Though it is widely used in different engineering sector and other refrigeration plant. As said earlier, cooling towers cool down the temperature of the water that is made too hot by manufacturing devices and methods. Cooling tower efficiency calculations cooling tower approach. 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. Principles of cooling towers all cooling towers operate on the principle of removing heat from water by evaporating a small portion of the water that is circulated through the unit.
Natural draft cooling tower design and construction in. Liquid heated by the process operation is pumped through pipes. 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. The height of the cooling tower in thermal power plant is about 9 feet or above from the ground level. Therefore, it is absolutely necessary to pre cool the water coming out of condenser before using again. 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. This is a very large tower in which the hot water encounters a natural draught which promotes cooling of the water by convection and. Increasing the range as a result of added heat requires an increase in tower size.
The basic working principle of cooling tower is to cool the hot water with the help of atmospheric air. This allows facilities to locate in areas with less water available because the. See the more detailed explanation of cooling towers systems, diagrams, pictures and principles below table of contents what is a cooling tower how do cooling towers work. Suptic air conditioning and refrigeration systems ranging from light commercial to industrial applications may rely on cooling towers to remove waste. 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. While it comes hot from the tower but goes back cold to the industrial process. Cooling tower terms and definitions btu british thermal unit a btu is the heat energy required to raise the temperature of one pound of water one degree fahrenheit in the range from 32 f to 212 f. Since the warm and moistureladen air having less density so move upwards naturally towards the dry and cooler air outside the tower. A guide to troublefree cooling towers a basic understanding of cooling tower operation and maintenance will help keep a cooling water system running in top condition, year after year by david m. The fan deck supports the motor and fan of the water spray system. Cooling towers summary the cooling tower removes heat from water used in cooling systems within the plant. In this case, the blowdown accounts for all system losses including leaks and drift, except for evaporation. 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. Natural draught tower utilize the principle of buoyancy to achieve the desired effect.
Cooling tower types cooling towers fall into two main categories. The fundamental principles of cooling towers are to cool down the heated water of industrial equipment and processes. Technical reference for water conservation in cooling towers. Typical closed loop cooling tower system is shown in figure 7. In this topic, we will look at how a cooling tower operates. The fundamental principal employed in accomplishing this removal of heat is the evaporation of water. A basic understanding of the system water distribution shall be established in order to properly operate and maintain a cooling tower on a water efficient manner. The working principle of wet cooling towers is based on evaporative cooling technique. In this design the fill is located outside the tower. Technical information for cooling towers using recycled water pdf.
Design of mechanical draftcooling tower and determination. The cooling tower must be adequately sized to reject this same amount of heat to the atmosphere. Understand the working principle and types of cooling. The second principal relationship defines cycles of. This course covers 18 sections of comprehensive information on evaporative cooling towers and provides important aspects of cooling tower types, sizing, selection and performance issues. A cooling tower water treatment system is an arrangement of technologies that remove damaging impurities from your cooling tower feed water, circulation water, andor blowdown. A critical element of operation at many combined cycle power plants is energy transfer in one or more cooling towers. Open or wet cooling towers are the most efficient way to reject heat from the cooling system because the water. The tower often consists of a sprinkler system which wets a highsurfacearea substrate plates continuously, while air flow through the chamber converts liquid to vapor. A cooling towers function is to remove heat from a building or process application that generates heat and must be dissipated. In principle, an evaporative cooling tower involves the movement of a fluid, usually water with some added chemicals, through a series of parts or sections to eventually result in the reduction of its heat content and temperature. Here the working fluid or the fluid used for heat exchange and the fluid that is actually evaporating is the same i.
They reject process heat from the cooling water to atmosphere and keep the water cool. Cooling towers work on the principle of heat rejection. The air, however, is introduced at the side either on one side singleflow. The device that comes in use for releasing the heat to the atmosphere is known as cooling tower. Cooling tower basics calculation formulas cooling tower. Doc cooling tower lab report sem yong hao academia. The hot water is habitually produced by air conditioning condensers or with some automated processes. Evaporation causes the heat to be removed from the make up water. What is a cooling tower water treatment system and how. Facts the flow rate through a cooling tower in a typical 700 mw power plant is about 315,000 galmin. Water savings of cooling tower efficiency measures for use in performance contracts. What is a cooling towers working principle, water cooling towers are widely used for thermal comfort in hospitals and hotels as well as in industrial areas.
Cooling towers overcome most of these problems and therefore are commonly used to dissipate heat from watercooled refrigera tion, airconditioning, and industrial process systems. Cooling tower operation forced draught cooling towers use the evaporation of a liquid often water into air to achieve cooling. In a counterflow cooling tower, water sprays are used to distribute the warm water see figure 8. However, in the real and practical sense, we seldom see such huge sized cooling towers and mostly smallsized cooling towers are common in use for discharging heat generated by air conditioning systems. This process can use air to cool hot water, or water to cool hot air, depending on the need. Technical reference for water conservation in cooling towers 1st edition. Due to the height of a building of this type it is important that the tall buildings are. In a crossflow cooling tower, the hot water basin is used to distribute the warm return water flow uniformly over the tower fill see figure 6. Cooling tower working principle and types of cooling. Cooling tower basics and common misconceptions introduction in comparison with most other industrial equipments, the water cooling tower is a simple device, based on the direct contact of two of the earths most common substances. If the hot water temp is constant and the range is specified with a lower cold water temp, then the tower. The water exits the cooling tower and is sent back to the exchangers or to other units for further cooling. An introduction to cooling tower water treatment course no.
Warm recirculating water is sent to the cooling tower where a portion of the water is evaporated into the air passing through the tower. Cooling range the difference in temperature between the hot water entering the tower and the cold water leaving the tower is the cooling range. The environment is friendly because when the hot water is cooled, the towers produce. This operates on the principle of heat transfer by a heat exchanger with extended fins. Cooling tower heat transfer fundamentals power engineering. In water treatment, it usually means circulating water with a ph of less than 7. Cooling tower plays a major role in chemical process industry.
The water consumption rate of a cooling tower system is only about 5% of that of a oncethrough system, making it the least expensive system to. Again, this will be a first issue releasing the actual engineering approach. What is the working principle in the cooling tower. Application of this principle to the design of large cooling towers has resulted in extremely stable performance levels for critical projects. Cooling tower efficiency calculation is described in this article. They extract heat to the atmosphere through evaporative cooling. If you read this book carefully, you can make any cooling tower design programs by yourself. Factors affecting cooling tower performance range, flow and heat load range is a direct function of the quantity of water circulated and the heat load. Most cooling towers work based on the principle of evaporative. The towers themselves are enclosed, steadyflow devices for cooling water by evaporation through direct contact with air. Design of mechanical draftcooling tower and determination of thermal efficiency prof. Power consumption is minimal due to few moving parts. Cooling tower fans are used on induced draft cooling towers to pull air up through the fill media.
A cooling tower is heat removal device that uses water to transfer process waste heat into the atmosphere. The water then gets distributed by cooling tower nozzles to the wet deck. The towers design principles royal borough of kensington and. Regardless of whether the air is pushed or pulled through the tower, and whether or not the air is fanassisted, the principle. Cooling towers save plants thousands to millions of dollars per year in water consumption and. Hot water from the chiller is sent to the top of the cooling tower where it is released into the tower. Thus due to this exchange of heat cooling takes place. In simple terms, we can define it as an ecofriendly device that can reduce the temperature of the warmest water in the most efficient way at any source. This type of tower is very much suitable for large area and heavy load. Lets understand the basic concept of how does a cooling tower work and what the varieties are there in the market.
For most industrial manufacturing, electric power generation and even airconditioning needs, cooling towers are a critical element of the design. Cooling tower evaporative cooling system measurement. The cooling tower is a device for cooling large quantities of water, which circulating in a water recycling system. During the cooling tower working process, about 5% of water evaporates, lowering the temperature of the water in the circulation process. As a consequence of this operating principle, there is a possibility. In general, the most applications rely on the use of evaporative cooling tower systems, which include wet cooling towers, cooling ponds or spray ponds. Induced draft cooling tower counter current flow type. What type of cooling tower you have open circulating, oncethrough, or closed loop. This will give the masterplan a centre of gravity, a focal point in the design. Download the working principle of cooling tower pdf. Cooling towers are used to reject heat through the natural process of evaporation. A cooling tower performs to cool down the water used in the industrial process. The heat is released to the air rather than to a lake or stream.
In practice the cooling tower efficiency will be in between 70 to 75%. The specific configuration of your system will depend on several things, including. Effective thermal design of cooling towers a stepbystep approach to coolingtower design, with an example calculation to make it clear jonny goyal air liquide engineering and construction, lurgi india. This will cover the basic workings of the most common type of cooling tower wet or open which you will find on most commercial high rise and industrial sites. Natural draft cooling tower design and construction in germany past since 1965, present and future christian lang 1. Cooling tower what it is how cooling tower works youtube. To rotate fan, it uses motor with speed around rpm. At the same time, air is being drawn through the airinlet louvers forcing water to evaporate. A cooling tower is a heat rejection device that rejects waste heat to the atmosphere through the. Size of the cooling tower can vary from a small rooftop unit to huge hyperboloid units as used in nuclear power stations. All cooling towers operate on the principle of removing heat from water be evaporating a small portion of water that is recirculated through the unit. There are important cooling tower heat transfer fundamentals and modern. Types of cooling towers natural draft and mechanical.
Here we explain in full detail how does a cooling tower work, cooling tower working principles with example text, pictures and diagrams. When power plant runs on peak load, it requires a very high rate of cooling water. The tower approach is defined as the difference between the water temperatures leaving the cooling tower minus the entering wetbulb temperature. Cooling towers have 95% efficiency, losing only 5% of circulating water to evaporation. Working principle is same as natural draught cooling tower, only difference is that here fan is mounted on the cooling tower. 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. The cooling tower, generally packed with brushwood or wooden laths. In this type of cooling tower, fan is used to circulate the air. Miscellaneous mechanical components doehdbk1018293 cooling towers summary the important information in this chapter is summarized below. As this occurs, a small volume of water is evaporated, reducing the temperature of the water being circulated through the tower. On forced draft cooling towers, the air is pushedforced by blowers at the bottom of the air inlet louver. In cross flow induced draft towers, the water enters at the top and passes over the fill. In principle, airflow passes through a heat exchange, a pipe or cellulose material.
902 850 665 1595 15 1038 1299 1125 814 1567 222 50 421 1438 588 1648 1208 1006 1579 946 766 1367 129 607 1431 517 1161 1139 1152 574 391 1016 169 590 1260 1151 1466 1101 261 1279 1308 26 308 1088 1340 341