Refrigeration cycle device
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Solution Overview
Problem
Refrigeration oil in compressors experiences increased viscosity at or below its pour point, leading to abnormal compressor stops, reduced user comfort, and potential lubrication failures due to overcurrent and uneven oil distribution, which affects the reliability of refrigeration cycle apparatuses, especially in low-temperature conditions.
Innovation Solution
A refrigeration cycle apparatus equipped with a detection unit to monitor oil temperature and a heating unit that heats the oil when it falls below the pour point, maintaining appropriate viscosity and preventing overcurrent issues by controlling the compressor and expansion valve operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the refrigeration cycle apparatus operates in low temperature environments, then the operating range is extended, but the refrigeration oil viscosity increases causing overcurrent and abnormal compressor stops
Solution Approach 1:
The heating unit pre-heats the refrigeration oil before the viscosity increase causes overcurrent and compressor stoppage. The detection unit monitors oil temperature and activates heating when temperature drops below a predetermined threshold, preventing the harmful effect of excessive viscosity before it occurs.
Solution Approach 2:
The detection unit continuously monitors refrigeration oil temperature and provides feedback to the control unit. Based on this feedback, the control unit adjusts the heating unit operation to maintain oil temperature within a safe range, preventing overcurrent while enabling low-temperature operation.
2Reliability
If heating is applied to maintain oil viscosity, then lubrication reliability is improved, but energy consumption increases
Solution Approach 1:
Instead of continuously heating the refrigeration oil, the heating unit operates only partially - specifically when the detection unit detects that oil temperature approaches the pour point. This partial action maintains adequate lubrication reliability while minimizing unnecessary energy consumption during normal operating temperatures.
3Reliability
If refrigeration oil concentration is uniform, then lubrication is improved, but two-phase separation occurs at low temperature causing high viscosity zones
Solution Approach 1:
The heating unit pre-heats the refrigeration oil before two-phase separation can occur. By maintaining temperature above the pour point through preliminary heating action, the system prevents the formation of high-viscosity oil zones that would result from concentration non-uniformity and two-phase separation.
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 maintains appropriate oil viscosity, preventing abnormal compressor stops and improving reliability by reducing driving torque and ensuring uniform oil circulation, thus enhancing the performance and durability of refrigeration cycle apparatuses in low-temperature environments.
Implementation Method 1
a heating unit configured to heat the refrigeration oil
Data Source
Figure 1~2
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Figure 5~6
AI summary
In a refrigeration cycle apparatus, refrigerant circulates successively through a compressor, a condenser, an expansion valve, and an evaporator. The refrigeration cycle apparatus includes a detection unit (100), a heating unit (50), and a controller (200). The detection unit (100) is configured to detect a temperature of refrigeration oil in the compressor. The heating unit (50) is configured to heat the refrigeration oil. The controller (200) is configured to operate the heating unit (50) when the temperature detected by the detection unit (100) is lower than a pour point of the refrigeration oil, and to stop the heating by the heating unit (50) when the temperature detected by the detection unit (100) reaches the pour point. Preferably, the heating unit includes a heater provided on an outer side of a compressor casing and at a lower portion of a motor unit.