Heat Pump Dryer Compressor Sizing for Energy and Cycle Time
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Solution Overview
Problem
Conventional heat pump laundry dryers face challenges in optimizing energy efficiency and cycle time duration while also striving to minimize the size of heat pump components, particularly the compressor, which affects the overall dryer size and efficiency.
Innovation Solution
The implementation of a heat pump system with a refrigerant circuit that includes a compressor chamber volume and refrigerant density product within specific ranges, allowing for optimized thermodynamic conditions and efficient energy use, along with a rotary or scroll compressor and a heat exchanger design that maintains stable temperatures and pressures, enhancing the drying process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the compressor chamber volume is reduced to minimize the size of heat pump components, then the overall size of the laundry dryer is reduced, but the energy efficiency and drying process performance deteriorate
Solution Approach 1:
The patent applies parameter changes by optimizing the compressor chamber volume to a specific range (5-15 cm³) and controlling the refrigerant density at compressor inlet (10-20 kg/m³) to achieve the optimal product value. This quantitative parameter optimization allows the compressor to be sufficiently small while maintaining efficient refrigerant compression and heat exchange performance, thereby resolving the contradiction between miniaturization and energy efficiency.
2Volume of moving object
If the compressor chamber volume is reduced to minimize the size of heat pump components, then the overall size of the laundry dryer is reduced, but the cycle time duration increases
Solution Approach 1:
The patent resolves this contradiction by precisely controlling the product of compressor chamber volume and refrigerant density to fall within a specific range. This parameter optimization ensures that the smaller compressor can still compress refrigerant efficiently and maintain adequate heat exchange rates, preventing excessive cycle time extension while achieving size reduction.
3Use of energy by moving object
If the product of compressor chamber volume and refrigerant density is optimized to improve energy efficiency, then the energy efficiency and cycle time are improved, but the compressor size control becomes more complex
Solution Approach 1:
The patent simplifies the complexity by establishing a quantitative design criterion: the product of compressor chamber volume and refrigerant density should fall within a specific range. This provides a clear design guideline that balances energy efficiency and cycle time without requiring overly complex control systems or design procedures.
Solution Approach 2:
The patent replaces complex mechanical design iterations with a quantitative parameter relationship approach. By defining the optimal product range of compressor chamber volume and refrigerant density, the invention substitutes elaborate mechanical optimization processes with a more straightforward parameter-based design method.
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 improves the energy efficiency and reduces the cycle time duration of the drying process while minimizing the size of the heat pump components, achieving an optimal match between compressor size and energy efficiency.
Implementation Method 1
Compressors force and compress the refrigerant into an airtight chamber
Implementation Method 2
a first heat exchanger for heating the process air and cooling the refrigerant
Implementation Method 3
a second heat exchanger for cooling the process air and heating the refrigerant
Implementation Method 4
the refrigerant flows in the refrigerant circuit where it is compressed by the compressor, condensed in the condenser, expanded in the expansion device and then vaporized in the evaporator
Implementation Method 5
the refrigerant flows in the refrigerant circuit where it is compressed by the compressor, condensed in the condenser, expanded in the expansion device and then vaporized in the evaporator
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The present invention relates to a laundry dryer (1) of the type comprising a heat pump system (20) having a refrigerant circuit (30) for a refrigerant (R) and comprising a process air circuit (10) in communication with a laundry container (9) suited for receiving laundry to be dried using process air (A). The refrigerant circuit (30) comprises: a first heat exchanger (21) for heating the process air (A) and cooling the refrigerant (R), said first heat exchanger (21) comprising a heat exchanger outlet (28) for expelling the heated process air (A) for the laundry container (9); a second heat exchanger (23) for cooling the process air (A) and heating the refrigerant (R); a refrigerant expansion device (22) arranged in the refrigerant circuit (30) between the first heat exchanger (21) and the second heat exchanger (23); and a compressor (24) arranged in the refrigerant circuit (30) between the second heat exchanger (23) and the first heat exchanger (21). The compressor (24) comprises a compressor chamber (260) and a compressor inlet (24a) where the refrigerant (R) is sucked for the compressor chamber (260). The product of the volume (Vd) of the compressor chamber (260) and the refrigerant density (RDS) at said compressor inlet (24a) in steady state condition of the heat pump system (20) is comprised between 40 cm 3*kg/m3 and 250 cm3*kg/m3.