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Impellers are the core components of turbomachinery in petrochemical and aeronautical engineering. In addition to conventional manufacturing (CM), additive manufacturing (AM) and remanufacturing (RM) can also be used in impeller production. This article presents a life cycle assessment method comparing the environmental impacts of different impeller manufacturing methods, including plunge milling (CM), laser cladding forming (AM combined with CM), and additive remanufacturing (RM). Results show that RM is the most environmentally favorable option, followed by AM and CM, in terms of global warming potential (GWP), Chinese resource depletion potential (CADP), water eutrophication potential (EP), and acidification potential. However, AM is not always more environmentally friendly than CM. The comparison of impeller production by CM and pure AM, in this case, indicates that the environmental burden of production using pure AM is approximately twice than that of CM. Compared with CM, the RM of impellers would reduce GWP, CADP, and EP by 64.7%, 66.1%, and 75.4%, respectively. The results of this study contribute to a scientific basis for the selection of manufacturing methods and the sustainable manufacturing of impeller production enterprises. [ABSTRACT FROM AUTHOR]

The application of Liquefied Natural Gas (LNG) in vehicles is considered to be an important way to solve the energy and environmental problems. In China, many waste diesel engines are beginning to be remanufactured to LNG engines. In this study, a life cycle assessment is carried out to quantify the energy saving and environmental emission of a remanufactured LNG engine and newly manufactured diesel engine, both engines are compared by means of material usage, cumulative energy requirements and environmental emissions over the entire life. The results show that, compared with diesel engine newly manufacturing, LNG engine remanufacturing could reduce 42.62% of primary energy demand (PED); the environmental impacts reduction of acidification potential (AP) and nutrient enrichment potential (EP) could reach to 69.61% and 71.34%, which are most distinct; global warming potential (GWP) and photochemical ozone formation potential (POCP) can be reduced by 46.42% and 43.90% respectively. [ABSTRACT FROM AUTHOR]

Carbonaceous deposits can reduce the durability and performance of diesel engines. Chemical cleaning methods are widely used to remove the deposits in remanufacturing industry but the wasted liquid is harmful to the environment. In this paper the supercritical CO 2 cleaning technology, an environmentally friendly approach, has been used to remove these contaminants. The surfaces of diesel engine valve before and after cleaned were examined by field emission scanning electron microscope (FE-SEM) and Fourier transform infrared spectroscope (FT-IR). The testing results showed that most organic compounds were dissolved and the stubborn contaminants were changed to be removed easily after cleaning by supercritical CO 2 fluid. The new cleaning method can reduce carbonaceous deposits significantly without changing the surface properties of the diesel engine valve. [ABSTRACT FROM AUTHOR]

Life cycle assessment (LCA) enables us to estimate potential resource and energy consumption as well as environmental emissions resulting from various activities within our economy. The present LCA intends to analyze the energy consumption and environmental emissions of the entire life cycle of an originally manufactured diesel engine compared with its remanufactured counterpart. Further, the article attempts to identify the processes in diesel engine manufacturing and remanufacturing life cycles that contribute most to energy consumption and environmental impacts. Six environmental impacts were assessed in this study: global warming potential (GWP); acidification potential (AP); eutrophication potential (EP); ozone depletion potential (ODP); photochemical ozone creation potential (POCP); and abiotic depletion potential (ADP). The results show that diesel engine remanufacturing could reduce 66% of energy consumption, compared to original manufacturing. The greatest benefit related to environmental impact is with regard to ODP, which is reduced by 97%, followed by EP, GWP, POCP, AP, and ADP, which can be reduced by 79%, 67%, 32%, 32%, and 25%, respectively. In the life cycle of diesel engine manufacturing, production of materials brings about larger environmental impacts, especially with regard to EP and ODP, whereas transportation of materials contributes most to POCP. The situation is similar for diesel engine remanufacturing. Production of materials brings about larger environmental impacts with regard to AP, EP, and ODP, whereas components remanufacturing and production of materials exhibit the same amount of GWP impact. Further, in remanufacturing, the reverse logistics of old diesel engines brings about lesser environmental impacts than the other life cycle stages, except with regard to POCP. [ABSTRACT FROM AUTHOR]

Abstract: This paper reports a method of on-line recycling for abrasives while using abrasive water jet to clean components to be remanufactured. It uses a stirring overflow separator to realize the separation of abrasives and dirt. Abrasives are broken into pieces due to the impact in cleaning process, and the contamination cleaned off mingles with abrasives suspension, all of which seriously influence the cleaning effect. Meanwhile, as new high-tech abrasives (such as ceramic abrasive, silicon carbide abrasive) appear continuously, the proportion of abrasives in wet abrasive blasting cleaning cost is increasing. Thus, it's more important to reuse the abrasives. The recycling of abrasives makes the abrasive water jet cleaning greener, more economical, and more sustainable. [Copyright &y& Elsevier]

Abstract There have been various restoring technologies in remanufacturing industry for the recovery of designed dimension. The life cycle environmental performance, economic benefits, and quality reputation of remanufactured products are influenced by the restoration process. An appropriate selection of restoring technology would enhance the sustainability and assure the quality requirement of remanufactured products. The primary objective of the present study is to develop an effective and comprehensive multi-criteria decision-making approach for the application to the remanufacturing process considering the environmental impact, economic cost, and technical property. We applied the fuzzy Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) approach to select a proper restoring technology for the crankshaft remanufacturing. The final results indicated that, based on the proposed criteria, the preferential ranking is brushing electroplating, plasma spray, plasma arc surfacing, and laser cladding. The present study would help facilitate and guide the selection of restoration technology in engine remanufacturing practice and benefit remanufacturers for the sustainability improvement. [ABSTRACT FROM AUTHOR]

Remanufacturing cleaning is an essential but high polluting process in remanufacturing. The novel remanufacturing technologies like supercritical CO 2 cleaning and liquid blasting cleaning are under development and possibly tend to substitute the conventional ones like high temperature decomposition and shot blasting. Therefore, it is necessary to demonstrate whether these newly emerged cleaning methods have the environmental superiority and to figure out hotspots for environmental performance promotion. The present study conducted a life cycle assessment (LCA) application on comparing these two types of cleaning technologies from the perspective of environment. Environmental impacts of supercritical CO 2 cleaning system using electricity from different power grids and high temperature decomposition cleaning system consuming different fuel mix are quantified separately. The results indicate that the novel cleaning technologies are environmental friendly compared with conventional ones. High temperature decomposition has the largest comprehensive environmental impact, followed by supercritical CO 2 cleaning, shot blasting, and liquid blasting cleaning. In addition, electricity and diesel (or natural gas) consumption are the main environmental loads contributors of supercritical CO 2 cleaning system and high temperature decomposition system, respectively. Furthermore, supercritical CO 2 cleaning is more environmentally favorable when using the electricity from central and southern power grid. And comprehensive environmental impact of high temperature decomposition decreases with the increasing percentage of natural gas in the fuel mix. [ABSTRACT FROM AUTHOR]

Laser cladding is one of the principal means of equipment remanufacturing and the environmental profiles of this technology has become a research focus. This paper examines the environmental impacts of cast iron cylinder head block remanufacturing through laser cladding using life cycle assessment (LCA), and compares it with the new cylinder head block manufacturing. Resource and energy consumptions of each manufacturing and remanufacturing processes are collected along the production line and then the results of six selected environmental impact categories are calculated. Consistency and sensitivity analysis is also conducted after life cycle impact assessment. The results reveal that cylinder head remanufacturing by laser cladding will achieve large environmental benefits, which can cut environment impact over the entire life cycle by 63.8% on average. This paper also discusses the trend of changes in environmental impacts using scenario analysis over different remanufacturing levels. By taking characterized global warming potential (GWP) as the assessment index, the result shows that remanufacturing will no longer be the preferred option if it needs to repair more than 16 cracks by laser cladding for the cylinder head. [ABSTRACT FROM AUTHOR]

The research about repair of metal cracks plays an important role in promoting the development of remanufacturing engineering. Crack in the SUS304 stainless steel was treated by electropulsing with peak current density of 4.1 kA/mm 2 . After seven times of electropulsing treatment, continuous healing areas in both left and right side of crack were formed. The process of rapid melting and solidification occurred in healing areas, columnar crystals and fine recrystallization zone were formed at the same time. The detour and joule heating effects were the main reason to realize crack healing and detailed healing processes were discussed. [ABSTRACT FROM AUTHOR]

Life cycle assessment (LCA) is a useful analysis tool to estimate the energy consumption and environmental emissions resulting from economic activities. This study provides a comparative LCA of remanufactured liquefied natural gas (LNG) and diesel engines. Furthermore, the paper identifies the processes that contribute most to energy consumption and environmental impacts during the life cycles of the two engines. Six environmental impacts were considered in this study: global warming potential (GWP); acidification potential (AP); eutrophication potential (EP); photochemical ozone creation potential (POCP); ozone depletion potential (ODP); and primary energy demand (PED). The results show that remanufacturing LNG engines reduces energy consumption by 41.91% compared with remanufacturing diesel engines. The greatest benefit related to the environmental impacts is EP, which is reduced by 73.69%, followed by AP, GWP and POCP, which are reduced by 71.49%, 47.14% and 43.90%, respectively. In addition, the cost benefit of the entire life cycle is also significant for LNG engines. In the life cycle of the two types of remanufactured engines, engine usage causes larger environmental impacts, especially with regard to PED and POCP, and component remanufacturing contributes most to ODP. However, it should be noted that in the remanufacturing stage, because more materials and energy are consumed for the LNG engine, the environmental impacts and costs are higher than those for the diesel engine. Nevertheless, the advantages of remanufacturing end-of-life diesel engines into LNG engines are obvious because of the significant benefits during LNG engine use. [ABSTRACT FROM AUTHOR]

Remanufactured mechanical products with high-added value are generally claimed to gain environmental benefits. These claims were made based on different products and assessment methodologies. The variability of life cycle assessment (LCA) results precludes a meaningful comparison across products and studies. This paper aims to critically and systematically evaluate the lifecycle environmental performance of remanufactured products compared with their new counterparts and to identify the key factors, strengths, and limitations in the assessment procedure. Faced with the noteworthy variations, we closely examined and harmonized the unit function, allocation approach, system boundary, impact assessment method, and the underlying assumptions in screened 20 papers regarding 11 types of products. The environmental indicators adopted in this study were global warming potential (GWP) and primary energy consumption (PEC). In terms of these two indicators, the environmental burdens of remanufactured products relative to newly manufactured alternatives were harmonized to the comparison ratios. With these harmonized samples, descriptive statistics were calculated using Monte Carlo Simulation to disclose the variations of comparison results and identify the general tendency. Results of this meta-study showed that remanufacturing could contribute to over 50% reduction for GWP when usage and end-of-life stages were excluded from the life cycle. The GWP and PEC of remanufactured mechanical products account for 28.5% and 25.9% of the new counterparts, respectively, on average. This meta-analysis of comparative LCAs on new and remanufactured products would advance the understanding of the environmental advantages of remanufacturing. • Meta analysis was performed on the comparison of new and remanufactured products. • Variation in the calculations of life cycle impact was harmonized. • Remanufactured products cause over 50% reduction in Global Warming Potential. • The key factors and limitations in the screened papers were identified. [ABSTRACT FROM AUTHOR]