Turbine Reverse Rotation for Liquid Phase Prevention
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Solution Overview
Problem
Turbines in exhaust heat recovery systems can be damaged due to liquid-phase working fluids remaining in the turbine, leading to cavitation and reduced efficiency.
Innovation Solution
A method of controlling the turbine by measuring the internal temperature of the heat exchanger and reversing its operation when the temperature is below a certain threshold to ensure the working fluid is reintroduced, and using a pump to inject pressurized working fluid when the temperature exceeds a threshold, thereby preventing damage and improving efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the turbine operates normally without temperature control, then the system structure is simple, but liquid-phase working fluid remains in the turbine causing cavitation and damage
Solution Approach 1:
The control method performs preliminary action by detecting the temperature of working fluid before it enters the turbine and preemptively reversing the turbine rotation when liquid phase is detected. This prevents cavitation and turbine damage before they can occur, rather than waiting for damage to happen and then taking corrective action.
Solution Approach 2:
The control system implements feedback by continuously monitoring the temperature of working fluid and using this information to automatically adjust turbine rotation direction. When temperature indicates liquid phase (below dew point), the system feedbacks this information and reverses rotation to prevent damage, creating a closed-loop control system that adapts to real-time conditions.
2Reliability
If the turbine is reversed to reintroduce working fluid, then liquid-phase working fluid is prevented from damaging the turbine, but the operation time and complexity increase
Solution Approach 1:
The control method applies periodic action by reversing the turbine rotation in short, periodic intervals when liquid-phase working fluid is detected. Rather than maintaining continuous reverse rotation, the system periodically reverses rotation to clear liquid phase and then returns to normal operation, minimizing time loss while ensuring turbine protection.
3Reliability
If a pump is used to inject pressurized working fluid when temperature is low, then the working fluid is properly maintained in gas phase, but the device complexity and energy consumption increase
Solution Approach 1:
The control system implements self-service by using the turbine's own reverse rotation to reintroduce working fluid into the heat exchanger, clearing liquid phase without requiring external energy input from a pump. The turbine's rotation itself performs the work of fluid redistribution, and only when this self-service mechanism fails does the system resort to pump assistance.
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
Prevents damage to the turbine by ensuring the working fluid is properly reintroduced and maintained in a gas phase, enhancing the overall efficiency of the exhaust heat recovery system.
Implementation Method 1
heat of exhaust gas evaporates a working fluid through a heat exchanger provided in an exhaust pipe
Implementation Method 2
heat of exhaust gas evaporates a working fluid through a heat exchanger provided in an exhaust pipe
Implementation Method 3
rotating the turbine in a reverse direction when the measured internal temperature is a predetermined temperature or less
Data Source
AI summary
A method of controlling a turbine of an exhaust heat recovery system in which heat of exhaust gas evaporates a working fluid through a heat exchanger provided in an exhaust pipe and the working fluid is supplied to the turbine may include measuring an internal temperature of the heat exchanger, and rotating the turbine in a reverse direction when the measured internal temperature is a predetermined temperature or less.