Refrigerator and operation method for refrigerator
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Solution Overview
Problem
In refrigerators with expander-integrated compressors, heat penetration due to refrigerant leakage from the compressor to the expander leads to decreased adiabatic efficiency and coefficient of performance (COP), as high-temperature refrigerant leaks through gaps and causes inefficiency, despite the use of non-contact bearings to reduce mechanical friction.
Innovation Solution
A three-stage compressor configuration with a middle-stage compressor and expander integrated into the expander-integrated compressor, along with an extraction line to redirect leaking refrigerant back into the circulation line, and a sealed casing to prevent external heat penetration, combined with pressure and temperature detection systems to control the extraction amount for optimal COP.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a non-contact type bearing is used to support the output shaft of the motor, then mechanical friction loss and abrasion are reduced, but heat penetration due to refrigerant leakage from the compressor to the expander increases
Solution Approach 1:
The patent extracts and removes the harmful high-temperature refrigerant that leaks from the compressor back-face side before it can reach the expander. An extraction line is provided that connects the interior space of the casing (where leaked refrigerant accumulates) to the refrigerant circulation line, allowing the leaked refrigerant to be extracted and returned to the circulation system, preventing heat penetration into the expander.
Solution Approach 2:
The patent introduces an intermediary extraction line and control valve system between the compressor and expander. This intermediary system captures leaked refrigerant in the casing interior space and redirects it through the extraction line to the refrigerant circulation line, preventing direct heat transfer from high-temperature leaked refrigerant to the expander while maintaining the benefits of non-contact bearings.
2Object-affected harmful factors
If the amount of refrigerant to be returned through the extraction line is increased, then heat penetration is reduced, but the load capacity of the magnetic bearing decreases
Solution Approach 1:
The patent employs a control valve in the extraction line that can dynamically adjust the flow rate of extracted refrigerant. The control valve responds to signals from the control unit, which monitors temperature and pressure conditions, to optimize the extraction amount in real-time. This dynamic control allows the system to prevent heat penetration while maintaining sufficient refrigerant flow for magnetic bearing lubrication and cooling.
Solution Approach 2:
The patent implements a feedback control system where temperature sensors and pressure sensors monitor the refrigerant conditions, and the control unit adjusts the control valve opening degree accordingly. This feedback mechanism ensures that the extraction amount is optimized to prevent heat penetration into the expander while maintaining adequate refrigerant flow for the magnetic bearing's load capacity and cooling requirements.
3Stress or pressure
If a three-stage compressor configuration is used, then the compression ratio is improved, but the device complexity increases
Solution Approach 1:
The patent merges the three-stage compressor and expander into a single integrated expander-integrated compressor unit. The three compressors (first, second, and third compressors) and the expander are connected in series within a common casing, sharing a unified refrigerant circulation path. This integration achieves high compression ratio through three stages while consolidating the structure, reducing the number of separate components and connections compared to independent compressor and expander units.
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 significantly reduces heat penetration into the expander, enhancing the adiabatic efficiency and refrigerating performance of the refrigerator by minimizing refrigerant leakage and optimizing energy usage, thereby improving the COP.
Implementation Method 1
at least one non-contact type bearing, disposed between the middle-stage compressor and the expander, for supporting the output shaft of the first motor without being in contact with the output shaft
Implementation Method 2
an expander for adiabatically expanding and cooling the refrigerant discharged from the high-stage compressor
Implementation Method 3
a compressor for compressing the refrigerant
Implementation Method 4
a cooling part for cooling an object to be cooled through heat exchange with a refrigerant
Data Source
AI summary
A refrigerator according to the present invention includes: a cooling part for cooling an object to be cooled through heat exchange with a refrigerant; an expander-integrated compressor including a compressor for compressing the refrigerant and an expander for expanding the refrigerant integrated therein; and a refrigerant circulation line configured to circulate the refrigerant through the compressor, the expander, and the cooling part. The compressor includes a low-stage compressor, a middle-stage compressor, and a high-stage compressor disposed in series in the refrigerant circulation line. The expander-integrated compressor includes: the middle-stage compressor; an expander for adiabatically expanding and cooling the refrigerant discharged from the high-stage compressor; a first motor having an output shaft connected to the middle-stage compressor and to the expander; at least one non-contact type bearing, disposed between the middle-stage compressor and the expander, for supporting the output shaft of the first motor without being in contact with the output shaft; and a casing for housing the middle-stage compressor, the expander, and the at least one non-contact type bearing.