Nelumbo, Inc., 26225 Eden Landing Rd, Hayward, CA 94545, USA.
Lawrence Berkeley National Laboratory, 1 Cyclotron Rd., Berkeley, CA 94720, USA.
Sci Total Environ. 2020 Nov 1;741:140312. doi: 10.1016/j.scitotenv.2020.140312. Epub 2020 Jun 18.
A global rise in HVAC-R utilization requires a deeper understanding of the industry's effect on electricity consumptions and greenhouse gas emissions. The Total Equivalent Warming Impact (TEWI) methodology was designed to analyze emissions from direct release of refrigerant and indirect emissions through electricity consumption of HVAC-R systems to increase the understanding of system design on emissions, and to guide refrigerant replacement. However, the original TEWI calculation neglects the system degradation due to corrosion. This paper studies on the impact of corrosion and highlights how the original TEWI method underrepresents the lifetime emissions due to energy efficiency decrease and refrigerant release. Corrosion impacts direct emissions by increasing refrigerant leakage rates over time and indirect emissions through heat exchanger efficiency degradation and suboptimal refrigerant level. A modified TEWI equation is proposed to capture the dynamic corrosion impacts over the lifetime of HVAC operations. Three scenarios (low corrosivity, conservative and moderate corrosivity) are examined to analyze different corrosion environments. This analysis indicates 6%-27% increase in TEWI emissions based on a typical residential air conditioner (AC), when the impacts of corrosion are included, with the greatest emissions increase from reduced electrical efficiency. The impact of several current and future corrosion protection scenarios on TEWI are also included. Appropriate corrosion mitigation can reduce total lifecycle emissions of systems by 6% ~ 10%. The proposed modified TEWI method is expected to provide a more accurate emission estimation for AC sustainability and policy making.
全球暖通空调制冷剂用量的增加，需要我们更深入地了解该行业对电力消耗和温室气体排放的影响。总等效变暖影响（TEWI）方法旨在分析制冷剂直接排放和暖通空调系统电力消耗产生的间接排放的影响，以提高对系统设计排放的理解，并指导制冷剂的替代。然而，原始的 TEWI 计算忽略了因腐蚀而导致的系统退化。本文研究了腐蚀的影响，并强调了由于能源效率降低和制冷剂泄漏，原始 TEWI 方法如何低估了整个生命周期内的排放。腐蚀会通过随着时间的推移增加制冷剂泄漏率来直接影响排放，并通过热交换器效率降低和制冷剂不足来间接影响排放。提出了一个修正的 TEWI 方程来捕捉暖通空调运行整个生命周期内的动态腐蚀影响。研究了三种情况（低腐蚀性、保守和中等腐蚀性）来分析不同的腐蚀环境。分析表明，在考虑腐蚀影响的情况下，典型的住宅空调（AC）的 TEWI 排放量增加了 6%-27%，其中最大的排放量增加来自于电力效率的降低。还包括了几种当前和未来的腐蚀防护方案对 TEWI 的影响。适当的腐蚀缓解措施可以使系统的整个生命周期排放量减少 6%至 10%。所提出的修正 TEWI 方法有望为 AC 的可持续性和决策制定提供更准确的排放估算。
