The power-saving Air Conditioning system at Abidjan Airport — Ivory Coast.

The facts

Management of Abidjan Airport was entrusted by the Ivory Coast authorities to the AERIA company, a subsidiary of Sofreavia, and to the Marseille Chamber of Commerce, on condition that they completely renovated and enlarged this airport.
This airport considers itself the “hub” of West Africa, with an average monthly attendance of 75,00 to 105,000 (over 1 million a year). The peak months are August and December, with over 100,000 people for each of these two months. The highest daily attendance recorded was 14 August 1997, and was 4,664 passengers.
The total floor area had been 10,000 m2 — it became 25,000 m2 after enlargement.


In a hot and damp equatorial climate, the question of air conditioning and resulting power consumption were, evidently, essential.

The Invitations to Tender were put out 1998, the main contractor being the OTH Mediterranée company.

As far as the air conditioning was concerned, the project envisaged a classical solution with:
- 3 identical chilled water production units, piston driven, with a performance coefficient (COP) of 3.5
- installations for air treatment and distribution,
- secondary reheating of all the air treatment units, provided by an exchanger fed by a water circuit whose heat source was the cooling water from the refrigeration units.

SEEE’s solution

SEEE proposed a variant on this based on the principle of treating the fresh air in zones

- The airport was divided into 3 parts each covering several zones (17 zones in all: Arrivals, Check In, Departures, luggage delivery, offices, Duty Free. Etc.).
- For each of these three parts, a variable throughput fresh air handling unit was planned, each being coupled with an extraction fan (also with variable throughput). The principle was that the CTANs cooled the air to 9°C, and, being fed with water at 5.5°C, they warm it up to a temperature of between 15° and 20°C.
Each fresh air handling unit to consist of:
• A pre-filter with 90% EU4 efficiency
• A bag filter with 95% EU7 efficiency
• A so-called “triple exchanger” system, in which one exchanger, fed with chilled water, was backed by two others, interconnected by two sets of piping and a transfer pump, the upstream exchanger cooling the air with energy recovered from the downstream exchanger. The system was so calculated that the third exchanger warmed the air to between 15° and 20°C.
• A variable speed circulating pump
• A backward-bladed fan with variable speed drive
- 17 zone treatment units each with a cold exchanger allowing the treatment of the sensible heat contributions of each zone were installed.

(By maintaining a constant over-pressure in the premises, this solution enabled the relative humidity to be controlled by only dehumidifying and reheating the volume of fresh air, instead or the total volume going through the treatment units).

- The production of iced water consisting of 3 production units with screw compressors, one being an emergency stand-bye unit, each with a capacity of 750Kw cold, capable of producing water at 5°C from cooling tower water at 32 - 37°C.
The refrigerant chosen was 134A, in conformity of the Montreal protocol recommendations.
- 60m3 of iced water storage, with a capacity of 350 Kwh, consisting of 2 x 30 m3 lagged, pressurised, vertical steel tanks, enables the units to be stopped when the demand for iced water is low. This storage allows two units to work at 75/80% of their maximum capacity, which corresponds to the optimum for their power and mechanical performance (reduced maintenance, increased life).

This solution enabled the achievement of the following power savings.

Thus SEEE’s solution enabled consumption to be halved and gave a saving of 145 million CFA per annum.

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