Thursday 29.10.2015 at 22:51 By Richard Fennelly (author) in New York : New York
Maximising Commercial Refrigeration Performance
White Papers & Briefings, Energy Management, Energy Management & Conservation, Heating, Ventilating & Air Conditioning (HVAC)
Richard Fennelly, director of product development for CoilPod, discusses the relationship between condenser coil cleanliness and energy efficiency in commercial refrigeration applications.
Plug-in refrigeration and freezer appliances are in all types of commercial food outlets and institutions. They are major energy “hogs”, consuming a significant amount of electricity even when properly maintained.
Unfortunately, most owners/operators of these units do not follow an important maintenance task that is uniformly recommended by the manufacturers of such appliances: frequent cleaning of their condenser coils. The result? A significantly higher electricity bill for each non-cleaned unit.
In February 2015, the Food Service Technology Center (San Ramon, CA, USA) presented data at two conferences showing how costly non-cleaned units can be to the owner, particularly for units that have been in service for a few years. Four differing commercial refrigerator and freezer units were tested for their electric consumption at a rate of $US 0.11 per KwH with both dirty and clean condenser coils. The yearly per unit electric energy savings for the cleaned units ranged from $220 to $625, with the average being $383. All four units showed an electric energy savings ranging from 46% to 50%.
In summary, an appliance unit of this type, when running with dirty coils, can be expected to consume about DOUBLE the electric of a unit with clean condenser coils; when cleaned, the unit consumes about half of the electric when running as compared to a non-cleaned unit.
In addition, these non-cleaned units are said by experts:
(1) to run less efficiently as the coils become more dirty causing premature appliance ageing due to longer run times;
(2) to have an increased chance of unanticipated equipment failure because of higher pressures and operating temperatures; and
(3) to frequently be in the need of unnecessary service calls.
The Food Service Technology Center (www.fishnick.com) has stated that “dirty condenser coils are the main source of service calls”. They recommend that the condenser coil in these appliances be cleaned at least once every calendar quarter. More frequent cleanings are recommended in environments where the coils are subject to more dust/debris contamination.
Given the above, one might expect that owners of such plug-in cooling appliances would have an interest in regularly cleaning the condenser coils in these appliances. We think that this non-attention to this important cleaning task occurs because the visually non-appealing condenser coil assembly lies hidden behind a panel or grille. It appears to be a matter of “out-of-sight, out-of-mind” for most owners of such appliances. Any unacceptable buildup of dirt and debris is generally not noticed until a service technician discovers it when responding to an unscheduled service call when the unit begins to malfunction. A recent market study has projected that the market in just refrigerated display cases is slated to grow from about $8.8 billion dollars in 2012 to about $16.3 billion dollars in 2019. This issue will most likely grow exponentially, especially for plug-in units which are projected for almost 68% of this growth.
We have conducted preliminary analysis on the likely energy waste in our home country (the USA) in just the commercial refrigeration sector. Our conclusion is that it could approach $10.8 billion yearly. It is a major problem.
The above benefits for a condenser coil unit cleaning program accord with 75% of the issues deemed most important by attendees interviewed at the 2013 Star Refrigeration Roadshow, namely: energy savings/efficiency (26%); operating cost (18%); reliability (14%); maintenance (14%); and performance (3%). This topic needs to be front and center for any organization interested in maximum efficiency for these appliances. It appears to be higher hanging and as yet unpicked fruit on the energy efficiency tree.
Since the plug-in appliances containing these condenser units are often located in indoor environments, the traditional cleaning method has been to use either a combination of brushing and vacuum. In many cases this does not removed debris imbedded within the coil structure. In such cases, a supply of compressed air has been used to dislodge such debris from deep inside the coil structure. However, using compressed air is problematic since, unless contained, the debris blown off by the blast of compressed air will pollute the indoor environment necessitating additional cleanup.
Condenser coil cleaning in an indoor setting using compressed air has sometimes involved two persons with one person directing the compressed air through the coil structure towards the second person who attempts to catch the blown off debris. The capture media of choice normally needed to be a damp cloth of some type. Damp towels or cloths served the purpose. We have even heard stories of refrigeration technicians borrowing dirty butcher aprons on their way out to the laundry for the task. In any case, such damp capture media often blow off the unit during the cleaning operation causing a mess in the surrounding area. If they do stay in place, the result was a debris-encrusted cloth item needing disposal or possible cleaning at some point if multiple coil units need cleaning at the store location.
Only recently, there have been some developments to create dust containment mechanisms to replace the traditional damp cloth capture method. These approaches utilize engineered products that seal the coil unit structure so that the debris blown off by a compressed air stream is contained from release to the atmosphere until vacuumed into a suitable vacuum device. A leading example of such a product, the COILPOD dust hood, is shown in the photo. It is a bag-like structure covering the coils during the cleaning operation having dual ports for the entry of compressed air (from either the exhaust port of a wet/dry vacuum or, better yet, a separate compressed air cylinder) and vacuum, respectively.
It appears that a majority of the owners of these plug-in cooling appliances are failing to have preventative maintenance programs in place that do this type of cleaning as often as it should be practiced. This is unfortunate since significant energy savings and prolonged appliance life are the results of doing the cleaning as recommended by the manufacturers and respected third party experts.
Visit www.coilpod.com for additional information.