Thermal storage unit for a refrigeration apparatus with a thermal storage and using co2 as refrigerant
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Solution Overview
Problem
Conventional refrigeration systems using carbon dioxide as a refrigerant face efficiency issues in warmer climates, and existing thermal storage systems with phase change materials are inefficient for active cooling and lack flexibility in energy storage, especially during peak demand periods.
Innovation Solution
A refrigerant circuit with a thermal storage unit utilizing carbon dioxide as a refrigerant, featuring a phase changing material and a sophisticated valve system for efficient heat exchange, allowing for flexible thermal energy storage and release, including during peak temperatures, using supercritical fluid conditions and a combination of three-way and four-way valves for optimized energy management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If carbon dioxide is used as refrigerant in warmer climates, then environmental friendliness is improved, but cooling efficiency deteriorates
Solution Approach 1:
The system pre-cools the phase change material in thermal storage during nighttime or off-peak hours when ambient temperatures are lower and CO2 refrigeration is more efficient. This stored cold energy is then utilized during peak demand periods, avoiding the inefficiency of active cooling during warm conditions while maintaining overall system productivity.
Solution Approach 2:
The invention utilizes phase change material that transitions between solid and liquid states to store and release thermal energy. During charging, the PCM absorbs heat during melting; during discharging, it releases heat during freezing. This phase transition mechanism enables efficient thermal energy storage that compensates for CO2's lower efficiency in warm climates.
2Quantity of substance
If active cooling of phase change material is implemented, then thermal storage capacity is improved, but energy efficiency deteriorates
Solution Approach 1:
The system uses the refrigeration system's own operation to charge the thermal storage without requiring separate active cooling. When the refrigeration system operates, the condensed refrigerant naturally cools the phase change material through thermal communication, utilizing waste cold energy that would otherwise be lost, thus improving overall energy efficiency while building thermal storage capacity.
Solution Approach 2:
A heat exchanger serves as an intermediary between the refrigerant circuit and the phase change material. This intermediary enables efficient thermal energy transfer from the refrigerant to the PCM during charging, and from the PCM to the refrigerant or ambient environment during discharging, maximizing thermal storage capacity while minimizing energy losses.
3Loss of energy
If phase change material is used as heat buffer, then energy efficiency is improved during operation, but control flexibility deteriorates
Solution Approach 1:
The system incorporates dynamic control mechanisms including multiple valves and switching devices that can redirect refrigerant flow to either the thermal storage unit or the main refrigeration cycle. This dynamic configuration allows the system to adapt between different operational modes (charging, discharging, direct cooling) based on real-time demands, maintaining control flexibility while preserving the energy efficiency benefits of PCM.
Solution Approach 2:
The thermal storage unit with phase change material serves multiple functions: it acts as a heat buffer during refrigeration operation, provides supplemental cooling during peak demand, and can be charged during off-peak hours. The integrated design allows the same PCM system to perform various roles depending on operational conditions, enhancing adaptability without sacrificing energy efficiency.
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 maintains high cooling capacity and efficiency by storing thermal energy during low temperatures and releasing it during peak demand, enhancing energy management and reducing energy consumption fluctuations, while being environmentally friendly.
Implementation Method 1
a phase changing material and a sophisticated valve system for efficient heat exchange, allowing for flexible thermal energy storage and release
Implementation Method 2
the phase change material transitions from liquid to solid when cooling demand on the chiller system is low or non-existent
Implementation Method 3
using CO2 as a refrigerant, featuring a phase changing material and a sophisticated valve system for efficient heat exchange
Implementation Method 4
a refrigerant circuit for a refrigeration apparatus with a thermal storage, which is using carbon dioxide (CO2) as refrigerant
Implementation Method 5
using supercritical fluid conditions and a combination of three-way and four-way valves for optimized energy management
Data Source
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AI summary
The present disclosure relates to a thermal storage unit 100 used for a refrigeration apparatus using CO2 as refrigerant, including: a thermal storage 20 including a thermal storage material 21, particularly a phase changing material PCM, a thermal storage unit gas port 62 configured to communicate to a utilization-side heat exchanger 80A disposed outside the thermal storage unit 100, a first thermal storage unit fluid port 72 configured to communicate to the utilization-side heat exchanger 80A, a second thermal storage unit fluid port 32A configured to communicate to a heat-source-side heat exchanger 11, disposed outside the thermal storage unit 100, and a third thermal storage unit fluid port 52A configured to communicate to an expansion device 12 disposed outside the thermal storage unit 100, wherein the thermal storage unit 100 further includes: a first switching mechanism 31 communicating among the second thermal storage unit fluid port 32A, the third thermal storage fluid port 52A, the thermal storage unit gas port 62 and one side of the thermal storage 20, and a second switching mechanism 41 communicating among the first thermal storage unit fluid port 72, the third thermal storage unit fluid port 52A and the other side of the thermal storage 20. Moreover, the disclosure relates to a refrigerant circuit 1 for a refrigeration apparatus with a thermal storage, which is using CO2 as refrigerant. Additionally, the disclosure relates to a heat exchange unit 200 that is particularly used for a refrigeration apparatus with a thermal storage, which uses CO2 as refrigerant.