Geothermal heat extractor
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Solution Overview
Problem
Conventional geothermal systems face inefficiencies in heat extraction from low- to moderate-temperature sources due to limited heat transfer per unit mass flow, sliding temperature changes, and the need for high pump power, especially when using water as a heat transfer fluid.
Innovation Solution
A geothermal heat extractor system that maintains the heat transfer fluid in a liquid state above its saturation pressure, vaporizes it at the geothermal source, and uses controlled flow valves to regulate the fluid flow, ensuring isothermal condensation at the external load, thereby maximizing heat extraction and minimizing pressure loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If water flow loops are used for heat extraction, then heat transfer is achieved, but the heat extracted per unit mass flow is limited and pump power consumption increases
Solution Approach 1:
The patent utilizes phase transition of the heat transfer fluid from liquid to vapor within the geothermal source. The fluid is injected in liquid form and flash-evaporates to vapor, absorbing latent heat of vaporization from the geothermal formation. This phase change enables significantly higher heat extraction per unit mass flow compared to conventional liquid-only heat exchange systems, thereby reducing the required mass flow rate and associated pump power consumption.
2Power
If conventional steam turbines are used for power generation, then electricity is generated, but the system requires fluids in excess of 150°C and is restricted to high-temperature geothermal resources
Solution Approach 1:
The patent changes the operating parameters of the power generation system by using an Organic Rankine Cycle (ORC) instead of conventional steam turbines. The ORC system employs an organic working fluid with a lower boiling point than water, enabling efficient power generation from medium-temperature (75-150°C) and low-temperature geothermal resources. This parameter change expands the applicable temperature range for geothermal power generation.
3Loss of energy
If water is used as heat transfer fluid, then heat transfer occurs, but sliding temperature change reduces system efficiency
Solution Approach 1:
The patent employs phase transition (liquid to vapor) of the heat transfer fluid within the geothermal source to maintain more stable temperature conditions. The flash evaporation process occurs at essentially constant pressure and temperature (the saturation temperature corresponding to the formation pressure), allowing the vapor to rise through the wellbore with minimal temperature change. This eliminates the sliding temperature gradient problem associated with liquid heat transfer, reducing thermal losses and improving overall system 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 enhances heat extraction efficiency by leveraging the higher heat of vaporization of the fluid, allowing for constant temperature condensation and reduced pressure loss, resulting in improved power generation capabilities from geothermal sources.
Implementation Method 1
the heat transfer fluid vaporizes in the heat transfer fluid return conduit by heat supplied to the heat transfer fluid return conduit from the geothermal heat source
Implementation Method 2
heat supplied to the heat transfer fluid return conduit from the geothermal heat source
Implementation Method 3
The vaporized heat transfer fluid is supplied from the heat transfer fluid return conduit to the external load
Data Source
AI summary
A geothermal heat extractor includes a heat transfer fluid and a heat transfer fluid supply conduit. The heat transfer fluid is maintained in the supply conduit in a liquid state at a pressure above its saturation pressure. The geothermal heat extractor further includes a heat transfer fluid return conduit, a geothermal heat source coupled thereto, at least one flow control valve configured to control the flow of the heat transfer fluid from the supply conduit to the return conduit, and an external load coupled to the return conduit. As the heat transfer fluid is provided to the return conduit in the liquid state, the heat transfer fluid vaporizes in the return conduit by heat supplied to the return conduit from the geothermal heat source. The vaporized heat transfer fluid is supplied from the return conduit to the external load.