Organic Rankine Cycle Controller Prevents Liquid Droplet Formation
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Solution Overview
Problem
Organic Rankine cycles (ORC) face issues with turbine efficiency and longevity due to liquid formation during vapor expansion, which occurs when the expansion curve intersects the saturation curve, leading to potential damage and reduced efficiency.
Innovation Solution
A control method that adjusts the temperature difference between the organic fluid at the turbine inlet and a threshold temperature to prevent liquid formation, achieved by varying the flow rate or rotational speed of the feed pump and the opening degree of valves in the heat exchanger, ensuring the expansion occurs in the overheated vapor area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the evaporation pressure is increased close to or above the critical pressure to improve cycle efficiency, then the power output increases, but liquid formation occurs during turbine expansion which damages the turbine and reduces efficiency
Solution Approach 1:
The invention changes the temperature parameter of the organic fluid by controlling the liquid supply to heat exchangers, thereby adjusting the vapor temperature at turbine inlet to maintain a safe temperature difference that prevents expansion curve intersection with the saturation curve
Solution Approach 2:
The controller continuously monitors the temperature difference between the current vapor temperature at turbine inlet and the threshold temperature, and adjusts the liquid supply to heat exchangers in real-time to maintain the temperature difference above the threshold value, preventing liquid formation
2Reliability
If the liquid supply to heat exchangers is increased to raise vapor temperature and avoid liquid formation, then turbine reliability improves, but the control system complexity increases
Solution Approach 1:
The system uses the existing liquid supply infrastructure to heat exchangers for temperature control, leveraging the already-present liquid supply mechanism to serve the additional function of temperature regulation without requiring entirely new control hardware
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 liquid formation in the turbine, thereby enhancing the efficiency and extending the lifespan of the turbine by maintaining the expansion outside the saturation curve, ensuring safe operation and optimal performance.
Implementation Method 1
at least one feed pump for the organic fluid feeding
Implementation Method 2
at least one heat exchanger for performing pre-heating, vaporization and eventually overheating
Implementation Method 3
vaporization phase of the same working fluid
Implementation Method 4
an expansion turbine for expanding the fluid
Implementation Method 5
Aim of the Rankine cycle is to transform heat in mechanical work
Implementation Method 6
a condenser for transforming the vapor into liquid
Data Source
AI summary
An embodiment of the present invention is a method of controlling an Organic Rankine Cycle system, the system comprising at least one feed pump (2), at least one heat exchanger (3), an expansion turbine (5) and a condenser (6), the organic Rankine Cycle comprising a feeding phase of an organic working fluid, a heating and vaporization phase of the same working fluid, an expansion and condensation phase of the same working fluid, wherein said method controls an adjusted variable (X), which is a function of an overheating of the organic fluid, by means of a controller (20) that acts by varying a control variable (Y), which is a parameter of the organic fluid in its liquid phase, and wherein the adjusted variable (X) is a temperature difference (ΔT) between a current temperature of the organic fluid in vapor phase at the turbine inlet and a temperature threshold (Tlim), under which the expansion phase involves the formation of a liquid phase of the organic fluid.