Segmented Evaporator Cylinder for Faster Small-Batch Freezing
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Solution Overview
Problem
Domestic appliances for producing frozen food products face challenges in achieving short freezing times and efficient heat transfer, especially when making small batches, due to the need to cool both the product and the cooling cylinder from ambient temperature, and existing designs are not optimized for varying capacities and models.
Innovation Solution
The appliance features a cooling cylinder with thermally-conductive walls and a divider member forming contiguous evaporator compartments, along with an auger and electric motor for efficient refrigerant flow and product scraping, allowing for modular construction and efficient heat transfer by controlling refrigerant flow and auger operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single continuous evaporator coil is used, then heat transfer is evenly distributed along the coil, but freezing time is extended when making small batches due to the need to cool the entire cylinder
Solution Approach 1:
The evaporator is divided into multiple separate segments positioned at different locations within the cooling cylinder. Each segment can be independently filled with refrigerant, allowing selective activation of only the portions needed for the current batch size. This segmentation enables rapid cooling of small batches while maintaining even heat transfer distribution through proper segment placement and configuration.
2Ease of manufacture
If the cooling cylinder is cooled from ambient temperature for each batch, then the appliance can make small batches cost-effectively, but the freezing time increases due to cooling both product and cylinder
Solution Approach 1:
The evaporator segments are pre-positioned and pre-filled with refrigerant before operation begins. When a batch is initiated, the refrigerant is already in place to immediately begin heat transfer to the product, eliminating the delay of filling and cooling the entire cylinder from ambient temperature. This preliminary preparation enables faster freezing while maintaining cost-effectiveness for small batches.
3Power
If refrigerant flow is distributed throughout the entire coil length, then heat transfer efficiency is maintained at capacity, but efficiency drops for small batches due to wide distribution of liquid component
Solution Approach 1:
The refrigerant distribution system is designed to dynamically adapt to batch size requirements. For small batches, refrigerant flow is concentrated in specific segments closest to the product, maximizing heat transfer efficiency. For larger batches, additional segments are activated and refrigerant distribution expands accordingly. This dynamic allocation maintains optimal heat transfer efficiency across varying batch sizes while providing versatility in production capacity.
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 configuration reduces freezing time and improves heat transfer efficiency, enabling effective production of frozen food products across different capacities and models, including small batches, while maintaining cost-effectiveness and operational efficiency.
Implementation Method 1
the cylinder wall and end cap being thermally-conductive and separating refrigerant on one side from product to be frozen on the other side
Implementation Method 2
the large liquid component of the refrigerant rapidly evaporates on meeting the room-temperature evaporator coil
Implementation Method 3
Since most heat transfer occurs when the liquid refrigerant is changed to vapour
Implementation Method 4
ice crystals formed on the heat-conductive outer wall of the cooling cylinder are scraped off by the auger
Data Source
AI summary
An appliance for producing frozen food products, such as ice cream or slush drinks, includes a cooling cylinder connected in a refrigeration circuit, the cooling cylinder including a thermally-conductive cylinder wall and end cap closing the distal end of the cylinder wall, the cylinder wall and end cap separating refrigerant on one side from product to be frozen on the other side. A divider member disposed adjacent the cylinder wall forms contiguous evaporator compartments spaced apart axially. Restrictor passages in the divider member permit communication between contiguous compartments and refrigerant first enters the first-cooled evaporator compartment at one of the axial ends and flows in series between the evaporator compartments. For fast, efficient freezing of small batches, the product to be frozen is either driven by the auger, or drains, toward the first-cooled evaporator compartment.