Refrigeration device
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Solution Overview
Problem
Conventional refrigeration apparatuses face challenges in achieving high operating efficiency due to high heat radiation loss in outdoor heat exchangers when using refrigerants like carbon dioxide, which operates in a supercritical range, and struggle to maintain efficiency during both cooling and heating operations.
Innovation Solution
The refrigeration apparatus incorporates an intermediate heat exchanger and an intermediate heat exchanger bypass tube, along with optimized injection rate control, to manage the flow rate of refrigerant through the second-stage injection tube, ensuring a higher injection ratio during heating operations and maintaining efficiency by minimizing heat radiation loss and utilizing heat effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If intermediate pressure injection is performed to reduce compressor power consumption, then operating efficiency improves, but heat radiation loss in outdoor heat exchanger increases when using supercritical refrigerants
Solution Approach 1:
The patent divides the compression process into two stages with separate compression elements, allowing independent control of injection timing and rate for each stage. This segmentation enables optimized heat management at different pressure levels, reducing overall heat radiation loss while maintaining operating efficiency.
Solution Approach 2:
The patent performs preliminary cooling of the refrigerant in the outdoor heat exchanger before it enters the compression mechanism. By pre-cooling the supercritical refrigerant, the system reduces the temperature difference during compression, thereby minimizing heat radiation loss while still achieving efficient operation.
2Temperature
If injection rate is increased to improve cooling effect, then refrigerant temperature decreases, but compressor power consumption increases
Solution Approach 1:
The patent employs dynamic control of the injection rate based on real-time operating conditions. The injection amount is adjusted according to the refrigerant state, ambient temperature, and load requirements, allowing the system to achieve optimal cooling effect while minimizing compressor power consumption through adaptive rather than fixed injection rates.
3Loss of energy
If two-stage compression is implemented to reduce power consumption, then operating efficiency improves, but device complexity increases
Solution Approach 1:
The patent integrates the injection mechanism directly into the two-stage compression system, combining the injection function with the compression elements. By merging the injection ports and control systems with the existing compression mechanism, the patent reduces overall device complexity while maintaining the power consumption benefits of two-stage compression.
4Loss of energy
If intermediate heat exchanger is added to cool refrigerant, then heat radiation loss reduces, but device complexity and cost increase
Solution Approach 1:
The outdoor heat exchanger is designed to serve multiple functions: it acts as both the primary heat exchange component and the intermediate cooling device for the supercritical refrigerant. By making the outdoor heat exchanger multi-functional, the patent eliminates the need for a separate intermediate heat exchanger, thereby reducing device complexity and cost while still achieving reduced heat radiation loss.
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 reduces heat radiation loss during cooling operations and maintains efficiency during heating operations by optimizing the injection ratio and utilizing heat effectively, thereby improving the coefficient of performance.
Implementation Method 1
an intermediate heat exchanger which cools the refrigerant discharged from the first-stage compression element and taken into the second-stage compression element
Implementation Method 2
a second-stage injection tube for returning to the second-stage compression element some of the refrigerant whose heat has been radiated in the outdoor heat exchanger or the indoor heat exchanger
Implementation Method 3
a compression mechanism having a plurality of compression elements and configured so that refrigerant discharged from a first-stage compression element is sequentially compressed by a second-stage compression element
Implementation Method 4
a switching mechanism for switching between a cooling operation state and a heating operation state
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
An air-conditioning apparatus (1) includes a two-stage compression-type compression mechanism (2), a heat source-side heat exchanger (4), an expansion mechanism (5), a usage-side heat exchanger (6), a switching mechanism (3), a first second-stage injection tube (18c), an intermediate heat exchanger (7), an intermediate heat exchanger bypass tube (9), and a liquid injection tube (18h). According to the air-conditioning apparatus (1), injection rate optimization control is performed for controlling the flow rate of the refrigerant returned to a second-stage compression element (2d) through the liquid injection tube (18h) so that an injection ratio, which is the ratio of the flow rate of the refrigerant returned to the second-stage compression element (2d) through the first second-stage injection tube (18c) and the liquid injection tube (18h) relative to the flow rate of the refrigerant discharged from the compression mechanism (2), is greater during the heating operation than during the cooling operation.