Product definition
Air conditioners fall into different categories depending on the technology used to extract heat from a room, depending on:
– Fluids used in heat exchangers: the water or air;
– From their conception, in a standalone block or several blocks (devices « split system »).
Air-Conditioning Units are mostly mobile products: they include all the components within the same box. Devices « split system » break down into two subsets connected together by a refrigeration link. The main portion (called condensing unit) containing in particular the compressor is located outside the room to be conditioned. The heat extracted from the building is expelled outward. The second part (air treatment housing) is located in the room to refresh: it generally contains a heat exchanger system and ventilation. This product is sometimes called « reversible »: it is then able to operate in the summer (cooling) and winter (heating).
Different subsets found on a standalone air conditioner air/air are:
– The compressor
– The exchanger
– The fan
– The electronic card
– The frame
Composition of an air conditioner
Figure 1: composition of an air conditioner
The « other » category includes refrigerant gas. The refrigerant used in most such product is the R-410A.
Current fleet
Figure 2: Sales data of air conditioners
Depollution and recycling of the product
Depollution / pre-treatment
This equipment contains refrigerant gas, the first step in remediation is to recover these gases. The clearance operation is similar to that of other LHA cold (see refrigerators), is semi-automated. An operator is punching the air conditioning system, refrigerant gases and the compressor oil are then sucked.
According to the treatment facilities the power cables may also be removed at this stage of depollution.
Treatment / Recycling
After the depollution step, air conditioners are crushed to enable the separation of different valuable materials. Compressors (solid parts) can sometimes be removed from air conditioners before crushing in order to avoid damage to crusher.
After the crushing process, steps of sorting are used to separate ferrous metals, nonferrous metals and plastics to direct them to appropriate treatment methods.
| Components / materials | Treatment system |
|---|---|
| Capacitor | Special burning facilities |
| Gas | Special burning facilities |
| Oils | Regeneration or special burning facilities |
| Compressor | Metals recycler (steel, copper) |
| Metals scraps | Steelworks |
| Plastics | Extrusion, Plastics industries |
| Aluminium/Copper | Metals recycler |
Table 1: Ways of processing of different fractions
Proposed improvement plan
The table below provides some ideas to improve the recycling of WEEE. These ideas are from studies on the recycling of some products and difficulties encountered by treatment operators responsible for the treatment of WEEE. These areas for improvement can initiate a deeper reflection from producers. However, each product has its specificities and a number of other constraints to fulfill.
| Encountered difficulties | Impact for recycling | Eco design opportunities |
|---|---|---|
| Presence of capacitors that may contain PCBs. | These capacitors must be removed during the depollution. | Identify these capacitors. Replace the capacitors by other startup systems. |
| Leakage of refrigerant gas from the product before its arrival at the treatment facilities. | These gases can not be recovered. | Improve circuit protection against impact. Prefer the use of gas non-destructive to ozone layer and with a low GWP(1) |
| Assembly of materials not compatible with each other for recycling : aluminium / copper / steel. See Figures 3 and 4. | The grinding of these parts does not always allow a good separation of these different materials. | Encourage single-material parts. Choose fasteners that will break during grinding in order to liberate the different pats / materials. |
| The variety of plastics used. | Plastics must be sorted to be recycled. | Prefer clear colored plastics, easier to sort. Reduce the number of different plastics in a single product. |
| Presence of painted parts or covered with adhesive. See Figure 5. | The adhesive will not separate from parts during grinding and will contaminate the recoverable fractions. | Avoid the use of adhesives, or glued labels. |
| It is difficult to recharge the product with refrigerant gas in case of leakage. | Lack of refrigerant gas does not allow proper operation of the product. | Make the circuit containing refrigerant gas less sensitive to leakages. Allow reloading of refrigerant gas in simple way. |
| Availability of spare parts. | Some parts are no longer available, or are hard to find for the user. | Provide after sales service and availability of spare parts over a period of time compatible with the lifespan of the product and not only on its commercial life. Standardize parts / components from one product to another. |
(1) GWP: Global Warming Potential. This index measures the ability of a gas contribute to the greenhouse effect over a period of time. The GWP of CO2, which serves as a reference, is 1. Each gas has a GWP, which allows to know the impact of a gas in relation to another.
In addition, Regulation 206/2012 of the European Commission has recently introduced measures of execution to air conditioners under the Directive ErP. This regulation aims to promote the use of refrigerants with low global warming potential. The regulation also establishes minimum requirements for energy efficiency air conditioners from 1 January 2013.
Concrete case: Dismantling of an air conditionner
Heat exchanger
Figure 3: Heat exchanger from an air conditioner
In this case grinding may not be sufficient to separate the copper part of the aluminium of this exchanger. Design a single material (all copper or all aluminium) could be considered.
Fan stator
Figure 4: A stator of a fan air conditioner
This piece is very compact and combines two materials would be desirable to separate during grinding. The aluminium could be replaced by a polymer overmold for better separation of the two materials during grinding.
Back panel
Figure 5: Back panel of steel on which air conditioner is glued adhesive foam tape.
Due to the presence of the adhesive onto the metal sheet it is likely to remain bonded to the sheet after grinding and will pollute the metal fraction coming from grinding.
References
– Engineering Techniques: Heating and coolind by thermodynamic systems – B2157 B. PLEYNET (1992) – french
РInventories of emissions of refrigerants and their evolution forecasts to 2025 РSt̩phanie BARRAULT, Sabine SABA, Denis CLODIC (2011) Рfrench
– COMMISSION REGULATION (EU) No 206/2012 of 6 March 2012 implementing Directive 2009/125/EC of the European Parliament and of the Council with regard to ecodesign requirements for air conditioners and comfort fans.