Application of LED in low temperature lighting

Power can be directly supplied through the LED Driver, making the efficiency of the entire transformer circuit as high as 90%, which has a great energy-
saving advantage. LED low-temperature lighting was first developed in 2002 by GELCORE and the American LRC Lighting Research Institute. Currently, Taiwan's LED packaging giants Everlight and Lite-On have both launched LED low-temperature lighting products. In 2008, some manufacturers launched household refrigerators with LED fresh-keeping technology, and the prospects are very promising. According to incomplete statistics, the global shipments of refrigerators and cold storage/freezers alone average hundreds of millions per year. If only 5 HighpowerLEDs are implanted in each unit, then the demand will be a huge market. With the increasing international calls for environmental protection and energy saving, it is estimated that LED low-temperature lighting will occupy the market share of low-temperature lighting systems with its greater advantages.

LED low-temperature lighting systems can maintain good luminous efficiency in low temperatures, and because they have light directivity, they can be designed under the shelves to make the illumination in the refrigerator more uniform. In recent years, they have been used to replace traditional fluorescent tubes in refrigerator/freezer low-temperature lighting systems. In 2008, home appliance manufacturers launched household refrigerators using LED fresh-keeping technology. Currently, Taiwan's major LED packaging manufacturers, including Everlight and Lite-On Technology, have launched LED low-temperature lighting products.

LEDs were used in low-temperature lighting in 2002 when GELCORE and the LRC Lighting Research Institute of the United States jointly developed a low-temperature lighting system, and installed the LED low-temperature lighting system in the refrigerators of PriceChopper supermarkets. Later, Wal-Mart invested 13 million US dollars in 2006 to introduce GELCORE's LED cold storage lighting system to more than 500 stores in the United States. According to data, the power consumption of this batch of LED cold storage lighting systems not only reduced energy consumption by 66% compared with traditional fluorescent tubes, but also saved 2.6 million US dollars in electricity bills per year. Currently, Wal-Mart has planned to introduce LED low-temperature lighting systems to all 6,000 stores around the world.

Mitsubishi Electric then launched LED low-temperature refrigerators/freezers in the third quarter of 2007 to replace fluorescent lamps on display shelves to improve the problem of low luminous efficiency of fluorescent lamps at low temperatures. In 2008, home appliance manufacturers have already launched household refrigerators using LED fresh-keeping and refrigeration technology, and the application of LED low-temperature lighting is accelerating.

At present, the global low-temperature lighting market can be divided into two major areas: refrigerators and cold/freezers. In 2006, the global shipment of refrigerators was 106 million units, and the shipment of cold/freezers was 58 million units. Among them, the global demand for commercial refrigerators/freezers is estimated to be more than 3 billion units, assuming that each door of commercial refrigerators/freezers uses 60 high-power LEDs. And the global demand for household refrigerators is estimated to be 500 million units, assuming that each backlight refrigerator uses 5 high-power LEDs.

Traditional refrigerators use 1-2 5-15W incandescent lamps, each priced at about $1, and refrigerators/freezers need 2-4 10-58W fluorescent lamps, each priced at an average of about $3-10. The total market size of low-temperature lighting for traditional refrigerators and refrigerators/freezers is about $400 million. With the advantages of LEDs being environmentally friendly and energy-saving, uniform illumination, good luminous efficiency at low temperatures, and power supply efficiency as high as 90%, Taiwan's LED packaging giants Everlight and Lite-On Technology have officially launched LED low-temperature lighting products.

Compared with traditional fluorescent lamps, according to the US Department of Energy, the electricity consumption of refrigeration equipment accounts for about 50% of the total electricity consumption of general supermarkets, and about 25% of the electricity consumption of refrigeration equipment is consumed in low-temperature lighting systems. When fluorescent tubes are used as refrigeration light sources, the mercury vapor pressure in the tubes is low, which makes the luminous efficiency worse. Only part of the light is irradiated on the surface of the refrigerated objects, resulting in uneven illumination of the illuminated objects and energy waste.

However, the luminous efficiency of LED lighting system decreases with the increase of temperature, but it is more efficient at low temperature. LED also has light directionality and can be designed under the shelf to make the illumination in the refrigerator more uniform. Therefore, in recent years, research and development of LED low-temperature lighting system has begun to replace traditional fluorescent tube low-temperature lighting.

As for the difference between CCFL and LED power supply, CCFL first needs to pass through the buck-boost DC/DC converter, which will consume 10% of the power, and then through the inverter to consume another 25% of the power, and finally only about 70% of the power is provided to the Fluorescenttube. But LED only needs to pass through the LED Driver to directly power it, making the efficiency of the entire voltage conversion circuit as high as 90%.