Heat Pump Dryer Compressor Control for Constant-Power Drying
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Solution Overview
Problem
Existing laundry drying appliances lack flexibility in user-selectable drying cycles, particularly in terms of power management and energy efficiency, leading to suboptimal drying performance and energy consumption.
Innovation Solution
A laundry dryer or washer/dryer equipped with a heat pump system featuring a variable-output compressor and a controller that adjusts the compressor's rotational speed to maintain constant power absorption during a portion of the drying cycle, along with options for different drying modes such as 'Quick Dry', 'Eco Dry', and 'Silent Dry' to optimize energy use and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the compressor operates at high power throughout the drying cycle, then drying performance is improved, but energy consumption increases
Solution Approach 1:
The compressor operates in multiple modes with variable power levels. During the initial transient phase, the compressor runs at high power to establish steady-state operation. During the subsequent portion of the drying cycle, the compressor power is reduced to a lower level while maintaining effective drying through optimized heat pump operation. This dynamic power adjustment resolves the contradiction by providing high drying performance only when necessary and reducing energy consumption during the majority of the cycle.
Solution Approach 2:
The drying cycle is divided into distinct temporal phases: an initial transient phase followed by a steady-state portion. The compressor power level changes periodically between these phases, operating at high power during the transient phase and at reduced power during the steady-state portion. This periodic action allows the system to achieve effective drying while minimizing overall energy consumption.
2Use of energy by moving object
If the compressor operates at low power, then energy consumption is reduced, but drying performance deteriorates
Solution Approach 1:
The system performs preliminary high-power compression during the initial transient phase to establish the heat pump system in steady-state operation. This preliminary action ensures that the refrigerant circulation and heat exchange processes are fully established before reducing compressor power. As a result, the system can maintain effective drying performance even at lower power levels during the subsequent portion of the cycle.
Solution Approach 2:
The compressor power parameter is changed from high to low after the initial transient phase. This parameter change is accompanied by corresponding adjustments in other system parameters (such as refrigerant flow rates and heat exchange conditions) to maintain effective drying performance at the lower power level, thus reducing energy consumption without significantly compromising drying effectiveness.
3Use of energy by moving object
If the compressor power varies during the drying cycle, then energy efficiency is improved, but control complexity increases
Solution Approach 1:
The drying cycle is segmented into distinct phases: an initial transient phase and a subsequent steady-state portion. The compressor control strategy is相应 segmented, with high power operation during the transient phase and reduced power operation during the steady-state portion. This segmentation simplifies the control logic by defining clear operational boundaries and power levels for each phase, making the variable power control more manageable despite the increased energy efficiency requirements.
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 provides users with flexible drying cycle options, improving drying performance while allowing for energy-efficient operation, reducing drying time in 'Quick Dry' mode and minimizing energy consumption in 'Eco Dry' and 'Silent Dry' modes.
Implementation Method 1
the moisture condensing system is an air-air heat exchanger, exploiting air taken in from the outside for cooling down the drying air (and thus cause the condensation of the moisture)
Implementation Method 2
the dried air flow is heated up by means of a heating arrangement
Data Source
AI summary
An appliance for drying laundry (100) includes a drying-air moisture-condensing system comprising a heat pump system (215,220,225) with a variable-output compressor (210) having a compression mechanism and an electric motor for driving the compression mechanism. A controller (265) is provided to vary the rotational speed of the electric motor so as to adjust the rotational speed of the compression mechanism in order to maintain constant a power absorbed by the compressor during at least a portion of a drying cycle.