Shifting Head Rotary Expander for Low-Grade Heat
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Solution Overview
Problem
Existing thermal heat engines, such as Organic Rankine Cycle (ORC) and thermal hydraulic engines, face inefficiencies and limited economic viability due to reliance on low-grade heat sources, phase changes, and linear reciprocating pistons, which result in reduced output and increased noise.
Innovation Solution
A rotary positive displacement device utilizing a shifting head mechanism with a compressible fluid to rotate a shaft, avoiding phase changes and leveraging controlled expansion and contraction for efficient power generation, capable of operating effectively with input temperatures below 500°F and reducing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If two phase changes per cycle are used to convert low-grade heat into work, then the engine can operate with low input temperatures, but the efficiency and output are dramatically reduced
Solution Approach 1:
The patent extracts and eliminates the phase change process from the thermodynamic cycle, using only single-phase compression and expansion of a working fluid. This removes the efficiency losses associated with phase transitions while maintaining the ability to operate with low-grade heat sources through the use of a positive displacement compressor and expander.
Solution Approach 2:
The patent changes the thermodynamic parameters by operating entirely in the single-phase region, avoiding the two-phase region that causes efficiency losses. By using a positive displacement mechanism, the system can operate with isentropic or near-isentropic compression and expansion, achieving higher temperatures and pressures without phase change, thereby improving efficiency and output.
2Temperature
If two phase changes per cycle are used, then the engine can operate with low-grade heat sources, but significant noise is generated
Solution Approach 1:
The patent removes the phase change process from the system, which is the primary source of noise in conventional ORC engines. By using single-phase compression and expansion in a positive displacement device, the rapid phase transitions that generate jet-engine-like noise are eliminated, resulting in significantly quieter operation.
3Temperature
If a linear reciprocating piston is used, then the piston can be stroked by low input temperatures, but efficiency challenges occur at each stroke reversal
Solution Approach 1:
The patent inverts the conventional linear reciprocating motion into rotary motion using a positive displacement mechanism. The rotary compressor and expander continuously rotate without the stop-and-reverse motion of linear pistons, eliminating the efficiency losses that occur at stroke reversal points while still being able to utilize low input temperatures.
Solution Approach 2:
The positive displacement rotary mechanism enables continuous compression and expansion without interruption or reversal. The rotary motion maintains continuous useful action throughout the cycle, avoiding the dead centers and direction reversals that cause efficiency losses in linear reciprocating systems, thereby improving overall productivity.
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 achieves enhanced efficiency and reduced noise by using a rotary positive displacement device with a shifting head mechanism, allowing for effective power generation from low-grade heat sources with improved thermal efficiency and operational consistency.
Implementation Method 1
leveraging controlled expansion and contraction for efficient power generation
Data Source
AI summary
A positive displacement expander with an operating fluid chamber of expansive volume regulated by a shifting head. The shifting head may enhance rotation of a housing utilized to rotate a shaft for providing work to any of a variety of power retrieval devices. Additional efficiencies may also be realized through unique hydraulic layouts for circulating of the operating fluid from a heat exchanger, through the rotary device and to a cold exchanger for continuous operating of the rotary device.