Heat-Pump Laundry Dryer With Selective Joule Heating Control
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Solution Overview
Problem
Existing laundry dryers and washers/dryers have inefficiencies in energy consumption and temperature control, with systematic activation of resistance heating leading to unnecessary energy use and slow, unreliable temperature control, which can damage laundry items.
Innovation Solution
A laundry drying appliance with a heat-pump system and a Joule-effect drying air heater, where the Joule-effect heater is user-activated and controlled by a temperature sensor to prevent overheating, allowing for flexible drying cycles and reduced energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If resistance heating is systematically activated to heat drying air, then drying speed is improved, but energy consumption increases unnecessarily
Solution Approach 1:
The system dynamically adjusts the heating strategy based on real-time temperature measurements. The control unit activates resistance heating only when the drying air temperature is below a predetermined threshold, transitioning from static systematic heating to dynamic conditional heating, thereby improving energy efficiency while maintaining drying speed when needed
Solution Approach 2:
A temperature sensor provides continuous feedback on the drying air temperature to the control unit. This feedback mechanism enables the system to monitor temperature conditions and activate or deactivate resistance heating accordingly, preventing unnecessary energy consumption while ensuring adequate drying speed when temperature conditions require it
2Temperature
If resistance heating is used to heat drying air, then drying temperature is improved, but temperature control reliability deteriorates due to slow response
Solution Approach 1:
The temperature sensor continuously monitors drying air temperature and provides real-time feedback to the control unit, enabling rapid detection of temperature changes and immediate adjustment of heating status, thus improving temperature control reliability and preventing overheating of laundry items
Solution Approach 2:
The system automatically regulates its own heating operation based on temperature feedback without requiring external intervention. The control unit independently decides when to activate or deactivate resistance heating based on predetermined temperature thresholds, ensuring reliable temperature control and preventing damage to laundry items
3Use of energy by moving object
If heat pump alone is used for heating drying air, then energy consumption is reduced, but heating speed becomes insufficient
Solution Approach 1:
The heating function is segmented into two components: the heat pump providing baseline energy-efficient heating, and resistance heating providing supplemental rapid heating when needed. This segmentation allows the system to maintain low energy consumption during normal operation while having the capability to increase heating speed when temperature thresholds are not met
Solution Approach 2:
The resistance heating provides partial or excessive heating action only when the heat pump alone is insufficient to reach the desired temperature. This partial action approach maintains energy efficiency during normal operation while ensuring adequate heating speed when required by temperature conditions
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 appliance provides flexible user-controlled drying cycles, reduces energy consumption by only activating the Joule-effect heater when necessary, and ensures timely and reliable temperature control to prevent damage to laundry items.
Implementation Method 1
a heat-pump system for de-moisturizing the moisture-laden drying air by condensing moisture in the moisture-laden drying air returning from the laundry treatment chamber
Implementation Method 2
a Joule-effect drying air heater energizable for contributing to the heating of the drying air
Implementation Method 3
a heat-pump system for de-moisturizing the moisture-laden drying air by condensing moisture in the moisture-laden drying air returning from the laundry treatment chamber and for heating the de-moisturized drying air before it re-enters into the laundry treatment chamber
Data Source
AI summary
An appliance for drying laundry (100) comprises an appliance cabinet (110), a laundry treatment chamber (105) inside the cabinet, and a drying air recirculation path (245) for causing recirculation of the drying air into/out from the laundry treatment chamber. The drying air recirculation path is at least partly external to the laundry treatment chamber. A drying air moisture condensing and heating system (215,220,225) located in the drying air recirculation path for dehydrating the moisture-laden drying air leaving the laundry treatment chamber and heating the dehydrated drying air before it re-enters into the laundry treatment chamber. The drying air moisture condensing and heating system comprises a first heat exchanger (215) and a second heat exchanger (220) of a heat pump (215,220,225,210), and further comprising a drying air propeller (250) inside the drying air recirculation path and a Joule-effect drying air heater (255), downstream the second heat exchanger, energizable for contributing to the heating of the drying air. The appliance includes a user interface (121) comprising a laundry treatment cycle selector (305) operable by a user for selecting a laundry treatment cycle, and a control unit (265) adapted to control the machine operation. The user interface comprises a command input means (315) operable by the user for imparting to the appliance an energization command to energize the Joule-effect heater. During the execution of the laundry treatment cycle selected by the user, the control unit causes the selective energization of the Joule-effect drying air heater based on the energization command imparted by the user.