Working Fluid Fill System for Low-Temperature Waste Heat Recovery
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Solution Overview
Problem
Current waste heat recovery systems, such as the steam-based Rankine cycle, are not practical for small flow rates and low temperature thermal sources due to high equipment costs and operational complexity, limiting their effectiveness in converting waste heat into usable energy.
Innovation Solution
A waste heat recovery system utilizing a thermodynamic cycle with a working fluid circuit that includes a waste heat exchanger, expander, recuperator, cooler, pump, and mass management system, employing carbon dioxide as the working fluid, which operates across high and low pressure sides to efficiently convert thermal energy into mechanical energy, with a fill system managing working fluid mass and pressure differentially.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If steam-based Rankine cycle is used for waste heat recovery, then heat conversion capability is improved, but device complexity and equipment cost increase
Solution Approach 1:
The patent changes the working fluid from water/steam to organic fluids with lower boiling points, enabling heat recovery from low-temperature sources. This parameter change simplifies the system by eliminating the need for multiple pressure-level boilers and complex steam generation equipment, while maintaining effective heat conversion capability.
Solution Approach 2:
The invention uses simpler, less expensive equipment components compared to traditional steam-based systems. The organic Rankine cycle system employs basic heat exchangers, expanders, and pumps rather than complex high-pressure boilers and steam turbines, reducing both equipment cost and operational complexity.
2Use of energy by moving object
If steam-based Rankine cycle is used for waste heat recovery, then heat conversion capability is improved, but equipment cost increases
Solution Approach 1:
By changing to organic working fluids with appropriate boiling points, the system can recover heat from low-temperature sources using simpler, less expensive equipment. The lower operating pressures and temperatures reduce material requirements and manufacturing complexity, significantly lowering equipment costs while maintaining heat conversion capability.
3Temperature
If steam-based Rankine cycle is used, then high temperature heat sources can be utilized, but adaptability to low temperature and small flow rate sources is reduced
Solution Approach 1:
The patent employs organic working fluids with lower boiling points than water, enabling the system to operate effectively with low-temperature heat sources. This parameter change in the working fluid properties allows the system to adapt to a wide range of thermal sources, from low-temperature industrial waste heat to small flow rate streams, significantly improving versatility.
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 effectively converts a wide range of thermal sources into mechanical energy, reducing costs and complexity by using a flexible thermodynamic cycle and efficient mass management, making it suitable for various thermal sources, including those with low temperature and small flow rates.
Implementation Method 1
a waste heat exchanger in thermal communication with a waste heat source also connected to the working fluid circuit, whereby thermal energy is transferred from the waste heat source to the working fluid in the working fluid circuit
Implementation Method 2
an expander located between the high pressure side and the low pressure side of the working fluid circuit, the expander operative to convert a pressure/enthalpy drop in the working fluid to mechanical energy
Implementation Method 3
a recuperator in the working fluid circuit operative to transfer thermal energy between the high pressure side and the low pressure side of the working fluid circuit
Implementation Method 4
a cooler in thermal communication with the low pressure side of the working fluid circuit operative to control temperature of the working fluid in the low side of the working fluid circuit
Implementation Method 5
a pump in the working fluid circuit and connected to the low pressure side and to the high pressure side of the working fluid circuit and operative to move the working fluid through the working fluid circuit
Data Source
AI summary
A waste heat recovery system and a method for operating a thermodynamic cycle using a working fluid in a working fluid circuit which has a high pressure side and a low pressure side. The system comprises a waste heat exchanger, a waste heat source, an expander, a recuperator, a cooler, a pump, and a mass management system connected to the working fluid circuit. The mass management system comprises a working fluid vessel connected to the low pressure side of the working fluid circuit and configured to passively control an amount of working fluid mass in the working fluid circuit.