Surged vapor compression heat transfer systems with reduced defrost phase separator
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Solution Overview
Problem
Conventional vapor compression heat transfer systems face inefficiencies due to frost buildup and oil separation issues, leading to reduced heat transfer capacity and increased energy consumption for defrosting, which affects cooling efficiency and product quality.
Innovation Solution
A surged vapor compression heat transfer system with a phase separator that introduces surges of vapor phase refrigerant into the evaporator, raising the temperature and preventing frost formation by maintaining the initial portion above the dew point, thereby reducing the need for defrosting and enhancing heat transfer efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional vapor compression systems operate without phase separation, then the system structure is simple, but frost buildup occurs on the evaporator and heat transfer efficiency decreases
Solution Approach 1:
The refrigerant flow is segmented into distinct liquid and vapor phases through the phase separator. The separator divides the single-phase refrigerant line into two separate outlets: one delivering liquid refrigerant and another delivering vapor refrigerant, allowing independent control of each phase to the evaporator
Solution Approach 2:
The phase separator acts as an intermediary device between the compression system and the evaporator. It receives refrigerant from the compressor and conditionally separates it into liquid and vapor phases before delivery, mediating the refrigerant state to optimize heat transfer while preventing frost buildup
2Ease of operation
If liquid refrigerant is delivered directly to the evaporator, then the system is simple to operate, but oil separation issues reduce cooling efficiency
Solution Approach 1:
The phase separator segments the refrigerant-oil mixture into separate liquid and vapor streams. This segmentation allows oil to be carried with the vapor phase while liquid refrigerant is delivered separately, preventing oil accumulation in the evaporator and maintaining cooling efficiency
Solution Approach 2:
The system delivers only the necessary liquid refrigerant to the evaporator while excess vapor is discharged separately. This partial delivery of liquid refrigerant prevents over-feeding that would cause oil separation issues, while still providing sufficient cooling capacity
3Reliability
If defrosting cycles are implemented frequently, then frost buildup is removed, but energy consumption increases and cooling efficiency decreases
Solution Approach 1:
The phase separator performs preliminary action by separating vapor phase refrigerant before it reaches the evaporator. This vapor is discharged separately to prevent frost formation in the first place, eliminating the need for subsequent defrosting cycles and their associated energy consumption
Solution Approach 2:
The vapor phase refrigerant, which would normally contribute to frost buildup if condensed in the evaporator, is converted into a beneficial separate stream. This vapor discharge prevents the harmful frost formation while the liquid refrigerant continues to provide cooling, turning a potential problem into a solution
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 improved heat transfer coefficients, reduced frost buildup, and increased cooling efficiency while minimizing the need for defrosting cycles, maintaining higher relative humidity and reducing energy consumption.
Implementation Method 1
A surged vapor compression heat transfer system with a phase separator that introduces surges of vapor phase refrigerant into the evaporator
Implementation Method 2
The surges of the vapor phase have a higher temperature than the liquid phase of the refrigerant, and thus heat the evaporator to remove frost
Implementation Method 3
raising the temperature and preventing frost formation by maintaining the initial portion above the dew point
Implementation Method 4
A compressor 110 or other compression device reduces the volume of the refrigerant, thus creating a pressure difference that circulates the refrigerant through the loop
Implementation Method 5
The compressed refrigerant is then passed through a condenser 120 or heat exchanger, which increases the surface area between the refrigerant and the second external medium 160. As heat transfers to the second external medium 160 from the refrigerant, the refrigerant contracts in volume
Implementation Method 6
The evaporator 140 increases the surface area between the refrigerant and the first external medium 150, thus increasing the heat transfer between the refrigerant and the first external medium 150. The transfer of heat into the refrigerant causes at least a portion of the expanded refrigerant to undergo a phase change from liquid to gas
Implementation Method 7
This expansion is often facilitated with a metering device 130 including an expansion device and a heat exchanger or evaporator 140. The expanded refrigerant enters the evaporator 140 in a substantially liquid state with a small vapor fraction
Data Source
AI summary
Surged vapor compression heat transfer systems, devices, and methods are disclosed having refrigerant phase separators that generate at least one surge of vapor phase refrigerant into the inlet of an evaporator after the initial cool-down of an on cycle of the compressor. This surge of vapor phase refrigerant, having a higher temperature than the liquid phase refrigerant, increases the temperature of the evaporator inlet, thus reducing frost build up in relation to conventional refrigeration systems lacking a surged input of vapor phase refrigerant to the evaporator.