Two-Stage Direct Expansion Evaporator for Complete Refrigerant Evaporation
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Solution Overview
Problem
Existing direct expansion evaporators in refrigeration systems are inefficient in transferring thermal energy for freezing products like ice cream and frozen yogurt, leading to energy waste and suboptimal product quality due to limited heat exchange areas and complex manufacturing processes.
Innovation Solution
A direct expansion evaporator with a two-stage heat exchange system, featuring a pre-cooling stage and a freezing stage, where the refrigerant enters at the dispensing end of the feeding channel and exits at the feeding end, allowing for prolonged refrigerant travel and complete evaporation, enhancing thermal energy transfer and reducing manufacturing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a traditional coil type evaporator is used, then the structure is simple, but the heat exchange efficiency is low due to limited contact area between copper tube and feeding tube
Solution Approach 1:
The patent transitions from a single-layer coil structure to a multi-layer nested coil structure, where inner and outer coils are arranged concentrically. This spatial arrangement in multiple dimensions significantly increases the heat exchange contact area between the refrigerant and the material being cooled, thereby improving heat exchange efficiency while maintaining manufacturing simplicity.
2Productivity
If a fin type heat exchanger is used, then the heat transfer rate is higher, but the fabrication procedure is complicated resulting in high manufacturing cost
Solution Approach 1:
The patent divides the heat exchanger into separate functional segments: the feeding tube for material transport and the nested coil structure for refrigerant circulation. This segmentation allows each component to be manufactured independently using simple processes, avoiding the complex welding and fin attachment procedures required by traditional fin type heat exchangers, while still achieving high heat transfer rates through the nested coil configuration.
3Productivity
If a spiral type heat exchanger is used, then the heat exchanging efficiency is enhanced, but the outer cylinder is longer and requires precise assembly process increasing manufacturing cost
Solution Approach 1:
The patent employs a nested doll principle by placing the inner coil inside the outer coil in a concentric arrangement. This nesting configuration maximizes the use of available space, prolongs the refrigerant traveling distance and heat exchange time, enhances heat exchanging efficiency, while keeping the overall structure compact and the assembly process simple, avoiding the need for precise assembly of long spiral structures.
4Speed
If the refrigerant travels a short distance in the heat exchange channel, then the system operates quickly, but the refrigerant evaporation is incomplete reducing heat exchange efficiency
Solution Approach 1:
The patent ensures continuous useful action by designing the nested coil structure to provide an optimized refrigerant flow path that maintains appropriate flow velocity throughout the entire heat exchange channel. The concentric arrangement of inner and outer coils creates extended heat exchange surfaces that allow complete refrigerant evaporation while maintaining efficient heat transfer, ensuring the refrigerant fully utilizes its cooling potential before exiting the 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 configuration increases the heat exchange efficiency, ensures complete refrigerant evaporation, reduces energy consumption, and simplifies manufacturing, making it suitable for mass production while maintaining the quality of frozen products.
Implementation Method 1
the refrigerant is rapidly evaporated to gaseous phase due to the pressure drop, so as to provide the thermal energy to the heat exchange chamber. The phase change from liquid to gas of the refrigerant absorbs dramatic heat energy
Implementation Method 2
When liquid refrigerant enters the evaporator through the expansion valve or a capillary tube, it rapidly vaporizes due to the sudden expansion of volume and reduction of pressure
Implementation Method 3
the heat is conductively transferred through two layers, the walls of copper tube and feeding tube, so that the heat transferring is inefficient
Data Source
AI summary
A direct expansion evaporator for making a frozen product from raw material includes a feeding channel, a heat exchange channel thermally communicating with the feeding channel, and a refrigerant flowing within the heat exchange channel for exchanging heat between the raw material within the feeding channel and the refrigerant within the heat exchange channel in an expanded evaporation manner. Therefore, the refrigerant releases the thermal energy via the phase changing from liquid to gaseous state of the refrigerant. The heat exchange channel has a pre-cooling portion for pre-cooling the raw material at a predetermined temperature and a freezing portion for freezing the raw material to a final predetermined temperature of the frozen product in two-stage evaporation manner. Thus, the direction expansion evaporator provides a relatively more efficient way for making the frozen product, so as to increase the quality of the frozen product.