Refrigerant Distribution Control in Multi-Circuit Refrigeration
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Solution Overview
Problem
Conventional refrigerating apparatuses face difficulties in accurately adjusting the cooling capacity of user side circuits due to imbalances in refrigerant distribution caused by gravity and pressure losses, especially when user side circuits have different installation levels or piping lengths, leading to insufficient cooling.
Innovation Solution
The apparatus includes a cooling expansion mechanism and a gas-liquid separator to ensure the refrigerant is distributed in a single liquid phase to user side circuits, with variable expansion valves and a compressor configuration that maintains high pressure above the critical pressure of the refrigerant, preventing liquid compression and enhancing controllability of cooling capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the refrigerating apparatus uses an expander in the heat source side circuit to improve COP, then the coefficient of performance is improved, but the refrigerant distribution becomes imbalanced due to two-phase state and gravity effects
Solution Approach 1:
The patent changes the pressure parameter by maintaining high pressure above the critical pressure of the refrigerant throughout the system. This prevents the refrigerant from entering a two-phase state, eliminating the gravity-induced distribution imbalance while preserving the energy recovery benefit of the expander.
Solution Approach 2:
The patent avoids phase transitions of the refrigerant by maintaining it in a supercritical single-phase state. By keeping the pressure above the critical pressure, the refrigerant does not condense into liquid and vapor phases, thereby eliminating the distribution problems associated with two-phase flow.
2Adaptability or versatility
If user side circuits are installed at different levels or with different piping lengths, then the system adapts to various installation conditions, but the refrigerant supply becomes insufficient due to pressure losses
Solution Approach 1:
The patent maintains high pressure above the critical pressure of the refrigerant, which fundamentally changes the refrigerant's physical state to supercritical. This eliminates the formation of two-phase flow and the associated pressure losses, ensuring sufficient refrigerant supply to all user side circuits regardless of installation level or piping length differences.
3Ease of operation
If flow adjusting valves are provided to adjust refrigerant amount, then the cooling capacity control is improved, but the refrigerant may still be supplied insufficiently due to pressure losses
Solution Approach 1:
The patent changes the fundamental pressure parameter to maintain it above the critical pressure of the refrigerant. This eliminates two-phase flow and the associated pressure losses, ensuring that flow adjusting valves can effectively control cooling capacity without suffering from refrigerant supply insufficiency due to pressure drops.
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 allows for precise control of refrigerant distribution and cooling capacity across user side circuits, regardless of their location, improving the apparatus's controllability and reliability by maintaining refrigerant in a single liquid phase and optimizing the coefficient of performance.
Implementation Method 1
a cooling heat exchanger (45) which cools the refrigerant sent from the expander (31) to the user side circuits (11, 12, 13) by heat exchange with the refrigerant of which pressure has been reduced in the cooling expansion mechanism (36)
Implementation Method 2
a gas-liquid separator (35) for separating the refrigerant flowing from the expander (31) into liquid refrigerant and gas refrigerant
Implementation Method 3
the high pressure of the refrigeration cycle is higher than a critical pressure of the refrigerant
Data Source
AI summary
Refrigerant sent from a heat source side circuit (14) to utilization side circuits (11, 12, 13) is made to be single-phase liquid by using cooling means (36, 45) or a vapor-liquid separator (35). Variable-opening utilization side expansion valves (51, 52, 53) are provided in the utilization side circuits (11, 12, 13) so that an expansion process in a refrigeration cycle is performed also in the circuits.