They represent a relatively inexpensive and dependable means of removing low grade heat from cooling water. A cooling tower is a heat rejection device which rejects waste heat to the atmosphere through the cooling of a water stream to a lower temperature. For example, a cooling tower sized to cool 4540 m3hr through a. Here evaporation occurs, removing heat along with the evaporated water. Drift loss of the cooling tower is normally provided by the cooling tower manufacturer based on the process design. An evaporative cooling tower is a heat exchanger that transfers heat from circulating water to the atmosphere. Hvac design cooling towers a suncam online continuing education course.
The theory of heat exchange in wet cooling towers is briefly summarized. Baltimore aircoil is the leading global manufacturer of cooling towers, closed circuit cooling towers, evaporative condensers, and ice thermal storage systems. The present paper is a detailed methodology for thermal design of 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. Cooling towers can be split into two distinct categories. Cooling towers are constantly exposed to environmental contaminants and bacteria. Related commercial resources ashrae handbook hvac systems and equipment chapter. Understanding the basics of cooling tower heat transfer. Factors affecting cooling tower performance capacity utilization amount of water circulated range determined by the process it is serving determined by heat load and water circulation rate thus range. Student can use the psychrometric chart for determining the specific humidity, specific enthalpy, relative humidity 3. Cooling tower transfer characteristics is one of the most, if not the most important parameters in cooling tower thermal design. Factors affecting cooling tower performance capacity 8. Water treatment for cooling towers 1 of 2 water treatment helps ensure that heattransfer surfaces perform to design specifications by amanda meitz, senior microbiologist, nalco diversified technologies, inc. System interactions are covered in more detail in system design options beginning on page 27.
Range range is determined not by the cooling tower, but by the process it is serving. Since evaporative cooling equipment requires large quantities of air, adequate spacing around the unit must be provided for it to perform properly. The cooling effect is obtained by the natural air which is entering in the gap provided by the louvers. The components used in the design of cooling tower are as follows.
Design and operation 2005 2018 trane a business of ingersoll rand. Wind loading is extremely important in cooling tower design for several reasons. A basic guide to understanding industrial cooling water systems. Unlike heat exchangers, where transfer coefficients for various configurations are widely published, cooling tower transfer characteristics are not commonly found in the open literature.
The hot water is then supplied to the cooling tower for cooling by the use of motor pump. Part i outlines the steps necessary to improve cooling tower operations including a simple checklist for easy reference. Cooling tower efficiency calculations cooling tower approach. Handbook of green building design and construction, 2012.
This handbook now contains more than 800 pages of valuable product and technical information, and we believe that you will find volume v to truly be the one resource for all of your customers design, application, and specification needs. Chilled water plant design guide december 2009 energydesignresources. In cooling towers with wellengineered mist eliminators, a common design drift rate is 0. 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. Operation and maintenance of cooling towers must be in accordance with. Best management practice and guidance manual for cooling. Water treatment chemicals utilized for cooling tower systems which contain molybdenum are prohibited in the jea sanitary sewer. L mass flow of water entering the cooling tower lbmin t.
Design of mechanical draftcooling tower and determination. The water exits the cooling tower and is sent back to the exchangers or to other. The size of the cooling towers may vary from small rooftop units to very large hyperboloid structures can be up to 200 metres 660 ft tall and 100 metres 330 ft in diameter, or in rectangular structures can be over 40 metres ft tall and 80 metres 260 ft long types of cooling tower a on the basis of heat transfer methods cooling towers are classified as. Understanding key components of cooling towers and. At these condi tions, the cooling tower rejects 15,000 btuih per nominal cooling tower ton. These design guideline are believed to be as accurate as possible, but are very general and not for specific design cases. The high exiting air velocities reduces the chance of re circulation. 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. Closed loop cooling tower system the makeup water source is used to replenish water lost to evaporation. The cooling tower casing and the water basin are made of strong corrosionproof fibreglass reinforced polyester resin. Oncethrough cooling was a common design feature for large power plants in the last century, as. Effect of condenserwater flow rate the condenser is sensitive to the water flow rate.
They were designed for engineers to do preliminary designs and process specification sheets. Calculate the enthalpy and temperature of exit air for the following cooling tower design conditions. If it is not available it may be assumed as for natural draft cooling tower d 0. These studies were complicated by the fact that the cooling tower market is typically driven by one of two powerful, yet often conflicting requirements. Once a tower characteristic has been established between the plant engineer and the manufacturer, the manufacturer must design a tower that matches the value 7. Chapter 33 pretreatment of cooling water systems chapter 34 air conditioning and refrigeration systems chapter 22 coilend deposition and corrosion control. Cooling towers clicking on a companys name will take you to their web site. Chapter 8 cooling towers system shutdown and start. The technical data is taken for mechanical draft cooling tower. This requires a rapid response, accurate detection and a tailored program to control biological growth.
Student can calculate effectiveness of the cooling tower, t. The water basin is an integrated part of the cooling tower casing, on this reason leakage is prevented for the examination of the spray nozzles and for maintenance on the adjustable float valve. This system sends cooling water out of the equipment and into a pond or cooling tower, which is open to the atmosphere. 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. Cooling tower fundamentals is devoted to the implementation of water cooling systems which satisfy design and environmental requirements with sound engineering and responsible cost. In open circuit systems the recirculating water returns to the tower after 1 one ton of refrigeration is equal to 12,000 btuhour. Warm water from the heat source is pumped to the top of the tower and will than flow. Cooling tower selection, sizing and troubleshooting, kolmetz handbook of process equipment design. Cooling tower efficiency guide property managers improving cooling tower operations how to use this guide this guide is structured in two parts. Design and operation considerations cooling towers are a very important part of many chemical plants. Nalco water will work with you to design a program from our complete line of oxidizing and nonoxidizing biocides, algaecides and biodispersants.
In the counter flow induced draft design, hot water enters at the top, while the air is intro. Induced draft towers are typically mounted with a fan at the top of the cooling tower, which allows hot air out and pulls air throughout. The most common is for a cooling tower that provides the required heat rejection capacity with a high level of reliability at low cost. Cooling towers and condenser water systems design and. Cooling tower efficiency guide property managers improving. Other factors, which we will see, must be stated along with flow rate m3hr. Evaporative cooling design guidelines ced engineering. As the universal solvent, water is capable of dissolving a variety of materials as well as holding. Mechanical draft cooling tower mechanical draft cooling towers are the most widely used in buildings, and rely on powerdriven fans to draw or force the air through the tower. To design cooling towers someone can find a forest of requirements. All cooling tower discharges must be in accordance with applicable state, local or federal rules and regulations. In our project we are going to design circular cooling tower named as induced draft cooling tower. Pdf cooling tower thermal design manual javier lara.
Student has deep understanding on principles of cooling tower 2. Every day a student or a professional is looking for a short and timely handbook with. For example, a cooling tower sized to cool 4540 m 3hr through a. The goal is to assure the implementation of water cooling systems which will satisfy all design and.
With respect to the cooling towers design, co mputeraided methods can be very helpful to obtain optimal designs oluwa sola, 1987. The thermal capability of a cooling tower used for air condition ing is often expressed in nominal cooling tower tons. It is then combined with makeup water, which replaces the evaporated water, and is sent through the system again. Evaporative cooling design guidelines manual iv this report by nrg engineering is funded by the new mexico energy minerals and natural resources department, 1220 south st. So, for our example drift would amount to approximately 1 gpm. A nominal cooling tower ton is defined as cooling 3 gpm of water from 95f to 85f at a 78f entering air wetbulb temperature.
15 250 157 1075 445 848 1238 680 1226 771 882 1508 488 1036 1409 1410 446 62 848 1530 483 365 1081 143 394 575 1048 1124 361 821 559 557 1016 252 606 1222 1156 257