Phase-Change Heat Engine Nozzle for Quasi-Isothermal Expansion
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Solution Overview
Problem
Existing systems for converting heat into work face inefficiencies due to non-isothermal expansions and high heat loss, particularly in waste heat recovery processes, leading to suboptimal energy density and system size.
Innovation Solution
A method and system utilizing a nozzle to mix pressurized heat transfer liquid (HTL) with a Liquid-Vapor-Phase-Changing (LVPhC) working fluid, allowing quasi-isothermal expansion and acceleration, which is then used to rotate a turbine and generate work, with the LVPhC being separated and recycled for further cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional heat-to-work conversion systems are used, then work can be generated, but heat loss is high and energy density per volume is low
Solution Approach 1:
The patent utilizes phase transitions of the working fluid (liquid to vapor in the evaporator, vapor to liquid in the condenser) to enable efficient heat transfer and work extraction. The phase change process allows for isothermal expansion that maintains temperature and minimizes heat loss while maximizing energy density.
Solution Approach 2:
The system changes thermodynamic parameters (temperature, pressure, phase) of the working fluid through controlled processes. The working fluid undergoes parameter changes from liquid at low temperature/pressure to vapor at high temperature/pressure, then back to liquid, enabling efficient energy conversion with minimal heat loss.
2Loss of energy
If conventional expansion processes are used, then work can be extracted, but the expansion is non-isothermal resulting in temperature reduction and heat loss
Solution Approach 1:
The patent employs isothermal expansion through phase transition where the working fluid expands from liquid to vapor phase at constant temperature. This phase change process maintains temperature stability during expansion, preventing the temperature reduction and heat loss associated with conventional adiabatic expansion processes.
Solution Approach 2:
The working fluid acts as an intermediary that facilitates heat transfer from the hot heat transfer liquid to the turbine during expansion. This intermediary enables isothermal expansion by continuously absorbing heat during the phase change process, maintaining constant temperature and minimizing heat loss.
3Productivity
If high energy density is achieved, then system efficiency improves, but system size would typically increase
Solution Approach 1:
The patent achieves high energy density in a compact volume by utilizing phase transitions of the working fluid. The phase change process concentrates energy transfer in a small volume during evaporation and condensation, enabling high energy density without proportionally increasing system size. The compact heat exchangers leverage phase change efficiency to maximize energy density.
Solution Approach 2:
The system achieves high energy density by rapidly changing thermodynamic parameters (pressure, temperature, phase) of the working fluid through compact heat exchangers. These parameter changes occur efficiently in small volumes, enabling high energy density per volume while keeping the overall system size compact.
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
Enhances energy density per volume by three orders of magnitude, reduces system size, and improves efficiency by maintaining nearly constant temperature during expansion, enabling high-energy conversion with minimal heat loss.
Implementation Method 1
vaporizing or bringing a liquid vapor phase-changing material (LVPhC) from a liquid phase to a vapor phase or a supercritical phase at a temperature of about T1 and a pressure of about P1
Implementation Method 2
mixing it in a nozzle with a heat transfer liquid (HTL) having a temperature of about T1 and a pressure of about P1... causing an acceleration of the HTL/LVPhC mixture
Implementation Method 3
ejecting the accelerated HTL/LVPhC mixture through a nozzle for converting its kinetic energy into work and collecting the LVPhC and the HTL at a pressure of P0
Implementation Method 4
The LVPhC is separated from the mixture and condensed after its ejection from the nozzle
Data Source
AI summary
The present disclosure provides a solution for a system and a method for converting heat into work. The solution makes use of a nozzle, in which pressurized heat transfer liquid (HTL) and a Liquid-Vapor-Phase-Changing (LVPhC) working fluid is about the same pressure are mixed to form a LVPhC-HTL mixture, which in turn undergoes evaporation and isothermal or quasi-isothermal expansion while flowing in the nozzle that results in acceleration of the mixture. The accelerated mixture is ejected from to thereby rotate a turbine and produce work from the generated kinetic energy. The LVPhC is separated from the mixture and condensed after its ejection from the nozzle and its pressure is elevated back to the working pressure in the nozzle. The present solution exploits the thermodynamic advantages of each phase of the LVPhC.