Minibar Refrigeration Control Using Occupancy-Based Compressor Switching
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Solution Overview
Problem
Conventional minibars in hotels generate noise due to compressor operation, which can disturb occupants, especially at night, as existing solutions like timers are not effective in determining the room's occupancy status.
Innovation Solution
A refrigeration unit with a control and management assembly that includes a signal input and control switch along the power line, which determines the presence or absence of electrical power supply based on sensors or mains switch data, allowing the compressor to be deactivated when people are present and activated when the room is empty, using a heat accumulator and safety device to maintain temperature.
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 can annoy occupants
Solution Approach 1:
The system uses occupancy detection feedback to control compressor operation. Sensors detect whether the room is occupied or unoccupied, and this information feeds back to the control unit which adjusts compressor operation accordingly - running continuously when unoccupied, stopping when occupied, thereby eliminating noise disturbance while maintaining temperature through alternative means.
Solution Approach 2:
The system changes the operational parameters of the refrigeration unit based on occupancy status. When the room is unoccupied, the compressor runs at full capacity to maintain temperature. When occupancy is detected, the compressor stops operating and the system switches to passive thermal maintenance mode, changing the operational state from active cooling to passive temperature holding.
2Object-affected harmful factors
If timers are used to deactivate the compressor during night hours, then noise is reduced, but the solution is not satisfactory because it cannot detect actual room occupancy
Solution Approach 1:
The system performs self-service by automatically detecting occupancy status through sensors and autonomously adjusting its operation. The control unit monitors sensor inputs and independently decides when to start or stop the compressor without requiring manual timer programming or user intervention, thereby accurately responding to actual occupancy conditions.
Solution Approach 2:
The patent replaces the mechanical timer-based control system with an electronic sensor-based detection system. Instead of using predetermined time schedules, the system uses electronic sensors to detect occupancy status and electronically controlled switches to manage compressor operation, substituting mechanical timing mechanisms with electronic information sensing and processing.
3Object-affected harmful factors
If a heat accumulator is inserted to defer compressor switching on, then noise is further reduced, but the solution remains insufficient without accurate occupancy detection
Solution Approach 1:
The heat accumulator performs preliminary cooling action by storing cold energy in advance during periods when the compressor operates. This pre-cooled thermal energy is then released passively to maintain temperature during periods when the compressor is stopped, allowing the system to prepare thermal reserves beforehand to ensure continuous temperature preservation without active compression.
Solution Approach 2:
The heat accumulator utilizes phase transition of the refrigerant or thermal storage material to store and release thermal energy. During compression phases, the accumulator absorbs and stores thermal energy; during expansion or discharge phases, it releases stored thermal energy to maintain temperature, leveraging phase change phenomena for thermal management.
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 solution effectively reduces noise disturbance by ensuring the compressor operates only when the room is unoccupied, maintaining a predefined temperature while being reliable, cost-effective, and safe, using commonly available materials.
Implementation Method 1
inserting in the minibar a heat accumulator, which is also cooled by the compressor and is capable of removing heat once the compressor is deactivated
Data Source
AI summary
A refrigeration unit and a respective control and management assembly, comprising a refrigeration assembly and at least one power input for its electrical power supply. The refrigeration unit comprising at least one signal input and at least one control switch, which is arranged along a power line which corresponds to the power input. The control switch controlling the power line and the data that arrive from the respective signal input being suitable for driving the control switch for consequently determining the presence/absence of electrical power supply for said refrigeration assembly.