To meet the government's new energy standard for refrigerators a 30% reduction for units manufactured after July 2001 ORNL researchers have designed and demonstrated a "fridge of the future" that uses half as much energy as today's refrigerator-freezers (RFs) and one-fifth as much as 1972 models: the 1 kilowatt-hour per day refrigerator.
In a cooperative research and development agreement (CRADA) with the Appliance Research Consortium (ARC), a subsidiary of the Association of Home Appliance Manufacturers, researchers adapted a standard 1996 baseline 20-ft3 RF cabinet (shown as unit A in the table below) by adding various features that would improve energy efficiency.
The changes involved
These improvements, shown as unit C in the table below, cut power consumption to 0.93 kWh/day, a performance that exceeds the 2001 energy standard and that would save $6.5 billion annually if all the 125 million RFs in the U.S. operated as efficiently.
Because the addition of vacuum insulation panels results in a significant cost increase to RF units, researchers also tested the unit without the vacuum insulation. This modified unit (unit B in the table) would still be about 44% more efficient than the 1993 standard and would save $4.5 billion annually in the United States.
|Simple payback time
|B||Unit A with 2-in.-thick doors, high-efficiency compressor, low-wattage condenser fan, and adaptive defrost scheme||1.16||47.6||53.38||6.6|
|C||Unit B with vacuum insulation around freezer section and larger evaporator||0.93||36.5||134.33||11.4|
|*Percentage of time compressor runs each hour.|
The minimum energy use achieved by unit C, 0.93 kilowatt-hours
per day (kWh/d), is 45% lower than the energy use of the baseline
unit and 54% lower than the DOE-mandated maximum of 2.01 kWh/d
for this size of RF. Estimated manufacturing costs increased by
$134 for this system, resulting in an 11.4 year simple payback,
assuming the consumer's cost is twice the manufacturer's cost.
Prototype B achieved a minimum energy use of 1.16 kWh/d, with an
estimated manufacturing cost increase of $53 and a simple payback
of 6.6 years.
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