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Climate change is a global issue affecting every industry. Automotive companies have been working to address this issue by reducing the greenhouse gas emissions of their vehicles. EPA has encouraged this by providing incentives in the Greenhouse Gas Emissions Rule of 2009. Improving the efficiency of MACs (mobile air conditioning systems) is part of this effort. Life-cycle climate performance (LCCP) is a comprehensive metric for estimating the greenhouse gases emissions produced by the construction, operation, and end-of-life recycling of a vehicle MAC (Mobile Air Conditioning) system. Many companies and organizations have conducted LCCP for their vehicles using various software tools.

The EPA has issued regulations in the Final Rulemaking for 2017-2025 Light-Duty Vehicle Greenhouse Gas Emission Standards and Corporate Average Fuel Economy Standards (420r12901-3). This document provides credits against the fuel economy regulations for various Air Conditioning technologies. One of these credits is associated with increased use of recirculation air mode, when the ambient is over 24°C (75°F.). The authors want to communicate the experiences in their careers that highlighted issues with air quality in the interior of the vehicle cabin. Cabin contamination sources may result in safety and health issues for both younger and older drivers. Alertness concerns may hinder their ability to operate a vehicle safely.

The United States Environmental Protection Agency (EPA) as well as the European Commission (EC) are developing test procedures to regulate mobile air conditioning system (MAC) efficiency to reduce greenhouse gas emissions and reduce global warming. In the United States, air conditioning related MAC credits can be earned by implementing an internal heat exchanger (IHX) into a MAC system. By integrating an IHX into a MAC system the, Coefficient of Performance (COP) can be increased at the same time increasing cooling capacity. This improvement in efficiency reduces the energy and/or fuel consumption of the MAC system. This paper will compare various IHX plumbing configurations for a dual evaporator system with R1234yf refrigerant. A MAC system optimized for efficiency as well as evaporator cooling capacity is used to assess these different IHX plumbing configurations.

This paper will compare systematically coaxial and non-coaxial internal heat exchanger types on the component and the system level as applied to R1234yf mobile air conditioning (MAC) systems. Pressure drop, heat transfer rate, effectiveness, and efficiency ratio of the Internal Heat Exchanger (IHX) are compared on the component level for the different heat exchanger types. At the system level, a MAC system optimized for efficiency as well as evaporator cooling capacity is used to assess these different internal heat exchanger types. System level factors that will be discussed include IHX heat transfer rate, pressure drop, compressor efficiency, compressor discharge temperatures, and the impact of these factors on the efficiency and capacity of the MAC system. This paper also describes the test bench used for the system level tests and the testing procedure applied.

This paper will examine a mobile air conditioning (MAC) system optimized for efficiency as well as evaporator cooling capacity. Different internal heat exchanger (IHX) capacities and various thermostatic expansion valve (TXV) parameters will be applied using R1234yf refrigerant. Factors that will be considered include IHX heat transfer and pressure drop, TXV superheat setting and slope, the effect of oil in circulation and how these factors impact the efficiency and capacity of the MAC system. The paper describes the test facility used and the test procedures applied.

This paper will examine the various design and performance criteria for optimized internal heat exchanger performance as applied to R134a and HFO-1234yf systems. Factors that will be considered include pressure drop, heat transfer, length, internal surface area, the effect of oil in circulation, and how these factors impact the effectiveness of the heat exchanger. The paper describes the test facility used and test procedures applied. Furthermore, some design parameters for the internal heat exchanger will be recommended for application to each refrigerant.

The purpose of this article is to study current refrigerant emission levels in China with reasonable accuracy of the first year vehicles. This is an initial survey on refrigerant irregular emissions based on JD Power investigation and warranty data from OEMs in 2008. Totally 49 brands and 8881 vehicles were included for the study, covering almost all the kinds of passenger vehicles in China market. Irregular emissions represent the refrigerant losses due to accidents and other environmental-related failures of the mobile AC system. This paper also wants to draw people's attention on irregular refrigerant emissions related to system design and reliability which is not focused yet. According to the calculation of irregular emissions from China vehicles by J.D Power result, the irregular emission is 5.8 g/yr, which can be a reliable number used in the GREEN-MAC-LCCP© model for China vehicles' refrigerant emissions.

The European f-Gas Directive phases out HFC-134a from Mobile Air Conditioning systems (MACs) in new vehicles by 2017. In the US pending California and USEPA regulations have incentives to phase out HFC-134a earlier than 2017. As a result industry is striving to transform all global markets to a single new refrigerant in order to simplify global marketing. One of the global tools to help evaluate alternatives during this transition is the global LCCP (Life Cycle Climate Performance) and the development of the GREENMAC- LCCP© model. This model has become the global standard to measure the Life Cycle Analysis (LCA) greenhouse emissions of any proposed alternative refrigerant for MACs starting from bench test results and supporting the car manufacturer choice of the best suitable alternative refrigerant from an environmental perspective.

The model for Life Cycle Climate Protection [LCCP] that has been developed under the guidance of the Interior Climate Control Committee has been expanded to consider global regions and the impact of vehicle populations in each region. As part of this project, there have been discussions concerning the impact of relative perceived comfort by the different world regions and how this might be comprehended in the model. The model uses an A/C on percentage for each region based on a comfort model developed by NREL [National Renewable Energy Lab]. Some have questioned if this is correct for all regions, as perceived comfort may be different in each region. In order to obtain actual comparison data on the different acceptable occupant comfort level requirements, the SAE Interior Climate Control Standards Committee conducted a mini-ride to evaluate perceived comfort by evaluation team members from different global regions.

The GREEN-MAC-LCCP© [Global Refrigerants Energy & Environmental - Mobile Air Condition - Life Cycle Climate Performance] model described here is an evolution of a previous GM model that assesses the lifecycle energy and GHG emissions associated with the production, use and disposal of alternative refrigerants and MAC components. This new model reduces the complexity of inputs and provides a consistent output analysis. This model includes Microsoft Excel Visual Basic© code to automatically make the calculations once inputs are complete.

The goal of this study is to assess the total Life Cycle Global Warming Impact of the current HFC-134a (R134a) refrigeration system and compare it with the effect of proposed alternatives, HFC-134a Enhanced, HFC-152 (R152a), R744, R744 Enhanced and R290, based on life cycle analysis (LCA). The enhanced systems include control strategies to elevate the compressor suction pressure as the evaporator load is reduced. The hydrofluorocarbons HFC-134a and HFC-152a are greenhouse gases (GHGs) and are subject to the Kyoto Protocol timetables, which when the treaty takes effect will require participating developed countries to reduce their overall CO2 equivalent emissions of six GHGs by at least 5% by 2012 from 1990 levels.

In recent years, climate protection has become as important as ozone layer protection was in the late 1980's and early 1990s. Concerns about global warming and climate change have culminated in the Kyoto Protocol, a treaty requiring its signatories to limit their total emission of greenhouse gases to pre-1990 levels by 2008. The inclusion of hydrofluorocarbons (HFCs) as one of the controlled substances in the Kyoto Protocol has increased global scrutiny of the global warming impact of HFC-134a (called R-134a when used as a refrigerant), the current mobile air conditioning refrigerant. Industry's first response was to begin improving current R-134a systems to reduce leakage, reduce charge, and increase system energy efficiency, which in turn reduces tailpipe CO2 emissions. An additional option would be to replace the current R-134a with a refrigerant of lower global warming impact. This paper documents the use of another HFC, R-152a, in a mobile A/C system.

The overall vision of this project was to develop a new technology that will be an enabler to reduce design and development time of HVAC systems by an order of magnitude. The objective initially was to develop a parametric model of an automotive HVAC Windshield Defrost Duct coupled to a passenger compartment. It can be used early on in the design cycle for conducting coarse packaging studies by quickly exploring “what-if” design alternatives. In addition to the packaging studies, performance of these design scenarios can be quickly studied by undertaking CFD simulation and analyzing flow distribution and windshield melting patterns. The validated geometry and CFD models can also be used as knowledge building tools to create knowledge data warehouses or repositories for precious lessons learned.