Zone Isolation Airflow for Semi-Trailer Reefers
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Solution Overview
Problem
Existing semi-trailer reefers face inefficiencies and high emissions due to reliance on diesel engines, poor refrigerant transfer configurations, and limited battery power, which compromise freezer performance and energy efficiency, and fail to achieve zero emissions standards.
Innovation Solution
An all-electric, solar and battery-powered semi-trailer reefer system using airflow control instead of refrigerant transfer to maintain temperature zones, with electric heater rods for defrosting and a regenerative wheel generator for backup power, eliminating remote evaporators and fossil fuel reliance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If refrigerant is transferred from Z1 evaporator to remote evaporators in Z2 and Z3, then cooling power is provided to Z2 and Z3, but Z1 freezer temperatures rise and cannot be maintained
Solution Approach 1:
The patent divides the refrigeration system into separate zones (Z1 freezer, Z2 refrigerator, Z3 ambient) with dedicated evaporators for each zone. The Z1 evaporator serves only the freezer, while Z2 and Z3 have their own remote evaporators, eliminating the refrigerant transfer problem that caused freezer temperature rise.
Solution Approach 2:
The patent introduces an intermediary fluid (air or inert gas) that flows through heat exchangers in each zone to transfer thermal energy without requiring refrigerant circulation between zones. This mediator enables independent zone control while maintaining freezer temperature stability.
2Power
If diesel engine powers the TRU compressor and fans, then cooling power is generated, but energy efficiency is poor and emissions are high
Solution Approach 1:
The patent replaces the diesel mechanical engine with an electrical system comprising an electric motor-driven compressor and electronic expansion valves. This substitution eliminates the inefficiencies of diesel combustion and mechanical power transmission, achieving superior energy efficiency and zero emissions while maintaining the required cooling power.
3Ease of repair
If hot refrigerant gas is used to defrost evaporators, then evaporators are defrosted, but cooling chamber temperatures rise and duty cycle increases
Solution Approach 1:
The patent extracts the defrosting function from the refrigerant cycle by introducing a separate heating system using electric heater rods or a dedicated hot water circulation system. This separation allows evaporator defrosting without introducing hot refrigerant gas into the cooling chambers, thereby maintaining stable cooling temperatures and reducing duty cycle.
4Adaptability or versatility
If remote evaporators are used in Z2 and Z3, then cooling is provided to multiple zones, but refrigerant transfer from Z1 compromises freezer performance
Solution Approach 1:
The patent segments the refrigeration system into independent zone circuits, with each zone (Z1, Z2, Z3) having its own evaporator and control system. This segmentation allows multi-zone cooling capability while ensuring that freezer performance in Z1 is not compromised by the operational demands of Z2 and Z3.
Solution Approach 2:
The patent applies local quality by providing each zone with evaporators sized and positioned specifically for its thermal requirements. Z1 has a dedicated evaporator optimized for freezer conditions, while Z2 and Z3 have their own evaporators configured for their respective temperature and load characteristics, ensuring optimal performance in each location.
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 solution significantly increases the coefficient of performance (COP) to over 2.25, reduces energy consumption, and extends run times to 60-70 hours, achieving zero emissions and sustainable operation comparable to diesel systems, while maintaining peak freezer performance and reducing greenhouse gas emissions.
Implementation Method 1
The TRU evaporator cools Z1 while Z2 and Z3 use remote evaporators
Implementation Method 2
Refrigerant is moved through the system via a 60-foot flow closed loop connecting the freezer refrigerant source in Z1 to remote evaporators in Z2 and Z3
Implementation Method 3
An all-electric, solar and battery-powered semi-trailer reefer system
Implementation Method 4
An all-electric, solar and battery-powered semi-trailer reefer system
Implementation Method 5
with electric heater rods for defrosting
Data Source
AI summary
Zone isolation of the all-electric semi-trailer reefer cold chambers completes the combination of refrigeration, battery, and solar technologies. Temperature controlled flow of cold air improves refrigeration efficiency and makes it possible to use solar panels to exclusively power a zero-emissions semi-trailer sized reefer.