Sealed Expansion Machine Cooling via Segmented Working Fluid Paths
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Solution Overview
Problem
In Rankine cycle devices with sealed-type expansion machines, high-temperature working fluids can damage electric power generators and reduce their lifespan, while efforts to limit temperature for safety also limit efficiency, and the use of liquid working fluids leads to energy losses and increased leak currents.
Innovation Solution
The implementation of a Rankine cycle device with a sealed container that includes a second inlet for a cooler working fluid in a gaseous phase, which cools the electric power generator and separates lubricant oil, positioned closer to the electric power generator than the expansion mechanism, to prevent overheating and demagnetization, and a radiator to recycle heat, enhancing efficiency and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high temperature working fluid is supplied to the expansion machine to improve cycle efficiency, then the enthalpy of the working fluid increases and efficiency improves, but the electric power generator may be damaged due to overheating
Solution Approach 1:
The patent segments the working fluid flow into two separate paths: one path supplies high-temperature working fluid to the expansion mechanism for power generation, while another path supplies lower-temperature working fluid to cool the electric power generator. This segmentation allows the system to simultaneously achieve high efficiency and protect the generator from overheating damage.
Solution Approach 2:
The patent introduces an intermediary cooling system where working fluid is used as the cooling medium for the electric power generator. The working fluid absorbs heat from the generator through heat exchange, acting as an intermediary that transfers heat away from the generator without requiring external cooling systems.
2Reliability
If the working fluid temperature is limited to protect the electric power generator, then reliability improves, but cycle efficiency decreases due to reduced enthalpy
Solution Approach 1:
The patent divides the working fluid circulation into multiple functional paths, allowing different temperature levels to be maintained in different zones. The expansion mechanism receives high-temperature fluid for maximum efficiency, while the generator area receives cooler fluid for protection, thus resolving the trade-off between reliability and efficiency.
3Temperature
If liquid working fluid is used for cooling, then cooling effect is achieved, but energy losses increase and leak currents are generated
Solution Approach 1:
The patent changes the physical state parameter of the working fluid from liquid to gaseous phase for the cooling function. By using gaseous working fluid instead of liquid, the system eliminates the problems of energy loss and leak currents associated with liquid cooling, while still achieving effective cooling through the gaseous phase heat exchange.
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
This configuration improves the reliability and efficiency of the Rankine cycle device by preventing overheating of the electric power generator, reducing leak currents, and effectively separating lubricant oil, thereby extending the generator's lifespan and maintaining high cycle efficiency.
Implementation Method 1
a second inlet (30a) for supplying, to an inside of the sealed container (10), a working fluid in a gaseous phase state which has been cooled by a cooler (4)
Implementation Method 2
a radiator (5) for cooling the working fluid drained from the second outlet (31a) and for supplying the working fluid to the pump (1)
Implementation Method 3
a pump (1) for pressurizing a working fluid
Implementation Method 4
a heater (2) for heating the working fluid pressurized by the pump (1)
Data Source
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AI summary
To improve the reliability of the Rankine cycle device using a sealed-type expansion machine, the Rankine cycle device 100 according to the present disclosure comprises a pump 1, a heater 2, an expansion machine 3, a radiator 5, and a cooling path 8. The expansion machine 3 comprises an expansion mechanism 11 for extracting a power from the working fluid, an electric power generator 12, a sealed container 10 containing the expansion mechanism 11 and the electric power generator 12, a first inlet 34a, a first outlet 35a, a second inlet 30a, and a second outlet 31 a. The radiator 5 is connected to the pump 1 with a flow path to cool the working fluid drained from the second outlet 31 a. The cooling path 8 which connects the first outlet 35a to the second outlet 30a has a cooler 4 to cool the working fluid drained from the first outlet 35a.