Pressurized Solar Loop Design to Eliminate Two-Phase Flow Instability
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Solution Overview
Problem
Conventional solar power systems using synthetic heat transfer fluids face issues with low energy density, flammability, and efficiency losses due to two-phase water/steam flow, leading to higher costs and safety concerns, while direct steam generation systems are inefficient and sensitive to solar flux and atmospheric conditions.
Innovation Solution
A pressurized solar power system that uses a closed loop of pressurized pipes to heat water above its boiling point, eliminating two-phase flow instability and leveraging water's superior heat transfer capabilities, along with a control system to manage variable solar energy input.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If synthetic heat transfer fluid is used in conventional CSP systems, then the system can operate at high temperatures, but the energy density is low and the fluid is flammable
Solution Approach 1:
The patent changes the physical state parameter of water by pressurizing it above its critical point (22.1 MPa, 374°C), transforming it from a liquid that boils at atmospheric pressure into a supercritical fluid capable of operating at much higher temperatures without phase change, thereby resolving the contradiction between temperature and energy density
Solution Approach 2:
The patent exploits the phase transition properties of water by operating above its critical point, where distinct liquid and vapor phases disappear, eliminating two-phase flow instability while maintaining high energy density characteristic of liquid water
2Loss of energy
If direct steam generation is used, then water's superior heat transfer capabilities are leveraged, but two-phase flow instability occurs
Solution Approach 1:
The patent changes the pressure parameter to above-critical levels, which eliminates the liquid-vapor phase boundary. This allows water to absorb heat efficiently like a liquid while remaining in a single supercritical phase, thereby maintaining both high heat transfer efficiency and flow stability without Ledinegg instability
Solution Approach 2:
The patent converts the typically harmful two-phase flow instability into a benefit by operating in the supercritical regime where phase transitions are suppressed, allowing the system to leverage water's high specific heat capacity without encountering boiling front instabilities
3Device complexity
If unpressurized pipes are used in DSG systems, then the system is simpler, but the system is sensitive to solar flux variations and atmospheric conditions
Solution Approach 1:
The patent changes the pressure parameter to supercritical levels, which fundamentally alters water's thermal properties. This allows the system to maintain stable operation under varying solar flux conditions because supercritical water's thermophysical properties are less sensitive to temperature fluctuations compared to subcritical two-phase systems
Solution Approach 2:
The patent implements a control system with sensors and actuators that monitor and adjust operating parameters in real-time, creating a feedback loop that compensates for solar flux variations and atmospheric conditions, thereby enhancing operational reliability
4Quantity of substance
If pressurized pipes are used to heat water above boiling point, then energy carrying capacity increases, but system complexity and pressure control requirements increase
Solution Approach 1:
The patent changes the pressure parameter to supercritical levels, which eliminates the need for complex two-phase flow control mechanisms. The single-phase supercritical fluid can be controlled using standard pressure regulation equipment, reducing overall system complexity despite the high pressure operation
Solution Approach 2:
The patent replaces complex mechanical two-phase flow control systems with simpler thermal control of supercritical water, where temperature and pressure are the primary control variables, reducing the need for complex flow distribution mechanisms
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 energy carrying capacity and efficiency, reducing costs and safety risks by using water instead of synthetic fluids and stabilizing energy output, allowing for smaller solar collectors and improved power generation.
Implementation Method 1
The solar collectors concentrate solar energy on the water flowing in the solar receiver of the pressurized closed solar loop such that the water is exposed to temperatures well above the atmospheric temperature of the boiling point of water
Implementation Method 2
the water inside the pipes of the closed solar loop at the solar receiver, the focal point of the solar collectors, is pressurized, the water flowing through the pipes of the closed solar loop can be heated well above the ordinary boiling point of water
Implementation Method 3
Circulation of the liquid water in the pressurized closed solar loop transfers heat from the solar collectors to a boiler to generate steam
Implementation Method 4
The steam is then used for powering a steam driven engine that turns a generator to produce electricity
Data Source
AI summary
Systems and methods for generating electrical power using a solar power system comprising pressurized pipes for transporting liquid water. The pressurized pipes flow through solar collectors which concentrate sunlight on the water flowing through the pipes. The pressurization in the pipes allows the water flowing through the pipes to absorb large quantities of energy. The pressurized and heated water is then pumped to a heat exchanger coil where the thermal energy is released to produce steam for powering a steam turbine electrical generator. Thereafter, the water is returned to the solar collectors in a closed loop to repeat the process.