Dual-Trailer Cooling Chambers for Field Harvest Cold Chain
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Solution Overview
Problem
Current systems for cooling perishable goods after harvest are inefficient as they require transporting produce to fixed-base cooling facilities, exposing it to heat and moisture loss, and involve cumbersome and costly ammonia-based refrigeration units that are difficult to transport and operate safely.
Innovation Solution
A portable cooling unit composed of dual trailers, where one trailer is for conveying perishable items through cooling chambers and the other provides independent cold air flows, allowing the cold chain to start at the harvest site without external connections, using safer refrigerants like Freon or glycol, and employing inter-trailer seals to maintain airflow and prevent leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fixed-base cooling units are used, then cooling capacity is sufficient, but the units are difficult and time-consuming to break down and transport
Solution Approach 1:
The cooling unit is divided into multiple independent modules including a refrigeration module, a conveyor module, and a control module. Each module can be independently transported and assembled at the destination, eliminating the need to break down large fixed-base units while maintaining sufficient cooling capacity through modular configuration.
2Power
If ammonia is used as refrigerant, then cooling efficiency is high, but safety risks and regulatory requirements increase
Solution Approach 1:
The refrigerant type parameter is changed from ammonia to alternative refrigerants such as hydrocarbon refrigerants (propane, isobutane) or synthetic refrigerants (R-134a, R-404A). This parameter change maintains adequate cooling efficiency while eliminating the severe safety risks and regulatory burdens associated with ammonia handling and transport.
3Temperature
If produce is transported to cooling facilities, then cooling can be performed, but moisture loss and textural degradation occur during transport
Solution Approach 1:
The cooling unit is deployed directly at the harvest site before produce is loaded onto transport vehicles. Cooling begins immediately after harvest, maintaining low temperatures throughout the entire process and preventing moisture loss and textural degradation that would occur during warm transport to distant cooling facilities.
4Power
If large quantities of ammonia are used, then cooling performance is adequate, but specialized permits and authorized technicians are required
Solution Approach 1:
The refrigerant quantity and type parameters are changed to use smaller amounts of alternative refrigerants instead of large quantities of ammonia. This reduces cooling performance slightly but eliminates the need for specialized EPA permits, ammonia handling certifications, and authorized technicians, thereby reducing regulatory complexity.
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 enables efficient and safe cooling of perishable items at the point of harvest, reducing moisture loss and textural degradation, and simplifies the cooling process by eliminating the need for large, ammonia-based fixed-base units, thereby improving the quality and safety of the produce while minimizing logistical and operational challenges.
Implementation Method 1
a refrigeration unit (150) for cooling and circulating a working fluid
Implementation Method 2
a plurality of fan units (158) to cool and circulate air from the refrigeration trailer through the cooling chambers in the conveyor trailer
Implementation Method 3
heat exchange coils (156) connected to the refrigeration unit, wherein the heat exchange coils are positioned within the compartments
Data Source
AI summary
A portable cooling unit is disclosed for cooling perishable items such as strawberries at a worksite such as a field where the strawberries are harvested. The cooling unit includes a conveyor trailer for receiving pallets of perishable items and conveying the pallets through a number of cooling chambers within the conveyor trailer. The cooling unit further includes a refrigeration trailer for supplying independent cold air flow paths to the different cooling chambers of the conveyor trailer. The conveyor and refrigeration trailers may operate as a self-sustained cooling unit, without any external connections to power or working fluid.