Refrigeration cycle apparatus
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Solution Overview
Problem
Existing air-conditioning apparatuses face challenges in efficiently performing defrosting operations without reducing heating capacity, particularly in low outdoor temperatures, and lack effective methods for determining the optimal start of defrosting during heating-defrosting simultaneous operations.
Innovation Solution
A refrigeration cycle apparatus with a main circuit, flow switching device, and parallel heat exchangers, equipped with a detector and controller that selects between reverse-defrosting and heating-defrosting simultaneous operation modes based on frost detection, allowing for efficient defrosting without stopping indoor heating and optimizing defrosting initiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If reverse cycle defrosting is used to defrost the outdoor heat exchanger, then defrosting effectiveness is improved, but indoor heating is interrupted and comfort level decreases
Solution Approach 1:
The outdoor heat exchanger is divided into multiple parallel heat exchangers, allowing selective defrosting of individual segments while others continue heating operations
Solution Approach 2:
The patent combines defrosting operation with heating operation by having defrosted refrigerant flow into evaporators that are simultaneously performing heating, enabling both functions to occur together
2Ease of operation
If heating-defrosting simultaneous operation is used to maintain indoor heating during defrosting, then heating continuity is improved, but defrosting efficiency decreases due to lower refrigerant flow rate
Solution Approach 1:
The system segments the outdoor heat exchanger into multiple parallel units, enabling one to be defrosted while others provide heating, and allows switching between them
Solution Approach 2:
The system performs preliminary defrosting of one heat exchanger while another is operating as evaporator, then switches roles after defrosting is complete, maintaining continuous heating
3Productivity
If defrosting is delayed until frost accumulation reaches a threshold, then heating capacity is maintained, but defrosting takes longer and heating interruptions may occur
Solution Approach 1:
The controller initiates defrosting operations in advance by switching parallel heat exchangers before complete frost accumulation occurs, maintaining heating capacity while reducing defrosting duration
Solution Approach 2:
The system implements periodic switching between parallel heat exchangers for defrosting and heating operations, creating a rhythmic cycle that maintains overall system performance
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
Enables efficient defrosting of parallel heat exchangers while maintaining heating capacity, allowing for continuous operation by determining the optimal defrosting start based on frost accumulation and outdoor conditions.
Implementation Method 1
a compressor (1) that compresses refrigerant
Implementation Method 2
an outdoor heat exchanger (5) that exchanges heat with outside air
Implementation Method 3
exchanges heat with outside air
Implementation Method 4
exchanges heat between refrigerant and air
Implementation Method 5
defrosting is performed with a low refrigerant flow rate by using the latent heat of condensation of refrigerant
Implementation Method 6
another outdoor heat exchanger serves as an evaporator to receive heat from outside air
Implementation Method 7
supplying refrigerant discharged from a compressor to the outdoor heat exchanger by reversing the refrigerant flow used for heating
Data Source
AI summary
An air-conditioning apparatus includes a selection unit and a determination unit, the selection unit selecting a reverse-defrosting operation mode or a heating-defrosting simultaneous operation mode, the reverse-defrosting operation mode being a mode in which all of parallel heat exchangers are defrosted by stopping a heating operation, the heating-defrosting simultaneous operation mode being a mode in which each parallel heat exchanger is sequentially defrosted while continuing a heating operation, the determination unit determining whether or not a defrosting operation is to be started, in which the determination unit is configured to start the defrosting operation in a state where the amount of frost deposited on the parallel heat exchangers is smaller in a case where the heating-defrosting simultaneous operation mode is selected than in a case where the reverse-defrosting operation is selected.