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Solution Overview
Problem
Existing heat source units face issues with unintentional removal of pump operation prohibition due to short circuits in interlock mechanisms and pump failures, leading to non-flowing usage fluid conditions, which can cause freezing or excessive load, and require additional flow rate sensors to detect, increasing cost and parts.
Innovation Solution
A heat source unit with a compressor, heater, first and second temperature sensors, and a controller that prohibits compressor startup based on a predetermined temperature difference between inlet and outlet usage fluid temperatures to detect non-flowing conditions without additional parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pump interlock mechanism is installed to prohibit compressor operation when the pump is stopped, then the reliability of preventing freezing and excessive load is improved, but the device complexity increases and the risk of short circuit failures increases
Solution Approach 1:
The invention extracts the flow detection function from the pump interlock mechanism and implements it directly in the controller by monitoring the temperature difference between inlet and outlet usage fluid. This eliminates the need for separate pump interlock switches and flow rate sensors, reducing device complexity while maintaining reliability in preventing freezing and excessive load.
Solution Approach 2:
The controller is given a multi-function: it not only controls the compressor operation but also detects usage fluid flow by monitoring temperature difference. This universal approach combines multiple functions into a single component, reducing the overall number of parts while ensuring reliable operation.
2Measurement precision
If a flow rate sensor is added to directly detect the flow rate of usage fluid, then the measurement precision of flow detection is improved, but the device complexity and cost increase
Solution Approach 1:
The invention uses temperature difference as an intermediary parameter to indirectly detect usage fluid flow. Instead of directly measuring flow rate with a sensor, the system monitors the temperature difference between inlet and outlet usage fluid, which serves as a reliable indicator of flow status. This intermediary approach achieves accurate flow detection without adding complex sensing equipment.
Solution Approach 2:
The invention replaces the mechanical flow rate sensor with a thermal-based detection method using temperature sensors and controller logic. This substitution eliminates the need for mechanical flow sensing components while achieving equivalent or superior detection accuracy through thermal field measurement.
3Ease of operation
If the pump interlock mechanism is used to detect pump operation status, then the ease of operation is improved, but the reliability decreases due to short circuit risks and pump failures
Solution Approach 1:
The system implements feedback by continuously monitoring the temperature difference between inlet and outlet usage fluid and using this information to determine actual flow status. This feedback mechanism provides reliable real-time detection of usage fluid flow, automatically controlling compressor operation based on actual conditions rather than relying on potentially faulty pump interlock signals.
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
Accurately detects non-flowing usage fluid conditions, preventing freezing and excessive load without additional sensors, reducing costs and parts, and ensuring reliable operation.
Implementation Method 1
a heater configured to heat the compressor
Implementation Method 2
a first heat exchanger configured to exchange heat between the refrigerant and usage fluid
Implementation Method 3
a first temperature sensor disposed on the first heat exchanger, a second temperature sensor disposed on the first heat exchanger
Implementation Method 4
a compressor configured to compress a refrigerant
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
To accurately detect a condition of nonflowing usage fluid in a heat exchanger, a heat source unit includes a compressor configured to compress a refrigerant, a heater configured to heat the compressor, a first heat exchanger configured to exchange heat between the refrigerant and usage fluid, a first temperature sensor disposed on the first heat exchanger, a second temperature sensor disposed on the first heat exchanger in a position where heat amount to be received by heat radiation from the heater is different from the first temperature sensor, and a controller configured to prohibit start-up of the compressor based on difference between temperatures detected by the first temperature sensor and the second temperature sensor.