Air-conditioning apparatus
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Solution Overview
Problem
Existing air-conditioning apparatuses face challenges in maintaining heating capacity and ensuring defrosting capacity during simultaneous heating and defrosting operations, leading to reduced comfort and reliability due to changes in refrigeration cycle states and inadequate control of actuators.
Innovation Solution
An air-conditioning apparatus with a refrigerant circuit including a main circuit and a bypass circuit, equipped with a compressor, cooling/heating switching device, indoor and outdoor heat exchangers, and control units that detect load and operation states to manage refrigerant flow and pressure, allowing for simultaneous heating and defrosting while maintaining heating capacity and ensuring appropriate defrosting capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If divided heat exchanger portions are alternately defrosted during heating operation, then defrosting function is achieved, but heating capacity is reduced and room temperature decreases
Solution Approach 1:
The outdoor heat exchanger is divided into multiple independent heat exchanger portions (first outdoor heat exchanger and second outdoor heat exchanger), allowing one portion to perform defrosting while the other maintains heating operation, thus preventing overall heating capacity reduction
Solution Approach 2:
The patent combines heating operation and defrosting operation into a simultaneous dual-operation mode where both functions are performed at the same time through different heat exchanger portions, eliminating the need to choose between heating and defrosting
2Temperature
If heating capacity is forcibly increased during simultaneous heating and defrosting, then room temperature is maintained, but defrosting capacity is insufficient
Solution Approach 1:
By segmenting the outdoor heat exchanger into multiple independent portions with separate control, the system can allocate refrigerant flow independently to each portion, ensuring adequate refrigerant supply for both heating and defrosting operations simultaneously
Solution Approach 2:
The system changes refrigerant flow parameters (flow rate, pressure) independently for each heat exchanger portion through separate flow control devices, allowing optimization of both heating capacity and defrosting capacity without mutual interference
3Reliability
If refrigeration cycle state changes during mode switching, then defrosting operation is enabled, but control of actuators becomes difficult
Solution Approach 1:
The refrigeration cycle is segmented into independent control zones with separate actuators for each heat exchanger portion, allowing independent control strategies for heating and defrosting operations without complex coordinated control
Solution Approach 2:
The system dynamically switches between different operation modes (heating only, simultaneous heating and defrosting, defrosting only) based on operational conditions, with the controller adapting control parameters for each mode to simplify actuator control
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
The apparatus achieves a balanced simultaneous heating and defrosting operation by controlling compressor and pressure-reducing device operations based on load and operation states, maintaining comfort and reliability by ensuring consistent heating capacity and adequate defrosting capacity.
Implementation Method 1
The defrosting refrigerant pressure-reducing device reduces the pressure of refrigerant that branches off from the main circuit, by adjusting the flow rate of the refrigerant in a refrigerant pipe
Implementation Method 2
The defrosting flow passage switching device switches a flow passage for refrigerant that is supplied to one of the parallel outdoor heat exchangers
Implementation Method 3
The backflow prevention device is provided between the defrosting flow passage switching device and the cooling/heating switching device to prevent backflow of low-pressure refrigerant that flows to a suction side of the compressor
Implementation Method 4
parallel outdoor heat exchangers are connected by refrigerant pipes
Data Source
AI summary
An air-conditioning apparatus includes a refrigerant circuit, an air-conditioning load state detection unit, an operation-state detection unit, and a controller. The refrigerant circuit includes a main circuit and a bypass circuit. The air-conditioning apparatus has a simultaneous heating and defrosting operation mode. In the simultaneous heating and defrosting operation mode, the controller controls a compressor, a pressure reducing device, and a defrosting refrigerant pressure-reducing device such that control amounts of the compressor, the pressure reducing device, and the defrosting refrigerant pressure-reducing device reach respective normal-time control target values that are set based on an air-conditioning load state and an operation state.