Refrigeration Device Pull-Down Control for Rapid Cargo Cooling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional refrigeration devices for containers face challenges in rapidly reducing the interior temperature to a set point during chilling operations, especially when dealing with hot cargoes like durians, as the transition from pull-down control to capacity control can lead to increased interior temperature due to respiration heat, resulting in longer cooling times and potential temperature overshooting.
Innovation Solution
A refrigeration device with an operation control unit that switches between pull-down control and capacity control, maintaining the pull-down control until the air temperature reaches the set temperature, and then switching to capacity control to manage cooling capacity, adjusting the suction proportional valve to maintain optimal temperature and prevent excessive cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the refrigeration device switches from pull-down control to capacity control when the cargo temperature drops to within the optimal temperature range, then the cooling capacity is reduced to prevent overcooling, but the interior temperature may increase rapidly due to respiration heat from hot cargoes
Solution Approach 1:
The control unit performs preliminary cooling with pull-down control at high cooling capacity until the blown air temperature reaches the set temperature, ensuring the interior is pre-cooled to the target temperature before switching to capacity control. This preliminary action prevents temperature increase from respiration heat and eliminates the need for extended capacity control operation.
Solution Approach 2:
The invention maintains continuous effective cooling by extending pull-down control until the blown air temperature reaches the set temperature, ensuring uninterrupted cooling action. This continuous useful action prevents temperature fluctuations and ensures rapid, stable temperature reduction without interruption or reversal.
2Speed
If pull-down control is used to rapidly cool the interior, then the cooling capacity is high and temperature reduction is fast, but the cooling capacity is excessive when the interior temperature approaches the set temperature
Solution Approach 1:
The control unit dynamically switches between pull-down control and capacity control based on real-time temperature conditions. Pull-down control operates at high capacity during the initial cooling phase, then transitions to capacity control with reduced capacity when the blown air temperature reaches the set temperature. This dynamic adjustment optimizes both cooling speed and energy efficiency throughout the cooling process.
Solution Approach 2:
The high-capacity pull-down control is applied preliminarily during the initial cooling phase when rapid temperature reduction is most needed. Once the blown air temperature reaches the set temperature, the system transitions to lower-capacity control, ensuring high cooling speed is used only when necessary and energy is conserved during the maintenance phase.
3Loss of energy
If the refrigeration device uses capacity control with lower cooling capacity, then energy consumption is reduced, but the time required to reduce the interior temperature to the set temperature increases
Solution Approach 1:
The system performs preliminary high-capacity cooling with pull-down control to rapidly reduce the interior temperature to near the set point, then transitions to lower-capacity capacity control for temperature maintenance. This preliminary action ensures most of the cooling is completed quickly, minimizing the time the system operates at high capacity while still achieving rapid overall temperature reduction.
Solution Approach 2:
The control unit dynamically adjusts cooling capacity based on the thermal state of the interior. During the initial cooling phase, high-capacity pull-down control is used for rapid temperature reduction. When the blown air temperature reaches the set temperature, the system dynamically transitions to lower-capacity capacity control, optimizing the balance between cooling speed and energy consumption throughout the entire cooling process.
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 approach reduces the time required to reach the set temperature and prevents overheating or undercooling, ensuring efficient and precise temperature control, even with hot cargoes, by maintaining a lower initial temperature at the switch from pull-down to capacity control.
Implementation Method 1
an evaporator that blows the air, having been cooled by the refrigerant, into the interior
Implementation Method 2
water condensation occurring on the cargoes in the interior
Data Source
AI summary
A refrigeration device executes a chilling operation for cooling an interior so that the temperature of the interior reaches a set temperature that is set within a predetermined temperature range. The refrigeration device has an operation control unit that, in the chilling operation, switches between pull-down control and capacity control for cooling the interior with a cooling capacity lower than that of the pull-down control. The operation control unit performs the pull-down control until the temperature of air blown toward the interior reaches at least the set temperature.