Design, installation and operation of the evaporative
condensers.
To
maximize energy efficiency of the refrigeration plant, evaporative condensers
should be designed, installed and operated properly. What does this
means?
Many refrigeration plants have multiple evaporative
condensers and these condensers should be installed as parallel circuits. Hot
gas enters the condenser and condenses into liquid ammonia, ammonia condensate
should freely flow out of the condenser. To operate properly, the condenser
should be free of liquid ammonia. At parallel installation and operation it can
be done if the pressure drop in each condenser is equal. However, this is not
possible in real life. Based on design, installation and operation, every
condenser has different pressure drops. Liquid ammonia of the condensers with
greater pressure drops will back up into these condensers. Heat transfer surface
and capacity of mentioned condensers will be reduced. To solve this issue, each
condenser should have a drain line trap. Height of these traps should be at
least 5 ft (1.5 m). However, many professional engineers prefer to have trap
height of 8 - 10 ft (2.4 - 3 m) to make sure that evaporative condensers are
free of liquid ammonia.
To
maintain energy efficient operation of the evaporative condensers, ammonia
system should be free of non-condensable gases. Check proper operation of the
air purger on a regular basis. Each purge point should be purged separately.
Make sure that purge points are not flooded with liquid ammonia, otherwise
non-condensable gases can not be purgered and energy efficiency of the plant
will suffer due to increased condensing pressure or increased condenser energy
use.
Most likely no other error in refrigeration systems is
as often made or has a great an impact on satisfactory performance of the
refrigeration plant as the design, installation and operation of the evaporative
condensers.