Technology
Developing highly efficient products and systems to significantly reduced energy consumption and CO2 emissions is one of the biggest challenges of this century. Heating and cooling buildings requires large amounts of energy, and experts agree that there is significant potential for efficiency improvements in air conditioning chillers and heat pumps for building cooling and heating.
[Source: B. Wellig, B. Kegel, M. Meier: Verdoppelung der Jahresarbeitszahl von Klimakälteanla-gen durch die Ausnützung eines kleinen Temperaturhubes, Swiss Federal Office of Energy SFOE, 2006]
The Energy Efficiency Ratio (EER) of a refrigeration system and the Coefficient of Performance (COP) of a heat pump are strongly dependent on the internal temperature swing. For compression refrigeration systems and heat pumps, the internal temperature swing corresponds to the difference between evaporating and condensing temperature. For modern building services systems, temperature strokes between 10 K and 30 K are sufficient throughout the year.
Heat pumps and air-conditioning refrigeration systems are often operated at full load for only a few days or even hours a year. As a result, the annual coefficients of performance are heavily dependent on partial load efficiencies. With turbo compressors, high compression efficiencies are possible at low pressure ratios in full-load and also in part-load operation. Consequently, turbo compressors are well suited for building heating and cooling applications, especially with small temperature strokes. The annual coefficients of performance possible with turbo compressors can be significantly higher than with other compressors.
State of the art
The use of turbo compressors in compression refrigeration systems and heat pumps originated in 1922 [Source: National Museum of American History, “Carrier Centrifugal Refrigeration Compressor.” [Online]. [Online]. Available: http://americanhistory.si.edu/collections/search/object/nmah_846092. [Accessed: 23-Aug-2018]], when the first centrifugal turbo compressor was introduced for these applications. Today, turbo compressors are widely used, especially in larger plants with up to several megawatts of cooling or heating capacity.