Heat source device
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Solution Overview
Problem
In heat source systems, especially centrifugal chillers, the high cost and external placement of electromagnetic flow rate meters pose challenges in accurately measuring chilled-water flow rates, leading to difficulties in control responsiveness and accuracy, with estimated flow rates often being inaccurate, requiring frequent on-site adjustments.
Innovation Solution
A heat source device employs a differential pressure sensor to measure the pressure difference across a heat exchanger, calculates the heating-medium flow rate using specific coefficients, and includes a controlling means to correct control commands based on real-time flow rates, enhancing accuracy and enabling automatic fine control. Additionally, it includes fault judgment and smoothing processing to stabilize control and detect potential issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an electromagnetic flow rate meter is used to measure chilled-water flow rate, then measurement precision is improved, but device cost increases and control responsiveness deteriorates due to external data placement
Solution Approach 1:
The patent merges the flow rate measurement function into the centrifugal chiller itself by installing a differential pressure sensor at the heat exchanger inlet/outlet. This integration eliminates the need for separate electromagnetic flow rate meters and external data transmission systems, thereby reducing device complexity and improving control responsiveness while maintaining measurement precision through direct pressure differential measurement
Solution Approach 2:
The patent replaces the electromagnetic flow rate measurement system with a differential pressure-based measurement system. By measuring pressure differential across the heat exchanger and calculating flow rate from this data, the system substitutes complex electromagnetic measurement with a simpler pressure-based approach, reducing cost and improving integration
2Device complexity
If flow rate estimation using pump characteristic curve is used instead of installing a flow rate meter, then device complexity is reduced, but measurement precision deteriorates leading to frequent manual adjustments
Solution Approach 1:
The patent replaces pump characteristic curve estimation with actual differential pressure measurement. By installing a differential pressure sensor at the heat exchanger, the system directly measures pressure differential and calculates actual flow rate, substituting theoretical estimation with empirical measurement to achieve higher precision without significantly increasing device complexity
Solution Approach 2:
The system enables self-service flow rate measurement by using the heat exchanger's own pressure differential as the measurement basis. The differential pressure sensor captures actual operating conditions, allowing the system to self-calculate flow rate without external estimation methods, thereby improving precision while maintaining simplicity
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 configuration allows for accurate and cost-effective measurement of heating-medium flow rates, improving control accuracy and enabling timely maintenance by detecting faults, such as flow rate changes or performance deterioration, with a single differential pressure sensor.
Implementation Method 1
a differential pressure sensor 41 for measuring an inlet-outlet differential pressure of the chilled water is provided at chilled-water inlet/outlet of the evaporator 26
Data Source
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AI summary
A heat source device is provided with a differential pressure sensor (41) that measures the differential pressure between an inlet pressure and an outlet pressure for the chilled water in an evaporator (26) and with a control device (30). The control device (30) possesses the coefficient of loss for the evaporator (26) and is provided with a chilled-water flow-rate computing portion (52) that calculates a chilled-water flow rate at the evaporator (26) on the basis of the coefficient of loss and the differential pressure output from the differential pressure sensor (41); a control-command computing portion (55) that generates a control command by using a specification heating-medium flow rate that is set in advance; and a control-command correcting portion (56) that corrects the control command generated by the control-command computing portion (55) on the basis of the difference between the chilled-water flow rate calculated by the chilled-water flow-rate computing portion (52) and a specification chilled-water flow rate that is set in advance.