Cooling Tower

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. Common applications for cooling towers are providing cooled water for air-conditioning, manufacturing and electric power generation.

Types of Cooling Towers


The classification is based on the type of air induction into the tower: the main types of cooling towers are natural draft and induced draft cooling towers.

TR in Cooling Tower
 

A water-chiller refrigeration ton is defined as: 1 Refrigeration Ton (RT) = 1 TONScond = 12000 Btu/h = 200 Btu/min = 3025.9 k Calories/h = 12661 kJ/h = 3.517 kW. 1 kW = 0.2843 Refrigeration Ton (RT) A ton is the amount of heat removed by an air conditioning system that would melt 1 ton (2000 lbs.) of ice in 24 hours.

Natural Draft Cooling Tower
 

NATURAL DRAFT COOLING TOWERS. Our natural draft wet cooling towers have been used to cool water, primarily in energy production, for almost 100 year. The tower operates on the stack effect which causes the hot air in the tower to rise (natural draft).. The necessary stack can be designed in various ways.

Effectiveness of Cooling Tower


iii) Cooling tower effectiveness (in percentage) is the ratio of range, to the ideal range, i.e., difference between cooling water inlet temperature and ambient wet bulb temperature, or in other words it is = Range / (Range + Approach).

 

Efficiency of Cooling Tower
 

No Nonsense Water Treatment – Cooling Tower Efficiency and Approach. Cooling towers use the evaporation to cool the circulated water. They can achieve water temperatures below the dry bulb temperature – tdb – of the air cooling air but not the wet bulb temperature

 

Forced Draft Cooling Tower
Factory-assembled cooling towers can be crossflow or counterflow, induced draft or forced draft, depending on the application. While all applications are different, the factory-assembled Marley NC crossflow, induced draft tower is widely used for HVAC and light industrial applications.

Induced Draft Cooling Tower


The working fluid and the evaporated fluid (usually water) are one and the same. fluid coolers (or closed circuit cooling towers) are hybrids that pass the working fluid through a tube bundle, upon which clean water is sprayed and a fan-induced draft applied

Wet Bulb Temperature
 

At 60°F [15.6°C] wet-bulb temperature, the cooling tower approach temperature ranges from 9.0°F (5.0°C) at design load to 2.8°F (1.5°C) at a 29% load. Note the approach temperatures at a constant 100% heat rejection load (14°F [7.8°C] range)

 

Dry-bulb Vs. wet-bulb Temperature


Wet Bulb temperature can be measured by using a thermometer with the bulb wrapped in wet muslin. The adiabatic evaporation of water from the thermometer bulb and the cooling effect is indicated by a "wet bulb temperature" lower than the "dry bulb temperature" in the air

Approach Temperature


Water leaving the tower and ambient wet bulb is the driving force that creates the cold water. If a cooling tower produces 85°F cold water when the ambient wet bulb is 78°F, then the cooling tower approach is 7°F.

Cross Flow Cooling Tower
Cross flow is a cooling tower system design in which the air flow is directed perpendicular to the water flow. 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.

Drift in a Cooling Tower
 

Drift, however, is the undesirable loss of liquid water to the environment via small droplets that become entrained in the leaving air stream. ... Drift eliminators are designed to capture large water droplets caught in the cooling tower air stream.