Sealed Screw Expander Generator Cooling Without Refrigerant Leakage
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Solution Overview
Problem
Existing ORC systems face refrigerant leakage through shaft seals and cooling challenges, especially in high-temperature expansion scenarios, where conventional semi-sealed or fully sealed screw expansion devices are ineffective.
Innovation Solution
A semi-sealed or fully sealed screw expansion power generation device with isolated expander and generator cavities, featuring a screw expander with a fixedly connected rotor and a shaft seal, and a refrigerant injection and outlet system for effective cooling through evaporation, preventing refrigerant leakage and addressing high-temperature cooling issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a shaft seal is used to connect the screw expander to the generator, then power transmission is achieved, but refrigerant leakage occurs through the shaft seal
Solution Approach 1:
The device is divided into two separate sealed cavities: the expander cavity and the generator cavity. The screw expander and generator are independently housed in their respective cavities, with each cavity sealed separately. This segmentation eliminates the need for a shaft seal that would allow refrigerant leakage, while still enabling power transmission through magnetic coupling between the cavities.
Solution Approach 2:
A magnetic coupling mechanism acts as an intermediary between the expander cavity and generator cavity. The magnetic field transmits rotational force from the screw expander to the generator rotor without requiring direct mechanical contact or penetration of the sealed cavities, thus preventing refrigerant leakage while maintaining power transmission.
2Temperature
If the generator is cooled by exhaust from expansion, then cooling is achieved, but this becomes impractical when expansion end temperature is very high
Solution Approach 1:
A liquid refrigerant circulation system is introduced as a hydraulic cooling mechanism. The refrigerant is pumped through channels in the generator cavity, absorbing heat from the generator through evaporation and phase change. This hydraulic cooling system replaces the inadequate exhaust-gas cooling method and effectively manages heat rejection even in high-temperature expansion scenarios.
Solution Approach 2:
The cooling mechanism utilizes phase transitions of the liquid refrigerant. The refrigerant evaporates in the generator cavity, absorbing latent heat from the generator, and then condenses elsewhere in the cycle. This phase change process provides efficient heat removal that is independent of the expansion exhaust temperature, enabling effective cooling in high-temperature applications.
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 solution effectively prevents refrigerant leakage and provides efficient cooling for the generator, even in high-temperature scenarios, ensuring reliable power generation in ORC systems.
Implementation Method 1
the generator is cooled through evaporation of the liquid refrigerant
Implementation Method 2
The overheated gas enters the expander 1' to work through expansion
Data Source
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AI summary
A screw expansion power generation device is disclosed, applicable to an Organic Rankin Cycle (ORC). The power generation device includes a semi-sealed or fully sealed shell. The shell includes an expander cavity and a generator cavity. The expander cavity is not in communication with the generator cavity. A screw expander is disposed in the expander cavity, and a generator is disposed in the generator cavity. A rotor of the screw expander is fixedly connected to a rotor of the generator. The power generation device drives the generator to generate power through rotation of the rotor of the screw expander. A liquid refrigerant injection inlet and a refrigerant outlet are disposed on the generator cavity, The generator is cooled through evaporation of a liquid refrigerant. The screw expansion power generation device of the present invention is semi-sealed or fully sealed. The screw expander and the generator are disposed in the shell as a whole. The generator may be a synchronous generator or an asynchronous generator, thereby preventing leakage of the refrigerant when the screw expansion generator generates power.