Two-Stage Tumble Dryer Heating for Heat Pump Temperature Limits
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Solution Overview
Problem
Conventional tumble dryers with heat pumps face inefficiencies due to high temperatures requiring compressor shutdown and additional heating methods, leading to energy loss and high energy consumption, while also limiting rapid drying capabilities.
Innovation Solution
A tumble dryer design featuring a two-stage heater with a thermal switch integrated into the heat pump circuit, allowing for controlled temperature management and eliminating the need for a relay, enabling efficient operation with a conventional controller and reducing energy loss by optimizing heat pump usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a heat pump is used to heat process air in a tumble dryer, then energy efficiency is improved, but the compressor must be shut down at high temperatures requiring additional heating methods
Solution Approach 1:
The patent combines the heat pump heating system with a supplementary electric heater system into a unified heating apparatus. The controller integrates both heating sources and automatically switches between them or operates them simultaneously based on temperature requirements, eliminating the need for separate control systems and reducing overall system complexity.
Solution Approach 2:
The controller acts as an intermediary between the heat pump and electric heater, managing their operation based on temperature sensor feedback. It seamlessly transitions between heat pump-only mode, combined mode, and electric heater-only mode, resolving the conflict between maintaining energy efficiency and providing sufficient heating capacity at high temperatures.
2Productivity
If additional heating methods are used to compensate for compressor shutdown, then rapid drying capability is maintained, but energy loss increases
Solution Approach 1:
The system employs periodic switching between heat pump operation and electric heater supplementation based on real-time temperature demands. The controller monitors temperature continuously and activates the electric heater only when and where additional heating is required, rather than operating continuously, thereby minimizing energy waste while maintaining drying productivity.
Solution Approach 2:
The electric heater provides partial heating action only when the heat pump capacity is insufficient, rather than operating at full capacity continuously. This partial action approach supplies just enough additional heat to maintain drying speed during high-temperature phases, avoiding excessive energy consumption.
3Adaptability or versatility
If a two-stage heater with parallel circuits is used, then temperature control flexibility is improved, but device complexity increases
Solution Approach 1:
The two-stage heater with parallel circuits is designed to perform multiple functions: it can operate in first stage only, second stage only, or both stages simultaneously. The same physical hardware structure supports different operational modes depending on temperature requirements, maximizing adaptability without proportionally increasing complexity.
Solution Approach 2:
The heater system is equipped with temperature sensors and automatic control that enable it to self-regulate its operation. The system automatically determines which stage(s) to activate based on temperature feedback, eliminating the need for complex external control mechanisms and reducing overall system complexity despite the multi-stage design.
4Loss of energy
If the heat pump operates continuously to maintain energy efficiency, then energy savings are maximized, but the ability to provide rapid heating is limited
Solution Approach 1:
The heating system dynamically adjusts its composition based on real-time conditions. The controller can transition from heat pump-only operation (energy-efficient mode) to combined or electric heater-dominated operation (rapid heating mode) depending on temperature demands, allowing the system to optimize both energy efficiency and heating speed as conditions change.
Solution Approach 2:
The system prepares for rapid heating by having the electric heater circuit ready and connected, capable of immediate activation when temperature thresholds are not met. This preliminary preparation ensures that rapid heating can be initiated without delay when needed, while maintaining energy-efficient heat pump operation during normal 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
This design enhances energy efficiency by up to 50% and allows for rapid drying without overheating, using a conventional control system and minimizing power grid issues, while maintaining energy savings and quick drying capabilities.
Implementation Method 1
a thermal switch (16) which is thermally coupled to the heat pump (6, 7, 8, 9)
Implementation Method 2
a heat pump (6, 7, 8, 9) with a heat sink (6), a heat source (7) and a heat transport device (8, 9)
Implementation Method 3
a heater (4) for heating the process air
Data Source
Figure 1
AI summary
The invention relates to a tumble drier (1) comprising a drying chamber (3) for the articles to be dried, a process air channel (2), in which a heating system (4) for heating the process air is provided and the heated process air can be conducted over the articles to be dried in the drying chamber (3) by means of a fan (5), and comprising a heat pump (6, 7, 8, 9) with a heat sink (6), a heat source (7) and a heat transport unit (8, 9), in addition to a controller (10). The heating system (4) is a two-stage system comprising a first heating stage (12) in a first circuit (14) and a second heating stage (13) in a second circuit parallel to the first. A thermoswitch (16) is situated in the first circuit (14) or in the second circuit (15), said switch being thermally coupled to the heat pump (6, 7, 8, 9). The invention also relates to a method for operating said tumble drier (1).