Estimating Hot Section Pressure in Waste Heat Recovery Systems
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Solution Overview
Problem
Monitoring the operating characteristics of waste heat recovery (WHR) systems is challenging due to the high temperatures and pressures in the hot section, making it costly and inconvenient to install and maintain physical sensors.
Innovation Solution
A controller estimates the pressure of the working fluid in the hot section of the WHR system by receiving pump data, valve position data, and pressure data, and calculates the flow rate and pressure changes across the system, eliminating the need for physical sensors in the hot section.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If physical sensors are installed in the hot section to monitor operating characteristics, then measurement precision is improved, but device complexity and maintenance difficulty increase due to high temperatures and pressures
Solution Approach 1:
The patent introduces cold section pressure sensors as intermediary measurement points, using the cold section as a mediator to indirectly infer hot section conditions. Instead of placing sensors directly in the harsh hot section environment, the system uses sensors in the milder cold section combined with thermodynamic calculations to determine hot section pressure, eliminating the need for complex high-temperature resistant sensors.
Solution Approach 2:
The patent replaces physical mechanical sensors in the hot section with a computational approach. Instead of using physical devices to directly measure hot section pressure, the system uses mathematical relationships (thermodynamic equations, isentropic expansion relations) combined with electronic sensors in the cold section to calculate the desired pressure values, substituting mechanical measurement with computational analysis.
2Reliability
If physical sensors are installed in the hot section, then operating characteristic monitoring is improved, but ease of manufacture and installation deteriorate due to high temperature requirements
Solution Approach 1:
The cold section serves as an intermediary zone where standard pressure sensors can be easily installed without requiring special high-temperature materials or complex cooling systems. The cold section acts as a buffer zone that allows conventional manufacturing and installation practices to be used while still providing information about hot section conditions through thermodynamic relationships.
3Measurement precision
If physical sensors are installed in the hot section, then flow rate monitoring is improved, but maintenance difficulty increases due to harsh operating conditions
Solution Approach 1:
The patent uses the cold section as a maintenance-friendly intermediary location. Sensors placed in the cold section can be accessed, maintained, and replaced using standard procedures without requiring shutdown of the entire system or specialized high-temperature maintenance equipment. The cold section environment allows routine maintenance activities to be performed safely and efficiently.
Data Source
AI summary
An apparatus includes a pump circuit structured to receive pump data indicative of an operating characteristic of a pump feeding a fluid to a waste heat recovery (WHR) system; a flow circuit structured to receive valve position data indicative of a position of a valve downstream of the pump, estimate a flow rate of the fluid exiting the pump, and estimate the flow rate of the fluid exiting the valve; and a pressure circuit structured to receive pressure data indicative of the pressure of the fluid exiting the valve, estimate a change in pressure of the fluid across the WHR system, and determine a pressure of the fluid in a hot section of the WHR system based on the pressure of the fluid exiting the valve and the change in the pressure of the fluid across the WHR system.