The mass balance around a cooling tower as illustrated in the figure to the right is. 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. In the report the theory of heat exchange i n wet cooling towers is briefly sumnarized. 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. When dealing with a cooling tower, to cool the incoming water being sprayed over the tower by 10 qf, then 1% of the flowrate over the tower must be evaporated. Here we explain in full detail how cooling towers operate with example text, pictures, diagrams and principles. Cooling tower formulas, delta cooling towers india your. Calculate a ton of cooling load using this formula. Unit in english system is fahrenheit, and in international system is celsius.
Following items will be discussed and calculated in this article. Cooling tower efficiency calculation is described in this article. For load, the same formula is used for the special purpose area as in a5, except, you. Cell cell entry notes and equation numbers test run entries or results a1 analysis of cooling tower data a2 damper position fill it in here a3 date due fill it in here a4 see word spreadsheet file a5 for details. Cooling load calculation cold room the engineering mindset. For the love of physics walter lewin may 16, 2011 duration. Again, this will be a first issue releasing the actual engineering approach of cooling tower with the examples in the world. Pdf 60 m3h nominal capacity cooling tower was designed, based on the required cooling water. The technical data is taken for mechanical draft cooling tower. The temperature difference between two points indicates a potential for heat to move from the warmer point to the colder point. A simplified calculation procedure of tower coefficient is presented. Other factors, which we will see, must be stated along with flow rate m3hr. Calculating fan power involved for a cooling tower posted in student. Note from formula 2 that heat load establishes only a required temperature differential in the process water and is unconcerned with the actual hot and cold water.
The water exits the cooling tower and is sent back to the exchangers or to other. The heat picked up in the heat exchanger is returned to the cooling tower where it is rejected to the atmosphere by evaporative and convective cooling. They reject process heat from the cooling water to atmosphere and keep the water cool. In ideal case the cold water temperature will be equal to the wet bulb temperature. In practice, the cooling tower efficiency will be in between 65 to 70%. Pdf a simplified procedure for calculating cooling tower. In this article explained about basic concepts of cooling tower, types of cooling towers, formula for cooling tower efficiency. Hvac cooling load calculations and principles sensible heat gain is the energy added to the space by conduction, convection andor radiation. Range range is determined not by the cooling tower, but by the process it is serving. The equivalent ton on the cooling tower side actually rejects about 15000 btuh due to the heatequivalent of the energy needed to drive the chillers compressor. Issue 1ive read a lot of material on cooling towers at this point whe.
A cooling tower is a heat rejection device that extracts waste heat to the. Data entires are shown in parenthese and calculation results are shown in brackets. It is the flow rate of water which is circulated in the cooling tower. This useful and easy program let you quickly and securely perform calculations for the design of a new cooling tower project, upgrade the performance of an existing counterflow tower and verify its efficiency and working conditions.
This equivalent ton is defined as the heat rejection in cooling. Abstract this paper presents detailed methodology of a induced draft cooling tower of counter flow type in which its efficiency, effectiveness, characteristics are calculated. Ntu is obtained through the numerical solution of a differential equation set as. Equipment enter the total kw for cooling from the equipment costs page as the kw for the servercomputer equipment, and set the load time for 75% and the runtime at 100%. What is the cooling capacity in tr of a cooling tower for. You now have multiple ways of determining blowdown from the equations above.
The purpose of a cooling tower is to conserve water. Theoretically, the evaporation quantity of water is 1. See the more detailed explanation of cooling towers systems. Unfortunately im pretty new at cooling towers and im having several issues with this. Calculations 418 now carry out the division on the right side of the equation. The calculation of cooling tower efficiency involves the range and approach of the cooling tower. Cooling tower makeup water quantity calculation saubhaya cooling tower makeup water quantity calculation saubhaya cooling towers understanding key components of and pdf cooling towers estimate evaporation losakeup water. If you read this book carefully, you can make any cooling tower design programs by yourself. Cooling tower extracts heat from the condenser water by two modes. How to calculate tons of cooling for a cooling tower. Cooling tower performance basic theory and practice subject.
Tower coefficient is commonly used to characterized the heat rejection capability of cooling tower. Introduction to design cooling towers someone can find a forest of requirements, guidance construction activities and. Intent in the foreword of cooling tower fundamentals published by marley cooling technologies, inc. Calculating the tons for a cooling tower requires you to understand some basic information about it works. Process leaks, windage, and drift are really just forms of uncontrolled blowdown.
Cooling tower calculations in excel free download at. Uses ashrae procedures for transfer function cooling load calculations, design heating load calculations, solar radiation calculations. Heat load of the cooling water is indicated by the standard heat transfer equation. When you sign up, we offer you a 1day free trial of 50 calculations. Cooling tower basics calculation formulas cooling tower efficiency. In the words of an excellent reference manual on cooling, evaporation is utilized to its fullest extent in. Cooling tower evaporative cooling system measurement. Cooling tower makeup water calculation pdf saubhaya makeup. The historical derivation of this 15,000 btulh cooling tower ton, as compared to the 12,000 btuih evaporator ton, is based. 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 various misconceptions arise when it comes to the thermal design of cooling towers.
Step1 first consider the cooling water exit temperature twex in column a in excel sheet so i. Latent heat gain is the energy added to the space when moisture is added to the space by means of vapor emitted by the occupants, generated by a process or through air infiltration from outside or adjacent areas. Calculates room and zone loads 24 hours a day for design days in all 12 months. This amount of heat could theoretically melt 1 ton of ice in 24.
An assortment of formulas for the protection of cooling water systems possibly supplemented with zinc at the corrosive end of the spectrum and high performance polymers at the scaling end. Cooling tower performance calculations are usually performed numerically. Cooling tower efficiency is limited by the ambient wet bulb temperature. The present paper is a detailed methodology for thermal design of cooling tower. Cooling tower efficiency calculations along with approach, range, cycle of concentration. Cooling load calculation cold room worked example lets consider a simplified example of a cooling load calculation for a cold room. Cooling tower blowdown equation by james mcdonald, pe, cwt originally published. The basic cooling tower process is outlined in figure 1.
Calculating fan power involved for a cooling tower. One of our most useful resources is the mechanism of threshold treatment. Cooling tower heat transfer fundamentals power engineering. Cstn july 2003 l et s take a look at how to calculate cooling tower blowdown. Pdf design and performance analysis of the cooling tower in the. Cooling tower calculations water technology report. It can be seen from formula2 that, the driving force of heat and mass transfer. The procedure is then applied to a popular cooling tower model, to illustrate. It is the loss of water from a cooling tower by evaporation. The effect of the air water ratio on counter flow cooling tower. A tower is sized to remove the chillers 12,000 btus plus 3,000 btus for the chillers parasitic heat. Two staves or sectors in series per cooling circuit. L mass flow of water entering the cooling tower lbmin t. If heat load calculations are low undersized equipment will be.
Cooling tower calculations cooling water treatment. Now if youre doing this for a real world example then i recommend you use a design software such as the danfoss coolselector app for speed and accuracy. Water savings of cooling tower efficiency measures for use in performance contracts. For example, a cooling tower sized to cool 4540 m 3hr through a. Cooling tower basics calculation formulas cooling tower. Design of mechanical draftcooling tower and determination. A tower ton is 15,000 btushour lets do another proof. The technical data has been taken from a mechanical draft cooling tower. A cooling tower is a heat rejection device which rejects waste heat to the atmosphere through the cooling of a. The recirculation rate and the temperature drop across the cooling tower are the two pieces of data needed to calculate the amount of water lost from the open recirculating cooling system due to evaporation. Basic concepts of cooling tower, types of cooling towers, formula for cooling tower efficiency makeup water, drift losses, evaporation losses. Formulas ra nge e ntering water tem per ature leavingwater temperature approa ch le avingw atertem per ature ambien twetb ulb temperature he at reje cted by a cooling tower.
Calculation of effect of cycles of concentration on amount. The following equation can be used for this calculation. Hi there, im involved a project where i must determine the power requirements of a forced draft cooling tower that uses a large fan. The method allows analytical calculation of cooling tower. Course contents evaporative coolers, often called swamp coolers, are cooling systems that use only water and a blower to circulate air. Several investigators have substantiated the effect of hot water temperature and air velocity on the counter flow tower. Seawater cooling tower drift rate the drift rate for a new cooling tower equipped with best available drift eliminators would be 0. Cooling tower efficiency calculations cooling tower approach. Conditioning formulas 1 btu amount of heat required to raise or lower temperature of one pound of water 1of 1 ton refrigeration 12,000 btuh 200 btumin 1 watt 3.
Cooling load calculations may be used to accomplish one or more of the following objectives. As this occurs, a small volume of water is evaporated, reducing the temperature of the water being circulated through the tower. Cooling tower efficiency calculations chemical engineering site. Cooling tower plays a major role in chemical process industry. 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. At these condi tions, the cooling tower rejects 15,000 btuih per nominal cooling tower ton.
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