Introduction; Cooling tower is completely misunderstood and is orphan merchandise. As cooling phrase is related to it, HVAC individuals have taken place of its good father.
Principle of Cooling Tower : Cooling Tower doesn’t work on principle of refrigeration. It works on adiabatic/Evaporation precept. Hence it really works on mass transfer, heat switch is just by product of mass transfer. If there isn’t any mass switch, no evaporation, there isn’t any heat switch of all and therefore no cooling.
Water can’t be cooled with lower than 30C approach. Hence cold water temperature achievable shall be 30C and greater than wet bulb temperature of air. Wet bulb temperature considered ought to be actual wet bulb temperature entry of entering air into cooling tower, not atmospheric wet bulb.
Precise wet bulb getting into in cooling tower i effected as a consequence of many elements. Heat supply near cooling tower, air motion of cooling tower is hindered; recycling because of measurement of tower and orientation of tower in respect to wind movement.
We shall talk about above factors in details now:
1. What is Cooling tower?
Basically cooling tower is process water recycling equipment, the place hot water is cooled to a atmospheric temperature, as a consequence of evaporation of fraction of circulating water (1 to 2%) which comes involved with circulating air and remaining (99 to 98%) water cools to chilly water temperature, and is recycled in system. Water misplaced is added as make up water.
2. Does Cooling tower cools the water?
Cooling tower just isn’t a refrigeration machine; it cannot cool water if there is no such thing as a heat input in system or temperature rise of system. Cooling tower will cool hot water to atmospheric temperature only. Fall in cooling tower temperature shall be same as rise in system.
Three. Cooling tower utilizes fan power, after which it must cool better than cooling tower without fan, natural draft or fanless one?
Fan just isn’t performing as compressor. It gives mechanical motion to air. It will increase G/L ratio. Therefore efficiency of fan sort tower may be greater than natural draft tower. But it can’t cool water less than atmospheric conditions.
4. Up to what temperature cooling tower can cool water?
Chilly water temperature from cooling tower relies upon upon primarily wet bulb temperature and cooling range.
Wet bulb is the lowest theoretical temperature, which the water can be, cooled. Virtually the chilly water temperature approaches however does not be equal to wet bulb temperatures, as a result of some drive is required for evaporation of water. This drive i.e. temperature difference between chilly water temperature and W.B.T. known as approach. Minimal approach (drive) is 30C.
Real strategy shall rely upon cooling tower design, primarily air to water contact and get in touch with time. This approach, therefore cold water temperature relies upon upon range additionally. Strategy is proportions to range. As for greater range (extra heat to be released per kg of water) more evaporation rates are required. Therefore more drive is required. Hence more approach is required.
Range and method relation for same cooling tower shall be as under: (wet bulb temperature: 24-280C)
5. Can cooling tower with fan cool water beneath wet bulb temp.?
Now W.B. is theoretical lowest temperature which will be achieved b adiabatic cooling on which cooling tower works. If we wish lower temperature than W.B., we must go for refrigeration and compressor shall be wanted. In cooling tower fan doesn’t work as compressor, and cooling tower with fan is not a refrigeration machine.
6. By growing fan energy can we get opproaches below 30C
Approach depends upon contact and phone time. There may be limiting L & G ratio to realize above as optimum. By growing fan power no finer consequence shall be achieved only fan power and and draft loss shall enhance.
7. How one can get finer approaches?
Contact and call time are proportional to top of tower. We’ve got to extend top to attain finer approaches. This will improve pumping energy as well fan energy and value of tower. Following desk give relation between height of tower and approaches.
Range : Eight-100C
eight. What other components needs to be stored in mind to pick out correct tower.
Other factors which effect cooling tower is recirculation and interference, recirculation is a part of discharge air coming into back into suction of air. Massive towers have more recirculating than smaller one. Rectangular tower has extra recirculation than spherical one. Longitudinal wind course can have lesser recirculation than perpendicular one. Decrease wind velocities have lesser recirculation, larger wind velocity more recirculation. By increasing fan cylinder top. Recirculation might be decreased.
Heat supply up wind of the cooling tower cab elevate the wet bulb temperature of the air coming into, the cooling tower, there by affecting its performance. Such heat supply may be heat/steam releasing gear in vicinity of tower or another tower in the quick vicinity. Restriction to the free movement of air to cooling tower also increases recirculation and interferences.
9. What must be superb location of cooling tower?
Cooling tower ought to be location in separate nook of manufacturing facility where there must be no restriction to free stream of air to cooling tower. Sufficient area needs to be left (1/3 to 1) size between two larger cooling tower say greater than a hundred’ in size to keep away from interference. Noise or vibration may not create drawback to neighborhood. Hot and humid, air can be discharged from cooling tower. Therefore location should such that it mustn’t create downside on account of dampness to vicinity. Larger cooling tower should be placed longitudinal to wind course to keep away from impact of recirculation. Superb position to rooftop.