Refrigerated Merchandiser Airflow Control for Uniform Product Cooling
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Solution Overview
Problem
Conventional refrigerated merchandisers experience temperature variability and inefficiency due to direct airflow towards upper shelves, leading to uneven cooling, mechanical thermostat imprecision, and inaccurate temperature representation, which affects product quality.
Innovation Solution
A refrigerated merchandiser system with sensors and a controller that calculates product temperature based on airflow temperature, using a refrigeration circuit with a compressor, condenser, and evaporator in series, and operates in different modes to maintain a consistent temperature range between 22-23°F, avoiding freezing and ensuring precise temperature control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the temperature of the refrigerated air is decreased to cool the product on lower shelves, then the product on lower shelves is cooled adequately, but the product on upper shelves freezes
Solution Approach 1:
The system applies different cooling strategies to different zones within the merchandiser. The controller adjusts refrigerated air flow and temperature based on the specific thermal needs of upper versus lower shelves, allowing each zone to receive appropriate cooling without causing freezing in over-cooled areas.
Solution Approach 2:
Temperature sensors positioned at multiple locations (including upper and lower shelves) provide continuous feedback to the controller. The controller uses this feedback to dynamically adjust refrigeration system operation, reducing cooling when upper shelf temperatures approach freezing points and increasing cooling when lower shelf temperatures rise.
2Ease of operation
If mechanical thermostats are used to control temperature, then the system is simple to operate, but the temperature differential between ON and OFF states is wide causing product temperature fluctuation
Solution Approach 1:
The system replaces mechanical thermostats with electronic temperature sensors and a microcontroller-based control system. This substitution enables precise temperature measurement and control, eliminating the wide temperature differentials inherent in mechanical thermostat switching while maintaining ease of operation through automated control.
Solution Approach 2:
The control system dynamically adjusts refrigeration system operation based on real-time temperature readings from multiple sensors. Rather than relying on fixed mechanical switch points, the system continuously modulates cooling to maintain temperatures within a narrow target range, adapting to changing thermal conditions throughout the merchandiser.
3Quantity of substance
If large quantities of product are stored on shelves to maximize inventory, then storage capacity is increased, but airflow patterns become turbulent causing substantial temperature variability
Solution Approach 1:
The system divides the merchandiser into multiple temperature monitoring zones with individual sensors positioned at different shelf levels and locations. This segmentation allows the controller to identify and address temperature variability in specific zones without requiring reduction of overall inventory, maintaining high storage capacity while managing temperature distribution.
Solution Approach 2:
The system changes operational parameters (refrigerated air flow rate, temperature setpoints, compressor cycling) based on real-time temperature measurements from multiple zones. When temperature variability is detected in certain areas, the controller adjusts parameters to redistribute cooling, maintaining uniform temperatures even with full inventory levels.
4Device complexity
If air temperature in the product display area is used to represent product temperature, then measurement is simple, but the temperature reading is inaccurate due to door openings and defrost cycles
Solution Approach 1:
The system uses air temperature sensors as intermediaries to indirectly measure product temperature, but positions these sensors in strategic locations where they are less affected by door openings and defrost cycles. The controller compensates for environmental disturbances by analyzing temperature trends and comparing readings from multiple sensor locations to derive accurate product temperature estimates.
Solution Approach 2:
Multiple temperature sensors provide continuous feedback to the controller, which uses algorithmic processing to distinguish between transient air temperature changes (caused by door openings or defrosting) and actual product temperature changes. This feedback mechanism enables accurate product temperature representation despite environmental disturbances.
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 consistent and precise temperature control, maintaining product quality by ensuring uniform cooling and preventing freezing, even in varying ambient conditions, while displaying the calculated product temperature for consumer visibility.
Implementation Method 1
The refrigeration system is in communication with the product storage area to introduce a refrigerated airflow into the product storage area to refrigerate the product
Implementation Method 2
The refrigeration system includes a refrigeration circuit that has a compressor, a condenser, and an evaporator in series
Data Source
AI summary
A refrigerated merchandiser including a case and a refrigeration system in communication with a product storage area of the case. The case includes a case top, a discharge passageway, and a return passageway, and the case top has a lower wall, a front wall, and a deflector. The refrigeration system includes a refrigeration circuit that has a compressor, a condenser, and an evaporator in series, where the evaporator is disposed in the case top. The refrigeration system further includes a fan that cooperates with the lower wall, the front wall, and the deflector to discharge a substantially laminar refrigerated airflow into and through the product storage area to refrigerate the product within a predetermined temperature range without directing the refrigerated airflow directly at the product.