Refrigeration Unit Drying Cargo Box via Alternating Thermal Cycles
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Solution Overview
Problem
The existing methods for drying a refrigerated cargo box after washing out for non-refrigerated products are inefficient, leading to delays, costly downtime, and poor productivity due to the natural drying process taking several hours.
Innovation Solution
A method involving the refrigeration unit's operation in alternating cycles of heating and cooling the circulating air to accelerate the drying process, with the unit cycling between heating for a preset period and then cooling until a preselected temperature is reached, and repeating this process for a preset drying time, or operating in a defrost cycle if the time exceeds the set period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If natural drying is used after wash out, then energy consumption is low, but drying time is excessively long causing delays and poor productivity
Solution Approach 1:
The refrigeration unit operates in alternating heating and cooling cycles to accelerate drying. The controller periodically switches between heating mode (to evaporate moisture) and cooling mode (to condense moisture on the evaporator), creating a periodic action that significantly reduces drying time compared to natural drying while maintaining reasonable energy consumption.
Solution Approach 2:
The method utilizes phase transitions of water between liquid, vapor, and ice states. During heating cycles, liquid water evaporates to vapor. During cooling cycles, water vapor condenses on the evaporator surface or freezes. These phase transitions are harnessed to rapidly remove moisture from the cargo box, solving the contradiction between fast drying and energy efficiency.
2Loss of time
If alternating heating and cooling cycles are used, then drying time is reduced, but energy consumption increases
Solution Approach 1:
The system converts the typically wasted heat from the refrigeration unit's operation into a useful heating function. During cooling cycles, the evaporator becomes cold and condenses moisture; during heating cycles, this same evaporator is used to heat and evaporate remaining moisture. This converts what would otherwise be wasted thermal energy into a beneficial drying mechanism, reducing total energy consumption while maintaining fast drying speeds.
Solution Approach 2:
The refrigeration unit performs multiple functions: it cools the cargo box during cooling cycles to condense moisture, and it heats the cargo box during heating cycles to evaporate moisture. This multi-functionality allows a single piece of equipment to handle both cooling and heating requirements of the drying process, eliminating the need for separate heating equipment and reducing overall energy consumption.
3Productivity
If the refrigeration unit operates in alternating cycles, then moisture removal efficiency is improved, but device complexity increases
Solution Approach 1:
The system uses its own existing components (evaporator, fan, refrigeration cycle) to perform both heating and cooling functions without requiring additional external equipment. The controller simply manages the timing and operation of existing components, allowing the system to service itself by using its inherent capabilities for moisture removal, thus improving efficiency without proportionally increasing complexity.
Solution Approach 2:
The controller monitors various parameters (temperature, humidity, cycle timing) and adjusts the operation of the refrigeration unit accordingly. This feedback mechanism ensures optimal switching between heating and cooling cycles, maximizing moisture removal efficiency while preventing excessive energy consumption or unnecessary complexity in the control 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
This method significantly reduces the drying time, enhancing productivity and equipment utilization by effectively removing moisture from the cargo box, allowing for quicker loading and departure.
Implementation Method 1
air from within the cargo box of the truck, trailer or container, is circulated through an evaporator heat exchanger in heat exchange relationship with refrigerant circulating through the refrigerant vapor compression system
Implementation Method 2
operating the refrigerant unit in alternating cycles of first heating the circulating air and then cooling the circulating air
Data Source
AI summary
A method is provided for accelerating the drying of a cargo box (18) of a refrigerated truck (12), trailer (16), or container following a wash out. In an aspect, the method includes circulating air from the cargo box (18) through an evaporator (30) of the refrigerant unit (20) and back to the cargo box (18); and operating the refrigerant unit (20) in alternating cycles of first heating the circulating air and then cooling the circulating air.