Waste Heat Recovery Cycle for Integrated Power and Space Conditioning
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Solution Overview
Problem
Existing systems fail to efficiently integrate internal combustion engines with electrical power generation, heating, and cooling functions, particularly in compact and portable designs, and do not effectively utilize waste heat for supplementary energy, leading to low efficiency and increased complexity.
Innovation Solution
A self-contained system integrating an internal combustion engine with a Rankine power cycle and a reconfigurable thermodynamic cycle, using a single working fluid and mechanical/thermal connections to drive both heating and cooling cycles, allowing flexible operation modes and efficient energy recovery from waste heat.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If absorption cooling is used to provide environmental cooling from low grade heat sources, then cooling function is achieved, but system efficiency is low and electrical power generation cannot be integrated
Solution Approach 1:
The patent combines the Rankine power generation cycle with the refrigeration cycle into a single integrated system. The Rankine cycle uses waste heat from the internal combustion engine to generate electricity, while the refrigeration cycle provides cooling. Both cycles share common components including the heat source from engine exhaust, condensers, and expansion devices, allowing simultaneous power generation and cooling with improved overall efficiency
Solution Approach 2:
The system is designed to perform multiple functions simultaneously: the internal combustion engine provides mechanical power for propulsion, its exhaust heat drives the Rankine cycle for electricity generation, and the same exhaust heat also drives the refrigeration cycle for cooling. The Rankine working fluid serves dual purposes in both power generation and refrigeration cycles
2Reliability
If separate working fluids are used for power and heat pump cycles, then cycle independence is maintained, but system complexity increases
Solution Approach 1:
A single working fluid (R134a refrigerant) is used in both the Rankine power generation cycle and the refrigeration cycle. The fluid circulates through both cycles, absorbing heat in the evaporator, condensing in the condensers, and expanding through the expansion device. This unified approach reduces the number of separate systems while maintaining functional independence through proper heat exchanger design
Solution Approach 2:
The patent merges the power generation and refrigeration cycles into one integrated thermodynamic system using a common working fluid. The Rankine expander and refrigeration compressor are both driven by the internal combustion engine, and the working fluid serves both cycles, reducing component count and system complexity while maintaining reliable operation
3Device complexity
If waste heat is not recuperated from the Rankine expander output, then system simplicity is maintained, but thermal energy utilization efficiency decreases
Solution Approach 1:
The recuperator pre-heats the liquid working fluid before it enters the heater/boiler by transferring heat from the warm expander outlet stream. This preliminary heating action reduces the amount of additional heat required from the engine exhaust, improving overall thermal efficiency. The control valve then regulates the pre-heated fluid to the appropriate temperature for the heating device
Solution Approach 2:
Instead of discarding the waste heat from the Rankine expander outlet to the environment, the system recovers this thermal energy through the recuperator heat exchanger. The recovered heat is used to pre-heat the working fluid entering the boiler, thereby reducing energy losses and improving the overall efficiency of the combined power and heating system
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 efficient and cost-effective generation of electrical power, heating, and cooling, with flexible operation modes and reduced component complexity, utilizing waste heat to supplement energy generation and maintain constant frequency power output.
Implementation Method 1
an internal combustion engine with a fuel supply system
Implementation Method 2
a Rankine cycle to provide power
Implementation Method 3
a heat pump cycle to provide heating or cooling
Implementation Method 4
recuperation, which transfers the remaining usable heat at the output of the Rankine expander to pre-heat fluid entering the heater or boiler
Data Source
AI summary
The present invention provides an apparatus for utilizing waste heat to power a reconfigurable thermodynamic cycle that can be used to selectively cool or heat an environmentally controlled space, such as a room, building, or vehicle. The present invention also integrates an electric machine, which may operate as a motor or generator, or both, and an additional prime mover, such as an internal combustion engine. Different combinations of these components are preferable for different applications. The system provides a design which reasonably balances the need to maximize efficiency, while also keeping the design cost effective.