Minibar Refrigeration Control Using Occupancy Detection and Heat Storage
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Solution Overview
Problem
Conventional refrigeration units in minibars, such as those found in hotels, generate noise due to compressor operation, which can disturb occupants, especially at night, as existing solutions like timers are not reliable in determining occupancy and may not fully eliminate noise.
Innovation Solution
A refrigeration unit with a control and management assembly that uses sensors or mains switches to detect presence or absence of occupants, controlling the power supply to the compressor, ensuring it operates only when no one is present, and includes a safety device to maintain temperature and a heat accumulator to defer compressor activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the compressor is activated by a thermostat when temperature limit is exceeded, then the desired temperature is maintained, but noise is generated that annoys occupants
Solution Approach 1:
The system performs preliminary cooling during unoccupied periods to pre-chill the compartment and heat accumulator, allowing the compressor to remain off during occupied periods while maintaining temperature. The control unit detects occupancy status in advance and activates the compressor only when the room is unoccupied, preventing noise disturbance while ensuring temperature stability.
Solution Approach 2:
A heat accumulator serves as an intermediary thermal storage device that absorbs excess cooling capacity during unoccupied periods and releases it during occupied periods. This mediator allows the system to decouple compressor operation from immediate cooling demands, enabling noise-free operation during occupancy while maintaining temperature through thermal energy storage.
2Object-affected harmful factors
If timers are used to deactivate the compressor during night hours, then noise is reduced, but temperature control reliability is compromised as occupancy cannot be accurately detected
Solution Approach 1:
The system employs occupancy detection sensors that provide real-time feedback about room occupancy status to the control unit. This feedback mechanism allows the system to adapt compressor operation dynamically based on actual occupancy conditions rather than following fixed timer schedules, ensuring both noise reduction during occupancy and reliable temperature control regardless of occupancy patterns.
3Object-affected harmful factors
If a heat accumulator is inserted to defer compressor activation, then noise duration is extended, but the solution remains inadequate as it cannot adapt to actual occupancy patterns
Solution Approach 1:
The system transitions from static timer-based control to dynamic occupancy-based control. The control unit continuously monitors occupancy status and adjusts compressor operation in real-time, enabling the system to adapt to varying occupancy patterns throughout the day. This dynamic approach allows the heat accumulator to be charged or discharged based on actual occupancy conditions rather than fixed schedules, optimizing both noise reduction and temperature control.
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 effectively reduces noise disturbance by ensuring the compressor operates only when the room is unoccupied, maintaining temperature reliability, safety, and cost-effectiveness using commonly available materials.
Implementation Method 1
a sensor for detecting the presence or absence of at least one person in the immediate vicinity of the unit
Implementation Method 2
a compressor which, in the presence of an electrical power supply, can be activated to remove heat inside a compartment
Implementation Method 3
the compressor can be activated to remove heat inside a compartment
Implementation Method 4
a heat accumulator to defer compressor activation
Implementation Method 5
a control switch, which controls the power line in order to determine the presence or absence of electrical power supply
Data Source
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AI summary
A refrigeration unit (1) and a respective control and management assembly, comprising a refrigeration assembly (2) and at least one power input (4) for its electrical power supply. The refrigeration unit (1) comprising at least one signal input (8) and at least one control switch (9), which is arranged along a power line (10) which corresponds to the power input (4). The control switch (9) controlling the power line (10) and the data that arrive from the respective signal input (8) being suitable for driving the control switch (9) for consequently determining the presence/absence of electrical power supply for said refrigeration assembly (2).