Adaptive Refrigeration Control to Prevent Food Surface Freezing
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Solution Overview
Problem
In professional food-service operations, large-volume deep-freezers often lack adequate refrigeration capacity to freeze food products within standard time allowances, leading to rapid temperature decrease in chillers that can result in 'blackening' effects, where surface layers freeze before core temperatures reach zero, spoiling delicate food products like vegetables and confectionaries.
Innovation Solution
A refrigeration apparatus that automatically adjusts the cooling process based on core and compartment temperatures using a core-temperature probe and control means, employing a method that compares temperatures with pre-defined values and adjusts set-points to ensure core temperatures reach the desired final value without excessive surface freezing, using a parabolic cooling curve model to comply with standard regulations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If high freezing capacity is used to quickly cool food products, then cooling speed is improved, but surface freezing occurs before core temperatures reach zero
Solution Approach 1:
The refrigeration apparatus dynamically adjusts the refrigeration capacity during the freezing process. It starts with high capacity for rapid cooling, then automatically reduces capacity as core temperature approaches target, preventing surface freezing while maintaining efficient cooling speed
Solution Approach 2:
The system uses core temperature probes to continuously monitor food product temperature and provides feedback to the control unit. Based on this feedback, the control unit automatically adjusts refrigeration capacity to match the actual freezing progress, ensuring core temperatures reach zero before surface freezing occurs
2Productivity
If large-volume deep-freezers are provided with adequate refrigeration capacity, then freezing capacity is improved, but device cost increases to unacceptable extent
Solution Approach 1:
Instead of providing continuously high refrigeration capacity, the system dynamically adjusts capacity based on real-time temperature feedback. This allows standard-sized freezers to achieve adequate freezing capacity when needed, eliminating the need for expensive oversized equipment
Solution Approach 2:
The system changes the operational parameters of the refrigeration apparatus during the freezing process. By varying refrigeration capacity as a parameter based on temperature progression, it achieves high effective freezing capacity without requiring permanently high-capacity equipment
3Loss of time
If temperature pull-down rapidity is increased to freeze food within time allowances, then freezing time is reduced, but compartment temperature decreases to very low values causing blackening effect
Solution Approach 1:
The system performs preliminary rapid cooling to quickly reduce compartment temperature and food core temperature, then stops before compartment temperature becomes excessively low. This preliminary action achieves time savings while preventing the blackening effect
Solution Approach 2:
The system applies partial cooling action - enough to achieve rapid freezing within time allowances but not excessive enough to cause compartment temperature to drop to harmful low values. It stops cooling when core temperature reaches target, avoiding over-cooling
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 prevents excessive surface freezing, maintaining food quality by ensuring core temperatures reach the desired level before stopping the cooling process, thus avoiding the 'blackening' effect and ensuring compliance with refrigeration standards.
Implementation Method 1
a core-temperature probe device (3), which is adapted to detect the temperature at the core of the food product
Implementation Method 2
The refrigeration apparatus is provided with a refrigeration compartment (1) in which a foodstuff is placed to be chilled
Implementation Method 3
control means, which are adapted to compare the detected temperatures with pre-defined values and, on the basis of said comparison, adjust the set-point for the chilling compartment temperature
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Method for chilling foodstuffs contained in a chilling compartment at controllable temperature, and adapted to perform according to an operating procedure comprising the steps of continuously pulling down the temperature inside the foodstuff to be chilled, until a pre-set value (Tf) is eventually reached, provided that the temperature inside said chilling compartment is lower than a pre-set value, and the temperature at the core of said foodstuff is lower than a pre-set value. In addition, before the process is allowed to move on to the final temperature pull-down step, further conditions are defined to ensure that the temperature pull-down pattern and rate inside the foodstuff are complying with the requirements provided for by the applying standards.