Heat Pump Dryer Preliminary Cooling for Fire Risk Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Heat pump type laundry dryers face increased energy consumption and prolonged operation times due to the need for a cooling process after drying to reduce the risk of fire, which can't be precisely predicted, affecting consumer satisfaction and safety.
Innovation Solution
Implementing a control unit that initiates a cooling process before the drying process ends by setting temperature thresholds, turning the compressor cooling fan ON when the process air reaches a certain temperature and OFF when it drops below another, thereby reducing the need for an additional cooling process and minimizing fire risk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cooling process is conducted after termination of the drying process to reduce fire risk, then safety is improved, but operation time is prolonged and energy consumption increases
Solution Approach 1:
The control unit initiates the cooling process before the drying process is completely terminated, by detecting when the process air temperature reaches a first threshold temperature (≤55°C). This preliminary cooling action reduces the laundry temperature in advance, eliminating the need for a separate post-drying cooling period and thereby shortening total operation time while maintaining safety
2Reliability
If the process air fan and compressor motor continue to run during cooling process to comply with safety prescriptions, then fire safety is ensured, but energy consumption increases
Solution Approach 1:
The cooling process is initiated in advance during the drying cycle when the process air temperature reaches the first threshold (≤55°C). By performing the cooling action preliminarily, the system avoids the need for extended operation of the process air fan and compressor motor after drying termination, thereby reducing overall energy consumption while maintaining the required safety temperature reduction
Solution Approach 2:
The system uses its own operational components (compressor cooling fan) during the drying process to simultaneously achieve both drying and preliminary cooling functions. The compressor cooling fan is controlled to operate based on temperature thresholds, allowing the system to self-regulate and perform multiple functions without requiring separate dedicated cooling operation
3Reliability
If the cooling process duration is extended to ensure temperature reduction below 55°C, then fire safety is improved, but operation time is prolonged
Solution Approach 1:
The cooling process is performed in advance during the drying cycle rather than after termination. The control unit monitors process air temperature and initiates cooling when the first threshold (≤55°C) is reached, ensuring the laundry is cooled before drying completes. This eliminates the need for extended post-drying cooling periods, maintaining high productivity while ensuring safety
Solution Approach 2:
The control unit continuously monitors process air temperature and uses this feedback to control the timing and duration of the cooling process. By detecting when the first threshold temperature is reached and when the second threshold is reached, the system precisely controls the cooling fan operation, ensuring adequate cooling without unnecessary extension of operation time, thereby optimizing both safety and productivity
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 energy consumption, shortens operation time, enhances safety by preventing fires, and improves consumer satisfaction by ensuring the laundry temperature is below 55°C before the drying process ends.
Implementation Method 1
The evaporator and the condenser are arranged in heat-exchange with the process air inside the duct for dehumidifying and heating the process air
Implementation Method 2
The heat absorbed by the evaporator is partly transferred back to the process air by means of the condenser
Implementation Method 3
The heat absorbed by the evaporator is partly transferred back to the process air by means of the condenser
Implementation Method 4
The evaporator and the condenser are arranged in heat-exchange with the process air inside the duct
Implementation Method 5
a fan for cooling the compressor and a sensor for sensing the process air temperature
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The present invention relates to a heat-pump type laundry dryer (1) comprising a drum (2), a process air circuit (3), a refrigerant circuit (4) which has a compressor (5) and a control unit (6) for conducting the drying process. The laundry dryer (1) of the present invention further comprising: a fan (7) for cooling the compressor (5) and a sensor (8) for sensing the process air temperature T_air, wherein the control unit (6) sets a first threshold temperature T_th1 which is equal to or smaller than 55°C, sets a second threshold temperature T_th2 which is less than T_th1 and initiates, prior to the termination of the drying process a cooling process in which the fan (7) is turned ON when T_air reaches T_th1 and the fan (7) is turned OFF when T_air drops below T_th2.