is exchanged with atmosphere using air as a medium. For example, a cooling tower sized to cool 4540 m 3hr through a. Chemical engineering site already published articles on cooling tower components and cooling tower efficiency calculations. Nov 17, 2012 when designing or selecting a cooling tower, one can minimise the first cost of the cooling tower and end up with a tower having high power consumption. How to optimize the energy efficiency of cooling towers. A cooling tower is a simple piece of equipment designed to remove heat energy from water through the process of evaporation. And you may be surprised to learn that there is much more to these cooling towers than you ever knew. Cooling tower is an essential piece in most of the chemical process industries and in hvac applications. Experimental the tested cooling tower is a forced draft counter. Oos the cooling tower heat exchange system was permanently out of service by april 1, 2006. A nominal cooling tower ton is defined as cooling 3 gpm of water from 95f to 85f at a 78f entering air wetbulb temperature.
The purpose of a cooling tower is to keep a process from raising temperatures too high were they either can be dangerous or lower the efficiency. According to them, the design of cooling tower is affected by tower characteristics and different types of losses generated in cooling tower. Chalk point cooling tower project, volumes 1 and 2, jhu ppspcpctp16. Normally during summer season the air density is low. Cooling towers make use of evaporation whereby some of the water is evaporated into a moving air stream and subsequently discharged into the atmosphere. Mechanical fan 1 according to air and water contact. If it is not available it may be assumed as for natural draft cooling tower d 0. In this type of cooling tower, fan is used to circulate the air. Cooling tower efficiency calculations cooling tower approach. The factory is located in dongguan, china wth branch offices in guangzhou, dongguan, shenzhen, beijing, shan dong and singapore. Icf100 the cooling tower heat exchange system has an intervening cooling fluid containing less than. Cooling towers may either use the evaporation of water to remove process heat and cool the working fluid to near the wetbulb air temperature or, in the case of closed circuit dry cooling towers, rely solely on air to cool the working fluid to. Induced draft systems can also force air into the tower with a blowthrough or pull it out through a drawthrough. Induced draft or mechanical draft cooling towers use some type of mechanical pressure, like a fan system, to push air upward inside the tower.
The answer depends on cooling tower categories and how we categorize cooling towers. The lower the approach the better the cooling tower performance. Theory of cooling towers cooling towers fall into two main subdivisions. Drift eliminators are also known as mist eliminators. The technical data has been taken from a mechanical draft cooling tower. Types of cooling towers natural draft and mechanical. Abstract this paper presents detailed methodology of a induced draft cooling tower of counter flow type in which its efficiency, effectiveness, characteristics are calculated. Water evaporates as a result of the hot water droplet coming in contact with the air which is being pumped out by means of a fan. Cooling technology institute cti is a not for profit technical.
Concentration concentration is the increase of impurities in the cooling water due to the evaporative process. Because water removes heat energy more efficiently than air, cooling towers significantly outperform their aircooled counterparts. By using a cooling tower, the plant is kept safe and operational. Cooling towers should be located as near as possible to the refrigeration systems they serve, but should never be located below them so as to allow the condenser water to drain out of the system through the tower basin when the system is shut down. Cooling towers can be categorized in a number of different ways, because there are so many differences between cooling towers.
May 08, 2017 drift reducers are important cooling tower parts that work to eliminate water droplets in the air and recycle the moisture for operational processes. Pdf prediction of evaporation losses in wet cooling towers. Cstn september 2002 a client had a large, threecell cooling tower system that was having problems maintaining conductivity. A few of the major requirements for a cooling tower to minimise or avoid the development of ld bacteria in a cooling tower are as follows. Understanding the different types of cooling towers. Other factors, which we will see, must be stated along with flow rate m3hr.
Range range is determined not by the cooling tower, but by the process it is serving. Cooling tower utilises cooling a stream of water which is at the higher temperature to a lower temperature in order to gain the required or desired cooling effect. For example, excessive water flow, excessive airflow, and water bypassing the tower drift. If there is available area, there will be even lower hp cooling tower options that enable a great amount of energy. A cooling tower as the name suggests is a device which releases excess heat from a system into the atmosphere. Pdf temperature control is a significant requirement in the most industrial process. Experimental study of cooling tower performance using. In this type of cooling tower the transfer of heat takes place through a surface which separates the working fluid from ambient air, such as in a tube to air heat exchanger, utilizing convective heat transfer. Cooling tower fan blade pitch angle is the angle made by the fan with the plane. The water in the cooling tower should not come into direct contact with sunlight. Nov 10, 2018 the answer depends on cooling tower categories and how we categorize cooling towers. The water consumption or the amount of make up water of a cooling tower is about 0. Department of energy idaho operations office idaho national engineering laboratory this is an informal report intended for use as a preliminaryor working document work supported by the u.
Cooling towers and the importance of maintenance plant. Cooling water systems an overview of cooling towers 2012 instructor. Crossflow towers can be as tall as counterflow towers, but theyre also more prone to freezing and are less efficient. Compared with the use and waste of city water the water consumption can be reduced with about 90 95%. Working principle is same as natural draught cooling tower. These ideas are what make a cooling tower work, but there is a lot more water to cool and evaporate in a cooling tower than the small amount of water the human body generates as sweat. Cooling towers might be one of the most crucial parts of any industrial process. Scale, in addition to causing physical blockage of piping, equipment, and the cooling tower, also reduces heat transfer and increases the energy use. Ultimately, it is a heat rejection device which utilizes the evaporative cooling process to transfer waste heat from the atmosphere. The fundamental principal employed in accomplishing this removal of heat is the evaporation of water. One helpful means to that end is the water cooling tower.
With the total area of 60,000 square meters of the factory, the production is more than 20,000 square. In a crossflow tower, air flows horizontally through the cooling tower s structure while hot water flows downward from distribution basins. The basins must be designed for minimum water content and have a sloping bottom panels. They are located in areas that are situated after the fill and water sprays and just before the area where the air exits the cooling tower see figures 6 and 8.
In this regard, it needs to be noted that for example, two years ago, kuwaits ministry of electricity and water issued a code of practice to be followed in order to rationalise the power. Again, this will be a first issue releasing the actual engineering approach. This section provides an introduction of cooling tower designs. Cooling towers are used to cool down water that goes through chillers and other heat exchanger equipment. Tower maintenance and operation levels also can influence the formation of drift droplets. Dec 25, 2011 a cooling tower is an equipment used to reduce the temperature of a water stream by extracting heat from water and emitting it to the atmosphere. In this regard, cooling towers are key parts of many power. The type of heat rejection in a cooling tower is termed evaporative in that it allows a small portion of the water being cooled to evaporate into a moving air stream to provide significant. This cooling tower quiz module covers the design, calculations, operations and cooling water treatment etc which will be a refresher. Working principle is same as natural draught cooling tower, only difference is that here fan is mounted on the. Cooling tower fan blades pitch angle is varied depending on seasonal requirements. Consensus indicates substantial agreement, but not necessarily unanimity. These towers utilize large fans to force air through circulated water.
Test your knowledge on cooling tower online quiz chemical. Cooling tower types cooling towers fall into two main categories. Unlike tall cooling towers used in large conventional plants, the cooling tower performance does not monotonously decrease with the increase of the crosswind speed. The principle of operation of cooling towers is very similar to that of the evaporative type of condensers, in which the warm water gets cooled by means of evaporation. Mar 11, 2018 a cooling tower as the name suggests is a device which releases excess heat from a system into the atmosphere. Drift reducers are important cooling tower parts that work to eliminate water droplets in the air and recycle the moisture for operational processes. Hot water from the chiller is sent to the top of the cooling tower where it is released into the tower. Cooling water problems and solutions ced engineering. Confidential cooling tower drift test report, midwest research institute, kansas city, mo, november 1983. At these condi tions, the cooling tower rejects 15,000 btuih per nominal cooling tower ton. Most towers have structural frames that support the exterior enclosures casings, motors, fans, and other components.
The water exits the cooling tower and is sent back to the exchangers or to other units for further cooling. Cooling tower fans are normally made from aluminum, fiber. Crossflow indicates that the airflow is horizontal in the filled portion of the tower while counterflow means the air flow is in the opposite direction of the falling water. The cooling tower had two possible makeup water sources. The air flow in either class may be crossflow or counterflow with respect to the falling water. Here we explain in full detail how cooling towers operate with example text, pictures, diagrams and principles. Cooling water systems an overview of cooling towers. Its also is the number one choice where work efficient longterm cooling solution is desired. These tall, opentopped, cylindrical structures are responsible for cooling water generated from industrial or hvac comfort cooling process. Drift loss of the cooling tower is normally provided by the cooling tower manufacturer based on the process design. Tceq form opua instructions for cooling tower attributes.
All cooling towers are designed to remove waste heat from water and transfer it to the atmosphere, but there are a lot of ways to accomplish this task. Mechanical draft towers utilize large fans to force or suck air through circulated water. One transfers the heat from warmer water to cooler air, mainly by an evaporation heattransfer. With air flow rate, cooling tower performance increases. In open circuit systems the recirculating water returns to the tower after 1 one ton of refrigeration is equal to 12,000 btuhour. If you read this book carefully, you can make any cooling tower design programs by yourself. See the more detailed explanation of cooling towers systems. Cooling towers can be split into two distinct categories. A cooling tower is an equipment used to reduce the temperature of a water stream by extracting heat from water and emitting it to the atmosphere. Mechanical draft cooling towers are much more widely used. Which is why a cooling tower adds in a few other factors to the equation. A cooling tower is a heat rejection device, which extracts waste heat to the atmosphere though the cooling of a water stream to a lower temperature. For our purposes, we will cover three kinds of cooling towers based on how air. Prediction of evaporation losses in wet cooling towers article pdf available in heat transfer engineering 279.
Percentages required for achieving consensus are given where appropriate. The rate of heat transfer in the spraytype cooling tower shown as. Which one from the following types of cooling towers consumes less power. They do this by abruptly forcing the moist air in another direction, separating the moisture from the air and redirecting it to another part of the cooling tower. Cooling tower technology finds its utility in largescale economical cooling solutions. Jul 30, 2018 cooling towers can be classified in two types 1 natural draught cooling tower. A schematic illustration and photo of the used experimental apparatus are shown in fig.
The thermal capability of a cooling tower used for air condition ing is often expressed in nominal cooling tower tons. Commonly cooling towers reach their objectives by either cooling the working fluid to near wet bulb temperature using evaporation or in case of closed circuit cooling towers the mechanism cools the working fluid to dry bulb temperature using air solely as the cooling medium. When power plant runs on peak load, it requires a very high rate of cooling water. A cooling towers function is to remove heat from a building or process application that generates heat and must be dissipated. In this type of cooling tower, fan is not used for circulating air but here, by enclosing the heated air in the chimney and it will create pressure difference between heated air and surrounding air. Cooling towers are generally classified either by build, heat transfer methods and airflow generation methods. Cooling tower control problem by james mcdonald, pe, cwt originally published. Monitor cooling tower, pumps, motors, fans, drive equipment, and instrumentation and resolve any problems in s timely manner. To rotate fan, it uses motor with speed around rpm. Understanding key components of cooling towers and.
Determination of optimum height for counter flow cooling tower. They do not use evaporation technique, so the consumption of makeup water is very less. Two basic types of water cooling processes are commonly used. The hybrid cooling tower is a compromise between the wet and the dry cooling tower. No liquid or water is hence used for cooling in this type of setup. Evaluate the energy use of the cooling tower, this is mainly the fan and pump horsepower hp. Experimental study of cooling tower performance using ceramic. Column anchor column anchor is a device for attaching the tower structure to the foundation. Natural draft designs use very large concrete chimneys to introduce air through the media.
Conductivity trend for manual or timed blowdown control. These types of towers are used only by utility power stations. The major concern during i study the cooling tower theory was how to computerize the cooling tower theory from the calculation of ntu to the cooling tower performance analysis. Determination of optimum height for counter flow cooling. Nov 30, 2016 cooling tower is an essential piece in most of the chemical process industries and in hvac applications. Hrvoc5 the stream directed to the cooling tower heat exchange system contains less than 5. For example, the thermal conductivity btu hr ft2 fin of copper is 2674, while the common cooling water scale calcium carbonate has a thermal conductivity of 6. Monitor the soundness and integrity of ct structure and report issued to maintenance. A cooling tower is a heat rejection device that rejects waste heat to the atmosphere through the cooling of a water stream to a lower temperature. By the term wet cooling tower 1 is meant a mixedflow heat exchanger that works on the principle of the. Manufacturers of cooling towers and air coolers, suppliers to the manufacturers and users, and owneroperators. In hvac environments towers are typically used to remove heat from a chiller. Department of energy assistant secretary for resource.
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