Variable-Composition Heat Transfer Fluid for Wider Solar Temperature Range
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Solution Overview
Problem
Current solar power systems face inefficiencies due to the limited operating temperature of heat transfer fluids, which restricts the maximum service temperature to around 400°C, leading to lower thermal efficiency and electric power production compared to fossil fuel power plants.
Innovation Solution
A variable composition organic heat transfer fluid system that adjusts its composition based on temperature, enriching in high boiling point components at high temperatures to reduce vapor pressure and adding low freezing point components at lower temperatures to maintain fluidity, thereby extending the operating temperature range from 0°C to 500°C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If higher molecular weight fluids are used to prevent evaporation at high temperatures, then vapor pressure is reduced, but the fluid solidifies at ambient temperatures
Solution Approach 1:
The patent applies dynamics by making the heat transfer fluid composition variable rather than fixed. The system dynamically adjusts the ratio of high molecular weight fluid (for high temperature stability) to low molecular weight fluid (for low temperature fluidity) based on operating conditions. During high temperature operation, the composition shifts to contain more high molecular weight fluid to prevent evaporation, while during ambient temperature operation, it contains more low molecular weight fluid to maintain fluidity and prevent solidification.
Solution Approach 2:
The patent changes the compositional parameters of the heat transfer fluid to resolve the contradiction. By varying the concentration of high and low molecular weight components, the system achieves different operational characteristics at different temperatures. The high molecular weight fluid component provides high temperature stability with low vapor pressure, while the low molecular weight fluid component ensures low temperature fluidity, and their ratio is adjusted as a variable parameter.
2Ease of operation
If conventional heat transfer fluids are used to maintain liquid state at ambient temperature, then fluidity is maintained, but maximum operating temperature is limited to around 400°C
Solution Approach 1:
The system transitions from a static fluid composition to a dynamic one that adapts to temperature changes. At ambient temperatures, the fluid contains sufficient low molecular weight components to maintain fluidity and pumpability. As temperature increases toward and exceeds 400°C, the composition dynamically shifts to contain more high molecular weight components that resist evaporation and decomposition, thereby extending the maximum operating temperature while maintaining ease of operation at lower temperatures.
Solution Approach 2:
The patent creates a composite heat transfer fluid system combining two types of fluids with complementary properties: low molecular weight fluids that provide low temperature fluidity and high molecular weight fluids that provide high temperature stability. This composite approach allows the system to achieve both ambient temperature pumpability and elevated temperature operational capability by leveraging the strengths of each component type.
3Productivity
If heat transfer operating temperature is increased above 400°C, then thermal efficiency and electric power production increase, but vapor pressure becomes excessive and chemical degradation occurs
Solution Approach 1:
The patent changes the compositional parameters of the heat transfer fluid to enable operation at temperatures above 400°C. By increasing the proportion of high molecular weight fluid components in the mixture at elevated temperatures, the system reduces vapor pressure and enhances chemical stability, preventing decomposition and maintaining reliability. This parameter adjustment allows the system to safely operate at higher temperatures, thereby increasing thermal efficiency and electric power production without suffering from excessive vapor pressure or chemical degradation.
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
This approach maintains the heat transfer fluid in a liquid state across a wide temperature range, enhancing thermal stability and efficiency, potentially increasing electric power production by 10% and improving the economics of solar power generation.
Implementation Method 1
The low freezing point component is removed from the heat transfer fluid as the heat transfer fluid is heated, for example by being removed in the vapor phase
Implementation Method 2
This heat is used to warm a heat transfer fluid which, in turn, transfers the absorbed heat to water to produce high-pressure superheated steam
Data Source
AI summary
The present invention provides systems and methods for transferring heat using a variable composition organic heat transfer fluid that remains liquid over a wide operating temperature range useful for solar heating applications. Variable composition heat transfer fluids of the present invention comprise a miscible mixture, optionally a completely miscible mixture, of a high boiling point component selected for its beneficial high temperature physical properties, and a low freezing point component selected for its beneficial low temperature physical properties. In some embodiments, the low freezing point component is removed from the heat transfer fluid as the heat transfer fluid is heated, for example by being removed in the vapor phase, thereby selectively varying the composition and physical properties (e.g., vapor pressure, boiling point, etc.) of the heat transfer fluid as a function of temperature.