Refrigeration device
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Solution Overview
Problem
In dual refrigerating apparatuses, mismatches in compressor specifications can lead to mismatched timing and biased changes in evaporation and condensation temperatures, prolonging the time to achieve a constant temperature in the storage and the cascade condenser.
Innovation Solution
A refrigerating apparatus with separate refrigerant circuits and sensors to control compressor operations based on detected temperatures, ensuring the cascade condenser and storage temperatures are maintained within predetermined ranges, allowing for synchronized control of the high-temperature and low-temperature side compressors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If control is made based on a single sensor detection output for both compressors, then the control system is simple, but the timing and rate of temperature changes in the cascade condenser and storage may not match, prolonging the time to achieve constant temperature
Solution Approach 1:
The control system is segmented into two independent control loops: one controlling the high-temperature side compressor based on cascade condenser temperature, and another controlling the low-temperature side compressor based on storage temperature. This segmentation allows each compressor to be optimized independently, resolving the timing mismatch problem while maintaining overall system simplicity.
Solution Approach 2:
The high-temperature side compressor is controlled in advance to stabilize the cascade condenser temperature before the low-temperature side compressor fully operates. This preliminary action ensures that the cooling foundation is established first, allowing the low-temperature side to then efficiently achieve the target storage temperature without timing conflicts.
2Adaptability or versatility
If compressor specifications are different or performances vary, then each compressor can be optimized for its specific function, but the evaporation and condensation temperature changes become mismatched, affecting overall system efficiency
Solution Approach 1:
Each compressor is controlled with locally optimized parameters: the high-temperature side compressor uses cascade condenser temperature as its control parameter, while the low-temperature side compressor uses storage temperature. This local quality approach allows each component to operate at its optimal performance point regardless of specification differences, maintaining high overall system efficiency.
Solution Approach 2:
The control system dynamically adjusts compressor operation parameters (rotation speed, capacity) based on real-time temperature measurements. By changing operational parameters rather than relying on fixed compressor specifications, the system accommodates different compressor types and performance characteristics while maintaining synchronized temperature control and high productivity.
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 improves the controllability of storage temperatures, ensuring the cascade condenser reaches a stable temperature quickly and maintaining the storage temperature within set limits, thus reducing the time required to achieve a constant cooling temperature.
Implementation Method 1
an evaporator of the high-temperature side refrigerant circuit (hereinafter referred to as a high-temperature side evaporator) and a condenser of the low-temperature side refrigerant circuit (hereinafter referred to as a low-temperature side condenser) form a cascade condenser so as to mutually exchange heat
Implementation Method 2
the inside of the storage is cooled by the cooling effect of the low-temperature side refrigerant circuit
Data Source
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AI summary
A refrigerating apparatus for keeping an inside of a storage at a predetermined low-temperature state includes first and second refrigerant circuits including compressors, condensers, decompressors, and evaporators, connected circularly with pipings to form refrigerating cycles, the circuit having a first or second refrigerant sealed therein as a working refrigerant, a first sensor which detects a temperature of a cascade condenser constituted by integrating the evaporator of the first refrigerant circuit and the condenser of the second refrigerant circuit in a heat exchangeable manner, first and second controllers which control operation performances of the first and second compressors in a variable manner based on first- and second-sensor-detected temperatures in order that the first- and second-sensor-detected temperatures are first and second temperatures, respectively, and a second sensor which detects a temperature inside the storage.