Clothes Dryer Heat Source Sequencing for Compressor Load Stability
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Solution Overview
Problem
Existing clothes dryers face inefficiencies in energy usage and drying time due to limitations in heat pump systems and the need for auxiliary heaters, which can lead to compressor overload and reduced reliability.
Innovation Solution
A controlling method that selectively uses a heat pump system and a heater as heat sources, where the heat pump system is turned on first, followed by the heater, and then both are turned off in sequence to optimize energy efficiency and prevent compressor overload, with checks for normal compressor operation to ensure stable drying.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a heater is used as the heating unit in a circulating type dryer, then thermal energy can be supplied as much as necessary, but thermal efficiency is lowered and energy consumption increases due to heat exchange with the heat exchanger
Solution Approach 1:
The control method performs preliminary action by turning on the heat pump system before turning on the heater. This allows the heat pump to pre-cool the exhaust air and establish a lower temperature baseline, so that when the heater subsequently heats the air, less thermal energy is wasted through the heat exchanger, thereby improving thermal efficiency while maintaining adequate thermal energy supply.
2Productivity
If a heater is used as the heating unit in an exhausting type dryer, then drying time is reduced by supplying thermal energy as required, but thermal efficiency is lowered and energy consumption increases due to direct discharge of hot air
Solution Approach 1:
The control method applies preliminary action by activating the heat pump system before the heater in an exhausting type dryer. The heat pump pre-cools the exhaust air, creating a temperature differential that allows the heater to more efficiently heat the air to the required drying temperature. This sequence enables faster drying while reducing the total thermal energy consumed compared to using the heater alone.
3Productivity
If both the heat pump system and heater are operated simultaneously, then drying performance is improved, but compressor overload may occur and reliability is reduced
Solution Approach 1:
The control method uses preliminary action by turning on the heat pump system first and allowing it to operate alone for a predetermined time period before activating the heater. This staged approach allows the heat pump compressor to gradually build up cooling capacity without sudden overload, while still achieving effective drying performance through the combined operation of both systems.
Solution Approach 2:
The control method implements periodic action by operating the heat pump system alone during an initial period, then switching to combined operation with the heater for the remainder of the drying cycle. This temporal separation of operations allows the compressor to handle variable loads in stages rather than continuous high-demand operation, improving reliability while maintaining drying effectiveness.
4Loss of energy
If the heat pump system is used alone as the heat source, then energy efficiency is enhanced, but drying time is extended due to limited heat supply capacity
Solution Approach 1:
The control method applies preliminary action by operating the heat pump system alone for a predetermined time period at the beginning of the drying cycle, allowing it to establish efficient heat recovery operation. After this initial period, the heater is activated to supplement heat supply capacity, reducing the overall drying time while the heat pump continues to operate efficiently during its designated phase.
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 method enhances energy efficiency, reduces drying time, and improves the reliability of the heat pump system by stabilizing load operations and preventing compressor damage, while allowing for user-selectable drying modes for convenience.
Implementation Method 1
The heat pump system includes two heat exchangers, a compressor and an expander (expansion apparatus). With the configuration of the heat pump system, a refrigerant which circulates in the system recollects energy contained in hot air exhausted and the recollected energy is used to heat air supplied into the drum
Implementation Method 2
the heat pump system includes an evaporator at an exhaust side from the drum and a condenser at an inlet side of the drum. Accordingly, a refrigerant absorbs thermal energy through the evaporator and then is pressurized by a compressor to be a refrigerant of high temperature and high pressure. Afterwards, the thermal energy contained in the refrigerant is transferred to air, which is introduced into the drum, through the condenser
Implementation Method 3
a refrigerant absorbs thermal energy through the evaporator and then is pressurized by a compressor to be a refrigerant of high temperature and high pressure. Afterwards, the thermal energy contained in the refrigerant is transferred to air, which is introduced into the drum, through the condenser
Implementation Method 4
a refrigerant absorbs thermal energy through the evaporator and then is pressurized by a compressor to be a refrigerant of high temperature and high pressure
Data Source
AI summary
A controlling method for a dryer is applied to a dryer, in which at least one of a heat pump system and a heater is selected as a heat source for heating air supplied in to a drum and a heat supply capacity of the heat pump system is more than that of the heater. The controlling method includes, when both the heat pump system and the heater are selected as the heat sources, turning the heat pump system on, turning the heater on after the heat pump system is normally turned on, turning the heater off to cool the drum and terminate drying after the drying is performed, and turning the heat pump system off after the heater is turned off.