Evaporator Fan Controllers
Evaporator Fan Control: Automatic Two-Speed Control vs. Constant Speed
An evaporator fan controller monitors refrigerant flow or compressor drive motor amps and reduces the speed of evaporator fans when the compressor is off. Especially useful for walk-in coolers and freezers.
The founders of Energy Control Equipment, Inc., manufacturers of the Frigitek controllers, were motivated by an awareness of how much waste heat is created by evaporator fans in walk-in coolers. They started developing their first single-phase controller in 1998. This technology became commercially available in 2001. Since then, they have developed a three-phase model (in 2005) and an "ECM" model (in 2008 -- for ECPM [Electronically Commutated Permanent Magnet] motors, also known as ECMs [Electronically Commutated Motors]).
All three controllers work on the same basic principle. They monitor refrigeration flow in the system. When refrigeration is not flowing, they slow the evaporator fan down to reduce fan energy and reduce the extra load on the compressor caused by excess heat given off by the fan when it is running. Fan control is achieved through reducing the voltage supplied to the fan motor. As the controller reduces fan motor voltage from 115 V down to 20 V (in a single phase application) the motor speed is reduced from approximately 1,600 RPM down to as low as 400 RPM (E Source, 2005). Expected savings depend heavily on the run-time of the existing compressor:
- If run-time is 10%, energy savings from this technology can be 50% or more of overall refrigeration system energy.
- If run-time is 20%, energy savings may be closer to 25%.
In a U.S. Department of Energy (US DOE), Federal Energy Management Program (FEMP) test, savings varied widely, from 13% to 59%, but generally the off-time was about 2 to 2.5 times the percentage savings. For example, compressor off time before installation of 31% yielded 13% savings.
Energy Savings: 30%
Energy Savings Rating:
Comprehensive Analysis What's this?
|1||Concept not validated||Claims of energy savings may not be credible due to lack of documentation or validation by unbiased experts.|
|2||Concept validated:||An unbiased expert has validated efficiency concepts through technical review and calculations based on engineering principles.|
|3||Limited assessment||An unbiased expert has measured technology characteristics and factors of energy use through one or more tests in typical applications with a clear baseline. |
|4||Extensive assessment||Additional testing in relevant applications and environments has increased knowledge of performance across a broad range of products, applications, and system conditions. |
|5||Comprehensive analysis||Results of lab and field tests have been used to develop methods for reliable prediction of performance across the range of intended applications.|
|6||Approved measure||Protocols for technology application are established and approved.|
Simple Payback is one tool used to estimate the cost-effectiveness of a proposed investment, such as the investment in an energy efficient technology. Simple payback indicates how many years it will take for the initial investment to "pay itself back." The basic formula for calculating a simple payback is:
Simple Payback = Incremental First Cost / Annual Savings
The Incremental Cost is determined by subtracting the Baseline First Cost from the Measure First Cost.
For New Construction, the Baseline First Cost is the cost to purchase the standard practice technology. The Measure First Cost is the cost of the alternative, more energy efficienct technology. Installation costs are not included, as it is assumed that installation costs are approximately the same for the Baseline and the Emerging Technology.
For Retrofit scenarios, the Baseline First Cost is $0, since the baseline scenario is to leave the existing equipment in place. The Emerging Technology First Cost is the Measure First Cost plus Installation Cost (the cost of the replacement technology, plus the labor cost to install it). Retrofit scenarios generally have a higher First Cost and longer Simple Paybacks than New Construction scenarios.
Simple Paybacks are called "simple" because they do not include details such as the time value of money or inflation, and often do not include operations and maintenance (O&M) costs or end-of-life disposal costs. However, they can still provide a powerful tool for a quick assessment of a proposed measure. These paybacks are rough estimates based upon best available data, and should be treated with caution. For major financial decisions, it is suggested that a full Lifecycle Cost Analysis be performed which includes the unique details of your situation.
The energy savings estimates are based upon an electric rate of $.09/kWh, and are calculated by comparing the range of estimated energy savings to the baseline energy use. For most technologies, this results in "Typical," "Fast" and "Slow" payback estimates, corresponding with the "Typical," "High" and "Low" estimates of energy savings, respectively.