Refrigeration cycle apparatus
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Solution Overview
Problem
Refrigeration cycle apparatuses face challenges in controlling refrigerant injection to enhance compressor activation performance and reduce motor temperature without compromising refrigeration capacity, particularly due to issues with liquid compression and energy efficiency.
Innovation Solution
A refrigeration cycle apparatus with a heat source circuit, subcooling coil, injection circuit, bypass, and solenoid valves controlled by a microcomputer to manage refrigerant flow into the compressor's intermediate pressure and suction sides, optimizing injection based on compressor activation states and temperature conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If refrigerant is injected into the intermediate pressure portion of the compressor, then refrigeration capacity is enhanced, but liquid compression may occur causing undesirable activation conditions
Solution Approach 1:
The system dynamically switches between intermediate pressure injection and suction side injection based on operating conditions. The controller adjusts the injection circuit configuration in real-time, transitioning from a static single-mode system to a dynamic multi-mode system that adapts to varying refrigeration demands and compressor states.
Solution Approach 2:
The injection system is segmented into two separate injection circuits: one for intermediate pressure injection and another for suction side injection. This segmentation allows independent control of each injection path, enabling the system to select the appropriate injection mode based on operational requirements without interference between the two methods.
2Temperature
If refrigerant is injected into the suction side of the compressor, then motor temperature is reduced, but refrigeration capacity is reduced due to decreased refrigerant circulation
Solution Approach 1:
The system employs dynamic control to switch between suction side injection (for motor cooling) and intermediate pressure injection (for refrigeration capacity) based on real-time temperature and operational conditions. This dynamic adjustment resolves the contradiction by allowing the system to prioritize motor cooling only when necessary.
Solution Approach 2:
The controller monitors motor temperature and refrigeration load parameters, changing the injection mode based on these parameter values. When motor temperature exceeds a threshold, suction side injection is activated; otherwise, intermediate pressure injection is used to maintain refrigeration capacity.
3Temperature
If a bypass between high-pressure side and low-pressure side is provided, then motor temperature is reduced, but low-pressure-side pressure increases reducing energy saving effect
Solution Approach 1:
Instead of directly bypassing from high-pressure to low-pressure sides, the system uses the compressor's suction side as an intermediary. Refrigerant is injected into the suction side, which cools the motor while maintaining proper pressure differentials. This intermediary approach achieves motor cooling without the adverse pressure effects of direct bypass.
4Reliability
If two injection circuits operate at all times, then compressor activation performance is improved, but control of injection flow rate and pressure becomes unclear
Solution Approach 1:
The system dynamically activates or deactivates specific injection circuits based on operational mode, rather than keeping both circuits continuously active. This dynamic control simplifies the control logic by ensuring only one injection circuit operates at a time, making flow rate and pressure control more manageable.
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 configuration improves compressor activation performance, maintains refrigeration capacity, and reduces motor temperature effectively, preventing undesirable activation conditions and energy inefficiencies.
Implementation Method 1
a subcooling coil configured to subcool the refrigerant flowing from the condenser
Implementation Method 2
at least one compressor configured to compress a refrigerant and discharge the refrigerant
Implementation Method 3
a first solenoid valve disposed closer to the compressor than a connection point between the injection circuit and the bypass, a second solenoid valve disposed in the bypass
Data Source
AI summary
A refrigeration cycle apparatus includes a controller configured to control opening and closing of a solenoid valve and that of a solenoid valve depending on any of a time when a compressor is activated, a time when the compressor is in normal operation, a time when a temperature of a motor of the compressor rises in the normal operation, and a time when the compressor stopped due to low-pressure cutoff is activated.