A Study into Refrigeration Cycle Working Fluids using an Air Cycle Machine Environmental Control System

The aircraft Environmental Control System (ECS) enables the aircraft to maintain a comfortable and safe environment for its passengers throughout its operating envelope. The Pressurised Air Conditioner (PACK) is the heart of the ECS, and is composed of multiple sub-systems: heat exchangers, valves, compressor, turbine, and a water separator. The PACK’s principle function is to enable conditioning of the hot, high pressure bleed air from the engine or APU, for temperature, pressure and humidity against the cabin requirements. The operation of the PACK is governed by a control system which has the ability to mask degradation in its component during operation until severe degradation or failure results. The required maintenance is then both costly and disruptive. The PACK has been reported as major driver of unscheduled maintenance by the operators. The aviation industry is currently proactively exploring innovative health management solutions that aid the maintenance of aircraft key systems based on predictive based maintenance approaches using online condition monitoring techniques. This paper presents a comprehensive review of the simulation and diagnostic methodologies applicable to fault diagnostics of the ECS PACK. The existing literature suggests that model-based and data-driven methods are effective for conducting fault detection and isolation of the PACK system. The conceived findings indicate that the model-based diagnostic approach have been extensively employed to conduct PACK diagnostics at component level only. Their successful implementation requires robust experimental verification and validation against the actual data under healthy and faulty conditions. Although a substantial amount of work has been reported on developing first principles based simulation models and diagnostic strategies for the ECS, the acquired findings suggest that there is a compelling need for a verified and validated ECS simulation model to enable accurate PACK system-level diagnostics based on single and multiple component level degradation scenarios. It has also been identified that the existing literature lacks the evaluation of humidity regulation and the effect of the control system on the PACK performance characteristics. Finally, a taxonomy of diagnostic techniques and simulation models is compiled based on the available literature.

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“…90 The results indicated that humid air impacts the ECS performance characteristics particularly at the ACM. 91…”

Section: Experimental Work On the Ecs Diagnosticsmentioning

confidence: 99%

A review of aircraft environmental control system simulation and diagnostics

Chowdhury

Ali

Jennions

2023

Proceedings of the Institution of Mechanical Engineers, Part G:

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“…(Scott & Davis, 1976) and (Junior, et al, 2009) make use of the coefficient of performance (COP) to analyse the contribution of the main thermodynamic parameters, such as compressor and turbine efficiencies or heat exchanger effectiveness, in the global performance of the ECS during a typical flight. Thermodynamic analysis has also proved useful when effects of humidity need to be studied, as is shown by (Childs, et al, 2016). Moreover, the system level performance of the components of an ECS can be inferred from a thermodynamic optimization, since the global performance of the system is affected by the thermodynamic irreversibility present in the actual system processes, as shown by (Pérez Grande & Leo, 2002) and (Vargas & Bejan, 2001).…”

Section: Introductionmentioning

confidence: 99%

Simulating faults in a Boeing 737-200 Environmental Control System using a thermodynamic model

Esperon-Miguez

Jennions

Escobar

et al. 2019

IJPHM

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The Environmental Control Systems ( ECS ), used to provide air to the aircraft cabin at the correct pressure and temperature, is a key driver of maintenance interruptions for military and civil aircraft. Fault detection is particularly difficult, due to the lack of instrumentation and the ability of the ECS’s control system to mask symptoms. Understanding how component degradation affects measurable thermodynamic parameters is key to developing a condition monitoring system for an ECS. This work focuses on the development of a thermodynamic model of a Boeing 737-200 ECS capable of simulating faults in three types of component: heat exchangers, valves, and water separators. The thermodynamic model has been validated using data collected on a ground-based instrumented B737-200 ECS. The results show how a thermodynamic model can be used to simulate the change of temperatures and pressures across the ECS when components degrade.

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Modeling and Control Strategies for Energy Management in a Wastewater Center: A Review on Aeration

Jamaludin,

Tsai,

Lin

et al. 2024

Energies

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Effective modeling and management are critical in wastewater treatment facilities since the aeration process accounts for 65–70% of the overall energy consumption. This study assesses control strategies specifically designed for different sizes of WWTP, analyzing their economic, environmental, and energy-related effects. Small WWTPs see advantages from the utilization of on/off and proportional–integral–derivative (PID) control methods, resulting in 10–25% energy savings and the reduction in dissolved oxygen (DO) levels by 5–30%. Cascade control and model predictive control (MPC) improve energy efficiency by 15–30% and stabilize DO levels by 15–35% in medium-sized WWTPs. Advanced WWTPs that utilize technologies such as MPC integrated with artificial intelligence (AI) and machine learning (ML) can decrease energy usage by 30–40% and enhance DO levels by 35–40%. Life cycle assessment (LCA) demonstrates substantial decreases in greenhouse gas (GHG) emissions: 5–20% for small, 10–25% for medium, and 30–35% for large WWTPs. These findings illustrate the feasibility and expandability of these tactics in both controlled laboratory environments and real-world situations, emphasizing the significance of customized methods for improving energy efficiency and sustainability in wastewater treatment. Subsequent investigations should prioritize integrating renewable energy sources and resolving obstacles in developing nations to enhance wastewater treatment plants’ energy efficiency and sustainability.

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A Study into Refrigeration Cycle Working Fluids using an Air Cycle Machine Environmental Control System

Cited by 3 publications

References 10 publications

A review of aircraft environmental control system simulation and diagnostics

A review of aircraft environmental control system simulation and diagnostics

Simulating faults in a Boeing 737-200 Environmental Control System using a thermodynamic model

Modeling and Control Strategies for Energy Management in a Wastewater Center: A Review on Aeration

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