Vapor compression refrigeration cycle device
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Solution Overview
Problem
Vapor compression refrigeration cycle devices face a challenge in maintaining necessary heating ability when the injection amount is small, particularly due to a small high and low pressure difference in the compressor, which limits their efficiency.
Innovation Solution
The device incorporates a main refrigerant circuit and a bypass refrigerant circuit with a control device that increases the number of compressor rotations when the pressure ratio between discharge and suction pressures, or discharge pressure, is below a reference threshold, ensuring sufficient heating ability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the injection amount is reduced to enhance efficiency, then energy efficiency is improved, but heating ability deteriorates
Solution Approach 1:
The compressor operates in two distinct modes: injection mode for high efficiency when heating demand is low, and high-rotation mode when heating demand is high. The system dynamically switches between these modes based on the magnitude of heating demand, allowing the compressor to optimize between efficiency and heating capability.
Solution Approach 2:
The system changes the rotational speed parameter of the compressor based on heating demand. When heating demand is large, the compressor rotates at a higher speed to increase the refrigerant circulation amount and thereby increase the heating ability, even if this reduces efficiency.
2Use of energy by moving object
If the pressure ratio is small, then efficiency is improved, but heating ability deteriorates
Solution Approach 1:
The system dynamically adjusts compressor rotation based on the pressure ratio and heating demand. When the pressure ratio is small and heating demand is high, the system switches to high-rotation mode to compensate for the reduced heating ability caused by the small pressure ratio.
Solution Approach 2:
The control device determines whether to increase compressor rotation based on feedback from the heating demand magnitude and pressure ratio conditions. This feedback mechanism allows the system to respond appropriately to changing operating conditions and maintain necessary heating ability.
3Power
If the injection amount is increased to improve heating ability, then heating ability is improved, but energy efficiency deteriorates
Solution Approach 1:
The system operates in injection mode (high efficiency) when heating demand is small, and only switches to high-rotation mode (lower efficiency) when heating demand is large. This dynamic operation ensures that the system maintains necessary heating ability only when required, thereby preserving energy efficiency during normal operation.
Solution Approach 2:
The system changes compressor rotation parameter based on heating demand magnitude. By increasing rotation only when necessary (large heating demand), the system avoids the energy efficiency deterioration that would result from continuously operating at high rotation speeds.
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 approach effectively maintains necessary heating ability by adjusting compressor speed based on pressure ratios and discharge pressures, enhancing the device's operational efficiency even when injection amounts are low.
Implementation Method 1
a compressor (11) which compresses a refrigerant
Implementation Method 2
a use-side heat exchanger (12), an intermediate heat exchanger (13) and a heat source-side heat exchanger (15)
Data Source
Figure 1
Figure 2(a)~2(b)
Figure 3
AI summary
[Object] It is an object of the present invention to provide a vapor compression refrigeration cycle device capable of obtaining necessary heating ability when an injection amount becomes small. [Solving Means] A vapor compression refrigeration cycle device of the invention includes: a main refrigerant circuit 10 formed by sequentially connecting a compressor 11, a use-side heat exchanger 12, an intermediate heat exchanger 13, a first expansion device 14 and a heat source-side heat exchanger 15 to one another through a refrigerant pipe 16; a bypass refrigerant circuit 20 which branches off from the refrigerant pipe 16 located between the use-side heat exchanger 12 and the first expansion device 14, and which is formed by sequentially connecting a second expansion device 21, the intermediate heat exchanger 13 and a compression midstream of the compressor 11; and a control device 50 for controlling valve opening degrees of the first expansion device 14 and the second expansion device 21; wherein when a pressure ratio of discharge pressure of refrigerant discharged from the compressor 11 and suction pressure of refrigerant sucked into the compressor 11 is equal to or smaller than a reference pressure ratio, the control device 50 controls the compressor 11 such that number of rotations of the compressor 11 is increased.