Refrigeration device and method for operating a refrigeration device
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Solution Overview
Problem
Household refrigeration appliances struggle to maintain a desired temperature difference between refrigerated and cold storage compartments due to temperature stratification caused by natural convection, leading to inefficient energy consumption and potential undercuts in required temperature differences.
Innovation Solution
A method and appliance design that dynamically adjusts the operation of a fan and refrigerant supply based on actual and ambient temperatures, utilizing a fan for forced convection when necessary and relying on natural convection for temperature stratification, with the fan operation being optimized to minimize energy use and maintain temperature differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a fan is operated continuously to drive air circulation within the storage space, then temperature differences within the storage space are significantly reduced, but the required temperature difference between the cold storage compartment and the refrigerated compartment may be undercut
Solution Approach 1:
The fan operation is made dynamic rather than continuous. The control device activates the fan only when the actual temperature exceeds a third threshold value, and deactivates it when the temperature falls below a fourth threshold value. This dynamic operation allows the system to maintain temperature uniformity when needed while preserving natural convection-based temperature stratification between compartments when the fan is off.
Solution Approach 2:
The fan operates periodically based on temperature thresholds rather than continuously. By switching the fan on and off in periodic cycles according to temperature conditions, the system achieves temperature uniformity during fan operation periods while allowing temperature difference recovery during off periods, thus resolving the contradiction between these two temperature requirements.
2Loss of energy
If the fan is switched on and off simultaneously with the compressor, then cooling efficiency is optimized, but temperature stratification required for different storage compartments is compromised
Solution Approach 1:
The fan control is decoupled from compressor control and made independent and dynamic. While the compressor operates based on cooling demands, the fan operates based on temperature threshold comparisons. This dynamic independence allows the fan to run during compressor operation to enhance cooling efficiency, and also allows the fan to run after compressor shutdown to restore temperature stratification, thus resolving the contradiction between cooling efficiency and temperature stratification.
3Stability of the object's composition
If the fan operates for extended periods to maintain temperature uniformity, then temperature differences within the storage space are reduced, but energy consumption increases
Solution Approach 1:
The fan operates periodically based on temperature thresholds rather than continuously. By switching the fan on only when the actual temperature exceeds the third threshold and off when it falls below the fourth threshold, the system achieves temperature uniformity only when necessary, significantly reducing fan energy consumption while maintaining acceptable temperature distribution.
Solution Approach 2:
The control device uses feedback from temperature sensors to dynamically adjust fan operation. By continuously monitoring the actual temperature and comparing it with threshold values, the system activates the fan only when temperature uniformity is needed, avoiding unnecessary fan operation and thus reducing energy consumption while maintaining temperature distribution stability.
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
Effectively maintains temperature stratification and reduces energy consumption by optimizing fan and refrigerant operation, ensuring consistent temperature differences between compartments while minimizing unnecessary fan runtime.
Implementation Method 1
refrigerant circuit with an evaporator thermally coupled to the storage space in order to extract heat from the storage space by supplying the evaporator with refrigerant
Implementation Method 2
a fan arranged in the refrigeration compartment, which is designed to generate air circulation within the storage room
Implementation Method 3
Due to natural convection within the storage room, temperature stratification occurs, with an area near the floor or below being cooler than an area higher up
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A method for operating a refrigeration appliance comprises detecting an actual temperature in a storage space of the refrigeration appliance extending in a vertical direction, which storage space has a refrigeration compartment and a cold storage compartment located below the refrigeration compartment in relation to the vertical direction, supplying an evaporator thermally coupled to the storage space with refrigerant in order to extract heat from the storage space when the actual temperature reaches or exceeds a first temperature threshold, interrupting the supply of refrigerant to the evaporator when the actual temperature reaches or falls below a second temperature threshold that is lower than the first temperature threshold, operating a fan positioned in the refrigeration compartment of the storage space to generate air circulation within the storage space when the actual temperature reaches or exceeds a third temperature threshold that is higher than the first temperature threshold,and stopping the operation of the fan when the actual temperature reaches or falls below a fourth temperature threshold that is less than the first temperature threshold and greater than or equal to the second temperature threshold.