Refrigeration cycle apparatus
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Solution Overview
Problem
Existing refrigeration cycle systems face excessive load on the compressor at startup due to varying conditions, which can lead to inefficiencies and potential damage.
Innovation Solution
A refrigeration cycle apparatus with a bypass refrigerant circuit and a controller that adjusts the opening degree of a bypass valve gradually when discharge pressure exceeds a predetermined threshold, preventing excessive refrigerant injection into the compressor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the bypass valve opening degree is increased rapidly to reduce compressor load, then the compressor load is reduced quickly, but the refrigerant flow becomes unstable and may cause system shock
Solution Approach 1:
The bypass valve opening degree is increased in multiple stages (first predetermined opening degree to second predetermined opening degree) rather than immediately to full opening. This staged periodic adjustment allows the refrigerant flow to adapt gradually, preventing sudden shocks to the system while still protecting the compressor from excessive load.
Solution Approach 2:
The bypass valve opening degree is dynamically adjusted based on real-time discharge pressure detection. The controller continuously monitors the discharge pressure and adjusts the bypass valve opening degree accordingly, transitioning from a static fixed opening to a dynamic adaptive opening that responds to system conditions.
2Productivity
If the bypass valve is kept closed to maintain high refrigerant flow through the main circuit, then the refrigeration efficiency is maximized, but the compressor experiences excessive load at startup
Solution Approach 1:
The bypass valve is opened to a first predetermined opening degree before the compressor reaches full operating conditions. This preliminary action reduces the initial load on the compressor during startup, and then the valve is gradually closed to the second predetermined opening degree as the compressor stabilizes, maximizing refrigeration efficiency during normal operation.
Solution Approach 2:
The bypass valve opening degree parameter is changed from a fixed state to a variable state that transitions between first and second predetermined opening degrees. This parameter change allows the system to optimize between compressor protection mode and high-efficiency refrigeration mode based on operating conditions.
3Reliability
If a bypass refrigerant circuit is added to the system to control compressor load, then the compressor load can be managed, but the system complexity increases
Solution Approach 1:
The bypass refrigerant circuit serves multiple functions: it controls compressor load during startup, stabilizes discharge pressure, and can be integrated with the existing economizer and expansion valve components. By making the bypass circuit multi-functional, the added complexity is justified by the multiple benefits it provides to the system.
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 prevents rapid increases in compressor load, ensuring efficient operation and reducing the risk of damage by stabilizing the refrigerant flow at startup.
Implementation Method 1
an economizer connected between the use side heat exchanger and the expansion valve
Implementation Method 2
a compressor having an injection port communicating with a compression chamber
Implementation Method 3
an expansion valve, and a heat source side heat exchanger connected in order
Implementation Method 4
a use side heat exchanger, an economizer, an expansion valve, and a heat source side heat exchanger connected in order
Data Source
Figure 1
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AI summary
The present disclosure provides a refrigeration cycle apparatus (1) that can restrain a load on a compressor from becoming excessive at the start of the compressor. The refrigeration cycle apparatus in the present disclosure includes: a bypass refrigerant circuit (20) branching off from a main refrigerant circuit (10) between a use side heat exchanger (12) and an expansion valve (14), the bypass refrigerant circuit communicating with an injection port (11a) through an economizer (13); a bypass valve (21) provided in the bypass refrigerant circuit, the bypass valve being configured to change an opening degree of the bypass refrigerant circuit; a discharge pressure sensor (40) configured to detect a pressure of a refrigerant discharged from a compressor (11); and a controller (50) configured to execute a high discharge pressure corresponding process for gradually increasing the opening degree of the bypass refrigerant circuit from a first predetermined opening degree to a second predetermined opening degree using the bypass valve when a pressure detected by the discharge pressure sensor is higher than a predetermined determination pressure at start of the compressor. The refrigeration cycle apparatus (1) in the present disclosure includes: a bypass refrigerant circuit (20) branching off from a main refrigerant circuit (10) between a use side heat exchanger (12) and an expansion valve (14), the bypass refrigerant circuit communicating with an injection port (11a) through an economizer (13); a bypass valve (21) provided in the bypass refrigerant circuit, the bypass valve being configured to change an opening degree of the bypass refrigerant circuit; a discharge pressure sensor (40) configured to detect a pressure of a refrigerant discharged from a compressor (11); and a controller (50) configured to execute a high discharge pressure corresponding process for gradually increasing the opening degree of the bypass refrigerant circuit from a first predetermined opening degree to a second predetermined opening degree using the bypass valve when a pressure detected by the discharge pressure sensor is higher than a predetermined determination pressure at start of the compressor.