A four-process cycle for a vuilleumier heat pump
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Solution Overview
Problem
Existing Vuilleumier heat pumps with crank-driven displacers have limitations in achieving high coefficients of performance, as they operate within a three-process cycle that restricts efficiency.
Innovation Solution
A mechatronically-actuated Vuilleumier heat pump is designed with a four-process cycle where the displacers have specific stationary and movement phases, allowing for greater control over their motion, with the cold and hot displacers remaining stationary at different times during each other's movements, and varying cylinder diameters and stroke lengths to optimize heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a three-process cycle is used in a Vuilleumier heat pump, then the device complexity is reduced, but the coefficient of performance decreases
Solution Approach 1:
The heat pump cycle is segmented into four distinct processes instead of three, with each process having specific displacer movement patterns. The cycle includes: (1) hot displacer moves from central to remote position while cold displacer remains stationary, (2) cold displacer moves from central to remote position while hot displacer remains stationary, (3) hot displacer moves from remote to central position while cold displacer remains stationary, and (4) cold displacer moves from remote to central position while hot displacer remains stationary. This segmentation allows for optimized heat transfer in each phase, improving overall efficiency and coefficient of performance.
2Productivity
If the hot displacer and cold displacer move simultaneously, then the cycle time is reduced, but the heat transfer efficiency decreases
Solution Approach 1:
The displacers operate in periodic sequences with distinct movement and stationary phases. Each displacer remains stationary for specific portions of the cycle while the other displacer moves, creating alternating periods of action and rest. This periodic action pattern ensures that heat transfer occurs during dedicated phases when one displacer is stationary, maximizing thermal efficiency while maintaining reasonable cycle times through the rhythmic alternation of displacer movements.
3Device complexity
If the displacers are crank-driven with fixed phase difference, then the mechanism simplicity is maintained, but the control flexibility over displacer motion is limited
Solution Approach 1:
The system transitions from static, fixed-phase crank-driven displacer actuation to dynamic, independently controlled displacer movement. Each displacer can be controlled separately to remain stationary or move as needed, allowing real-time adjustment of movement patterns, speeds, and timing. This dynamic control enables optimization of heat transfer processes while maintaining manageable system complexity through independent actuation mechanisms.
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 four-process cycle enhances the coefficient of performance by allowing for more efficient heat transfer and longer cycle completion times, resulting in improved energy efficiency compared to traditional three-process cycles.
Implementation Method 1
Volume in the hot chamber is greater when the hot displacer is in the central position than when the displacer is in the remote position. Volume in the cold chamber is greater when the cold displacer is in the central position than when the cold displacer is in the remote position.
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
A four-process cycle is disclosed for a Vuilleumier heat pump that has mechatronically-controlled displacers. Vuilleumier heat pumps that use a crank to drive the displacers have been previously developed. However, mechatronic controls provides a greater degree of freedom to control the displacers. The four-process cycle provides a higher coefficient of performance than prior cycles in the crank-driven Vuilleumier heat pump and those previously disclosed for a mechatronically-driven Vuilleumier heat pump.