Expansion Machine Heating Jacket for Waste Heat Recovery
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Solution Overview
Problem
Bottoming cycle apparatuses, such as Rankine cycle systems, face inefficiencies due to inactive periods caused by poor quality heat availability and component warm-up times, which affect operational uptime and thermal management.
Innovation Solution
An expansion machine with a heating jacket connected to the working fluid circuit, featuring a bypass valve that controls the flow of working fluid between the expansion machine and the heating jacket based on temperature and operational conditions, such as rotational speed and torque demand, to optimize thermal management and reduce warm-up times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the working fluid is directed to the expansion machine inlet to generate power, then energy production occurs, but the expansion machine warm-up time increases during poor quality heat availability
Solution Approach 1:
The working fluid circuit is segmented into two separate paths: one leading to the expansion machine inlet for power generation, and another leading to the heating jacket for warm-up. The bypass valve enables selective routing of working fluid between these two paths based on operational conditions, allowing the system to address both power production and warm-up requirements independently.
Solution Approach 2:
The heating jacket provides preliminary warming action to the expansion machine before the working fluid is directed to the expansion inlet for power generation. By pre-heating the expansion machine components during periods of poor quality heat availability, the system reduces subsequent warm-up time when returning to normal power generation operation.
2Reliability
If the bypass valve directs working fluid to the heating jacket, then the expansion machine warms up faster, but operational uptime decreases due to reduced power generation
Solution Approach 1:
The bypass valve is dynamically controlled based on real-time monitoring of working fluid temperature and expansion machine temperature. The control system adjusts the valve position to optimize the balance between warming up the expansion machine and maintaining power generation, ensuring that working fluid is directed to the heating jacket only when necessary for warm-up while maintaining operational uptime.
3Temperature
If the working fluid temperature is low (poor quality heat), then the expansion machine cannot operate efficiently, but directing fluid to the heating jacket reduces available fluid for power generation
Solution Approach 1:
The heating jacket acts as an intermediary component that utilizes low-temperature working fluid to warm the expansion machine components. Instead of directly introducing cold working fluid to the expansion machine (which would be inefficient), the heating jacket serves as a mediator that transfers thermal energy from the low-quality heat to the expansion machine, preparing it for efficient operation while still utilizing the available thermal energy.
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 solution enhances operational uptime by improving thermal management during periods of poor heat quality and reduces warm-up times, thereby increasing system efficiency and extending operational periods.
Implementation Method 1
a heating jacket that is connected to receive working fluid for the purpose of heating the expansion machine
Data Source
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AI summary
A waste heat recovery apparatus, for use with an internal combustion engine, includes a working fluid circuit to circulate working fluid, a boiler connected on the working fluid circuit and adapted to recover waste heat from a source to heat working fluid, an expander connected on the working fluid circuit to receive working fluid from the boiler, and, a heating jacket associated with the expander. The working fluid circuit downstream of the boiler includes a first branch connecting to an inlet of the expander and a second branch connecting to the heating jacket. A valve is connected on the working fluid circuit to selectively control working fluid flow to one of the first branch for expansion and recovering work or to the second branch to heat the expander responsive to a temperature of the working fluid.