Cooling by evaporation is a natural occurrence. The most typical example all of us expertise is perspiration, or sweat. As perspiration evaporates it absorbs heat to cool your physique.
The precept underlying evaporative cooling is the fact that water will need to have heat utilized to it to vary from a liquid to a vapor. When evaporation occurs, this heat is taken from the water that remains within the liquid state, leading to a cooler liquid.
Evaporative cooling systems use the same principle as perspiration to supply cooling for equipment and buildings. A cooling tower is a heat-rejection gadget, which discharges warm air from the cooling tower to the ambiance via the cooling of water. Within the HVAC trade, the term “cooling toweris used to describe both open- and closed-circuit heat-rejection equipment.
In an HVAC system, heat is generated by the sun shining on the constructing, the computers, and other people. The heat is picked up within the air handlers which are indirectly tied to the refrigerant by means of several heat exchangers. The heat boils the refrigerant from a liquid to a vapor. Cooling Tower water is circulated by a heat exchanger where refrigerant vapor is condensed and heat is transferred to the water. The aim of the cooling towers is to cool the warm water returning from the heat exchanger so it may be reused. Within the open cooling tower, the heat return water from the heat exchanger is sprayed over the “fill The fill gives the surface space to enhance the heat transfer between the water and air, causing a portion of the water to evaporate. That cool water then loops again to the start of the process, to absorb more heat from the heat exchanger.
In a closed circuit cooling tower, cold water or a solution of ethylene or propylene glycol is used to supply cooling. Unlike in an open cooling tower, the fluid used to offer cooling is enclosed in a coil and isn’t uncovered on to the air. Cold water is recirculated over the outside of the coil, which comprises the fluid that has been heated by the process. Throughout operation, heat is transferred from the fluid through the coil to the spray water and then to the environment as a portion of the water evaporates. The cool fluid in the coil then loops again to the start of the method, to be reused in the process.
A ton of air-conditioning is the rejection of 12,000 BTUH. A cooling tower ton truly rejects about 15,000 BTUH as a result of heat-equivalent of the energy needed to drive the chiller’s compressor. A cooling tower ton is outlined because the heat rejection in cooling 3 GPM of water coming into at 95°F and leaving the cooling tower at 85°F, with an coming into wet bulb temperature of 78°F, which amounts to 15,000 BTUH.The determine under exhibits the relationship between water and air as they move by way of a cooling tower. The curve signifies the drop in water temperature (point A to B) and the rise in the air wet bulb temperature (Level C to D) in their respective passages through the cooling tower.
From a heat switch standpoint, a cooling tower’s performance while cooling a given quantity of water is influenced only by the wet bulb temperature of the entering air. That is clearly indicated within the psychrometric analysis of the air path in a cooling tower as indicated under. The true path is approximated by the dotted curved line from Point A to Point C. To simplify the air path for functions of clarification, it’s broken down into Line AB and BC. Within the evaluation, air enters the tower at an unsaturated condition (Point A). Before reaching the fill, it is saturated adiabatically as it travels to level B. Passing by way of the fill, it absorbs heat from the falling water, thereby growing the full heat content material of the air. Since the air is regularly being washed with falling water, the process follows the saturation line to the ultimate temperature of the air leaving the tower, Point C.
Throughout the adiabatic change, Point A to Level B, there is no cooling of the water. On this stage there is just a conversion of air sensible heat into latent heat as the air dry bulb temperature drops to that of the wet bulb temperature. The efficient heat elimination takes place between Factors B and C where the saturated air is at the wet bulb temperature. The wet bulb temperature of the air is the only air situation influencing the performance of the tower.