Heat Engine Startup: Supercritical Fluid Bypass to Prevent Cavitation
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Solution Overview
Problem
Industrial heat engine systems face challenges during startup due to excessive thermal energy absorption, leading to altered working fluid states, mechanical damage, and potential system failure from thermal stress and cavitation, particularly during the transition of the working fluid between vapor and liquid phases.
Innovation Solution
The method involves circulating a working fluid in a heat engine system with a pump system that maintains the working fluid in a supercritical state on the low pressure side and a subcritical or supercritical state on the high pressure side, using a turbopump and start pump to manage thermal energy transfer and pressure control through heat exchangers, and employing a bypass system to avoid excessive heating during startup.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the working fluid absorbs thermal energy from the heat exchanger during startup, then the heat exchanger transfers thermal energy efficiently, but the working fluid state changes to outside the design scope causing mechanical damage and system failure
Solution Approach 1:
The patent applies preliminary action by initiating the circulation of working fluid through the circuit before introducing thermal energy from the heat exchanger. The pump system establishes proper fluid flow and system pressurization in advance, ensuring the working fluid is ready to safely absorb thermal energy without causing state changes that would lead to mechanical damage or system failure.
Solution Approach 2:
The patent employs dynamics by using a controllable pump system that can adjust the flow rate of working fluid during startup. By dynamically controlling the circulation speed and timing, the system manages thermal energy absorption gradually, preventing excessive temperature rises that would alter the working fluid state beyond design parameters and cause reliability issues.
2Use of energy by moving object
If the working fluid is pumped in liquid phase, then energy conversion efficiency increases, but bubbles may form causing cavitation and catastrophic damage to the pump
Solution Approach 1:
The patent applies preliminary action by establishing proper system pressurization and fluid circulation before the pump begins operating in the liquid phase. The pump system is pre-conditioned with adequate backpressure and the working fluid is ensured to remain above saturation temperature and pressure, preventing bubble formation and cavitation damage while enabling efficient liquid-phase pumping for optimal energy conversion.
Solution Approach 2:
The patent employs feedback by implementing monitoring of pressure and temperature conditions in the working fluid circuit. The system uses this feedback to adjust pump operation and maintain conditions that prevent cavitation (staying above saturation point) while maximizing energy conversion efficiency through liquid-phase pumping. The feedback loop ensures safe operation boundaries are maintained.
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 reduces the risk of mechanical damage and cavitation, ensuring stable operation by maintaining the working fluid in a controlled state, thereby preventing overheating and thermal stress on components and optimizing energy conversion efficiency.
Implementation Method 1
transferring thermal energy from the waste heat stream to the working fluid by a heat exchanger
Implementation Method 2
circulating a working fluid within a working fluid circuit by a pump system
Implementation Method 3
flowing the working fluid through a power turbine... configured to convert the thermal energy from the working fluid to mechanical energy
Implementation Method 4
power turbine coupled to a power generator configured to convert the mechanical energy into electrical energy
Data Source
AI summary
Provided herein are heat engine systems and methods for starting such systems and generating electricity while avoiding damage to one or more system components. A provided heat engine system maintains a working fluid (e.g., sc-CO2) within the low pressure side of a working fluid circuit in a liquid-type state, such as a supercritical state, during a startup procedure. Additionally, a bypass system is provided for routing the working fluid around one or more heat exchangers during startup to avoid overheating of system components.