Single-Circuit Refrigerator Control for Multi-Zone Cooling Balance
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Solution Overview
Problem
Conventional single-circuit refrigeration devices face challenges in maintaining setpoint temperatures in multiple zones without costly optimization, particularly when the ambient temperature varies, leading to inefficient compressor runtime and insufficient cooling in zones with different specific cooling requirements.
Innovation Solution
The solution involves setting a second switch-off condition that occurs earlier than the first, allowing for shorter compressor runtimes that benefit the temperature zone cooled by the upstream evaporator, with a waiting time defined from compressor switch-on or switch-off, and using a second temperature sensor to detect liquid refrigerant arrival for precise cooling control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the compressor runtime is extended to cool the colder temperature zone, then the colder zone receives sufficient cooling, but the warmer zone experiences excessive cooling and energy waste
Solution Approach 1:
The system dynamically adjusts compressor runtime based on real-time temperature conditions in both zones and ambient temperature. By extending runtime only when necessary (detected through the waiting time mechanism and ambient temperature sensing), the system ensures adequate cooling in the colder zone without continuous operation that would cause excessive cooling and energy waste in the warmer zone.
Solution Approach 2:
The control system changes the operational parameters of the compressor based on detected conditions. When the waiting time expires or ambient temperature is low, the system adjusts the compressor runtime parameter to be longer than the standard cycle, providing targeted additional cooling to the colder zone without unnecessarily extending runtime during normal conditions.
2Loss of time
If a large-format evaporator is used to shorten compressor runtimes, then the upstream temperature zone benefits from reduced cooling time, but the downstream temperature zone may receive insufficient cooling
Solution Approach 1:
The system segments the cooling control into two independent temperature zones with separate temperature sensors and independent switch-on/switch-off conditions. The upstream zone (warmer) and downstream zone (colder) can have different compressor runtime requirements, and the control system manages each zone's cooling needs separately through the dual-condition control logic, preventing the downstream zone from receiving insufficient cooling while still benefiting from shortened runtimes when appropriate.
Solution Approach 2:
The control system dynamically determines compressor runtime based on which switch-off condition is met first (upstream or downstream temperature condition). This dynamic adjustment ensures that the compressor runs long enough to adequately cool the downstream zone when needed, while still allowing for shortened runtimes when the upstream zone's cooling requirement is met first and ambient conditions are favorable.
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 approach ensures efficient maintenance of setpoint temperatures in both zones, shortening compressor runtimes for zones with low specific cooling requirements without compromising cooling in zones with higher requirements, thus enhancing the overall efficiency of the refrigeration device.
Implementation Method 1
Both temperature zones, here a freezer compartment (2) and a normal cooling compartment (3), are each assigned an evaporator (5, 6)
Implementation Method 2
the refrigerant can circulate either through both evaporators connected in series at the same time or through neither of them
Implementation Method 3
a compressor (7), a condenser (8) mounted, for example, on a rear wall of the housing (1)
Implementation Method 4
the refrigerant can circulate either through both evaporators connected in series at the same time or through neither of them
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The invention concerns a refrigerator, in particular a domestic refrigerator, having at least two different temperature zones which are cooled by means of evaporators connected in series to a compressor. A temperature sensor is disposed in one of the temperature zones. A control circuit is connected to the temperature sensor and arranged to switch on the compressor when the temperature at the first temperature sensor exceeds a switch-on temperature (Ton) (S2) and to switch it off again when a first switch-off condition recurs (S4), and to switch on the compressor (S7) if a predetermined waiting time (twmax; twmin) has elapsed since the last time the compressor was operated (S2-S4; S7-S9).