Self-powered, long-term, low-temperature, controlled shipping unit
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Solution Overview
Problem
Current shipping freezers face limitations such as lack of temperature control, reliance on external power, use of flammable fuels, limited shipping durations, and mechanical reliability issues due to numerous wearing parts.
Innovation Solution
A shipping container system utilizing a cryogenic tank for liquid nitrogen, with a thermally sealed payload bay and a controller for closed-loop temperature control, powered by rechargeable batteries, and featuring a cryogenic valve with heating fins to prevent 'sticky valve' issues, allowing for independent operation and reliable temperature maintenance between 20°C and -150°C for extended periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If mechanical compressors with Diesel generators are used for cooling, then cooling capacity is improved, but device complexity and reliability deteriorate due to multiple wearing parts
Solution Approach 1:
The patent replaces the mechanical compressor-Diesel generator system with an electronic expansion valve and liquid nitrogen evaporation system. The mechanical compressor and Diesel generator are eliminated, replaced by electronic control of nitrogen flow through expansion valves, which evaporate to provide cooling. This substitution removes multiple wearing parts (pistons, bearings, crankshafts, fuel injectors, belts, gears) while maintaining cooling capacity, thereby improving reliability.
2Power
If Diesel generators are used for power, then power availability is improved, but safety deteriorates due to flammable fuel and harmful emissions
Solution Approach 1:
The Diesel generator is completely replaced by an electronic control system that regulates liquid nitrogen flow. The system uses electronic expansion valves controlled by a microprocessor to manage nitrogen evaporation and cooling, eliminating the need for combustion-based power generation. This removes all safety hazards associated with flammable fuel storage, handling, and combustion, as well as harmful exhaust emissions.
3Temperature
If liquid nitrogen is used for cooling, then cooling effectiveness is improved, but temperature control deteriorates as product temperature approaches nitrogen liquefaction temperature
Solution Approach 1:
The patent employs dynamic control of the nitrogen evaporation process through electronic expansion valves that can be precisely regulated. The system continuously monitors temperature and adjusts the nitrogen flow rate dynamically, allowing the evaporation process to adapt to changing thermal loads and maintain precise temperature control. This prevents the product temperature from approaching the nitrogen liquefaction temperature while maintaining effective cooling.
Solution Approach 2:
The system incorporates temperature sensors and a microprocessor-based control system that continuously monitors the cooling process and provides feedback to the expansion valves. This closed-loop control adjusts nitrogen flow in real-time to maintain the desired temperature, preventing overheating or over-cooling and ensuring precise temperature control throughout the shipping process.
4Temperature
If solid Carbon Dioxide blocks are used for cooling, then cooling is achieved, but temperature control deteriorates as temperature is fixed at sublimation point of -78°C
Solution Approach 1:
The patent changes the physical state parameter of the cooling medium from solid (Carbon Dioxide blocks) to liquid (liquid nitrogen), which enables dynamic control of the cooling process. Liquid nitrogen can be controlled to evaporate at specific rates, allowing temperature adjustment across a wide range. This parameter change from solid to liquid state provides the versatility to control temperatures between -196°C and -50°C, unlike fixed sublimation-point solid CO2.
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 system provides controllable temperatures, independent operation from external power for 10+ days, improved safety with non-combustible fuel, and higher reliability due to fewer moving parts, reducing cooling losses and ensuring consistent temperature control during shipping.
Implementation Method 1
liquid nitrogen coolant flows therethrough
Implementation Method 2
tubing coupled to the payload bay for cooling when liquid nitrogen coolant flows therethrough
Implementation Method 3
a thermal box housing the payload bay and the tubing to thermally seal the payload bay from outside environment
Implementation Method 4
a cryogenic tank for storing liquid nitrogen coolant
Data Source
AI summary
A shipping vessel includes a cryogenic tank secured to the shipping foundation; a payload bay to receive products therein; a tube connected to the cryogenic tank and thermally coupled to the payload bay; a housing secured to the shipping foundation, said housing covering the tube and the payload bay to thermally seal the payload bay from outside environment; a controller mounted on the housing and having a sensor to determine temperature in a closed-loop and maintaining a set point within a predetermined range; and an energy storage device coupled to the controller and electronics to provide power for a predetermined shipping period.