Expansion Valve Control for Heat-Storage Defrost Heating
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Solution Overview
Problem
Conventional air conditioning apparatuses face challenges in simultaneously performing heat storage, air-warming, and defrosting operations due to inadequate control of indoor and outdoor expansion valves, leading to insufficient defrosting or excessive air-warming capabilities.
Innovation Solution
The air conditioning apparatus employs a control system that adjusts the opening degrees of indoor and outdoor expansion valves based on the correlation between refrigerant condensation temperature and indoor temperatures during defrosting, prioritizing air-warming initially and then transitioning to prioritize defrosting, while considering pressure losses and superheating effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the indoor expansion valve opening degree is increased to enhance air-warming capability during defrosting operation, then air-warming performance is improved, but defrosting capability becomes insufficient
Solution Approach 1:
The patent implements dynamic control of the indoor expansion valve opening degree based on operational phase. During the first defrosting time period, the opening degree is set to a first value that balances air-warming and defrosting. After the first defrosting time elapses, the opening degree is changed to a second value (smaller than the first) to prioritize defrosting completion. This dynamic adjustment resolves the contradiction by adapting the valve opening to different stages of the defrosting operation.
Solution Approach 2:
The patent applies preliminary action by establishing a predetermined first defrosting time period and corresponding first opening degree value before the defrosting operation begins. This pre-planned control strategy allows the system to initially prioritize air-warming capability while ensuring defrosting will be completed subsequently, resolving the contradiction between immediate air-warming performance and overall defrosting reliability.
2Reliability
If the indoor expansion valve opening degree is decreased to enhance defrosting capability, then defrosting performance is improved, but air-warming capability becomes excessive
Solution Approach 1:
The patent uses dynamic control to adjust the indoor expansion valve opening degree based on the defrosting operation timeline. During the initial phase (first defrosting time), a larger opening degree maintains adequate air-warming capability. After the first defrosting time elapses, the opening degree is reduced to a second value to enhance defrosting capability, thus resolving the contradiction by timing the capability adjustment to operational needs.
3Reliability
If the outdoor expansion valve opening degree is increased to enhance defrosting capability, then defrosting performance is improved, but system balance is disrupted
Solution Approach 1:
The patent implements feedback control by having the outdoor-side control part continuously monitor and adjust the outdoor expansion valve opening degree based on the defrosting operation progress and system conditions. The control part decides the opening degree considering both defrosting capability and system balance, using feedback from temperature sensors and operational timing to maintain optimal performance throughout the defrosting process.
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 ensures balanced defrosting and air-warming capabilities, effectively completing defrosting while maintaining adequate air-warming performance, even at varying outdoor temperatures.
Implementation Method 1
a heat storage heat exchanger for performing heat exchange between a refrigerant and a heat storage medium
Implementation Method 2
a heat storage operation for storing heat in the heat storage medium
Implementation Method 3
a defrosting operation for defrosting the outdoor heat exchanger by causing the outdoor heat exchanger to function as a heat radiator of the refrigerant
Implementation Method 4
a heat-storage-utilizing operation for radiating heat from the heat storage medium by causing the heat storage heat exchanger to function as an evaporator of the refrigerant
Implementation Method 5
an air-warming operation for causing the indoor heat exchangers to function as heat radiators of the refrigerant
Data Source
Figure 1
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Figure 3
AI summary
An air conditioning apparatus (1) comprising a refrigerant circuit (10) having a compressor (21), an outdoor heat exchanger (23), indoor heat exchangers (42a, 42b), and a heat storage heat exchanger (28) for performing heat exchange between a refrigerant and a heat storage medium; the air conditioning apparatus being capable of performing a heat storage operation, and also of simultaneously performing a heat-storage-utilizing operation and an air-warming operation during a defrosting operation. In the air conditioning apparatus (1), indoor units (4a, 4b) provided with indoor expansion valves (41a, 41b) have indoor-side control parts (48a, 48b) for deciding the opening degrees of the indoor expansion valves (41a, 41b) when only an air-warming operation is performed, and an outdoor unit (2) provided with an outdoor expansion valve (24) has an outdoor-side control part (38) for deciding the opening degree of the outdoor expansion valve (24) when only the air-warming operation is performed, and deciding the opening degrees of the indoor expansion valves (41a, 41b) and the opening degree of the outdoor expansion valve (24) when the air-warming operation is performed during the defrosting operation accompanying the heat-storage-utilizing operation.