Air Conditioner Defrosting Control for Stable Heating Capacity
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Solution Overview
Problem
In air-conditioning apparatuses, defrosting of outdoor heat exchangers in low temperatures leads to reduced heating capacity due to high-pressure refrigerant causing condensation, resulting in insufficient heating for heavy indoor loads and discomfort.
Innovation Solution
An air-conditioning apparatus with a bypass pipe and flow control system that diverts refrigerant to specific parallel heat exchangers for defrosting while maintaining heating, adjusting compressor frequency and flow control to match indoor heating demands, thereby preventing excessive refrigerant condensation and maintaining high heating capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-pressure refrigerant is used for defrosting the outdoor heat exchanger, then defrosting efficiency is improved, but refrigerant condensation increases and heating capacity decreases
Solution Approach 1:
The outdoor heat exchanger is divided into multiple parallel heat exchangers, allowing selective defrosting of individual units while others continue heating operations. This segmentation enables localized defrosting without compromising overall system heating capacity.
Solution Approach 2:
Different regions of the outdoor heat exchanger system are assigned different functions: some units are dedicated to defrosting operations while others maintain heating functions. This local differentiation optimizes both defrosting efficiency and heating capacity simultaneously.
2Reliability
If refrigerant flow for defrosting is increased, then defrosting performance is improved, but available refrigerant for heating decreases
Solution Approach 1:
The refrigerant flow is segmented into separate channels for defrosting and heating operations. By providing dedicated flow paths and control mechanisms for each function, the system can optimize refrigerant distribution to maintain both defrosting performance and heating capacity.
Solution Approach 2:
The refrigerant flow distribution is made dynamic through flow control devices that can adjust allocation in real-time based on system conditions. This dynamic control allows the system to adapt refrigerant distribution between defrosting and heating needs.
3Duration of action of moving object
If the outdoor heat exchanger is divided into parallel heat exchangers for selective defrosting, then continuous heating is maintained, but system complexity increases
Solution Approach 1:
The outdoor heat exchanger is divided into multiple parallel units with independent flow control, enabling selective operation. This segmentation allows continuous heating by switching between units during defrosting cycles.
Solution Approach 2:
Each parallel heat exchanger unit is designed to perform multiple functions - serving as evaporator for heating and as defrosting target when needed. This multi-functionality reduces the need for separate dedicated components.
4Power
If compressor frequency is reduced to prevent excessive refrigerant condensation, then heating capacity is maintained, but defrosting efficiency decreases
Solution Approach 1:
The system separates defrosting and heating functions into different parallel heat exchanger units, allowing the compressor to maintain high frequency for efficient defrosting while other units continue heating operations.
Solution Approach 2:
The useful heating action continues uninterrupted by utilizing parallel heat exchanger units that remain operational during defrosting of other units, maintaining continuous heating output.
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
Efficient defrosting without stopping indoor heating, ensuring adequate heating capacity for varying indoor loads and improving comfort by managing refrigerant flow and pressure to prevent excessive condensation.
Implementation Method 1
a compressor (1)
Implementation Method 2
a plurality of parallel heat exchangers (50, 51) connected in parallel with each other
Implementation Method 3
a flow control device (11) provided at the bypass pipe (37) and adjusting an amount of flow of refrigerant flowing in the bypass pipe (37)
Implementation Method 4
refrigerant that is caused to flow into the parallel heat exchanger to be defrosted is high in pressure and high in saturation temperature and is likely to condense
Data Source
AI summary
An air-conditioning apparatus includes a controller configured to operate in a heating normal operation mode and a heating-defrosting operation mode. In a case of switching from the heating normal operation mode to the heating-defrosting operation mode, the controller makes a selection from an initial control mode 1, in which control is performed such that an initial frequency of the compressor is set to a predetermined maximum frequency and an initial opening degree of the flow control device is set to an opening degree lower than a predetermined maximum opening degree, and an initial control mode 2, in which control is performed such that the initial opening degree of the flow control device is set to the predetermined maximum opening degree and the initial frequency of the compressor is set to a frequency lower than the predetermined maximum frequency, to execute the heating-defrosting operation mode.