R32 Subcooling Circuit for Low-GWP HFC Refrigeration
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Solution Overview
Problem
Commercial refrigeration systems using R125 and R143A blends face efficiency and environmental impact issues due to higher Global Warming Potential (GWP) and refrigerant glide problems, which affect cooling capacity and system reliability.
Innovation Solution
A dual condensing unit system with a remote condenser and evaporator design, incorporating a subcooling circuit with R32 blends to enhance efficiency and reduce GWP, featuring a main refrigeration circuit with HFC blends like R404A or R507, and an air conditioning circuit with R410A or R407C, allowing for precise cooling capacity control and reduced compressor power requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If R125 and R143A blend refrigerants are used to achieve zero ODP, then ozone depletion is prevented, but system efficiency decreases and GWP increases
Solution Approach 1:
The refrigeration system is divided into two separate circuits: a main refrigeration circuit using HFC blend (R125/R143A) for zero ODP, and a subcooling circuit using R32 blend for efficient heat exchange. This segmentation allows each circuit to use refrigerants optimized for its specific function, maintaining zero ODP while improving overall system efficiency through the high-performance subcooling circuit.
2Object-affected harmful factors
If R404A or R507 refrigerants are used to achieve zero ODP, then ozone depletion is prevented, but GWP becomes very high (3920-3985)
Solution Approach 1:
The R32 blend subcooling circuit acts as an intermediary that enhances the thermal performance of the main HFC circuit. By using R32 blend (lower GWP) in the subcooling circuit to provide intense heat exchange, the system achieves better overall efficiency with reduced total refrigerant charge of high-GWP HFC, thereby reducing the effective GWP impact while maintaining zero ODP.
3Object-generated harmful factors
If R407A or R407C refrigerants are used to achieve lower GWP, then environmental impact is reduced, but refrigerant glide issues cause unstable cooling capacity
Solution Approach 1:
The system uses a second refrigerant circuit (R32 blend) that copies the essential heat exchange function of the main circuit but with superior thermal properties. The R32 blend subcooling circuit provides stable, glide-free heat exchange that compensates for the refrigerant glide issues in the main HFC circuit, ensuring stable cooling capacity while maintaining lower GWP.
4Use of energy by moving object
If mechanical subcooling is added to improve system efficiency, then efficiency increases, but device complexity increases
Solution Approach 1:
The subcooling circuit is merged with the main refrigeration circuit through thermal coupling at the condenser level. Both circuits share the same condenser housing and cooling fan, and the subcooling evaporator is integrated into the condenser assembly. This merging approach adds subcooling functionality while minimizing the increase in overall system complexity through shared components and compact integration.
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 system achieves increased efficiency and reduced environmental impact by minimizing flash gas at the expansion device, lowering refrigerant flow rates, and reducing the size of refrigerant pipes, while maintaining reliable operation across various applications.
Implementation Method 1
The main refrigeration circuit is thermally coupled internally in the condensing unit with the subcooling evaporator for cooling the liquid refrigerant from the main condenser to provide the subcooling
Implementation Method 2
a main condenser...cooling the liquid refrigerant from the main condenser
Implementation Method 3
One condenser and one compressor is assembled with an expansion device and evaporator/heat exchanger in a preassembled subcooling circuit
Implementation Method 4
a main expansion device...The main refrigeration circuit is thermally coupled internally in the condensing unit with the subcooling evaporator for cooling the liquid refrigerant from the main condenser
Implementation Method 5
a main evaporator and circulating a low or medium temperature refrigeration refrigerant and operating efficiently in the intended refrigeration cycles
Data Source
AI summary
A refrigeration system having a main circuit including a main compressor thermally coupled with a secondary or subcooling circuit. The main circuit uses a HFC blend, such as but not limited to, R125/R143A blend or R32/R125/R134A blend as a refrigerant and the subcooling circuit uses an R32 blend. Some embodiments may include more than one main compressor. Some embodiments of the secondary circuit may include more than one secondary compressor. The combined system of differing refrigerants provides increased efficiencies and reduced Global Warming Potential (GWP) over single refrigerant systems for low and medium temperature refrigeration applications.