Heat recovery system
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional heat recovery systems in aerospace applications are inadequate in managing increasing low-grade heat in modern gas turbine engines, leading to elevated oil or fuel temperatures that compromise engine efficiency.
Innovation Solution
A pulsed pressure heat recovery system that alternates between heat transfer and energy extraction phases, utilizing a pressure vessel with a heat exchanger and a flow loop featuring non-return valves and a turbine to convert low-grade heat into usable power, with optional features like a pump and secondary heat exchanger for enhanced efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional heat exchangers are used to manage waste heat, then heat transfer occurs, but the system cannot convert low-grade heat into usable power and oil temperatures rise
Solution Approach 1:
The system employs periodic pulsing action where the valve alternates between open and closed states, creating cycles of pressure buildup and release. This periodic operation enables the working fluid to repeatedly vaporize, expand through the turbine to generate power, and then reset, thereby converting low-grade heat into usable mechanical power while managing oil temperatures effectively
Solution Approach 2:
The system utilizes phase transitions of the working fluid between liquid and vapor states. During the charged state, the fluid vaporizes by absorbing heat from the oil. During expansion, the vapor drives the turbine. The phase change enables efficient heat absorption at relatively low temperatures, converting thermal energy into mechanical work while preventing oil overheating
2Power
If a pulsed pressure system with valve is added, then power generation capability improves, but device complexity increases
Solution Approach 1:
The valve operates autonomously based on pressure differential without requiring external control systems. When pressure in the first chamber exceeds the second chamber by a predetermined threshold, the valve automatically opens to equalize pressures. This self-regulating mechanism eliminates the need for complex control electronics, sensors, and actuators, thereby adding power generation capability while minimizing increases in system complexity
Solution Approach 2:
The system combines multiple functions into integrated components. The heat exchanger serves both as a thermal transfer device and as the containment chamber for the working fluid. The turbine is directly coupled to the valve mechanism, merging the power extraction function with the pressure equalization function. This functional integration reduces the number of separate components and simplifies the overall system architecture
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 system effectively reduces oil temperatures, converts low-grade heat into mechanical power, and improves overall engine efficiency by alternating heat transfer and energy extraction phases, enhancing power generation and mechanical power output.
Implementation Method 1
the heat exchanger enables heat transfer from the heated second fluid to vaporise the first fluid
Implementation Method 2
the turbine extracting energy from expansion of the vaporised first fluid flowing therethrough
Data Source
AI summary
A pulsed pressure, heat recovery system includes a pressure vessel for holding a vaporisable first fluid. The vessel contains a heat exchanger, and provides communication to the heat exchanger for flow of a heated second fluid. The heat exchanger enables heat transfer from the second fluid to vaporise the first fluid. The system also includes a flow loop for the first fluid extending from an outlet of the vessel to an inlet to the vessel, having in series: a first non-return valve, a turbine and a second non-return valve. The first non-return valve allows the vaporised first fluid to flow from the vessel to the turbine when the pressure of the vaporised first fluid in the vessel exceeds a predetermined limit. The turbine extracts energy from expansion of the vaporised first fluid. The second non-return valve prevents flow reversal around flow loop between the turbine and the inlet.