Active Coolant Pressure Control for Waste Heat Recovery
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Solution Overview
Problem
Existing waste heat recovery (WHR) and coolant systems face challenges in maintaining coolant fluid pressure due to small leaks and varying coolant temperatures, which affect cycle efficiency and risk engine damage from boiling.
Innovation Solution
An active coolant pressure control system using a pressure source like an air brake system to maintain target coolant pressure based on temperature and engine load, preventing boiling and optimizing heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If coolant pressure is passively maintained without active control, then system complexity is reduced, but coolant temperature stability deteriorates due to small leaks and varying engine loads
Solution Approach 1:
The patent implements a feedback control system where a pressure sensor continuously monitors coolant pressure in the expansion tank and sends signals to an electronic control unit. The ECU compares the measured pressure against target pressure values and adjusts the pneumatic valve accordingly to maintain pressure within desired ranges, ensuring temperature stability despite leaks or varying engine loads.
Solution Approach 2:
The system utilizes the vehicle's existing air brake system as a pressure source, eliminating the need for a dedicated compressor or pump. The pneumatic valve is actuated by compressed air from the brake system, and the control logic automatically manages pressure regulation without external intervention, making the system self-sufficient.
2Object-affected harmful factors
If coolant pressure is actively controlled to prevent boiling, then engine protection is improved, but system complexity increases due to additional control components
Solution Approach 1:
The patent introduces a pneumatic valve as an intermediary component that mediates between the air brake system and the coolant expansion tank. This valve controls the introduction of compressed air into the expansion tank, thereby regulating coolant pressure indirectly through gas pressure, which prevents direct mechanical contact and simplifies the control mechanism.
Solution Approach 2:
The system leverages the dual-purpose nature of the air brake system, which serves both braking functions and provides compressed air for pressure control. By utilizing this existing multi-functional system, the patent avoids adding dedicated single-function components, thereby reducing overall system complexity while maintaining effective engine protection.
3Productivity
If coolant pressure is increased to raise operating temperature, then cycle efficiency improves, but risk of boiling increases without pressure control
Solution Approach 1:
The patent implements dynamic pressure control where the target coolant pressure is not fixed but varies based on engine operating conditions. The electronic control unit receives inputs from temperature and pressure sensors and adjusts the pneumatic valve in real-time to maintain optimal pressure levels that prevent boiling while maximizing heat recovery efficiency across different engine loads and temperatures.
Solution Approach 2:
The system dynamically changes the pressure parameter of the coolant based on operating conditions. By adjusting pressure through the pneumatic valve, the boiling point of the coolant is shifted to match required operating temperatures, allowing efficient heat recovery at higher temperatures without risking boil-off, as the pressure is continuously adapted to maintain the liquid phase.
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 maintains coolant fluid at a higher temperature for longer periods, enhancing cycle efficiency and preventing damage by actively controlling pressure, thus improving waste heat recovery and engine cooling.
Implementation Method 1
The coolant heat exchanger is positioned along the working fluid circuit and is structured to transfer heat from the coolant fluid to the working fluid
Implementation Method 2
The pressure line is structured to receive pressurized air from the pressure source and to provide the pressurized air to the coolant tank
Implementation Method 3
A valve is operatively coupled to the pressure line upstream of the coolant tank
Implementation Method 4
Some WHR systems use a Rankine cycle. A Rankine cycle is a thermodynamic process in which heat is transferred to a working fluid in a Rankine cycle circuit. The working fluid is pumped to a boiler where it is vaporized. The vapor is passed through an expander
Implementation Method 5
An Organic Rankine cycle ('ORC') is a Rankine cycle in which the working fluid is an organic, high molecular mass fluid with a liquid-vapor phase change at a lower temperature than that of water
Data Source
AI summary
A waste heat recovery (WHR) and coolant system with active coolant pressure control includes an engine cooling system, a WHR system, and a coolant pressure control system. A coolant heat exchanger positioned along each of the engine cooling and working fluid circuits, and is structured to transfer heat from the coolant fluid to the working fluid. The coolant pressure control system includes a pressure line operatively coupled to an air brake system and to the coolant tank. A valve is coupled to the pressure line upstream of the coolant tank. A coolant pressure controller is in operative communication with each of the valve, an air pressure sensor, and a coolant temperature sensor. The coolant pressure controller is structured to determine a target coolant pressure based on a coolant temperature and control a valve position of the valve so as to cause the air pressure to approach the target coolant pressure.