Split Rear-Mounted Refrigeration Unit for Trailer Drag Reduction
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Solution Overview
Problem
Conventional refrigeration units in tractor trailers, typically diesel-powered and front-mounted, face inefficiencies due to drag reduction designs that limit space for refrigeration systems, making it difficult to maintain effective cooling while reducing fuel consumption and drag.
Innovation Solution
A split trailer refrigeration unit with two independently powered and controlled rear-mounted portions, each equipped with an electric compressor, condenser, and evaporator, connected via a frame to the trailer door, utilizing an electrical storage unit and external power interface to optimize refrigeration and charging modes, and an aerodynamic skin to reduce drag.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a diesel-powered generator is used to provide operational power to the refrigeration unit, then the trailer can be maintained at a cool or cold temperature, but fuel consumption increases and drag is increased
Solution Approach 1:
The patent replaces the diesel-powered mechanical generator system with an electric-powered refrigeration unit. The electric compressor is powered by an electrical storage unit (battery) instead of a diesel generator, eliminating the need for fossil fuel combustion and mechanical power generation, thereby reducing fuel consumption and associated drag from the power generation system
Solution Approach 2:
The electrical storage unit serves multiple functions: it powers the electric compressor during refrigeration operation and can be charged from external power sources during transit. This multi-functionality allows the system to maintain cooling without relying on fuel-consuming onboard generators
2Loss of energy
If the gap between the tractor and the trailer is reduced to reduce drag, then vehicle efficiency increases, but space for mounting refrigeration systems is reduced
Solution Approach 1:
The refrigeration unit is divided into separate modular components: the electric compressor, condenser, evaporator, and electrical storage unit are positioned as distinct modules within the trailer. This segmentation allows flexible arrangement of components to fit within the reduced space available due to the smaller gap between tractor and trailer, while maintaining all necessary refrigeration functions
Solution Approach 2:
The patent utilizes vertical space and three-dimensional arrangement within the trailer to accommodate the refrigeration components. By positioning components in multiple dimensions rather than only horizontal space, the system fits within the constrained space created by reduced gap dimensions
3Loss of energy
If a rear-mounted refrigeration unit is used to reduce drag, then aerodynamic efficiency improves, but the system complexity increases due to power delivery challenges
Solution Approach 1:
The patent replaces complex mechanical power delivery systems (belts, shafts, couplings) with an electrical power delivery system. The electric compressor is directly powered by the electrical storage unit through electrical connections, eliminating the need for mechanical power transmission components and reducing overall system complexity despite the rear-mounted configuration
Solution Approach 2:
The electrical storage unit (battery) acts as an intermediary between the power source and the electric compressor. This intermediary allows flexible positioning of the compressor in the rear-mounted configuration while managing power delivery through electrical rather than mechanical means, simplifying the power transmission system
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 split refrigeration unit efficiently maintains trailer temperature with reduced drag and fuel consumption by utilizing electric power and adaptive operation modes, ensuring continuous cooling while minimizing space constraints and aerodynamic losses.
Implementation Method 1
an electrically driven compressor
Implementation Method 2
a condenser
Implementation Method 3
an evaporator
Implementation Method 4
an electrical storage unit
Data Source
Figure 1~2
Figure 3
AI summary
A split trailer refrigeration unit for a tractor trailer includes a first portion (140A) having an electrically driven compressor (230), a condenser (210) and an evaporator (220). Also included is a second portion (140B), having an electrically driven compressor, a condenser and an evaporator. At least one of the first portion and the second portion include a set of power electronics (242) and a battery (240) connecting an electricity source to the corresponding electric compressor. The set of power electronics is configured to control power characteristics of power provided from the electricity source to the electric compressor. A frame (142) is configured to structurally mount each of the first portion and the second portion to a rear trailer door.