Lecture series on steam and gas power systems by prof. Types and performance evaluation, efficient system operation, flow control strategies and energy saving opportunities, assessment of cooling towers 7. Cooling system a system, which controls the engine temperature, is known as a cooling system. If it is not available it may be assumed as for natural draft cooling tower d 0. Combining the mass flow equations with the energy equation leads to the final equation relating the mass flow rate of the dry air to the circulating cooling water of. Cooling tower efficiency calculations chemical engineering site. A suite of cooling tower applications that is indispensable to anyone responsible for the peak performance of cooling towers. Indian institute of technology kanpur national programme. 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. They reject process heat from the cooling water to atmosphere and keep the water cool. Basic concepts, adiabatic saturation temperature lec 2. After the water has been chilled, it is distributed via pumps, pipes, and valves the distribution system to the loads, where a heat exchangerfor example, a cooling coil in an airhandlertransfers heat from the air to the chilled water, which is returned to the chiller.
The mixing of warm water and cooler air releases latent heat of vaporization, causing a. On the other hand, cooling towers are much larger than tradional hvac systems and are used to remove heat from cooling tower water systems in petroleum refineries, plants, natural gas processing plants, petrochemical plants, and other industrial processes and facilites. The most common is for a cooling tower that provides the required heat rejection capacity with a high level of reliability at low cost. May 19, 2017 cooling tower makeup water calculation with example may 19, 2017 may 19, 2017 rifka aisyah utility system its been a while since the last time i write an article about utility system. Cooling tower performance calculations are usually performed numerically. A cooling tower is heat removal device that uses water to transfer process waste heat into the atmosphere.
This is the process that takes place in a cooling tower. It is based on around fortyfive years of experience in the construction of cooling towers gained by plant and structural design engineers, by construction companies, checkup engineers and operators. Process design of cooling towers project standards and specifications page 4 of 34 rev. I do not say that this is all the different type of heat exchangers have been listed over here. Wacon white paper counterflow vs crossflow cooling towers 1 cross flow or counter flow cooling tower. Analysis a the mass flow rate of dry air through the tower remains constant mm m aa a12, but the mass flow rate of liquid water decreases by an amount equal to the amount of water that vaporizes in the tower during the cooling process. Since no work is done and no heat transfered externally, the cooling tower energy equation reduces to an enthalpy balance equation.
In kuwait for example, the ministry of electricity and water issued two years ago a code of practice to be followed in order. Oct 07, 2012 how a chiller, cooling tower and air handling unit work together duration. 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. A cooling tower is a heat rejection device which rejects waste heat to the atmosphere through the cooling of a. Necessity of cooling system the cooling system is provided in the ic engine for the following reasons. Important psychrometric processes namely, sensible cooling and heating, cooling. And you may be surprised to learn that there is much more. 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. The technical data has been taken from a mechanical draft cooling tower. As their name implies, natural draft cooling towers rely on natural convection to circulate air throughout the tower, which then cools the water. You can see that, the, we have taken the height of the tower, a small portion of the cooling tower with a height d y the area is d a.
A series of spray nozzles in each hot water basin distribute the water evenly over the fill. Cooling tower efficiency kw fan versus ton heat rejection when designing or selecting a cooling tower one can minimize the first cost of the cooling tower and end up with a tower having high power consumption. 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. Mar 20, 2009 well this was the presentation on cooling towers that i created for my own presentation. 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. To better help you understand the differences between the different types of cooling towers available today, weve compiled this quick guide. This section provides an introduction of cooling tower designs. Cooling towers overcome most of these problems and therefore are commonly used to dissipate heat from watercooled refrigera tion, airconditioning, and industrial process systems. For example, a cooling tower sized to cool 4540 m 3hr through a. Feb 26, 2017 lecture series on steam and gas power systems by prof. The calculation of cooling tower efficiency involves the range and approach of the cooling tower. If you read this book carefully, you can make any cooling tower design programs by yourself.
Good business starts with a good budget that includes keeping the overhead down. Chapter 8 cooling towers system shutdown and start. Cooling tower plays a major role in chemical process industry. Gravity systems, employed on bacs crossflow cooling towers, feature hot water basins mounted on top of the tower above the fill. These tall, opentopped, cylindrical structures are responsible for cooling water generated from industrial or hvac comfort cooling process. Cooling tower fill media what is cooling tower fill media. 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. Test your knowledge on cooling tower online quiz chemical. 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. Apr 08, 2018 cooling tower efficiency calculation is described in this article. Natural draft cooling tower design and construction in germany past since 1965, present and future christian lang 1.
Chemical engineering site already published articles on cooling tower components and cooling tower efficiency calculations. 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 the following we show a schematic diagram of a cooling tower in the context of a steam power plant. Drift loss of the cooling tower is normally provided by the cooling tower manufacturer based on the process design. Merkel developed a cooling tower theory for the mass evaporation of a small portion of water and sensible heat transfer between the air and water in a counter. For example, excessive water flow, excessive airflow, and water bypassing the tower drift. Cooling towers cooling towers, closed circuit cooling. This cooling tower quiz module covers the design, calculations, operations and cooling water treatment etc which will be a refresher for the experience.
In this system, a centrally located fan at the top, takes suction from the tower and discharges it to the atmosphere. Rp m 2 rp m 1 cfm 2 c fm 1 staticpressure 2 static pressure 1 cfm 2 cfm 12. 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. Nptel syllabus mass transfer operations i web course course outline. Cooling tower is an essential piece in most of the chemical process industries and in hvac applications. As this occurs, a small volume of water is evaporated, reducing the temperature of the water being circulated through the tower. Cooling tower efficiency is limited by the ambient wet bulb temperature. Process design of cooling towers project standards and specifications page 2 of 34 rev.
Types of cooling towers natural draft and mechanical draft. The present paper is a detailed methodology for thermal design of cooling tower. At these condi tions, the cooling tower rejects 15,000 btuih per nominal cooling tower ton. Abstract this paper presents detailed methodology of a induced draft cooling tower of counter flow type in which its efficiency, effectiveness, characteristics are calculated. Nov 30, 2016 test your knowledge on cooling tower online quiz last updated november 30, 2016 cooling tower is an essential piece in most of the chemical process industries and in hvac applications. Natural draft cooling tower design and construction in. Cooling towers are designed and manufactured in many sizes and configurations. All of the required cooling water was assumed to be makeup water, with the. Tradional hvac heating and cooling systems are used in schools, large office buildings, and hospital. Cooling tower bureau of energy efficiency 5 syllabus cooling tower. The tower characteristic is determined by the ratio of range and logmeanenthalpy difference. An introduction to water cooling towers ced engineering.
After picking heat in the condenser the water goes to the cooling tower cooling tower you must have seen cooling towers it outside the hotels in the buildings. Optimization of the operating conditions for cooling tower applications in cooling water is extremely significant in order to get the most energy efficient operating point for these systems. F o r m u l a s a n d t a b l es formulasandtables fanlaws. Referring to the diagram above the mass flow rate of the makeup water is given by the difference in specific humidity. Cooling tower efficiency calculation is described in this article. Cooling tower efficiency calculations cooling tower approach. 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. Evaporation losses e it is calculated on the basis of heat. Again, this will be a first issue releasing the actual engineering approach. Heat exchanger and as i have told psychrometry is very important and in a cooling tower we can theoretically get a cold water temperature as low as wet bulb. In this article explained about basic concepts of cooling tower, types of cooling towers, formula for cooling tower efficiency. The temperature of the burning gases in the engine cylinder reaches up to 1500 to 2000c, which. Conventional analysis of performance of cooling tower. Approach approach is difference between recoiled water temperature and.
Cooling tower outlet temperature is called cooling tower range. 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. Range hot water temperature cold water temperature cooling tower efficiency calculation. Which cooling tower is best for tropical climates the climate conditions can somehow affect the performance of cooling towers due mainly to the fact that they make use of the surrounding air as well as water supply to do their job. Tower maintenance and operation levels also can influence the formation of drift droplets. Its also is the number one choice where work efficient longterm cooling solution is desired. Cooling tower makeup water calculation with example.
The method allows analytical calculation of cooling tower. 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 are a very important part of many process plants. Drift eliminators are also known as mist eliminators. Large commercial properties feature cooling towers and. Cooling towers make use of evaporation whereby some of the water is evaporated into a moving air stream and subsequently discharged into the atmosphere. Mar 11, 2018 size of the cooling tower can vary from a small rooftop unit to huge hyperboloid units as used in nuclear power stations. Cooling towers might be one of the most crucial parts of any industrial process. Cooling tower info pdf, delta cooling towers india your. The thermal capability of a cooling tower used for air condition ing is often expressed in nominal cooling tower tons.
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. A cooling tower as the name suggests is a device which releases excess heat from a system into the atmosphere. Other factors, which we will see, must be stated along with flow rate m3hr. Other types of water losses were therefore neglected.
Almost 14 th of makeup water water added in a cycle to substitute water losses in a cooling tower is dissipated 25. Nptel provides elearning through online web and video courses various streams. The merkel integral was calculated by conventional method as well as by equation 6. A cooling tower extracts heat from hot water greater then. Janssen, operational and engineering director wacon international ltd. Now, we are trying to do some sort of energy balance for a small control volume. Understanding the different types of cooling towers. Range range is determined not by the cooling tower, but by the process it is serving. Part of every business is having a clean and comfortable place for customers and clients to do business in. Cooling tower technology finds its utility in largescale economical cooling solutions. Fill media is by far one of the most important cooling tower. Design of mechanical draftcooling tower and determination.
Cooling towers employ either gravity distribution or pressurized spray systems to distribute water over the fill. 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. These studies were complicated by the fact that the cooling tower market is typically driven by one of two powerful, yet often conflicting requirements. Mechanism of drying and drying equilibria, drying rate curve. Drift eliminators are installed to prevent water entrained in the air from leaving the system. 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 manufacturer of your cooling tower usually lets customers order new gearboxes or have trained technicians that can repair or rebuild a faulty gearbox using original equipment manufactured parts. How a chiller, cooling tower and air handling unit work together duration. The technical data is taken for mechanical draft cooling tower. 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. Air conditioning, example problems on dehumidification.
In this paper, a simple differential equation for counter flow wet cooling tower is solved analytically taking into consideration the nonlinear dependency of the saturated air enthalpy on temperature. Determination of optimum height for counter flow cooling. By using a cooling tower, the plant is kept safe and operational. The only between the induced draft cooling tower and forced draft cooling tower is that the fan is located at the top in the induced draft cooling tower. The fanlaws can be used topredi ctthe pe rformance ofa towerwitha nonstandard motor. In addition, guideline vgbr 6 e, code of practice for life. This area is nothing, but the heat transfer area it is. Cooling tower basics calculation formulas cooling tower. 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.
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