Refrigeration cycle device
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Solution Overview
Problem
Conventional refrigeration cycle apparatuses face reliability issues with the high-stage compressor due to a decreased compression ratio and vane jumping phenomenon when low-temperature hot water is generated, leading to overheating and user discomfort.
Innovation Solution
A refrigeration cycle apparatus with a low-stage and high-stage refrigerant circuit, a water circuit, a heat dissipating device, and a control device that switches flow paths and adjusts compressor rotation speed based on required capacity and temperature differences to maintain reliable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the rotation speed of the compressor in the high-stage refrigerant circuit is increased to raise the compression ratio, then the reliability of the compressor is improved, but the second refrigerant overheats the water, resulting in a loss of user comfort
Solution Approach 1:
A heat dissipating device is introduced as an intermediary component between the second refrigerant circuit and the water circuit. This device selectively dissipates heat from the second refrigerant or water to prevent overheating while allowing the compressor to operate at higher rotation speeds for improved reliability. The heat dissipating device acts as a mediator that decouples the direct thermal interaction, enabling independent optimization of compressor reliability and water temperature control.
2Temperature
If the compression ratio in the compressor of the high-stage refrigerant circuit is decreased, then the user comfort is improved by preventing water overheating, but the reliability of the compressor deteriorates due to the occurrence of a vane jumping phenomenon
Solution Approach 1:
The heat dissipating device serves as a mediator that allows the system to maintain lower compression ratios (improving water temperature control) while preventing compressor reliability issues. By actively managing heat dissipation, the system can operate the compressor in a more reliable operating range without transferring excessive heat to the water, thus resolving the contradiction between temperature control and compressor reliability.
3Temperature
If a heat dissipating device is added to manage heat release, then the water temperature control is improved, but the device complexity increases due to additional flow path switching valve and bypass flow path
Solution Approach 1:
The system employs dynamic flow path switching capability through a controllable valve that can direct refrigerant flow either through the heat dissipating device or through a bypass flow path. This dynamic adaptability allows the system to optimize performance based on operating conditions while maintaining a relatively simple base structure. The bypass flow path provides a straightforward alternative route that reduces complexity compared to having the heat dissipating device as the sole thermal management component.
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
Improves the reliability of the refrigeration cycle apparatus by preventing compressor deterioration and maintaining user comfort through efficient heat management and load balancing.
Implementation Method 1
a cascade heat exchanger, and through which a second refrigerant heat-exchanged with the first refrigerant in the cascade heat exchanger circulates
Implementation Method 2
a water-refrigerant heat exchanger, and through which water heat-exchanged with the second refrigerant in the water-refrigerant heat exchanger circulates
Implementation Method 3
a heat dissipating device that is connected to at least one of the high-stage refrigerant circuit and the water circuit, to release heat of any one of the second refrigerant and the water
Data Source
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AI summary
In a refrigeration cycle apparatus, in a low-stage refrigerant circuit, a first refrigerant circulates. In a high-stage refrigerant circuit, a second refrigerant that is heat-exchanged with the first refrigerant in a cascade heat exchanger circulates. A water circuit includes a second indoor heat exchanger and a water-refrigerant heat exchanger, and water that is heat-exchanged with the second refrigerant in the water-refrigerant heat exchanger circulates therein. A heat dissipating device is connected to at least one of the high-stage refrigerant circuit and the water circuit, and is connected though the bypass flow path so as to bypass the second refrigerant or the water. The control device switches, during the heating operation by the indoor unit of the second indoor heat exchanger, to the first heating operation in which the second refrigerant or the water is flowed to only the bypass flow path, or to the second heating operation in which the second refrigerant or the water is flowed to both the heat dissipating device and the bypass flow path, and determines a rotation speed of the second compressor based on required capacities of the indoor unit of the second indoor heat exchanger and the heat dissipating device.