Nested Regenerator Layout for Low-Dead-Volume Solar Heat Pumps
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Solution Overview
Problem
Stirling and Vuilleumier cycle devices face inefficiencies due to systemic 'dead volume' that limits work output and scalability, as well as issues with fluid friction and heat transfer, leading to wasted energy and increased complexity in larger systems.
Innovation Solution
The design minimizes dead volume by integrating the regenerator within the displacer/regenerator space, using nested tapered elements to purge working fluid into the active cylinder, and employs an electronic control system for flexible timing and phase optimization, reducing mechanical and fluid friction, and incorporating insulating materials to prevent longitudinal heat conduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the system is scaled up into larger, more powerful devices, then the power output increases, but the dead volume increases proportionally, reducing the percentage of working fluid in contact with heat transfer area and causing loss in power and efficiency
Solution Approach 1:
The regenerator is nested within the displacer/regenerator space, with the displacer enveloping the regenerator. This nested configuration allows the regenerator to occupy the space inside the displacer, minimizing the overall volume required and reducing dead volume while maintaining functionality in scaled-up systems
Solution Approach 2:
The system divides the working fluid spaces into distinct segments: the active cylinder chamber where useful work occurs, the displacer/regenerator space containing the regenerator, and the heat transfer areas. This segmentation ensures that working fluid is properly distributed and maximizes the proportion of fluid in contact with heat transfer surfaces
2Loss of energy
If open passages are used for fluid flow to avoid frictional losses, then fluid flow resistance decreases, but dead volume increases, limiting work output
Solution Approach 1:
The passage geometry is optimized locally: open passages are provided in the active cylinder chamber to minimize frictional losses during fluid flow, while the regenerator and displacer regions are configured to minimize dead volume. The regenerator uses a matrix structure that provides adequate flow paths without excessive volume, and the displacer is positioned to minimize the volume of the displacer/regenerator space
3Loss of energy
If the regenerator is given sufficient space for heat storage, then heat transfer efficiency improves, but dead volume increases, reducing the proportion of working fluid in contact with heat transfer area
Solution Approach 1:
The regenerator is nested within the displacer/regenerator space, utilizing the internal volume of the displacer for heat storage. This configuration allows the regenerator to have sufficient heat storage capacity while occupying space that would otherwise be dead volume, thereby maintaining a high proportion of working fluid in contact with heat transfer areas
Solution Approach 2:
The regenerator employs a porous matrix structure that provides extensive surface area for heat transfer within a compact volume. This porous configuration allows adequate heat storage and transfer efficiency without requiring excessive regenerator volume that would increase dead volume
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 approach enhances work output per unit volume, improves scalability, reduces energy losses, and increases efficiency by ensuring all working fluid interacts with the heat transfer surface, allowing for flexible cycle timing and reduced mechanical complexity.
Implementation Method 1
a first, driving/heated cylinder (1) heated on one end, through a heated head (2)
Implementation Method 2
The thermal pressurization of working fluid in the heat exchange cavity (9) of the driving/heated cylinder
Implementation Method 3
cooled on the other end, through a cooled head (3)
Implementation Method 4
The thermal pressurization of working fluid in the heat exchange cavity (9) of the driving/heated cylinder (1) is used directly, to compress working fluid in the warm end heat exchange cavity (10) of the driven/cooling cylinder (7)
Implementation Method 5
when the stack is forced together, all interstitial spaces are closed, thereby eliminating what would otherwise be dead volume
Implementation Method 6
interleaved with insulating material of similar geometry... to minimize losses due to systemic longitudinal heat flow within the matrix
Data Source
AI summary
A method and apparatus that reduces the dead volume in a heat engine or heat pump, such as a duplex Stirling or Vuilleumier cycle device, by nesting the components of the displacer and regenerator such that nearly all working fluid is purged from the interstices of the regenerator elements and all other working fluid spaces that are not involved in doing useful work at each portion of the cycle. Particularly, a more scalable and efficient method and apparatus for providing solar air conditioning or refrigeration by means of a heated cylinder that alternately pressurizes and depressurizes a separate cooling cylinder by directly transferring thermally induced pressure changes to that cooling cylinder at optimized times in the cycle, under the control of a numerically controlled actuation system that can cycle at a much lower rate than mechanically coupled or harmonically phased systems.