Stirling Cycle Heat Pump with Offset-Rotor Working Chambers
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Solution Overview
Problem
Existing heat pumps face inefficiencies and environmental concerns due to the use of refrigerants with high Global Warming Potential, toxicity, and flammability, and are limited by temperature ranges and bulkiness in multistage designs.
Innovation Solution
A Stirling device utilizing the Stirling cycle, comprising a shaft, motor, working chambers, coolant portions, and a regenerator portion, with movers and sliders configured to facilitate efficient and environmentally friendly heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If traditional heat pumps use refrigerants for heat transfer, then heat transfer function is achieved, but environmental harm increases due to high Global Warming Potential, toxicity, and flammability
Solution Approach 1:
The patent removes the refrigerant substance from the heat transfer system entirely, replacing it with a Stirling cycle mechanism that uses a sealed working fluid (such as helium or nitrogen) contained within a closed loop. This extraction of the harmful refrigerant eliminates environmental release risks while maintaining heat transfer functionality through mechanical work and heat exchange processes.
Solution Approach 2:
The patent replaces the chemical/phase-change-based refrigerant system with a mechanical thermodynamic system (Stirling cycle). The Stirling engine uses a piston-cylinder arrangement with a working gas that undergoes isothermal compression and expansion, replacing the need for refrigerants that undergo phase changes. This mechanical substitution eliminates toxicity and flammability issues associated with traditional refrigerants.
2Use of energy by moving object
If heat pumps use Vapor Compression Cycle or Rankine Cycle, then heat transfer is achieved, but efficiency is lower compared to other heat cycles
Solution Approach 1:
The patent changes the thermodynamic parameters and processes of the heat transfer cycle from conventional Vapor Compression or Rankine cycles to a Stirling cycle. The Stirling cycle operates with isothermal compression and expansion processes, maintaining constant temperature during heat addition and rejection, which theoretically achieves higher efficiency compared to the non-isothermal processes in traditional cycles. This parameter change optimizes the thermodynamic efficiency of the system.
3Adaptability or versatility
If heat pumps use multiple stages to expand temperature range, then operational temperature range increases, but device size and cost increase
Solution Approach 1:
The patent employs a dynamic Stirling cycle system where the working fluid undergoes continuous cyclic compression and expansion processes. The dynamic nature of the Stirling engine allows it to adapt to different temperature differentials between heat source and sink, enabling a wide operational temperature range within a single-stage configuration. The reciprocating motion of pistons and regenerator mechanism dynamically adjusts heat transfer rates to maintain efficiency across varying temperature conditions.
Solution Approach 2:
The Stirling cycle system serves multiple functions within a single integrated mechanism: it acts as both a heat engine and a heat pump depending on operational mode, and can operate with various working fluids (helium, nitrogen, hydrogen) to accommodate different temperature ranges. This multi-functionality eliminates the need for separate stages for different temperature applications, reducing overall device size and complexity.
4Temperature
If multistage heat pumps are used to overcome temperature limitations, then temperature range expands, but heat energy loss increases between stages
Solution Approach 1:
The Stirling cycle maintains continuous useful action through its closed-loop thermodynamic process. The working fluid continuously circulates through isothermal compression, constant volume heat addition, isothermal expansion, and constant volume heat rejection phases without interruption. This continuity eliminates the energy losses that occur in multistage systems during fluid transfer and intermediate cooling between stages, as the process operates as an integrated cyclic system with no breaks in the thermodynamic sequence.
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 Stirling device provides highly efficient and eco-friendly heat transfer, overcoming limitations of traditional heat pumps by using a Stirling cycle, enabling applications in heat pumps, engines, and generators.
Implementation Method 1
a Stirling device configured to provide a highly efficient and more environmentally friendly heat transfer using the Stirling cycle
Implementation Method 2
a regenerator portion located between the first coolant portion and the second coolant portion
Data Source
AI summary
A Stirling device is disclosed. The Stirling device comprises a shaft, a motor configured to rotate the shaft about an axis, two working chambers, two coolant portions, and a regenerator portion. Each working chamber comprises a rotor rotating about the axis, connected to the shaft, and having a center offset from the axis; a slider coupled to the rotor; a first mover configured to move in a first direction perpendicular to the first axis based on a movement of the slider; and a second mover configured to move in a second direction perpendicular to the first axis and different from the second direction based on the movement of the slider. Both coolant portions are located between the two working chambers and each comprises an inlet port and an outlet port. The regenerator portion is located between the two coolant portions.