Combined Economizer Heat Exchanger for Multi-Temperature CO2 Cooling
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Solution Overview
Problem
Transport refrigeration systems using CO2 as a refrigerant face challenges in efficiently managing temperature variations for frozen and non-frozen perishables, as existing economizer heat exchanger configurations are costly and space-intensive, requiring separate units for different temperature ranges.
Innovation Solution
A combined economizer heat exchanger system with a single housing and alternating heat transfer paths, utilizing a compressor with multiple cylinders and expansion devices, where the economizer heat exchanger includes two portions for parallel flowpaths to optimize heat transfer and reduce manufacturing costs and space requirements, utilizing CO2 as the primary refrigerant.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If separate economizer heat exchangers are used for different temperature ranges, then temperature control capability is improved, but device complexity and space requirements increase
Solution Approach 1:
The patent combines multiple economizer heat exchangers into a single integrated unit with multiple flowpaths. The housing contains several heat exchanger assemblies arranged in parallel, each handling different temperature ranges (e.g., frozen and non-frozen perishables). This merging approach maintains the temperature control capability of separate units while reducing overall system complexity and space requirements.
Solution Approach 2:
The single economizer heat exchanger housing performs multiple functions simultaneously by incorporating different flowpaths for different temperature ranges. The first flowpath handles frozen goods cooling while the second flowpath handles non-frozen perishables, making one device universal for multiple temperature control needs that previously required separate units.
2Adaptability or versatility
If separate economizer heat exchangers are used for different temperature ranges, then temperature control capability is improved, but manufacturing cost increases
Solution Approach 1:
By merging multiple economizer heat exchangers into a single housing with shared components (housing, refrigerant flow distribution, expansion devices), the manufacturing cost is reduced compared to producing and installing multiple separate units. The integrated design allows for economies of scale in manufacturing while maintaining the capability to handle different temperature ranges through internal flowpath configuration.
3Device complexity
If a single economizer heat exchanger handles multiple temperature ranges, then device complexity is reduced, but heat transfer efficiency may worsen
Solution Approach 1:
The single economizer heat exchanger is segmented into multiple independent flowpaths within the housing. Each flowpath (first and second economizer flowpaths) is configured to handle specific temperature ranges with dedicated heat exchanger assemblies. This segmentation allows each section to optimize heat transfer for its specific function while being part of a unified structure, preventing the efficiency loss that might occur in a completely mixed design.
Solution Approach 2:
Different portions of the heat exchanger housing are designed with local quality variations - specific heat exchanger assemblies are optimized for frozen goods while others are optimized for non-frozen perishables. This allows each local section to have the appropriate heat transfer characteristics for its specific temperature range, maintaining overall heat transfer efficiency while managing multiple functions in a single unit.
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 combined economizer heat exchanger system enhances efficiency and capacity by optimizing heat transfer and reducing costs and space, allowing for flexible temperature control in transport refrigeration units, effectively addressing the need for broad temperature ranges without the need for separate units.
Implementation Method 1
The economizer heat exchanger includes a first portion configured to provide heat transfer from the primary flowpath to a first economizer flowpath. The economizer heat exchanger includes a second portion configured to provide heat transfer from the primary flowpath to a second economizer flowpath.
Implementation Method 2
A charge of the refrigerant may comprise at least 50%, by weight, carbon dioxide.
Data Source
AI summary
A refrigeration system includes a compressor. A heat rejection heat exchanger is downstream of the compressor along a refrigerant primary flowpath. An expansion device is downstream of the heat rejection heat exchanger along the primary flowpath. A heat absorption heat exchanger is downstream of the expansion device along the primary flowpath. An economizer heat exchanger is between the heat rejection heat exchanger and the expansion device along the primary flowpath. The economizer heat exchanger includes a first portion configured to provide heat transfer from the primary flowpath to a first economizer flowpath. The economizer heat exchanger includes a second portion configured to provide heat transfer from the primary flowpath to a second economizer flowpath.