Cooling towers used to backup or restore the water. In one design, the hot water is pumped from the condenser to the tower. No, it is sprayed into the tower basin. The water temperature decreases, as it gives off heat of air circulating through the cooling tower. Some of the towers are rather large, so they operate with capacitors yielding to 1600 tons of cooling capacity (see Fig. 8-14).
Most of cooling that takes place in the tower results from the evaporation of the water as it falls through to the tower.
The lower the wet bulb temperature of the incoming air, the more efficient air decrease in temperature of water entering the tower. The following factors influence the effectiveness of the tower:
The average difference between saturated vapor pressure, air and pressure in a water tower
The duration of exposure and the amount of water surface is exposed to the air
The speed of the air through the tower
The direction of air flow relative to the exposed water surface (parallel, transverse, or counter)
Theoretically, the lowest temperature to which the water can be cooled air temperature (wet bulb temperature) entering the tower.
However, from a practical point of view, it is impossible to achieve air temperature In most cases the temperature of the water leaving the tower will reach at least 7 to 10F (14 to 12C) above, the air temperature.
The range of tower-water temperature on the cooling tower and the temperature of water coming from the tower. In this range should be adapted to the operation of the condenser is to ensure maximum efficiency.
The cooling capacity of the machine automatically adjust the cooling load changes in the position of the compressor inlet guide vanes) (see Fig. 8-13).
The temperature sensing device in the circuit cooling water at the outlet of the machine steeper constantly transmitting signals solid state module in the car-control center. Module, in turn, transfers increases and modulated signals temperature for automatic guide vane actuator.
The fall of temperature chilled water outlet chain of causes of guide vanes to move in the direction of " closed". This reduces the rate of evaporation of the coolant and the steam flow to the compressor. Machine capacity decreases. Increasing the temperature of the chilled water opens the blade. More refrigerant vapor passes through the compressor and increase capacity.
Modulation of temperature control center allows precise control of the guide vane answer regardless of the load on the system.