Closed-Loop Air Cooling for Turbomachine Cold Start Testing
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Solution Overview
Problem
Conventional cold start testing of gas turbine engines is costly, wasteful, and hazardous due to the use of large amounts of liquid nitrogen, requiring complex and expensive infrastructure, and is affected by environmental conditions, with long cooling times and potential delays.
Innovation Solution
A forced air convection apparatus using a duct assembly and air handling system with a blower and heat exchanger for closed loop recirculatory airflow, replacing nitrogen with air to cool turbomachines, allowing simpler construction and reduced environmental impact, and enabling faster cooling with less energy and smaller air requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If liquid nitrogen is used for cooling the turbomachine, then the target temperature of -40°C can be achieved, but large amounts of nitrogen are consumed and discharged into the atmosphere causing environmental waste and cost
Solution Approach 1:
The patent implements a closed-loop system where air is continuously circulated through the turbomachine, cooled by a refrigeration unit, and recirculated back. This recovers and reuses the cooling medium repeatedly rather than discarding it after single use, eliminating nitrogen consumption while maintaining effective cooling to -40°C
Solution Approach 2:
The system uses ambient air as the cooling medium, which is freely available and requires no external supply infrastructure. The refrigeration unit cools this air in a self-sustaining cycle, eliminating the need for expensive liquid nitrogen delivery and handling infrastructure
2Temperature
If liquid nitrogen is used for cooling, then the turbomachine can be cooled to -40°C, but health and safety risks arise due to nitrogen being an asphyxiant requiring expensive monitoring equipment
Solution Approach 1:
The patent changes the cooling medium from nitrogen gas to air, fundamentally altering the chemical composition parameter. Air is breathable and non-toxic, eliminating asphyxiation risks while the refrigeration unit maintains the required low temperature of -40°C through thermal parameters
3Temperature
If a hermetically sealed cooling chamber is used for nitrogen cooling, then the turbomachine can be cooled effectively, but the chamber is complex to design and construct requiring expensive infrastructure
Solution Approach 1:
The patent divides the cooling system into separate functional modules: a refrigeration unit for cooling air, a ducting system for air distribution, and a recirculation system. This segmentation allows each component to be independently optimized and assembled, reducing overall system complexity compared to a monolithic hermetic chamber
Solution Approach 2:
The patent introduces air as an intermediary cooling medium between the refrigeration unit and the turbomachine. This intermediary allows heat transfer without requiring direct contact between the refrigerant and engine components, simplifying the thermal coupling design
4Productivity
If conventional nitrogen cooling infrastructure is installed, then cold start testing can be performed, but the installation and commissioning process is time consuming requiring 12 to 14 weeks
Solution Approach 1:
The patent employs portable, temporary cooling equipment rather than permanent infrastructure. The refrigeration unit and ducting can be quickly deployed and removed, eliminating lengthy installation and commissioning processes while providing full cold start testing capability
Solution Approach 2:
The system is designed to be dynamically deployable and reconfigurable. The ducting and refrigeration units can be rapidly assembled and adjusted on-site without fixed installation, allowing the system to be adapted to different test configurations quickly
5Reliability
If conventional cold start testing is performed, then engine starting capability can be certified, but major delays occur when an engine fails to start requiring re-cooling
Solution Approach 1:
The closed-loop recirculation system maintains continuous cooling capability. When a test failure occurs, the system can immediately resume cooling without interruption or reconfiguration, keeping the turbomachine at the required -40°C temperature continuously throughout the test program
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The forced air convection apparatus reduces costs and energy consumption, minimizes environmental impact, allows access during cooling, and maintains target temperatures even in adverse weather, achieving faster and more efficient cold start testing with reduced infrastructure needs.
Implementation Method 1
an air handling system having a blower arranged to blow air from the one or more inlets of the duct assembly to the one or more outlets of the duct assembly, and further having a heat exchanger configured to cool the air flowing through the duct assembly
Implementation Method 2
an air handling system having a blower arranged to blow air from the one or more inlets of the duct assembly to the one or more outlets of the duct assembly
Data Source
AI summary
A forced air convection apparatus and method for cooling turbomachines is provided. The forced air convection apparatus for cooling a turbomachine, the apparatus comprising: a duct assembly having one or more outlets which are removably joinable to one or more corresponding air intakes of the turbomachine, and further having one or more inlets which are removably joinable to one or more corresponding exhausts of the turbomachine to enable closed loop recirculatory airflow through the turbomachine and the duct assembly and back to the turbomachine; and an air handling system having a blower arranged to blow air from the one or more inlets of the duct assembly to the one or more outlets of the duct assembly, and further having a heat exchanger configured to cool the air flowing through the duct assembly.