Cascaded Recompression Closed Brayton Cycle Heat Extraction
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Solution Overview
Problem
Recompression closed Brayton cycle systems are inefficient in extracting heat from open cycle heat sources due to high efficiency in recuperation, leaving significant energy untapped.
Innovation Solution
A cascaded recompression closed Brayton cycle system with separate flow paths at the high-temperature portion and retaining a single recompression flow path to each compressor, utilizing multiple turbines and recuperators to maximize heat extraction by preheating fluid streams before they enter the turbines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If high efficiency recuperation is used in recompression closed Brayton cycle systems, then system efficiency is improved, but heat extraction from open cycle heat sources becomes insufficient
Solution Approach 1:
The patent divides the single turbine flow path into multiple separate turbine flow paths (first turbine, second turbine, third turbine) operating at different temperature levels. Each turbine handles a specific temperature range, allowing the system to extract heat more effectively across the entire temperature spectrum while maintaining efficient recuperation in each segment. This segmentation resolves the contradiction by enabling both high system efficiency and complete heat extraction.
2Device complexity
If single turbine flow path is used, then system simplicity is maintained, but heat extraction capability is limited
Solution Approach 1:
The patent segments the heat extraction process into multiple parallel flow paths, each with its own turbine and recuperator. The first turbine handles high temperature flow, the second turbine handles intermediate temperature flow, and the third turbine handles lower temperature flow. This segmentation enables comprehensive heat extraction while keeping each individual flow path relatively simple and manageable.
Solution Approach 2:
The patent transitions from a single-dimensional (single flow path) approach to a multi-dimensional (multiple parallel flow paths) approach. By adding the dimension of parallel flow paths operating at different temperature levels, the system achieves complete heat extraction without proportionally increasing overall system complexity, as each parallel path can be designed and operated independently.
3Ease of operation
If heat source flow is reduced from 900°C to 700°C in single turbine system, then system operation is simplified, but significant energy remains untapped
Solution Approach 1:
The patent segments the temperature reduction process into multiple stages across three turbines. The first turbine reduces temperature from 900°C to an intermediate level, the second turbine further reduces it to another intermediate level, and the third turbine completes the reduction to the final temperature. This segmentation allows the system to extract energy progressively at manageable temperature drops in each stage while maintaining operational simplicity through standardized turbine designs.
Solution Approach 2:
The patent applies preliminary heating to the working fluid before it enters each turbine stage, ensuring optimal inlet conditions for each turbine. This preliminary action (heating) prepares the fluid for efficient energy extraction in each subsequent turbine stage, enabling complete energy utilization while maintaining smooth and simple system operation throughout the multi-stage process.
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 enhances the efficiency of heat extraction from the heat source, reducing costs and energy loss, while maintaining the efficiency benefits of recompression closed Brayton cycle technology.
Implementation Method 1
a first recuperator where the first turbine discharge stream transfers heat to the first turbine feed stream
Implementation Method 2
a second recuperator where the second turbine discharge stream transfers heat to the second turbine feed stream
Data Source
AI summary
The present disclosure is directed to a cascaded recompression closed Brayton cycle (CRCBC) system and method of operation thereof, where the CRCBC system includes a compressor for compressing the system fluid, a separator for generating fluid feed streams for each of the system's turbines, and separate segments of a heater that heat the fluid feed streams to different feed temperatures for the system's turbines. Fluid exiting each turbine is used to preheat the fluid to the turbine. In an embodiment, the amount of heat extracted is determined by operational costs.