Binary Working Fluid ORC for Geothermal Heat Recovery
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional low-temperature geothermal energy recovery systems using single-component working fluids face inefficiencies due to complex and costly multi-stage Organic Rankine cycles, while binary-component working fluids suffer from thermal performance penalties due to phase separation and non-equilibrium conditions during vaporization and condensation.
Innovation Solution
A modified ORC cycle system utilizing a binary- or tertiary-component working fluid with a vertically-oriented vaporizer for partial boiling, counter-flow heat exchangers, and a condenser spray to maintain thermodynamic equilibrium and enhance heat and mass transfer, avoiding phase separation and improving thermal performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-component working fluid is used in a binary cycle system, then the system structure is simple, but the thermodynamic conversion efficiency is low due to temperature mismatch with geothermal fluid
Solution Approach 1:
The patent uses a binary-component working fluid (composite fluid) instead of a single-component fluid. The binary mixture allows the working fluid temperature profile to match the geothermal fluid temperature profile more closely, reducing thermal mismatch and improving thermodynamic conversion efficiency while maintaining system simplicity
2Loss of energy
If a binary-component working fluid is used to improve thermodynamic efficiency, then conversion efficiency increases, but phase separation and non-equilibrium conditions during vaporization and condensation reduce thermal performance
Solution Approach 1:
The patent introduces a vapor-liquid separator that creates different local conditions for vapor and liquid phases. The separator ensures that vapor goes to the turbine while liquid returns to the heat exchanger, maintaining local equilibrium conditions and preventing phase mixing that would degrade thermal performance
Solution Approach 2:
The patent segments the vaporization and condensation processes by introducing a vapor-liquid separator between the heat exchanger and turbine. This segmentation allows independent optimization of vapor quality for turbine inlet and liquid return to heat exchanger, maintaining thermodynamic equilibrium and stable thermal performance
3Loss of energy
If a multi-stage ORC is implemented to achieve high conversion efficiency, then power generation efficiency improves, but system complexity and cost increase significantly
Solution Approach 1:
The patent uses a binary-component working fluid that inherently provides improved temperature matching and thermodynamic efficiency in a single-stage cycle, eliminating the need for complex multi-stage configurations while achieving high conversion efficiency
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 system achieves higher conversion efficiency by matching enthalpy-temperature characteristics of the working fluid with the geothermal fluid, reducing turbine backpressure and improving heat recovery, thus enhancing overall energy conversion efficiency.
Implementation Method 1
The geothermal fluid is exchanged against the working fluid in exchanger 104. The heat transferred to the relatively low-boiling working fluid causes it to boil.
Implementation Method 2
The working-fluid vapor exits turbine 106 and flows to air-cooled condenser 110. In the condenser, the working-fluid vapor gives up heat to the air and condenses to a liquid.
Implementation Method 3
The working-fluid vapor flows to turbine 106, where its energy content is converted to mechanical energy as it drives the turbine.
Data Source
AI summary
A power system based on a binary power cycle and utilizing a multi-component working fluid is disclosed. The working fluid is partially vaporized and a split recirculation approach is used to control the enthalpy-temperature profiles to match the heat source. A portion of the unvaporized working fluid is sprayed into the condenser.