Refrigeration Cycle Bypass Subcooling for Low-GWP Stability
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Solution Overview
Problem
Conventional refrigeration cycle devices using HFC refrigerants have high Global Warming Potential (GWP), leading to environmental concerns due to chemical stability and long atmospheric persistence, while low-GWP refrigerants with combustible properties face limitations in refrigeration capacity and stability due to limited permissible amounts and pressure losses in evaporators.
Innovation Solution
A refrigeration cycle device incorporating a combustible refrigerant with a heat exchanger to subcool the refrigerant and control the superheat degree, using sensors and valves to manage the refrigerant flow and pressure differences, ensuring stable operation and minimizing pressure losses in evaporators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If HFC refrigerant is used, then refrigeration stability is improved, but Global Warming Potential increases
Solution Approach 1:
The patent changes the chemical composition parameter of the refrigerant from HFC to a low-GWP alternative (such as R32, R125, or R134a), accepting the trade-off of reduced chemical stability in exchange for environmental benefits. The patent then compensates for the instability through system design modifications including subcooling and pressure control mechanisms.
2Object-affected harmful factors
If low-GWP refrigerant is used, then Global Warming Potential is reduced, but refrigeration capacity decreases
Solution Approach 1:
The patent applies subcooling to the refrigerant before it enters the expansion device, which increases the refrigerant's enthalpy difference across the evaporator. This preliminary action of cooling the liquid refrigerant below its saturation temperature compensates for the lower refrigeration capacity of low-GWP refrigerants by maximizing the heat absorption potential in the evaporator.
Solution Approach 2:
The patent modifies operating parameters including pressure control and temperature management to optimize the thermodynamic cycle for low-GWP refrigerants. By adjusting these parameters, the system compensates for the inherent lower capacity of alternative refrigerants and achieves desired refrigeration effects.
3Object-affected harmful factors
If low-GWP refrigerant is used, then Global Warming Potential is reduced, but operational stability worsens
Solution Approach 1:
The patent incorporates pressure sensors and control valves that continuously monitor and adjust the refrigerant pressure and flow. This feedback control system compensates for the operational instability of low-GWP refrigerants by maintaining optimal pressure differentials and flow rates, ensuring stable system operation despite the refrigerant's lower chemical stability.
Solution Approach 2:
The patent dynamically adjusts operating parameters such as expansion valve opening, compressor speed, and heat exchanger temperatures to maintain stable operation with low-GWP refrigerants. These parameter modifications compensate for the refrigerant's tendency toward instability and ensure consistent performance.
4Productivity
If subcooling is applied to low-GWP refrigerant, then refrigeration efficiency is improved, but pressure losses increase
Solution Approach 1:
The patent uses an intermediary heat exchanger (subcooler) that utilizes the heat from the high-pressure refrigerant to subcool the liquid refrigerant. This intermediary device enables efficient heat transfer and subcooling while minimizing pressure losses by maintaining appropriate pressure differentials and using counter-current flow arrangements.
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
The solution enables stable operation of refrigeration cycle devices with low-GWP refrigerants by maintaining a subcooling state at the expansion valve and optimizing evaporator pressure differences, reducing pressure losses and enhancing refrigeration efficiency while ensuring safety and environmental sustainability.
Implementation Method 1
heat exchange between the low-temperature/low-pressure refrigerant that has passed through the bypass expansion valve and the medium-temperature/high-pressure refrigerant that directly flows into the expansion valve
Implementation Method 2
subcools the combustible refrigerant discharged from the condenser
Implementation Method 3
an expansion valve that expands the combustible refrigerant subcooled by the heat exchanger
Implementation Method 4
an evaporator that evaporates the combustible refrigerant expanded by the expansion valve
Implementation Method 5
a compressor that compresses a combustible refrigerant
Implementation Method 6
a condenser that condenses the combustible refrigerant compressed by the compressor
Data Source
AI summary
A refrigeration cycle device 100 where a combustible refrigerant circulates includes a bypass pipe 5 that is connected so that part of the refrigerant that flows through a circulation pipe extending from a condenser 2 to a flow control valve 3 bypasses the flow control valve 3 and an evaporator 4; a bypass flow control valve 6 that controls the amount of the refrigerant flowing through the bypass pipe 5; a heat exchanger 7 that allows heat exchange between the refrigerant that flows through the bypass pipe 5 after flowing out of the bypass flow control valve 6 and the refrigerant that flows through the circulation pipe after flowing out of the condenser 2; and a subcooling degree sensor T73 that detects the subcooling degree of the refrigerant at the inlet of the flow control valve 3. At least either the flow control valve 3 or the bypass flow control valve 6 is controlled so that the subcooling degree of the refrigerant at the inlet of the flow control valve 3 is equal to or greater than or a predetermined value.