What is Refrigeration Operating Efficiency for Coolrooms and Freezers?

01 December 2016

Coolrooms and freezers are high-end engineering constructs, but they’re also influenced by intangible forces. There’s the mathematics of thermal envelopes to consider, plus the laws of thermal dynamics, rules that conserve energy within the refrigeration unit. Refrigeration operating efficiency is an important parameter here, one that determines how well the cooling space runs, but what factors subscribe to this calculable rating?

Refrigeration Operating Efficiency 

Performance coefficients are important in the walk-in coolroom and freezer sector because these oversized refrigerators consume more energy than any other appliance. Keep that fact in mind next time a coolroom door is left open for several minutes. Better yet, use unbiased science to work out the performance rating. The quotient we’re referring to uses an end-to-end binary, a series of summated figures that begins with input energy and culminates with the frosty output stage as cooling power.

Net Refrigeration Capacity 

There are two sets of energy variables at work, as illustrated above. Primarily, the refrigeration cycle uses chemicals and a proprietary mechanical system to create a chilled environment, but it’s an electrical input rating that raises the question of energy expenditure, for electricity is consumed, whereas chemical processes loop endlessly. Net refrigeration capacity, therefore, uses the input electrical power load and the output walk-in heat loading factor to calculate the energy capacity of the unit. As this figure gels, the capacity rating creates a unique profile of the rooms cooling envelope.

Assessing Contributing Mechanisms 

The fans in the refrigerator add to the electrical side of the loading factor, as do the light bulbs, door heaters, and pumps that dominate the power input variable. On the other side of the calculation, chemical refrigerants offer condensation savings while the compressor delivers mechanical economy. All of these accessories will obviously influence the efficiency ratio, so the furrowed brow on an engineer’s forehead will only deepen as he’s forced to resort to complex calculus equations. But, at the end of the day, we shouldn’t lose sight of the fact that this ratio is based on a coefficient that directly compares input power to output power.

Born out of a need to resolve loss factors and create an easy to illustrate performance coefficient, the refrigeration operating efficiency rating uses two sets of energy variables to achieve this feat. Input power, obviously, is electrical, but it’s split up into numerous components. Meanwhile, the output energy rating, which is defined by cooling power, is plugged into the ratio calculation as the second energy variable.

Mark Connelly
C&M Coolroom Services
E-mail: markconnelly@cmcoolrooms.com.au
Mobile: 0412 536 315

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