Axial Evaporator Airflow Layout for Compact Trailer Refrigeration
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Solution Overview
Problem
Traditional centrifugal fan systems in trailer refrigeration systems occupy excessive space, leading to non-optimized coordination with the evaporator heat exchanger and excessive flow losses, resulting in high fan power consumption and design constraints for the condenser air management system.
Innovation Solution
The implementation of high-speed, electrically powered axial fan arrangements with circular to rectangular outlet nozzles for 90-degree flow turning, optimized using fan and flow-path analysis techniques, including three-dimensional computational fluid dynamics, and verified experimentally for performance and packaging benefits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If centrifugal fans with scroll housings are used, then fan performance is improved and flow turning is achieved, but system space occupancy increases excessively
Solution Approach 1:
The invention extracts and removes the scroll housing from the fan assembly, retaining only the essential axial fan component. This eliminates the bulky housing structure while preserving the core fan functionality, directly reducing system space occupancy while maintaining fan performance through optimized axial fan blade design
Solution Approach 2:
The invention transitions from the traditional centrifugal fan's horizontal flow path to a vertical flow path arrangement. The axial fan is positioned to blow air vertically upward through the evaporator coil, with a diffuser component managing the vertical-to-horizontal flow transition. This dimensional change eliminates the need for large scroll housings and optimizes space utilization in the vertical dimension
2Reliability
If centrifugal fans with large scroll housings are used, then fan performance is improved, but flow losses increase and fan power consumption increases
Solution Approach 1:
The invention replaces the mechanical scroll housing flow turning mechanism with a diffuser-based flow management system. The diffuser component efficiently transitions air flow from vertical to horizontal direction through pressure gradient management rather than mechanical turning, reducing flow separation and turbulence losses, thereby lowering fan power consumption while maintaining effective cooling performance
Solution Approach 2:
The invention changes the flow path parameters from horizontal centrifugal flow to vertical axial flow with diffuser-mediated transition. This parameter change optimizes the flow velocity distribution and pressure characteristics, reducing flow losses and improving overall system efficiency, which directly reduces the power consumption required to achieve the same cooling effect
3Ease of operation
If centrifugal fans are used, then evaporator air management is achieved, but design flexibility for condenser air management system is reduced
Solution Approach 1:
The invention segments the air management functions by using a compact axial fan assembly with integrated diffuser for the evaporator, separate from the condenser air management system. This segmentation frees up space and design flexibility in the condenser area, allowing for optimized condenser fan and heat exchanger arrangements without interference from large evaporator fan housings, thereby improving overall system adaptability
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 provides a compact, high-efficiency evaporator air management system that reduces space occupancy, minimizes flow losses, and optimizes fan power consumption, enhancing overall system design and performance.
Implementation Method 1
an evaporator fan comprising: at least one axial fan having a vertically oriented axis for drawing air through said evaporator coil and discharging it vertically upward
Implementation Method 2
a nozzle disposed downstream of said axial fan for turning the airflow substantially 90° from its upward flow path
Implementation Method 3
the evaporator coil, which subsequently removes heat from the air stream and thereby cools the cargo
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
An improved evaporator air management system for trailer refrigeration systems, including an electrically powered, vertical axis, axial flow fan, arranged so as to draw air through a horizontally mounted evaporator coil. The flow is then driven upward through a nozzle and discharged into the trailer. The nozzle shape graduates from a circular cross-section to a wide-aspect ratio rectangular cross-section, while turning through 90°. The preferred choice of axial flow fan for the invention is the vane-axial type incorporating outlet guide vanes. Provision is made for a single fan-nozzle configuration which may be either centered or transversely off-set with respect to the evaporator coil. An additional option provides for an arrangement with a pair of side-by-side fan-nozzles.