Device and method for operating volumetric expansion machines
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Solution Overview
Problem
Current ORC systems face inefficiencies and operational limitations due to high exhaust vapor temperatures exceeding 100°C, which can lead to generator overheating, premature aging, and poor lubrication issues, restricting the use of waste heat for heating or process applications.
Innovation Solution
Incorporating an exhaust vapor chamber between the expansion machine and generator, where a liquid working medium is injected to cool the expanded vapor, effectively lowering temperatures and enhancing cooling efficiency, thereby extending the operational range of expansion machines to higher vapor infeed temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the exhaust vapor temperature is increased to improve thermal efficiency and extend the field of use, then the thermal efficiency increases, but the generator winding temperature exceeds the limit temperature causing premature aging or failure
Solution Approach 1:
The exhaust vapor chamber is segmented into a cooling section and a non-cooling section. The cooling section is equipped with cooling channels that allow coolant to flow through, creating a temperature gradient within the chamber. This segmentation enables different thermal management strategies in different regions, allowing the generator to operate at higher temperatures while protecting critical components.
Solution Approach 2:
A coolant is introduced as an intermediary substance to transfer heat from the exhaust vapor and generator. The coolant flows through cooling channels in the exhaust vapor chamber, absorbing excess heat and preventing the generator winding temperature from exceeding limit temperatures, thus enabling higher thermal efficiency operation.
2Use of energy by moving object
If the exhaust vapor temperature is increased to improve thermal efficiency, then the thermal efficiency increases, but the bearing lubricant viscosity decreases causing deteriorated bearing lubrication
Solution Approach 1:
The bearing housing is segmented with integrated cooling channels that allow coolant to flow directly around the bearings. This creates a localized cooling zone that maintains optimal lubricant viscosity at the bearing interface, independent of the higher temperatures in the exhaust vapor chamber, thus preserving bearing lubrication quality while enabling higher thermal efficiency.
Solution Approach 2:
The coolant flow is arranged to cool the bearings and lubricant before the lubricant reaches the bearing contact surfaces. This preliminary cooling action ensures that the lubricant maintains appropriate viscosity characteristics, preventing deterioration of bearing lubrication even when operating at higher thermal efficiency temperatures.
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 solution allows for the safe operation of expansion machines at higher temperatures, improves generator efficiency, and enhances lubrication, enabling the utilization of waste heat while minimizing additional energy expenditure and component requirements.
Implementation Method 1
Through evaporation of a liquid working medium, the expanded working medium is cooled downstream of the expansion machine
Implementation Method 2
the liquid medium evaporates upon coming into contact with the hot exhaust vapor and lowers thus the temperature in the expanded medium
Implementation Method 3
a generator connected to a shaft of the expansion machine and used for generating electric energy from mechanical energy of the expansion machine
Data Source
AI summary
A device is provided comprising an expansion machine for generating mechanical energy by expanding vapor of a working medium; a generator connected to a shaft of the expansion machine and used for generating electric energy from mechanical energy of the expansion machine; wherein the expansion machine and the generator form a structural unit with an exhaust vapor chamber between the expansion machine and the generator, and wherein, when the expansion machine is in operation, working medium expanded into the exhaust vapor chamber contacts the generator; and means for feeding, in particular injecting, a liquid working medium into the exhaust vapor chamber. Also provided is an ORC device comprising the device and a method for operating the device.