Standard

SAE J2766

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Merknad: Denne standarden har en ny utgave: SAE J2766

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Omfang

This recommended best practice outlines a method for estimating CO2-equivalent emissions using life cycle analysis. History Many companies and other organizations, including Daimler, Fiat, GM, JAMA, NREL (U.S.), Sintef (Norway), and TNO (the Netherlands), have conducted partial or complete life cycle analysis to evaluate the environmental impact of alternative refrigerant MAC systems. The life cycle analysis described here includes additional components that contribute to the CO2 equivalents that are attributed to MAC systems. It is commonly referred to as life cycle climate performance (LCCP) analysis and it is being used now for analysis of emission credits in the U.S. Studies conducted by JAMA performed partial life cycle analyses which assess the total equivalent warming impact (TEWI) of alternative refrigerants. TEWI consists of two terms: (a) the direct component, which is associated with the direct release of the chemical into the atmosphere, and (b) the indirect component, which is associated with the carbon dioxide (CO2) emissions emitted during the use phase of the MAC (Mobile Air Conditioning) system. Direct emissions result from the direct leaks of the refrigerant into the atmosphere and are an aggregate of the following emissions: Regular emissions, which refer to the refrigerant leaks from the A/C system during operation Irregular emissions, due to accidents, stone hits, product defects, etc. Service emissions, from garages during maintenance and repair End-of-life emissions, from the recovery or complete release of refrigerant at the end-of-life of the vehicle Leakage, during refrigerant production and transportation. Thus, the direct CO2 emissions are evaluated based on the GWP of each chemical and the amount of refrigerant mass emitted into the atmosphere. The direct emissions are expressed in terms of CO2-equivalent (CO2-eq.) emissions Indirect emissions result from the energy consumption associated with manufacturing, use, and disposal of the MAC system, and is an aggregate of the following CO2 emissions that result from: Manufacturing and end-of-life recycling processes of various refrigerants Manufacturing and end-of-life recycling processes of each component of the MAC system MAC operation, such as those associated with the operation of the compressor and engine cooling fan, during the lifetime of the vehicle Fuel consumption due to MAC’s mass transportation onboard the vehicle throughout the lifetime of the vehicle Thus, the indirect component is reported in terms of CO2 emissions, considering the carbon content of the fuel utilized in each process or during vehicle operation. The JAMA and NREL studies do not include the CO2 emissions associated with the end-of-life recycling processes. Furthermore, the NREL study considers only the indirect component of the TEWI. Studies conducted by GM assess the LCCP of alternative refrigerants. Such complete LCCP studies include more CO2 contributions as compared to TEWI. Assumptions and methodology for either TEWI-based or LCCP-based analyses can have a large impact on the conclusions, as it was indicated in the results presented by such studies. These updates to the SAE J-standard are the result of the SAE-IMAC-GHG-CRP efforts to improve the LCCP analysis model. The new tool is called the IMAC-GHG-LCCP tool. It reflects changes to improve the user interface and increase the operation speed as compared to the GREEN-MAC-LCCP tool. This tool uses data from the TMY3 database.          

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