Scroll Expansion Device for Variable Ratio Energy Conversion
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Solution Overview
Problem
Existing expansion devices in working fluid circuits, such as those used in Clausius-Rankine and Organic Rankine cycles, face inefficiencies in converting heat energy into mechanical energy, particularly due to high vibration and friction in conventional piston expanders, and lack flexible control over working medium flow and pressure.
Innovation Solution
A scroll working machine with a fixed and movable scroll element, featuring Archimedean spiral surfaces and multiple inlets with separate control valves, allows for variable expansion ratio and flow regulation, reducing vibration and enhancing energy conversion efficiency by adapting to changing heat input.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a piston expander is used for heat energy conversion, then mechanical energy can be obtained from waste heat, but high vibration and friction occur reducing efficiency
Solution Approach 1:
The patent replaces the traditional piston-crank mechanism with a scroll mechanism consisting of a fixed scroll element and a movable scroll element. The movable scroll element is driven by an eccentric drive that converts rotational motion into the reciprocating motion needed for expansion, eliminating pistons, connecting rods, and crankshafts. This substitution reduces mechanical friction and vibration while maintaining the heat-to-mechanical energy conversion function.
2Adaptability or versatility
If a conventional expansion device with fixed geometry is used, then the structure is simple, but it lacks flexibility in adapting to varying heat input and load ranges
Solution Approach 1:
The patent incorporates an eccentric drive mechanism that enables the movable scroll element to vary its position and the expansion chamber volume dynamically. The eccentric offset allows the expansion ratio to change during operation, enabling the device to adapt to varying heat input conditions and load ranges while maintaining a relatively simple overall structure.
3Ease of operation
If multiple inlets with separate control valves are added to the scroll working machine, then flexible control over working medium flow and pressure is achieved, but the device complexity increases
Solution Approach 1:
The patent divides the single inlet into multiple inlets (first inlet and second inlet) arranged at different positions on the fixed scroll element, with each inlet having its own control valve. This segmentation allows independent control of working medium flow into different expansion chambers or stages, providing flexible pressure and flow regulation while distributing the control complexity across multiple simpler components.
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 enables efficient conversion of waste heat from internal combustion engines into mechanical energy with reduced vibration and improved system adaptability, increasing overall engine efficiency and flexible operation across varying load ranges.
Implementation Method 1
an expansion device for use in a working fluid circuit, in which a process sequence can be carried out within the working fluid circuit which corresponds to that of a Clausius-Rankine cycle or an Organic Rankine cycle
Implementation Method 2
an eccentric drive, the movable scroll element being circularly movable relative to the fixed scroll element by means of the eccentric drive
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to an expansion device (1) for use in a working medium circuit, wherein within the working medium circuit a process can be carried out which corresponds to that of a Clausius-Rankine cycle or an Organic Rankine cycle. According to the invention, the expansion device (1) is designed as a scroll-type working machine which can be traversed in the expansion direction by a working medium (AM) which circulates in the working medium circuit (AK), wherein an expansion ratio of the scroll-type working machine and/or a supply of working medium (AM) to the scroll-type working machine can be varied. The invention also relates to a method for operating an expansion device (1).