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More details can be found in the “global status report on renewables 2018” (REN, 2018). 11.6.1 Energy efficiency factors Energy efficiency is the measure of the energy input to a machine to deliver a required output. A correct selection of refrigerant depends on a number of factors that should be considered in the TEWI/LCCP analysis, as follows: Fluid properties affecting / decreasing energy efficiency: - High viscosity drives increased compressor power, - Low latent heat of vapourisation drives increased mass flow rates - Temperature glide in blends reduces heat exchanger effectiveness unless the heat exchanger design utilizes the temperature glide; Mulroy (1988) showed a 30% increase in energy efficiency when matching the refrigerant temperature glide to the air side temperature glide. - Reduced thermal conductivity may reduce heat exchanger effectiveness - Specific heat capacity - Poor adjustment for the annual operation envelope; this includes system requirements for refrigerants with a low critical point such as R-744 in high ambient conditions. Application scope: 11.7 Energy efficiency is measured at individual components, refrigeration and air conditioning systems, and the surroundings (e.g. buildings). The energy efficiency at component level contributes to the upper levels, therefore efficiency is defined by proper design and application of each individual component as well as by the whole system design. Life cycle considerations Concepts and selection criteria for refrigerants for various applications, i.e., for each sector of the refrigeration and air conditioning industry, are presented in other chapters of this report. Selection criteria for refrigerants with regards to sustainability are described in section 11.4.1 in this chapter. The common understanding of sustainability applied to refrigeration among the different sectors is the need to design, operate, maintain, and take back refrigeration and air conditioning systems with minimised resource usage and emissions, both direct and indirect. Technical design criteria consider standards, regulations, as well as voluntary agreements. Energy use worldwide is increasing with the majority of growth expected in the non-OECD countries as can be seen in Fig. 11-2 (adapted from IEA, 2017). Energy demand between 2015 and 2040 is expected to grow by approximately 28%, or 3,770 million tons oil equivalent (mtoe) worldwide. The increase in global demand is forecast to come from non-OECD countries (i.e., developing countries). IEA expects that the OECD (developed) countries energy demand will decline by about 4% while non-OECD demand increase by 49% (GEI, 2017). Refrigeration consumes a large portion of the total energy consumption with a forecast increase of energy use, see Fig 11-3. According to the IIR, 17 % of all electricity used worldwide is being used for refrigeration and air conditioning (IIR, 2017). 2018 TOC Refrigeration, A/C and Heat Pumps Assessment Report 221PDF Image | Heat Pumps Technical Options
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