WHR System Shutdown Control Using Pre-Cooled Compensation Tank Flow
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Solution Overview
Problem
Conventional WHR systems face pressure drops during inactive periods due to condensation of working fluid, leading to potential ambient air infiltration, which is slow to resolve using passive cooling methods.
Innovation Solution
Active cooling by circulating cool working fluid from a compensation tank to the main circuit using a pump and valve system, with controlled pressure differences and cooling means, to rapidly condense and manage working fluid state, preventing pressure drops and ensuring all fluid is in a liquid state for safe shutdown.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If passive cooling by ambient air is used to cool the working fluid in the main circuit, then the system structure is simple, but the cooling speed is slow and the shutdown time is extended
Solution Approach 1:
The compensation tank pre-cools the working fluid before it enters the main circuit. During normal operation, the working fluid in the compensation tank is continuously cooled by the cooling device, so when shutdown occurs, the pre-cooled fluid from the compensation tank can immediately replace the hot fluid in the main circuit, achieving fast cooling without requiring the main circuit to cool down from scratch
Solution Approach 2:
The compensation tank acts as an intermediary between the cooling device and the main circuit. It stores pre-cooled working fluid and supplies it to the main circuit during shutdown, mediating the heat transfer process and enabling rapid cooling of the main circuit without directly connecting the cooling device to the main circuit
2Reliability
If the pump circulates working fluid for a long period after ignition is turned off to ensure complete condensation, then the risk of ambient air infiltration is eliminated, but the shutdown time is extended and energy consumption increases
Solution Approach 1:
The control device monitors the temperature and pressure of the working fluid in real-time and adjusts the pump operation accordingly. When the working fluid temperature drops below the dew point or pressure reaches a preset value, the control device automatically stops the pump, ensuring complete condensation while minimizing shutdown time and energy consumption
Solution Approach 2:
The compensation tank prepares pre-cooled working fluid in advance during normal operation. When shutdown occurs, this pre-cooled fluid is rapidly supplied to the main circuit, accelerating the condensation process and reducing the time the pump needs to operate, thereby quickly eliminating the risk of ambient air infiltration
3Productivity
If the working fluid temperature in the main circuit is very high at shutdown, then the system has been operating efficiently, but the pump must circulate the working fluid for a relatively long period to condense all gaseous working fluid
Solution Approach 1:
The cooling device continuously pre-cools the working fluid in the compensation tank during normal operation. When shutdown occurs regardless of how hot the main circuit fluid is, the pre-cooled fluid from the compensation tank is immediately supplied to the main circuit, reducing the temperature differential and accelerating condensation, thus shortening pump circulation duration while maintaining high operational efficiency
Solution Approach 2:
The system divides the working fluid into two separate circuits: the main circuit for heat recovery during operation and the compensation tank for pre-cooling. This segmentation allows the compensation tank to independently prepare cold fluid without interfering with the main circuit's efficient operation, enabling rapid shutdown regardless of main circuit temperature
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
Facilitates a fast and controlled shutdown phase, preventing pressure drops and ensuring all working fluid is in a liquid state, thereby reducing the risk of ambient air infiltration and enhancing system reliability.
Implementation Method 1
The working fluid in the compensation tank is cooled by ambient air
Implementation Method 2
flow means which supply cool working fluid flow from the compensation tank to the main circuit
Implementation Method 3
ambient air cools the gaseous working fluid in said isolated spaces to a temperature at which the working fluid condenses
Data Source
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AI summary
The present invention relates to an arrangement and a method for controlling a shutdown phase of a WHR-system. The WHR system comprises a main circuit (4) which comprises a pump (3), an evaporator (5), an expander (7) and a condenser (10), and a compensation tank (12) which is configured to compensate for volume changes of a working fluid in the main circuit (4) during operation of the WHR system. The arrangement comprises a control unit (26) configured to receive information when the shutdown phase of the WHR system is to be initiated and flow means able to supply working fluid from the compensation tank (12) to the main circuit (4). The control unit (26) is configured to activate said flow means such that working fluid is supplied from the compensation tank (12) to the main circuit (4) when it receives information indication that the shutdown phase of the WHR system is to be initiated.