Control method for heat-pump water heater
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Solution Overview
Problem
In heat-pump water heaters, the constantly changing evaporation and condensation temperatures during heating operations lead to suboptimal compressor frequency operation, resulting in energy waste due to inefficient energy use.
Innovation Solution
A control method that calculates the optimal compressor operating frequency by fitting an energy efficiency ratio formula incorporating evaporating and condensing temperatures, and adjusting the compressor frequency in real-time to maximize energy efficiency, using a formula that simplifies calculations and reduces energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the compressor operates at a fixed frequency according to water temperature and ambient temperature, then the control system is simple, but the energy efficiency ratio is suboptimal because evaporation and condensation temperatures constantly change
Solution Approach 1:
The patent implements dynamic frequency adjustment by continuously calculating the optimal compressor operating frequency based on real-time evaporation and condensation temperatures. The control system transitions from static fixed-frequency operation to dynamic variable-frequency operation, allowing the compressor to adapt its speed to changing thermal conditions and maintain peak energy efficiency throughout the heating process.
Solution Approach 2:
The patent changes the operating parameters of the compressor by adjusting its frequency based on calculated optimal values derived from energy efficiency ratio formulas. The system modifies key parameters including compressor frequency, evaporation temperature, and condensation temperature to maximize energy efficiency. This parameter optimization resolves the contradiction by enabling high efficiency through calculated parameter adjustment rather than simple fixed operation.
2Loss of energy
If the compressor frequency is adjusted in real-time to maintain optimal energy efficiency, then energy consumption is reduced, but the calculation complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing optimal frequency values and energy efficiency ratio formulas before actual operation. The system prepares calculation models in advance that can be quickly executed during runtime, reducing the computational burden during real-time operation. This approach allows real-time optimization without requiring complex on-the-fly calculations, thus reducing energy consumption while managing calculation complexity through advance preparation.
Solution Approach 2:
The patent replaces complex mechanical trial-and-error frequency adjustment methods with mathematical calculation-based optimization. Instead of using mechanical sensors and iterative adjustment mechanisms, the system uses energy efficiency ratio formulas and computational algorithms to directly determine optimal compressor frequency. This substitution of mechanical systems with computational methods reduces both energy consumption and physical device complexity while achieving real-time optimization.
Data Source
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AI summary
A control method for a heat-pump water heater, comprising: a fitting calculation step, comprising (11) calculating energy efficiency ratios of a compressor monomer at different evaporation temperatures, condensation temperatures and compressor operating frequencies; (12) fitting an energy efficiency ratio formula; and (13) calculating a first-order derivative of the energy efficiency ratio formula, and obtaining an optimal operating frequency formula of the compressor by making an equation value of the first-order derivative be 0; and a starting operation step, comprising (21) periodically obtaining the evaporation temperature and the condensation temperature, calculating the optimal operating frequency of the compressor, and adjusting the compressor based on the optimal operating frequency.