Creating a new model to predict cooling tower performance. A read is counted each time someone views a publication summary such as the title, abstract, and list of authors, clicks on a figure, or views or downloads the fulltext. Best management practice and guidance manual for cooling towers prepared by jea for the control of pollutants discharged to the sanitary collection system. Since the cooling towers are based on the principles of evaporative cooling, the maximum cooling tower efficiency depends on the wet bulb temperature of the air. In a counterflow cooling tower, water sprays are used to distribute the warm water see figure 8. The cooling tower had two possible makeup water sources. Cooling towers with open and closed water circuits are available. Both types function as heat exchangers based on the counter flow principle. Article information, pdf download for a contribution to the theory of natural. There are two shapes of cooling tower rectangular and circular cooling tower. Liquidgas lg ratio of a cooling tower is the ratio between water and the air mass.
Industrial cooling towers are used to remove surplus heat from water. This section provides an introduction of cooling tower designs. Cooling tower express warranty applies to all evapco cooling towers including axs, at, cat, sun, lpt, lste, pmtq, uss, and ut models. Cooling tower performance basic theory and practice subject. Here evaporation occurs, removing heat along with the evaporated water. Simulation of a counterflow and crossflow cooling tower by the stepwise integration method montri pirunkaset abstract the stepwise integration method is an approximation method for determining the water temperature in the fill layers for a counterflow cooling tower and in the fill cells for a crossflow cooling tower. Hot water from the chiller is sent to the top of the cooling tower where it is released into the tower. 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.
Cooling tower theory atmosphere of earth enthalpy scribd. Preventive maintenance program and plan for cooling towers. Intent in the foreword of cooling tower fundamentals published by spx cooling technologies, inc. Types of cooling towers natural draft and mechanical draft. Abstract this experiment was conducted to perform energy and mass balance on the cooling tower system and to observe the effects of one of the process variables on the exit temperature of water. The mass and heat process cooling tower has always been received much attention. There are principally two kinds of cooling towers, dry and wet. Operation of the cooling tower as heat rejection device is based on a principle where waste thermal energy is extracted from hot water to the.
Experimental the tested cooling tower is a forced draft counter. Introduction an open circuit or evaporative cooling tower is a heat rejection device that rejects heat to the atmosphere by cooling a water stream to a lower temperature. An induced draft fan draws the air across the wetted fill and expels it through the top of the structure. It is then combined with makeup water, which replaces the evaporated water, and is sent through the system again. A cooling tower is a specialized heat exchanger in which air and water are brought into direct contact with each other in order to reduce the waters temperature. Types and performance evaluation, efficient system operation, flow control strategies and energy saving opportunities, assessment of cooling towers 7. Some additional calculation such as water makeup, fan and. Usually the transfer uses water to move the heat out, which has been heated by an airconditioning condenser or some type of industrial process.
Cooling towers have certain design values, but seasonal variations require adjustment and tuning of water and air flowrates to get the best cooling tower effectiveness. The project deals with the performance study and analysis of induced draft cooling tower, which is one of the deciding factors used for increasing the power plant efficiency also modelling and analysis of flow using software. Theory cooling tower terms cooling range the difference between the water temperature at entry to and exit from the tower. A ruleofthumb method for the optimized design of cooling towers is presented. Your theory is that as the water sprays into the tower the droplets will hit the pipes like a ball draining down a pinball. In evaporation, the heat is taken away from the bulk of water, which is thus cooled. We look at how the size of the spray affects efficiency and note the two common forms of, natural draft cooling towers, which are the spray type and the surprisingly more. Finally, outside air is drawn across the cooling tower, removing the heat from the water through the process of evaporation. If it is not available it may be assumed as for natural draft cooling tower d 0.
The merkel equation the fundamental equation of heat. Those theories are briefly described in this guideline to provide the basic understanding of its calculation. See the more detailed explanation of cooling towers systems. The figure below provides a conceptual view of chilled water airconditioning system with watercooled condenser. The evaluation provides a characterization of side stream filtration technology, describes typical applications, and details specific types of filtration technology. A survey of wet cooling tower literature was performed to develop a simplified method of cooling tower design and simulation for use in power plant cycle optimization. Frederick merkel was on the faculty of the technical college of dresden in germany. The cooling is caused only by the heat exchange or convective cooling. Cooling tower evaporative cooling system measurement. Experimental study of cooling tower performance using ceramic. The fan deck supports the motor and fan of the water spray system. A cooling tower is a specialized heat exchanger in which two fluids air and water are brought into direct contact with each other to affect the transfer of heat.
Cooling tower control problem by james mcdonald, pe, cwt originally published. F o r m u l a s a n d t a b l es formulasandtables fanlaws. Cooling tower info pdf, delta cooling towers india your. Determination of optimum height for counter flow cooling tower ashraf kotb department of mechanical power engineering, ain shams university, cairo, egypt abstract a model for counter flow cooling tower is present with treatments to recover the simplifications in the literature. Fundamentals of hvac controls the application of heating, ventilating, and airconditioning hvac controls starts with an. The theory of heat exchange in wet cooling towers is briefly summarized. A cooling tower is an evaporative heat extractionrejection device. The theoretical modeling of cooling towers is quite complex given the. Cooling tower thermal design manual the early investigators of cooling tower theory grappled with the problem presented by the dual transfer of heat and mass. The project objective is to study the operation of cooling towers, to show how they can be realistically modeled. Get a water systems operating permit city of vancouver. Closed circuit systems differ in that the return fluid often water, or sometimes water mixed with glycol circulates through the tower structure in a coil, while cooling tower water recirculates only in the tower. One helpful means to that end is the water cooling tower. The lg ratio of a cooling tower is the ratio of the liquid water mass flowrate l to gas air mass flowrate g.
Determination of optimum height for counter flow cooling tower. In a cooling tower, the water enters warm and leaves cooler, and the air enters cool and leaves warmer. Rp m 2 rp m 1 cfm 2 c fm 1 staticpressure 2 static pressure 1 cfm 2 cfm 12 ho rsep ower 2 ho rsepow er 1c fm cfm 3 formulas. Cooling tower sizing can simply be done by graphical methods. In recent years the mechanical draught cooling tower has had the benefit of. With the total area of 60,000 square meters of the factory, the production is more than 20,000 square. A critical element of operation at many combined cycle power plants is energy transfer in one or more cooling towers. Effective thermal design of cooling towers a stepbystep approach to cooling tower design, with an example calculation to make it clear jonny goyal air liquide engineering and construction, lurgi india various misconceptions arise when it comes to the thermal design of cooling towers. This system sends cooling water out of the equipment and into a pond or cooling tower, which is open to the atmosphere. 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.
Cooling tower efficiency calculations cooling tower approach. Intent in the foreword of cooling tower fundamentals published by marley cooling technologies, inc. There are important cooling tower heat transfer fundamentals and modern. Cooling tower bureau of energy efficiency 5 syllabus cooling tower. Cooling towers in a cooling tower water is made to trickle down drop by drop so that it comes in contact with the air moving in the opposite direction. The cooling tower fill constant ka is defined and values derived. An example of a mass and energy balance on the laboratory cooling tower will be presented along with the results of experiments in which the rate of heat dissipated by the tower was calculated at full. The makeup water source is used to replenish water lost to evaporation.
A contribution to the theory of natural draught cooling towers b. The air, however, is introduced at the side either on one side singleflow tower or opposite sides doubleflow tower. 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. Simulation of a counterflow and crossflow cooling tower by. Here we explain in full detail how does a cooling tower work, cooling tower working principles with example text, pictures and diagrams. Common types of cooling tower natural, forced and induced. The factory is located in dongguan, china wth branch offices in guangzhou, dongguan, shenzhen, beijing, shan dong and singapore. This article provides engineering information about the two main types of cooling towers. A simplified thermal modelling of cooling tower for. The fanlaws can be used topredi ctthe pe rformance ofa towerwitha nonstandard motor.
The cooling tower effectiveness is the ratio of range to the ideal range. In 1956, zivi and brand 6 extended merkels analysis to include cross. Principles and practice, third edition, aims to provide the reader with a better understanding of the theory and practice, so that installations are correctly designed and operated. The purpose is to define a preventive maintenance program and plan for cooling towers at the suny polytechnic quad c building utica new york.
Best practice guidelines water conservation in cooling towers au 1. Rp m 2 rp m 1 cfm 2 c fm 1 staticpressure 2 static pressure 1 cfm 2 cfm 12. The purpose of this document is to assist the purchaserconsultant in effectively sizing, selecting and evaluating a particular cooling tower. The water leaving a cooling tower will never be as cool as the air.
Common cooling tower nomenclature, components and terminology. Simulation of a direct evaporative cooler and a cooling. Pdf on sep 22, 2011, eusiel rubiocastro and others published optimal design of cooling towers find, read and cite all the research you need on researchgate. Again, this will be a first issue releasing the actual engineering approach. Cooling tower plume prediction code revision 1 a computerized methodology for predicting seasonalannual impacts of visible plumes, drift, fogging, icing. Drift eliminators are installed to prevent water entrained in the air from leaving the system. Cooling tower fans are normally made from aluminum, fiber. Cooling tower performance basic theory and practice. The hybrid cooling tower can serve not only as a dry heat exchanger but also as a wet cooling tower. Drift loss of the cooling tower is normally provided by the cooling tower manufacturer based on the process design.
This report is available at no cost from the national renewable energy laboratory at. 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. On this page we discuss the introduction to cooling towers and the principle of operation. Cstn september 2002 a client had a large, threecell cooling tower system that was having problems maintaining conductivity. The water is sprayed down to the basin or through a heat exchange. As a result of this some water is evaporated and is taken away with air. It is a tower used for cooling the water which is discharged from the condenser. An opencircuit cooling tower, commonly called a cooling tower, is a specialized heat exchanger in which two fluids air and water are. The remainder of this report will explain the theory behind the operation of a cooling tower and how the laboratory cooling tower is operated. Cooling tower performance in free cooling applications is dependent upon both the system and cooling tower design. The primary task of a cool ing tower is to reject heat into the atmosphere. This cooling technology institute cti publication is published as an aid to cooling tower purchasers and designers. Warm recirculating water is sent to the cooling tower where a portion of the water is evaporated into the air passing. There is no evaporation in dry towers since there is no direct contact of water and air.
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. Cooling towers can be classified in two types 1 natural draught cooling tower. Cooling tower process is generally related with vapor pressure of water and humidity. The merkel equation the fundamental equation of heat transfer in wet cooling towers is presented and discussed.
Cooling tower performance basic theory and practice white papers a cooling tower is a specialized heat exchanger in which two fluids air and water are brought into direct contact with each other to affect the transfer of heat. The cooling tower must be adequately sized to reject this same amount of heat to the atmosphere. An introduction to water cooling towers ced engineering. In this thesis, a new model to predict cooling tower performance is created to give a more accurate picture of the various energy conservation measures that are available for cooling towers. Drift eliminators are also known as mist eliminators. The term induced draft denotes that air is drawn by fans through the flow of falling water and up and out of the cooling tower. Because of this pressure difference air enters in to the cooling tower. Manufacturers express warranty evapco warrants the mechanical equipment components consisting of the fans, bearings, pulleys, shafts, belts, gear reducers, drive shafts. Many literatures which are related to the modeling and experiment of cwct can be found. Irrespective of what engineering industry you work in, knowing a bit about cooling towers will always serve you well. 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.
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. Here we explain in full detail how cooling towers operate with example text, pictures, diagrams and principles. However, cti makes no warranty of fitness for particular purpose or. Cooling towers are a very important part of many chemical plants. Abstract 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 cooling towers are us ed in all heat producing industries. 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. The hybrid cooling tower is a combination of the advantages of a wet and a dry cooling tower. January 1, 2020 as of january 1, 2020, all existing once through cooling equipment, nonrecirculating liquid ring pumps, and other single pass systems must be disconnected from the citys water system. Cooling load the rate at which heat is removed from the water.
Best management practice and guidance manual for cooling. In the wl 320 open wet cooling tower, water is sprayed into the tower from above and distributed as widely as possible using baffles. Simulation of a direct evaporative cooler and a cooling tower by the effectivenessntu method p. It may be used by anyone desiring to do so, and efforts have been made by cti to assure the accuracy and reliability of the data contained herein. Experimental study of cooling tower performance using. Cooling towers overcome most of these problems and therefore are commonly used to dissipate heat from watercooled refrigera tion, airconditioning, and industrial process systems. The wetbulb temperature is a type of temperature measurement that reflects the physical properties of a system with a mixture of a gas and a vapor, usually air and water vapor.
This water is often discharged to the sanitary sewer system. Cooling tower heat transfer fundamentals power engineering. They represent a relatively inexpensive and dependable means of removing low grade heat from cooling water. Cooling tower operation forced draught cooling towers use the evaporation of a liquid often water into air to achieve cooling. Cooling towers are used to reject heat through the natural process of evaporation. It shows the liquid and the gas flowing side by side, separed by the na. In cross flow induced draft towers, the water enters at the top and passes over the fill. If you read this book carefully, you can make any cooling tower design programs by yourself. The merkel theory overcomes this by combining the two into a single process based on enthalpy potential. Even a marginal improvement in the efficiency of evaporative cooling equipment, heat exchangers and chillers can offer owners significant savings over the lifespan of the cooling systems.
The entire scope of cooling towers is too broad, and the technology far. It accomplishes this by providing intimate mixing of water and air, which results in cooling primarily by evaporating approximately 1 % of the flow for each 10. The tower takes the heat from the water stream and rejects it to. Review the bulletin related to discharge from cooling tower drains pdf file 372 kb once through cooling and other single pass systems. In hvac environments towers are typically used to remove heat from a chiller.
We are dedicated to designing and manufacturing the highest quality products for the evaporative cooling and industrial refrigeration markets around the globe. To determine the relationship between the cooling load and cooling range of a cooling tower. The technology evaluation assesses side stream filtration for cooling towers. As this occurs, a small volume of water is evaporated, reducing the temperature of the water being circulated through the tower. Inquiry documents should define the owners plan for.