Refrigerant Valve Control for Faster Defrost in Split Heat Exchangers
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Solution Overview
Problem
Conventional refrigeration apparatuses with vertically divided heat-source-side heat exchangers in an upward-blowing-type heat source unit face challenges during defrost operations, where frost on both upper and lower heat exchangers melts at different rates due to uneven refrigerant flow, leading to prolonged defrost times and potential refrigerant backflow to the compressor.
Innovation Solution
The apparatus controls the opening degrees of the first and second heat-source-side flow rate adjusting valves to achieve a defrost flow rate ratio that prioritizes refrigerant flow to the lower heat exchanger, ensuring simultaneous melting of frost and preventing backflow by maintaining valve settings throughout the defrost operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the heat-source-side heat exchangers are designed with vertically divided configuration in an upward-blowing-type heat source unit, then the air flow rate distribution is optimized for cooling and heating operations, but the refrigerant flow becomes uneven during defrost operation causing prolonged defrost time and potential backflow
Solution Approach 1:
The invention dynamically adjusts the opening degrees of flow rate adjusting valves during defrost operation to change refrigerant flow distribution. Specifically, the opening degree of the flow rate adjusting valve for the lower heat exchanger is increased while the upper heat exchanger's valve opening is decreased, enabling balanced defrost performance across both vertically divided heat exchangers
Solution Approach 2:
The invention changes the refrigerant flow rate parameters by adjusting valve opening degrees based on operational mode. During defrost operation, the system modifies the flow rate distribution ratio between upper and lower heat exchangers by controlling the opening degrees of respective flow rate adjusting valves, thereby optimizing defrost efficiency and preventing backflow
2Productivity
If the flow rate adjusting valves are controlled to prioritize refrigerant flow to the upper heat exchanger during cooling operation, then the cooling performance is improved, but liquid refrigerant accumulates in the lower heat exchanger during defrost operation
Solution Approach 1:
The system dynamically switches valve control strategies between cooling and defrost modes. During cooling, the upper heat exchanger receives priority refrigerant flow for optimal cooling efficiency. During defrost, the control reverses to prioritize the lower heat exchanger, preventing liquid refrigerant accumulation and potential backflow to the compressor
Solution Approach 2:
The invention changes the flow rate distribution parameters by adjusting valve opening degrees according to operational mode. In cooling mode, the valve opening ratio favors the upper heat exchanger. In defrost mode, the ratio is inverted to favor the lower heat exchanger, thereby preventing refrigerant accumulation and backflow risks
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 shortens defrost time by increasing refrigerant flow to the second heat exchanger, preventing refrigerant accumulation and backflow, and simplifies control during the defrost operation.
Implementation Method 1
a heat-source-side heat exchanger (24, 25) that can be caused to function as an evaporator or a radiator of the refrigerant
Implementation Method 2
an outdoor fan in an upper part, that has an intake port in a side part, and that is configured so as to suction air into the interior from the intake port and to exhaust the air to the exterior from the exhaust port
Implementation Method 3
causing the first and second heat-source-side heat exchangers to function as radiators of refrigerant when frost forms on the first and second heat-source-side heat exchangers which function as evaporators of the refrigerant
Data Source
Figure 1
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Figure 3
AI summary
A first heat-source-side flow rate adjusting valve (26), an opening degree of which is adjustable, is connected to a liquid side of an upper-side first heat-source-side heat exchanger (24), and a second heat-source-side flow rate adjusting valve (27), an opening degree of which is adjustable, is connected to a liquid side of a lower-side second heat-source-side heat exchanger (25). In a defrost operation for defrosting the first and second heat-source-side heat exchangers (24, 25), the opening degrees of the first and second heat-source-side flow rate adjusting valves (26, 27) are controlled so as to achieve a defrost flow rate ratio, which is a flow rate ratio at which more refrigerant flows to the second heat-source-side heat exchanger (25) than during an air-cooling operation.