ORIENTAL COLLEGE OF TECHNOLOGYSession: 2016-17

Presented ByName : Ayush BalagopalRoll no:0126ME141038ME - V Semester

Guided By:Name : Prof. Abdul Hameed KhanDepartment of Mechanical Engineering

“Thermal Analysis Of Natural Draught Cross-Flow Cooling Tower With the Help Of CFD”

Rajiv Gandhi Proudyogiki Vishwavidyalaya, Bhopal

OBJECTIVE OF WORK

The Main Objective Of My Proposed Work is take different air entering angles and check cooling effect of that angles

CONTENTS Abstract Introduction Application of ETHE Literature Review Design Parameter Experimental Setup Experimental Result Calculations CFD Analysis conclusion Future Scope References

What is the cooling tower ? A cooling tower is a secondary heat transfer

device in any typical Thermal power plant. A primacy heat transfer equipment such steam condenser needs large quantities of cooling water which needs to be cooled externally using a secondary device such as a cooling tower. One of the earliest and simplest cooling towers available is a nature draught cross flow type. Plat 1 and 2 show photographic views of typical natural draught cooling tower used in power plants.

INTRODUCTION Cooling is an important operation on all chemical and on many other

types of industrial plant. Large quantities of heat have often to be removed from the plant fluids, and water is one of the most readily available agents to which this heat may be transferred. To give some idea of the quantities of water involved, it may be noted that a large power station can require cooling water at a rate of about 15,000,000 gallons per hour, while one large chemical works pumps water from a river at the rate of over 7,700,000 gallons per hour. The most obvious source of water for a large industrial plant is a river, estuary, or canal, in fact many such plants are sited near to suitable bodies of water of this kind. It is clear from the foregoing that the large-scale use of cooling water may not always be consistent, for practical or economic reasons, with the use of a one – through cooling system, i.e. of a system in which the water, after passing once through the plant coolers, is discharged to waste. Under this condition, the use of a circulating system may become advisable. In this system, the water leaving the plant coolers is not allowed to run to waste but is circulated repeatedly, first passing through some device, such as a water cooling tower, in which the heat picked up from the plant fluids is transferred to the atmospheric air. In this way, it is much more economically water system then from canal.

Types of cooling tower

1-Mechanical cooling tower. 2-natural draft cooling tower. 3-Induced draft cooling tower. 4-Forced draft cooling tower.

Categorization by air-to-water flow

Cross flow is a design in which the air flow is directed perpendicular to the water flow (see diagram below). Air flow enters one or more vertical faces of the cooling tower to meet the fill material. Water flows (perpendicular to the air) through the fill by gravity.

Counter flow

In a counter flow design the air flow is directly opposite of the water flow (see diagram below). Air flow first enters an open area beneath the fill media and is then drawn up vertically. The water is sprayed through pressurized nozzles and flows downward through the fill, opposite to the air flow.

LITERATURE REVEIW The first serious attempt in cooling tower analysis seems to have

been made in 1907 when I. V. Robinson [1] produced a pioneer paper on natural draught towers. In this, the performance of the tower was reduced to a “figure of merit”. Unfortunately, being accustomed to working on condensers where the absorbent heat has a specific heat which is virtually constant, his calculations for the driving force were based upon the assumption that heat transfer depend upon the mean temperature difference instead of on the total heat content of the air. He also tried to determine a “friction constant” for the tower which combined the shell resistant and the water lift weight.

In 1922, P. Robinson and C. S. Roll [2] presented a thesis on cooling tower performance, followed by a theoretical analysis by Walker, Mc Adams and Lewis [3] in 1923. In both instances the investigators developed the basic equations for total mass and energy transfer, and considered each processes separately.

LITERATURE REVEIW The practical use of basic differential equation, however, was first

presented by Merkel [4] in which he combined the equations for heat and water vapour transfer and showed the utility of total heat or enthalpy difference as a driving force to allow for both sensible and latent heats. The basic postulation and approximations that are inherent in Merkel’s theory are:

The resistance for heat transfer in the liquid film is negligible. The mass flow rate of water per unit cross sectional area of the tower

is constant, i.e. there is no loss of water due to evaporation. The specific heat of the air – steam mixture at constant pressure is

the same as that of dry air. The Lewis number for humid air is unity. The analysis of cooling tower performance has been studied and

developed over the last century. Investigations on the performance and its factors have been widely studied. Heat and mass transfer are the core principles in these analyses.

LITERATURE REVEIW Bahidarah [5] stated that the method generally used for

cooling tower calculation was developed by Merkel over 70 years ago. The equation was presented in a differential from known as Merkel mathematical modelling and was used for describing the distributions of water and air-conditions along the cooling tower. However, an obvious disadvantage of Merkel equation was based on the assumptions that evaporation of water flow was neglected in energy balance and saturated air was at the exit. These assumptions made the results inaccurate.

A detailed explanation of the procedure for developing Merkel’s basic equation applied to counter – flow cooling towers was outlined by Baker and Shryock [6].

LITERATURE REVEIW Zubair [7] investigated the performance

characteristics through the cooling tower. The result showed that a majority mode of heat transfer rate is evaporation, where it was 62.5% of the total heat transfer rate at the bottom and about 90% of that at the top of the tower. Since evaporation is by far the most effective factor in cooling towers, the accuracy of the predicted conditions are directly dependent on it.

PrIVIOUS Work

The previous work of given field done on the given point

1.cop calculation 2.simple thermal analysis using

formulas 3.cooling effectiveness check only

28degree

PROPOSED WORK

First of all to take the reading by jp thermal plant by cooling tower regulating cometies

After that these reading to use in CFD softwer as diffrent air entering angles and to check how much angle give more effective ness.

THANKS

definition

Computational fluid dynamics (CFD) is a computer-based simulation method for analysing fluid flow, heat transfer, and related phenomena

such as chemical reactions. OR Computational fluid dynamics (CFD) is the use of applied mathematics,

physics and computational software to visualize how a gas or liquid flows -- as well as how the gas or liquid affects objects as it flows past. Computational fluid dynamics is based on the Navier-Stokes equations.These equations describe how the velocity, pressure, temperature, and density of a moving fluid are related.

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THANKS