Appliance Design - July 2008 - (Page 35)

CONTROLS & SENSORS W Responsive Refrigeration vide near-perfect evaporator heat absorption across a wide range of thermal load conditions. The result of this more precise control is significant utility cost savings, as well as prolonged equipment life. A typical refrigeration cycle schematic is shown in Fig. 1. This cycle is utilized in one form or another in all common refrigeration, air conditioning and heat pump appliances. The cycle uses a suitable refrigerant compound that is formulated to change phase from liquid to gas and vice versa, at suitable temperatures and pressures for a particular application. A typical home air conditioning application serves as a good example to illustrate how the cycle works. The cycle starts at the system compressor. The refrigerant at the compressor input is a cool, low-pressure gas. The compressor physically compresses the refrigerant into a hot, high-pressure gas, which then enters the condenser coil. Here the refrigerant changes phase from a hot, high-pressure gas to a hot, high-pressure ith global energy prices soaring to record high levels and no end in sight, appliance manufacturers struggle to find innovative and effective ways to improve energy efficiency. Among the most energyconsuming and expensive of all appliances are compressor-based heating and cooling systems. These include living space heating, cooling and comfort control equipment, as well as refrigerators and freezers that are present in millions of households and businesses throughout the world. And that is why any efficiency improvements to compressor-based equipment can have a significant impact on both the end-users and society as a whole. With that in mind, Freescale Semiconductor developed a control system that can be used in compressorbased home and commercial appliances to optimize refrigeration cycle efficiency. Specifically, the control system targets an important parameter called evaporator superheat. The control accurately monitors and controls this parameter to pro- Evaporator superheat control adapts to changing conditions. by virginia macdonald Virginia MacDonald is a product definer at Freescale Semiconductor Sensors and Actuators Solutions Div., Tempe, Ariz. applianceDESIGN July 2008 35 www.applianceDESIGN.com http://www.appliancedesign.com

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Appliance Design - July 2008 Contents Editorial Shipments/Forecasts News Watch Heating Elements Gas Technology Motors & Pumps Controls & Sensors Design Marts Association Report: AHAM Advertiser's Index

Appliance Design - July 2008

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