Refrigeration – Automatic control – Air compessor – cooler and expander
Reexamination Certificate
2000-07-28
2001-10-02
Wayner, William (Department: 3743)
Refrigeration
Automatic control
Air compessor, cooler and expander
C062S087000, C062S402000
Reexamination Certificate
active
06295822
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to an apparatus for air-conditioning the cabin of a passenger aircraft using externally supplied fresh air as well as bleed air from an engine of the aircraft. Such an air-conditioning apparatus includes at least one heat exchanger, a blower, a compressor, an expansion turbine, a condenser, at least one water separator, and a reheater.
BACKGROUND INFORMATION
Air-conditioning plants or packs of the above described general type for cabin air-conditioning systems of passenger aircraft are generally known as such. They prepare and provide a stream of fresh air, to which typically a flow of so-called recirculation air is mixed, in order to adjust the temperature and the air flow velocity of the prepared mixed ventilation air in such a manner so as to achieve the greatest comfort for the occupants of the aircraft. The provision of recirculation air also reduces the required amount of fresh air or bleed air and thereby reduces the overall energy requirements. The recirculation air is typically used cabin air that is recycled and then used again. In this manner, a fresh air volume flow is constantly provided into the pressurized fuselage, while the aircraft is operating on the ground as well as during flight, so as to ensure proper ventilation of the cabin, the cockpit, the electronic bays as well as the freight compartments, and particularly to ensure a constant good air quality in the cabin and in the cockpit.
The conventional air-conditioning packs typically used for this purpose constantly develop and provide the maximum achievable cooling power or cooling capacity. Thereby, the maximum possible quantity of water is continuously removed from the air, in order to reduce or completely prevent the occurrence of icing at the outlet of the expansion turbine of the air-conditioning pack or plant. Thereby, it is possible to reduce the quantity of bleed air that must be tapped from the engine, which would appear at first to reduce the fuel consumption of the engine. Nonetheless, the disadvantage of such a conventional system is that it requires a comparatively large heat exchanger capacity in order to cool the air upstream of the expansion turbine and to remove the water that is contained in the air. The air flow resistance arising in the system due to such heat exchangers make it necessary to use a relatively high bleed air pressure to achieve an adequate air flow, which in turn requires relatively high engine rotational speeds or requires the bleed air to be tapped from a higher compressor stage, i.e. a compressor stage having higher pressure, of the engine. This in turn ultimately leads to an increase in the fuel consumption. Considered alternatively, if the fuel consumption is maintained the same, then a comparatively small fresh air quantity would be available for use in the air-conditioning system. In any event, there is a disadvantageous balance between the fuel consumption and the available fresh air quantity.
SUMMARY OF THE INVENTION
In view of the above, it is an object of the invention to provide an air-conditioning arrangement of the general type mentioned above, which is improved in such a manner so that it can achieve the maximum system power or capacity on the one hand, and minimize the fuel consumption on the other hand, while utilizing the lowest possible bleed air pressure. Another object of the invention is to provide such an air-conditioning system that can be operated in different modes depending on the respective existing operating condition of the aircraft and the air-conditioning demands at any given time, so as to allow the performance and the economy of operation of the air-conditioning system to be adapted or optimized for different operating situations of the aircraft. The invention further aims to avoid or overcome the disadvantages of the prior art, and to achieve additional advantages, as are apparent from the present specification.
The above objects have been achieved in an aircraft air-conditioning apparatus according to the invention, including a heat exchanger, a blower, a compressor, an expansion turbine, a condenser, a reheater, a first high pressure water separator, a second low pressure water separator, respective air lines connecting together the several above mentioned components, and shut-off valves interposed in respective air lines to control the operation of the system. More particularly, the first high pressure water separator is arranged in a first air flow path formed by respective components and air lines, and the second low pressure water separator is arranged in a second air flow path formed by respective components and air lines. The two air flow paths can be separated from each other by appropriately switching the shut-off valves. Namely, the shut-off valves can be switched to respectively alternatively switch the air-flow through the first air flow path with the first high pressure water separator or through the second air flow path with the second low pressure water separator. Throughout this specification, the general term “air line” encompasses all possible lines through which air may flow, such as ducts, conduits, pipes, hoses, channels, and passages, for example. The water separators can be any conventionally known water separators, whereby the high pressure water separator is adapted to operate at a relatively higher air pressure (e.g. upstream of the expansion turbine), while the low pressure water separator is adapted to operate at a relatively lower air pressure (e.g. downstream of the expansion turbine).
With such an arrangement, the apparatus according to the invention advantageously combines two different types of air-conditioning sub-systems or circuits, and uses each one most efficiently during the optimum operating conditions therefor. Namely, the invention makes use of the advantages offered by an air-conditioning circuit using a high pressure water separator during operation on the ground or at relatively low flight altitudes. On the other hand, the apparatus also makes it possible to switch off portions of the air circuit of the air-conditioning pack or plant during periods of non-use, i.e. periods of operation in which the full air-conditioning capacity is not needed. Instead, during such operating conditions, a low pressure water separator is used in order to remove the water from the air as required and thereby maintain the proper operating function with low bleed air pressures, while the high pressure water separator and related components are switched out of the operating circuit.
Various detailed embodiments of the inventive apparatus minimize the number of necessary components and therewith the cost and the weight of the overall system, on the one hand, and also further increase the operating efficiency, on the other hand. Such preferred detail embodiments will be discussed below.
REFERENCES:
patent: 5918472 (1999-07-01), Jonqueres
patent: 5921093 (1999-07-01), Jonqueres
patent: 6128909 (2000-10-01), Jonqueres
DaimlerChrysler Aerospace Airbus GmbH
Fasse W. F.
Fasse W. G.
Wayner William
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