Refrigerating and air-conditioning apparatus for use in a defrosting operation
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Solution Overview
Problem
Existing refrigerating and air-conditioning apparatuses face challenges in performing defrosting operations during heating cycles, particularly under frost-forming conditions, leading to discomfort and inadequate ventilation, as they struggle to maintain appropriate air temperatures and ventilation levels.
Innovation Solution
A refrigerating and air-conditioning apparatus with multiple refrigeration cycles, each comprising a compressor, four-way valve, outdoor and indoor heat exchangers, and a ventilation damper system, allowing independent heating and defrosting operations, and a controller that manages ventilation to ensure adequate air circulation during heating and prioritizes ventilation before initiating defrosting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single refrigeration cycle is used for both heating and defrosting operations, then the device complexity is reduced, but the system cannot perform defrosting while simultaneously continuing the heating operation
Solution Approach 1:
The system is divided into a first refrigeration cycle dedicated to heating operations and a second refrigeration cycle dedicated to defrosting operations. This segmentation allows each cycle to operate independently, enabling the heating cycle to continue providing warmth while the defrosting cycle removes frost from the outdoor heat exchanger without interference.
Solution Approach 2:
The outdoor heat exchanger serves multiple functions: it acts as a heat source for heating operations during the first refrigeration cycle and as a heat sink for defrosting operations during the second refrigeration cycle. The four-way valve enables the outdoor heat exchanger to switch between these different functional roles as needed.
2Ease of operation
If air from the indoor heat exchanger is mixed with outdoor air in the indoor fan casing during defrosting operation, then the ventilation is improved, but the outlet air temperature is lowered causing discomfort
Solution Approach 1:
The system separates the air handling paths: the first indoor unit handles heating air separately, while the second indoor unit handles defrosting-related air flow. This prevents mixing of heated air with cold air from the defrosting operation, maintaining comfortable outlet air temperature while still providing ventilation through coordinated operation of both units.
Solution Approach 2:
The controller acts as an intermediary that coordinates the operation of multiple indoor units and ventilation dampers. It manages the complex air flow distribution, ensuring that heated air and defrosting air are properly separated and distributed to maintain comfort while achieving adequate ventilation during defrosting operations.
3Use of energy by moving object
If the ventilation damper is closed during defrosting operation to prevent temperature drop, then the heating efficiency is improved, but the ventilation amount becomes insufficient
Solution Approach 1:
The system performs preliminary ventilation before the defrosting operation begins. The controller opens the ventilation damper of the first indoor unit prior to starting defrosting, allowing fresh air to enter the room in advance. This ensures that adequate ventilation is provided before the heating cycle is interrupted for defrosting, maintaining both heating efficiency and ventilation requirements.
Solution Approach 2:
The system employs periodic ventilation cycles coordinated with defrosting operations. The ventilation damper is opened during specific periods before and after defrosting, creating a periodic pattern of air exchange that maintains adequate ventilation over time while allowing the heating cycle to resume efficiently after defrosting completes.
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 simultaneous heating and defrosting operations while maintaining comfort by ensuring continuous heating and adequate ventilation, preventing temperature drops during defrosting and improving overall air quality through controlled ventilation management.
Implementation Method 1
an outdoor heat exchanger, a pressure reducing device, and an indoor heat exchanger that are connected to one another
Implementation Method 2
a four-way valve, an outdoor heat exchanger
Data Source
AI summary
A refrigerating and air-conditioning apparatus performs, even during a heating operation under air conditions leading to formation of frost, a defrosting operation while simultaneously continuing the heating operation and improves comfort through heating by securing an appropriate amount of ventilation. A plurality of refrigeration cycles independently performs a heating operation and a defrosting operation. By controlling a ventilation damper of an indoor unit that is to perform a defrosting operation to increase the amount of ventilation, a prior ventilation operation for securing the time-averaged required amount of ventilation including the period in which the defrosting operation is being performed is performed before the defrosting operation, and after the prior ventilation is terminated, the defrosting operation is started.