commercial refrigeration, evaporator fan motor
Evaporator fan motors used in commercial refrigeration applications are fractional horsepower in size, are responsible for moving air across the evaporator coil, and typically run at one speed. Historically, shaded-pole motors have been the most commonly used evaporator fan motors in commercial refrigeration equipment and beverage vending machines. These motors, a type of single-phase AC induction motor, are the simplest and least expensive type of fractional-horsepower motor. They are also the least efficient, with the common 9â€“12 W sizes exhibiting an efficiency of approximately 20%. Electronically commutated (EC) motors, also known as brushless DC motors, became widely commercialized in the late 1980s, and their use in commercial refrigeration applications has increased within the last 10 to 15 years because of economic incentives and regulatory requirements. Another motor type, the permanent split capacitor (PSC) motor, offers a mid-point between shaded-pole and EC motor price and efficiency levels. Typically for commercial refrigeration evaporator fan motor applications, EC motors are 66% efficient and PSC motors are usually about 29% efficient. Â A new motor technology, a type of permanent magnet synchronous AC motor that can directly use grid-supplied AC current without the need to rectify to DC, has recently been commercialized. This new motor has the potential to significantly reduce the energy consumption of evaporator fans in commercial refrigeration equipment. Previously, synchronous motors have been prohibitively expensive for evaporator fan applications because of the high cost of the electronic control circuit that is required to bring the synchronous motor up to synchronous speed. However, this new motor technology makes use of a novel patent-pending controller that is simpler and lower in cost than previous synchronous motor controllers or EC motor controllers, making the new motor a cost-effective alternative in the commercial refrigeration market. Â In this paper, the results of field demonstrations, consisting of side-by-side measurements of the power consumption of the new motor technology versus shaded-pole, PSC, or EC evaporator fan motors in identical refrigerated display cases, are presented. Measured quantities include fan motor power, current, and power factor, as well as display case discharge and return air temperatures and ambient store temperature. Currently, field demonstrations are being conducted at six supermarkets and commissaries located in Kansas City, MO, San Antonio, TX and San Diego, CA, with the duration of these tests ranging from approximately one month to over six months. Initial results from the field demonstrations indicate that the new synchronous AC motor technology is approximately 20 to 30% more energy efficient than existing EC motors and nearly 80% more energy efficient than shaded-pole motors. In addition, the new motor exhibits a power factor of approximately 0.86, which is on average 40% greater than that of existing evaporator fan motors. Analyses indicate that retrofitting the installed base of commercial refrigeration evaporator fan motors with the new motors would produce a 68% evaporator fan site energy savings, or 4.9Ã—109Â kWh/year for the installed base of commercial refrigeration evaporator fan motors. This would result in an annual cost savings of $516 million and reduce the annual CO2 equivalent emissions by 8.1Ã—109Â lb.