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 factors, with lengthy cooling times and high costs associated with nitrogen disposal and safety measures.
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 for more efficient and cost-effective cooling with reduced environmental impact and improved accessibility during the cooling process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If liquid nitrogen is used for cooling the turbomachine, then the required temperature of -40°C can be achieved, but large amounts of nitrogen are consumed and discharged into the atmosphere causing environmental waste and high costs
Solution Approach 1:
The patent implements a closed-loop system where exhaust air from the turbomachine is captured, cooled in a heat exchanger, and recirculated back to the air intake. This recovery and reuse of cooling air eliminates the need for continuous nitrogen consumption and atmospheric discharge, directly addressing the substance loss problem while maintaining effective cooling.
2Temperature
If liquid nitrogen is used for cooling, then the turbomachine can be cooled to -40°C, but nitrogen is an asphyxiant requiring expensive monitoring equipment and major health and safety precautions
Solution Approach 1:
The patent replaces expensive nitrogen with ordinary air that is already present in the environment. Air is not an asphyxiant and does not require special monitoring equipment or safety precautions. The system uses readily available air as the cooling medium, eliminating the harmful factors associated with nitrogen while maintaining the required cooling temperature of -40°C.
3Temperature
If liquid nitrogen soaking is used for cold start testing, then the turbomachine can be cooled to -40°C, but access to the engine during the soaking process is not possible
Solution Approach 1:
The patent extracts the cooling function from a sealed chamber environment and implements it through an external air handling system that connects to the turbomachine via ducts. This allows the cooling process to occur while the engine remains accessible in its normal location, enabling personnel to monitor and service the engine during the cooling process while still achieving the required -40°C temperature.
4Reliability
If conventional cold start infrastructure with cooling chambers is used, then cold start tests can be performed, but the infrastructure is complex to design and construct with costs ranging from $12M to $15M
Solution Approach 1:
The patent segments the cooling function into a separate, modular air handling system that operates independently from the turbomachine and test facility infrastructure. The cooling system consists of discrete components (ducts, blowers, heat exchangers) that can be installed and operated without requiring a complex sealed chamber environment, dramatically reducing infrastructure complexity and cost while maintaining reliable cold start testing capability.
5Temperature
If conventional cold start testing with nitrogen soaking is used, then the turbomachine can be cooled to -40°C, but the cooling process requires 18 to 24 hours
Solution Approach 1:
The patent implements continuous recirculatory cooling where air is continuously drawn from the intake, passed through the turbomachine, cooled in the heat exchanger, and returned to the intake. This continuous circulation of cooled air rapidly removes heat from the engine components, reducing the cooling time from 18-24 hours to a much shorter duration while achieving the required -40°C temperature.
6Reliability
If conventional cold start testing is performed, then cold start certification can be achieved, but the cost to perform one test program ranges from between $1.5M to $2.0M including nitrogen costs
Solution Approach 1:
The patent recovers and recirculates the cooling air within a closed-loop system, eliminating the need to continuously supply and dispose of expensive nitrogen. This recovery system dramatically reduces the operational cost of each test program from $1.5M-$2.0M to a fraction of that amount, while maintaining the reliability needed for cold start certification.
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 significantly reduces cooling time and costs, minimizes environmental impact, and allows for more frequent cold start tests, maintaining target temperatures even in adverse weather conditions, with a simpler infrastructure and safer working conditions.
Implementation Method 1
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
Figure 1~2
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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.