Refrigerant vapor compression system
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Solution Overview
Problem
Refrigerant vapor compression systems, particularly those using carbon dioxide, face challenges in energy efficiency and cooling capacity when operating in transcritical pressure regimes, as traditional designs are suboptimal for natural refrigerants like carbon dioxide.
Innovation Solution
The system incorporates a series arrangement of compression stages with multiple heat exchangers and intercoolers, including round tube plate fin, louver fin mini-channel flat tube, and brazed plate heat exchangers, along with an economizer circuit and secondary fluid management, to enhance heat exchange efficiency and energy transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If traditional subcritical refrigerant pressure designs are used, then system simplicity is maintained, but energy efficiency and cooling capacity are insufficient for natural refrigerants like carbon dioxide
Solution Approach 1:
The compression process is divided into multiple stages with intercooling between stages. The refrigerant compression system includes a first compression stage, a second compression stage, and optionally a third compression stage, with intercoolers positioned between stages to cool the refrigerant. This segmentation allows the system to handle the high pressure requirements of transcritical CO2 systems while managing heat generation more effectively, improving energy efficiency without overwhelming complexity
Solution Approach 2:
Intercoolers are positioned to cool the refrigerant before it enters subsequent compression stages. The first intercooler cools refrigerant between the first and second compression stages, and the second intercooler cools refrigerant between the second and third compression stages. This preliminary cooling action reduces the temperature and pressure of the refrigerant before further compression, improving overall energy efficiency
2Productivity
If multiple heat exchangers and intercoolers are added to improve heat exchange efficiency, then energy efficiency and cooling capacity improve, but device complexity increases
Solution Approach 1:
The heat exchanger is designed to serve multiple functions within a single component. It acts as a refrigerant heat rejection heat exchanger, an intercooler, and facilitates heat exchange between the refrigerant and both air and brine secondary fluids. This multi-functionality allows the system to achieve high cooling capacity and energy efficiency while avoiding the need for separate components for each function, thereby limiting the increase in device complexity
3Adaptability or versatility
If transcritical pressure regime operation is implemented for carbon dioxide, then natural refrigerant usage is enabled, but heat rejection and intercooling efficiency are reduced
Solution Approach 1:
The system is designed to operate in the transcritical pressure regime specific to carbon dioxide, with the heat exchanger and intercoolers optimized for these parameters. The heat exchanger includes configurations such as round tube plate fin or louver fin mini-channel flat tube designs that are particularly effective for transcritical CO2 operation, enabling efficient heat rejection and intercooling while maintaining compatibility with natural refrigerants
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 configuration improves energy efficiency and cooling capacity by optimizing heat exchange processes across multiple stages, allowing for effective operation in both air-cooled and brine-cooled modes, particularly suited for transcritical carbon dioxide refrigerant systems.
Implementation Method 1
A first refrigerant heat rejection heat exchanger is disposed downstream with respect to refrigerant flow of the second compression stage for passing the refrigerant in heat exchange relationship with a flow of a first secondary fluid
Implementation Method 2
passing the refrigerant in heat exchange relationship with a flow of a first secondary fluid
Implementation Method 3
heat exchange relationship
Implementation Method 4
A first refrigerant intercooler is disposed intermediate the first compression stage and the second compression stage for passing the refrigerant passing from the first compression stage to the second compression stage in heat exchange relationship with the flow of the first secondary fluid
Implementation Method 5
passing the refrigerant passing from the first compression stage to the second compression stage in heat exchange relationship with the flow of the first secondary fluid
Implementation Method 6
a compression device having at least a first compression stage and a second compression stage arranged in series refrigerant flow relationship
Implementation Method 7
An economizer includes a vapor line in fluid communication with a suction inlet to the second compression stage
Data Source
AI summary
A refrigerant vapor compression system includes a compression device having at least a first compression stage and a second compression stage arranged in series refrigerant flow relationship. A first refrigerant heat rejection heat exchanger is disposed downstream with respect to refrigerant flow of the second compression stage. A first refrigerant intercooler is disposed intermediate the first compression stage and the second compression stage. The first refrigerant intercooler is disposed downstream of the first refrigerant heat rejection heat exchanger with respect to the flow of the first secondary fluid. An economizer includes a vapor line in fluid communication with a suction inlet to the second compression stage. A second refrigerant heat rejection heat exchanger is disposed intermediate with respect to refrigerant flow of the second compression stage and the first refrigerant heat rejection heat exchanger. A second refrigerant intercooler is disposed intermediate the first compression stage and the second compression.