| dc.description.abstract | Cooled water is necessary for air conditioners, manufacturing processes, power
generation and many other purposes. Cooling tower is an equipment used to reduce the
temperature of water by extracting heat from water and emitting it to the atmosphere. Cooling
towers are able to lower the water temperatures more than other devices that use only air to
reject heat, like the radiator in a car and are therefore more cost-effective and energy efficient.
In the past most of the processes requiring cooling used piped town water through the
equipment. After cooling the equipment the water was drained to the gutter. So, the water was
totally wasted after using it once. Cooling towers were introduced so that the wastage of water
can be reduced by recycling the water. Cooling towers make use of evaporation. Some of the
water is evaporated into a moving air stream and subsequently discharged into the atmosphere.
The evaporation process only takes place on the surface of a liquid and needs latent heat of
vaporization to happen. Sensible heat is drawn from the body of the water to the surface to
supply the energy needed for the latent heat. It can be seen that for a little evaporation a lot of
sensible heat will be needed therefore the main body of the circulating water is cooled for very
little loss of water.
The main purpose of this study is to work on developing mathematical model for
cooling tower and examine methodically the performance of a model of closed loop 10 ART
counter flow induced draft bottle type cooling tower which has been developed only for this
project purpose.
A detailed mathematical model for a counter flow induced draft cooling tower has been
developed using Merkel Theory. Dr. Merkel developed a cooling tower theory for the mass
and sensible heat transfer between the air and water in counter flow cooling tower. Several
experiments has been conducted by changing the L/G (L= water flow rate; G= air mass flow
rate) ratio with the help of changing the flow rate (L) of water to observe the behavior of
different characteristics, represented in graphical form. Tower characteristics graph has been
plotted at 90%, 100% and 110% water flow rate. The performance prediction of cooling tower
related with the performance curves by means of the simple method is made by a few design
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parameters as well as water flow rate, L/G, KaV/L (Tower Demand), range, cold water
temperature, wet bulb temperature, and fan BHP. The performance prediction by the detail
method is requiring all the actual cooling tower dimensions, thermal rating conditions, and all
the mechanical rating conditions. Calculation of pump selection for the circuit has been shown.
The efficiency obtained from the experiment we have conducted varies from 35% to
45% which indicates the good performance of the system we have developed. | en_US |
