Refrigeration appliance with a humidity control and method for controlling such appliance
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Solution Overview
Problem
Refrigeration appliances face challenges in simultaneously controlling temperature and humidity to create an optimal environment for food preservation, with existing technologies failing to minimize oscillations and efficiently manage thermal and humidity losses.
Innovation Solution
Implementing a closed-loop control system using PID control logic to manage a variable cooling capacity compressor and fan operation, ensuring precise temperature and humidity control by adjusting compressor duty cycle and fan activity based on error calculations and set values, maintaining a stable cooling capacity and humidity level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a variable cooling capacity compressor is used to meet cooling demand, then temperature control is improved, but humidity control becomes difficult due to thermal losses
Solution Approach 1:
The patent implements a closed-loop feedback control system that continuously monitors both temperature and humidity levels in the refrigerator compartment. The control unit receives real-time data from temperature and humidity sensors, compares actual values with target values, and dynamically adjusts the compressor capacity and fan operation accordingly. This feedback mechanism enables simultaneous control of both temperature and humidity, resolving the contradiction by making the system responsive to both parameters rather than just temperature.
Solution Approach 2:
The patent employs dynamic control strategies where the compressor operates at variable cooling capacities and the fan speed is continuously adjusted based on real-time conditions. Instead of fixed on/off control, the system dynamically modulates the cooling capacity to match the actual thermal and humidity loads, enabling precise control of both temperature and humidity simultaneously while compensating for thermal losses.
2Use of energy by moving object
If the compressor is switched off to reduce energy consumption, then energy efficiency is improved, but temperature and humidity oscillations increase
Solution Approach 1:
The patent replaces traditional binary on/off compressor control with continuous variable capacity control. The compressor operates dynamically at different cooling capacities based on real-time temperature and humidity demands, allowing it to run at low capacities rather than completely shutting off. This dynamic operation maintains temperature and humidity stability while reducing energy consumption compared to frequent on/off cycling.
Solution Approach 2:
The patent ensures continuous useful action by keeping the compressor running at variable capacities rather than allowing complete shutdowns. The control system continuously modulates the compressor output to match the cooling demand, maintaining uninterrupted cooling action that prevents temperature and humidity oscillations while optimizing energy consumption through capacity modulation rather than on/off switching.
3Reliability
If fan speed is increased to improve air circulation and humidity distribution, then humidity control is improved, but energy consumption increases
Solution Approach 1:
The patent implements dynamic fan control where the fan speed is continuously adjusted based on real-time humidity and temperature conditions. The control unit modulates fan operation to provide sufficient air circulation for humidity distribution only when and where needed, rather than running at constant high speed. This dynamic adjustment maintains humidity distribution uniformity while minimizing fan energy consumption.
Solution Approach 2:
The patent changes the operational parameters of the fan from fixed speed to variable speed control. The control system adjusts fan speed as a controllable parameter based on the actual humidity control requirements, allowing optimization of the balance between humidity distribution effectiveness and energy consumption by selecting the minimum necessary fan speed at each moment.
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 reduces temperature and humidity fluctuations within the refrigerator compartments, maintaining a constant cooling capacity and optimal food preservation conditions by continuously compensating for thermal losses and adjusting fan and compressor operations according to specific conditions.
Implementation Method 1
an evaporator and a fan blowing air over said evaporator
Implementation Method 2
a variable cooling capacity compressor
Implementation Method 3
a condenser, an evaporator
Data Source
Figure 1~2
Figure 3a
Figure 3b
AI summary
A refrigeration appliance (A) comprises at least one compartment (RC) for food preservation, a control circuit driving a refrigeration circuit comprising a variable cooling capacity compressor (20), a condenser, an evaporator and a fan for blowing air over said evaporator (14), the compartment comprising a temperature sensor (10) and a humidity sensor (12). The control circuit is adapted to switch ON the fan when the compressor is OFF or when the compressor is working at low cooling capacity in order to increase the humidity level in the compartment.