Cool weather
When is the best time of the year to save energy?
Periods of cool weather is the best time to improve the efficiency of
refrigeration plants.
Why?
To
run a refrigeration plant efficiently, it should be operated at optimum set
points. The best set points of the condensing pressure, suction pressure, hot
gas defrosting, etc. should be determined and implemented. However, different
ambient conditions require different effort to implement these set points.
Example.
During summer operation ambient air has wet bulb
temperature of 75°F. Optimum condensing pressure at these conditions is 150
psig. However, condensers of our plant are undersized and condensing pressure is
178 psig. To achieve optimum condensing pressure and to save energy, condenser
capacity should be doubled. This action requires significant investment and many
companies will not invest in additional condenser capacity.
During period of cool weather, optimum condensing
pressure was determined as 80 psig. However, there are several barriers to run a
refrigeration plant at such low condensing pressure. These barriers are hot gas
defrosting, liquid injection oil cooling, oil carry-over, etc., but every
barrier has a solution. During fall, winter and spring many refrigeration plants
run at minimum condensing pressure of 110 - 120 psig, because operation of these
plants are not optimized. Typically, optimization of the refrigeration plant
operation will require a small investment that is 10 - 20 times less than
investment in additional condensers.
Mother Nature gives us cool weather and the opportunity
to achieve significant energy savings without significant capital investments. I
suggest to every company to use this opportunity.