747-8 空调系统改进简介

竹君子 · 发表于 2015-1-9 10:25:34

附件是747-8 空调系统改进简介，供参考

Inside the 747-8
New Environmental Control System
The Boeing 747-8 includes a new environmental control system (ECS) that integrates the air supply control system and the cabin air-conditioning and temperature control system.

By André Brasseur, Service Engineer;
Will Leppert, Service Engineer; and
Alexis Pradille, Service Engineer, Liebherr Technical Services

The 747-8 ECS increases cooling capacity and improves performance and maintainability,while providing a common 747 platform with simplified flight deck interfaces.
The system’s architecture integrates more functions in fewer line replaceable units (LRUs) to maximize efficiency and reliability and to simplify troubleshooting.
This article provides an overview of the design of the 747-8 ECS and in-service support.

Performance and reliability
A robust ECS is important for cabin safety and comfort. The 747-8 uses an ECS that offers digital control, lighter weight,increased reliability, and reduced maintenance compared to earlier technology.Changes to the air supply control system (ASCS) and cabin air-conditioning and temperature control system (CACTCS) combine to provide the 747-8 greater cooling capacity as well.
The 747-8 ECS uses new technologies to improve performance. These include an integrated air system controller (IASC) and the associated software. In addition, the system uses high-pressure water separation to dry out the air within the air cycle machine upstream of turbine section input,as well as pressure sensors to provide input to the IASC for icing control.
Combined, these technologies help improve the efficiency and reliability of the system, allowing for increased efficiency of bleed air and a reduction in bleed air penalties. That, in conjunction with the improved maintainability achieved through the placement of LRUs and LRU components,helps reduce operating and maintenance costs.
Other key improvements in the new ECS include an advanced new bleedsystem and true subfreezing packs.
Advanced bleed system
The 747-8 airplane is powered by General Electric GENX-2B engines. The engine bleed systems supply air from the engine compressor. There are four identical engine