Refrigeration cycle apparatus
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Solution Overview
Problem
Conventional refrigeration cycle apparatuses face challenges in achieving optimal performance and compressor cooling due to inadequate control of gas and liquid injection, leading to inefficient operation and potential compressor damage.
Innovation Solution
A refrigeration cycle apparatus with a control unit that switches between gas and liquid injection based on detection of discharge temperature, superheat degree, and compression ratio, using a branch channel expansion valve to adjust refrigerant flow, ensuring appropriate heat exchange and stable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If liquid injection is performed directly into the compressor without using the supercooling heat exchanger, then the compressor cooling effect is improved, but the system performance improvement is lost
Solution Approach 1:
The system dynamically switches between liquid injection and gas injection modes based on real-time compressor discharge temperature and operating conditions. The control unit adjusts the injection type and amount to optimize both compressor cooling and system performance, transforming a static injection system into a dynamic adaptive one.
Solution Approach 2:
The system changes the physical state parameter of the injected refrigerant (liquid vs. gas) based on operating conditions. By controlling the degree of evaporation in the supercooling heat exchanger, the system can inject refrigerant in different states (fully liquid, partially evaporated, or fully gas) to achieve optimal cooling and performance for each operating scenario.
2Productivity
If gas injection is performed using the supercooling heat exchanger, then the system performance is improved, but the compressor cooling effect is insufficient under high compression ratio conditions
Solution Approach 1:
The system dynamically adjusts the evaporation degree in the supercooling heat exchanger based on compressor discharge temperature and compression ratio. When high cooling is needed, the system reduces evaporation to maintain more liquid content for better cooling effect. When performance optimization is needed, the system increases evaporation to achieve gas injection with improved COP.
Solution Approach 2:
The system controls the evaporation parameter of the refrigerant in the supercooling heat exchanger to switch between liquid injection and gas injection modes. By adjusting the evaporation degree, the system can optimize both the cooling effect and performance improvement for different operating conditions.
3Temperature
If the superheat degree control is insufficient, then the compressor becomes excessively cooled, but liquid pressure compression occurs causing instability
Solution Approach 1:
The control unit continuously monitors compressor discharge temperature and adjusts the injection parameters (type and amount of refrigerant) based on feedback from temperature sensors. This closed-loop control prevents both excessive cooling and insufficient cooling, maintaining stable operation across varying conditions.
Solution Approach 2:
The system proactively adjusts injection parameters before excessive cooling or liquid pressure compression can occur. By monitoring compression ratio and discharge temperature trends, the control unit preemptively modifies the injection strategy to prevent instability conditions.
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 solution enables improved performance and stability by selectively controlling gas or liquid injection, preventing excessive cooling and liquid compression, thereby enhancing the reliability and efficiency of the refrigeration cycle.
Implementation Method 1
a supercooling heat exchanger performing a heat exchange between the refrigerant passing through the expansion valve and the refrigerant flowing through a main flow channel in a downstream of the condenser
Implementation Method 2
an evaporator evaporating the refrigerant
Implementation Method 3
a condenser condensing the refrigerant
Data Source
AI summary
According to one embodiment, a refrigeration cycle apparatus includes a main flow channel of a refrigerant, a compressor, a condenser, an evaporator, a branch channel, an expansion valve, a supercooling heat exchanger, an injection flow channel, and a control unit. The control unit determines, based on whether the determination condition is satisfied or not, a determination condition for adjusting an opening degree of the expansion valve and adjusts the opening degree of the expansion valve according to a first target value for a discharge temperature of the refrigerant from the compressor, or a second target value for a superheat degree of the refrigerant flowing through the injection flow channel.