Three-Stage CO2 Energy Storage for Flexible Cooling and Firefighting
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Solution Overview
Problem
Current CO2 trans-critical refrigeration systems face limitations due to large system throttling losses, restricted CO2 infusion volume, and limited single-stage compression capacity, which hampers their efficiency and application scope, especially in firefighting and multi-temperature range refrigeration.
Innovation Solution
A multipurpose energy supply system utilizing a three-stage CO2 compression refrigeration circulation with split-flow and back heating, incorporating a three-stage cold network and a firefighting network, allowing for flexible energy use, enhanced efficiency, and expanded firefighting capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If simple trans-critical circulation is adopted, then system structure is simple, but system throttling loss is large and energy efficiency is low
Solution Approach 1:
The patent divides the single-stage compression system into three-stage compression with separate compression, condensation, and expansion processes. This segmentation allows optimization of each stage independently, reducing overall throttling losses while maintaining manageable system complexity through modular design.
Solution Approach 2:
The system implements dynamic control of compression ratios and refrigerant flow distribution across three stages, allowing the system to adapt operating parameters in real-time to minimize throttling losses while responding to varying cooling loads and environmental conditions.
2Reliability
If CO2 infusion volume is restricted, then system safety is improved, but firefighting radiation scope is limited
Solution Approach 1:
The patent transitions from single-stage to three-stage compression, adding dimensional complexity to the system architecture. This enables greater CO2 storage capacity and distribution capability while maintaining safety through staged pressure management and controlled release mechanisms across multiple system levels.
Solution Approach 2:
The system serves multiple functions: refrigeration across three temperature stages, heat recovery for heating applications, and firefighting capability. The multi-functional design allows the same CO2 circulation infrastructure to support both climate control and safety applications, expanding versatility without compromising safety.
3Device complexity
If single-stage compression is used, then device complexity is low, but refrigeration temperature difference capability is limited
Solution Approach 1:
The patent segments the compression process into three distinct stages, each handling a specific temperature range. This segmentation enables the system to achieve a much broader refrigeration temperature difference capability by distributing the compression work across multiple stages with intermediate cooling and heat recovery processes.
Solution Approach 2:
The system changes operating parameters including compression ratio, refrigerant pressure, and temperature at each of the three stages. By adjusting these parameters independently at each stage, the system achieves extended temperature coverage while managing complexity through standardized stage design.
4Loss of energy
If three-stage compression with multi-stage energy storage is adopted, then energy efficiency is improved, but device complexity increases
Solution Approach 1:
The patent merges multiple functions into the three-stage system: compression, condensation, heat recovery, expansion, and refrigeration are integrated across the three stages. This consolidation achieves energy efficiency through heat recovery and reduced throttling losses while managing complexity by combining rather than adding separate systems.
Solution Approach 2:
The system recovers heat from the compression and condensation processes to pre-cool refrigerant or provide heating output, making the system self-sufficient. This self-service approach reduces external energy input requirements and improves overall efficiency while the complexity is offset by the elimination of separate heating or pre-cooling systems.
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 higher efficiency and flexibility by decoupling compression stages, reducing energy losses, and expanding firefighting coverage, while optimizing compressor and expander operations for multi-stage refrigeration and heating applications.
Implementation Method 1
CO2 has a critical temperature of only 31.1° C., a critical pressure as high as 7.38 MPa, and a large throttling loss in a trans-critical circulation
Implementation Method 2
an improvement to back heating technology and expansion equipment
Implementation Method 3
a first-stage ejector to shoot the high-pressure gaseous CO2 circulating medium to the low-pressure CO2 circulating medium in the second-stage CO2 compression refrigeration circulation system
Data Source
AI summary
A multipurpose system of cooling and heating supply and firefighting servo-control based on energy-storage CO2 circulation and an operating method thereof are provided, the system based on the CO2 compression refrigeration circulation with three-stage compression and multi-stage energy storage, provides three-levels standing cool volume for the cool end, domestic hot water and heating for the hot end, and extinguishing agents CO2 for the firefighting end. By means of a new modular process design, the system realizes the independent operation and free combination of refrigeration circulation in multi-stages, so as to achieve the purpose of adjustable working conditions, flexible output and high efficiency of energy utilization. The multi-stage energy storage of liquid CO2 can realize the “flexibility” of system power consumption, and acts as a standing safety module for firefighting to be put into the safe operation of the energy system.