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View Subscription Details: Letter ( 07/04/2006 ) - HTML Format

Misconceptions in Industrial Refrigeration
 
There are several misconceptions in our industry, related to energy efficiency.

1. Energy savings are not so important to us (compared to production or safety), because energy costs are not a significant part of total expenses.

In our time, may be energy costs are not a major part of total expenses of production facility, but price of energy is steadily going up. As the demand for energy increases and the finite energy resources of our planet are depleted, the value of energy in the future will continue to increase.

However, in my opinion, the major factor for improving energy efficiency is global warming. In Europe, governments require food companies to reduce energy consumption up to 20 %. Sooner, rather than later, these requirements will come to North America. Stay ahead of regulations. It is more expensive and inconvenient to adjust to regulations, than to develop business according to political mega trends.

2. We have energy efficient refrigeration plant, because it is new and it has sophisticated PLC, VFDs.
Energy saving equipment just gives you an opportunity to keep the best set points and operating strategies. I have visited many refrigeration plants in Ontario and very often people do not use the optimum set points and operating strategies. Several refrigeration plants have very good energy saving feature as wet bulb approach for head pressure control. Unfortunately, some companies do not use this feature at all and operate their refrigeration plants at constant head pressure 120-150 psig all year around. Other companies are using this feature, but they have wrong setting for wet bulb approach. I suggest for every company to check your settings and operating strategies with energy efficiency expert. You do not need significant investment for this step and your payback will be within a few months.

3. Energy savings is a tricky business. Sometimes you have savings, sometimes you do not. 
Recently, one manager told me that he was approached by many contractors and sale persons with proposals to sell energy saving equipment. They promised him a very good payback. This manager was concerned about an estimation of potential energy savings. 

Every energy saving estimation is based on certain assumptions. If these assumptions are accurate, the given estimation will be close to real life energy savings. Very often the sales persons exaggerate potential energy savings by using wrong assumptions.

Example. Compressor VFD costs $ 100,000. Potential annual energy savings is $ 40,000. Payback is 2.5 years.
It looks like a good investment. Potential energy savings were estimated for average compressor capacity 20 % and average head pressure 150 psig. In real life, capacity of trimming compressor with VFD will change from 10 % to 100 %. Average capacity would most likely be ( 100 + 10 ) / 2 = 55 %.
Head pressure for this estimation should be chosen around 120 psig because for 60 % of total operating time, this plant has 110 psig head pressure. For average capacity 55 % and average head pressure 120 psig, potential annual energy savings would be $ 20,000 or 5 years payback. 

To make the right decision, this manager should be an energy efficiency expert in industrial refrigeration. Probably, this is impossible. I have a suggestion to every company. Find your trusted independent (no brand preference) consultant in every area of potential energy savings (steam, electrical, refrigeration and etc.) These consultants will help you avoid unnecessary investments and they will give you valuable information to make the right decision.

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