Variable Surface Heat Exchanger With Rotating Frost-Clearing Shield
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Solution Overview
Problem
Existing refrigeration systems face challenges in precise temperature control due to low temperature differences and frost buildup on heat exchangers, leading to inefficient heat transfer and potential product damage during chilling or freezing processes.
Innovation Solution
A variable surface area heat exchanger with a moveable insulated shield that adjusts heat transfer by rotating along the exterior surface, allowing for controlled exposure of the heat transfer area and incorporating a knife edge to remove frost, enabling precise temperature control and efficient heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the heat exchanger surface area is kept constant to simplify the system, then the device complexity is reduced, but the temperature control precision deteriorates because the heat transfer rate cannot be adjusted when heat load changes
Solution Approach 1:
The heat exchanger surface area is made variable through a rotating shield mechanism that can dynamically adjust the exposed surface area of the heat exchanger to the refrigerant. This allows the system to adapt the heat transfer rate to changing heat loads while maintaining precise temperature control, resolving the contradiction between constant surface area simplicity and temperature control precision.
2Productivity
If the refrigerant temperature is lowered to increase the temperature difference and heat transfer rate, then the heat transfer efficiency is improved, but the temperature control precision deteriorates because the temperature drops below the desired set point
Solution Approach 1:
Instead of changing the refrigerant temperature, the system dynamically adjusts the heat transfer surface area by rotating the shield. This allows the refrigerant temperature to remain stable while the heat transfer rate is controlled by varying the exposed surface area, thereby maintaining both high heat transfer efficiency and precise temperature control.
Solution Approach 2:
The system changes the parameter of heat transfer surface area rather than refrigerant temperature to control the heat transfer rate. This parameter change allows independent optimization of both heat transfer efficiency and temperature control precision, as the surface area can be adjusted without affecting the refrigerant temperature stability.
3Reliability
If the air temperature is reduced to compensate for anticipated heat load increases, then the temperature control reliability is improved, but the product quality deteriorates due to excessive cooling and frost buildup
Solution Approach 1:
The variable surface area heat exchanger allows the system to respond dynamically to actual heat load conditions rather than relying on anticipatory cooling. The shield rotation adjusts the heat transfer rate in real-time based on actual temperature and heat load conditions, maintaining reliable temperature control without excessive cooling that causes product damage and frost buildup.
4Productivity
If the heat exchanger surface is kept exposed to maximize heat transfer, then the heat transfer efficiency is improved, but frost buildup increases which deteriorates heat transfer and temperature control
Solution Approach 1:
The rotating shield mechanism dynamically adjusts the heat exchanger surface exposure based on operating conditions. When frost buildup is detected or anticipated, the shield can reduce surface exposure to minimize further frost accumulation while maintaining adequate heat transfer. This dynamic adjustment resolves the contradiction between maximizing heat transfer efficiency and preventing frost-related reliability issues.
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 solution allows for precise temperature control and efficient heat transfer by varying the heat transfer surface area and preventing frost buildup, maintaining product quality and system efficiency.
Implementation Method 1
The air inside the refrigerated space is cooled by forced or natural convection over the surface of the heat exchanger
Implementation Method 2
The air inside the refrigerated space is cooled by forced or natural convection over the surface of the heat exchanger
Implementation Method 3
a cold surface at the heat exchanger which tends to become covered in frost that has been condensed from air external to the refrigerated space
Implementation Method 4
incorporating a knife edge to remove frost
Data Source
AI summary
A heat exchanger apparatus includes a housing having a sidewall defining a chamber in the housing for containing a cryogen; and a first insulation member movably mounted for coaction with the sidewall, the first insulation member moveable to a position to expose or cover a select portion of the sidewall to provide a heat transfer effect.