Cold source unit, refrigeration cycle apparatus, and refrigerator
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Solution Overview
Problem
Existing refrigeration cycle apparatuses, such as refrigerators, face challenges in accurately detecting small amounts of refrigerant leakage due to manufacturing variations in temperature sensors and the use of non-azeotropic refrigerants, which complicates the determination of refrigerant appropriateness and leakage detection.
Innovation Solution
The implementation of a cold source unit with a controller that adjusts compressor rotation speed and uses multiple temperature sensors to correct detection errors, determining refrigerant sufficiency by calculating temperature differences and adjusting the refrigerant composition control based on enthalpy and pressure measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If temperature sensors are used to detect refrigerant temperature for determining refrigerant appropriateness, then refrigerant amount determination can be performed, but manufacturing variations in temperature sensors cause detection errors that reduce measurement precision
Solution Approach 1:
The system uses feedback control by continuously monitoring the temperature difference between the refrigerant before and after heater heating, and adjusting the heater output accordingly. This feedback mechanism compensates for temperature sensor manufacturing variations by using the actual measured temperature difference to determine refrigerant state, rather than relying on absolute temperature values that are subject to sensor calibration errors.
Solution Approach 2:
The invention changes the measurement parameter from absolute temperature to temperature difference (ΔT). By measuring the change in temperature caused by heater heating rather than the absolute temperature itself, the system eliminates the influence of temperature sensor manufacturing variations and calibration offsets, thereby improving measurement precision for refrigerant state determination.
2Quantity of substance
If a receiver is provided between condenser and expansion valve to store liquid refrigerant, then refrigerant can be stored, but the degree of supercooling at condenser outlet does not change much when refrigerant amount decreases, making leakage detection difficult
Solution Approach 1:
The invention introduces a heater as an intermediary device between the receiver and expansion valve. This heater actively heats the liquid refrigerant, creating a measurable temperature difference that serves as an indicator of refrigerant state. The heater-mediated temperature measurement allows detection of refrigerant amount changes even when the receiver buffers the changes, thereby improving leakage detection sensitivity.
Solution Approach 2:
The system performs preliminary heating of the refrigerant before it reaches the expansion valve by using the heater in the liquid line. This preliminary action creates a controlled temperature change that can be measured to infer refrigerant state, allowing detection of refrigerant amount changes before they propagate through the entire system and are buffered by the receiver.
3Loss of information
If multiple temperature sensors are used to detect refrigerant temperature at different positions, then more comprehensive data can be obtained, but device complexity increases
Solution Approach 1:
The system segments the temperature measurement function by placing temperature sensors at specific critical locations (before and after the heater) rather than distributing them throughout the entire refrigeration cycle. This segmentation approach obtains sufficient refrigerant state information from key measurement points while avoiding the complexity of comprehensive multi-point monitoring.
Solution Approach 2:
The invention extracts only the essential temperature measurements needed for refrigerant state determination - specifically the temperature difference across the heater - rather than measuring temperature at every possible location in the system. This extraction of critical measurement points reduces device complexity while maintaining the ability to detect refrigerant leakage and determine refrigerant appropriateness.
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 enables accurate detection of small refrigerant leaks and improves the accuracy of refrigerant composition analysis, reducing the required heater capacity and enhancing the reliability of refrigerant management systems.
Implementation Method 1
a heater (40) configured to heat the refrigerant flowing through the second flow path (F2)
Implementation Method 2
a plurality of temperature sensors (122, 123) disposed at the second flow path (F2)
Implementation Method 3
calculate an average value of the temperatures detected by the plurality of temperature sensors, and perform correction on each of the plurality of temperature sensors based on a difference between the average value and a temperature detected by a corresponding one of the plurality of temperature sensors
Implementation Method 4
a compressor (10) configured to suction the refrigerant and discharge the compressed refrigerant
Implementation Method 5
a condenser (20) configured to condense the refrigerant discharged from the compressor (10)
Implementation Method 6
first expansion device (50) and second expansion device (92)
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A cold source unit (2) includes a first flow path (F1) configured to receive refrigerant from an evaporator (60) and send out the refrigerant toward a first expansion device (50) via a compressor (10) and a condenser (20); a second flow path (F2) configured to send, to the compressor (10) not via the first expansion device (50) and the evaporator (60), the refrigerant that has passed through the condenser (20); a second expansion device (92) provided at the second flow path (F2); and a plurality of temperature sensors (121 to 123) disposed at the second flow path (F2). A controller (100) is configured to control a refrigeration cycle apparatus (1) such that temperatures detected by the plurality of temperature sensors become equal to each other, and calculate an average value of the temperatures detected by the plurality of temperature sensors, and perform correction on each of the plurality of temperature sensors based on a difference between the average value and a temperature detected by a corresponding one of the plurality of temperature sensors.