Refrigeration cycle apparatus
Solution Overview
Problem
Pressure detection circuits in refrigeration cycle apparatuses using CO2 as refrigerant in a supercritical state experience amplified pressure pulsation, making it difficult to accurately detect refrigerant pressure due to the use of capillary pipes and inverter-driven compressors, leading to potential malfunction of pressure switches.
Innovation Solution
A refrigeration cycle apparatus with a pulsation suppression unit that includes a pressure detection pipe with no narrowed sections and a heater to maintain refrigerant temperature, connected to pressure detectors via an inverter power source that adjusts compressor frequency, ensuring accurate pressure detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a capillary pipe is used as the pressure detection pipe to alleviate pressure increase, then pressure switch malfunction is prevented, but pressure pulsation is amplified making accurate pressure detection difficult
Solution Approach 1:
The pressure detection pipe is divided into multiple sections with different diameters. The first section (from main circuit to pressure detector) has a smaller diameter to prevent pressure switch malfunction, while the second section (from pressure detector to terminal) has a larger diameter to reduce pressure pulsation amplification and improve detection accuracy.
Solution Approach 2:
Different sections of the pressure detection pipe are given different local properties (different diameters) to fulfill different functions: the upstream section prioritizes pressure switch protection, while the downstream section prioritizes accurate pressure detection.
2Reliability
If the pressure detection pipe diameter is reduced to prevent pressure increase, then pressure switch protection is improved, but pressure pulsation amplification occurs
Solution Approach 1:
The pressure detection pipe is segmented into two sections with different diameters. The first section uses a smaller diameter to provide pressure switch protection, while the second section uses a larger diameter to minimize pressure pulsation amplification.
Solution Approach 2:
Different sections of the pipe are assigned different local qualities (diameters) to simultaneously achieve pressure protection and pulsation stability.
3Adaptability or versatility
If inverter power source is used to control compressor frequency, then system adaptability is improved, but pressure pulsation increases during frequency changes
Solution Approach 1:
The pressure detection pipe's second section uses a larger diameter to provide stability against pressure pulsations generated during inverter-driven frequency changes, while maintaining the adaptability benefits of the inverter control 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
The solution effectively suppresses pressure pulsation, allowing for precise refrigerant pressure detection and reliable operation of pressure detectors, enhancing the apparatus's performance and safety.
Implementation Method 1
a heater configured to heat a part of the pressure detection pipe between the branching section and the narrowed pipe section
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A refrigeration cycle apparatus 1 includes a main circuit 10 connecting at least a compressor 11, a gas cooler 12, a pressure reducing device 13, and an evaporator 14 by a pipe and configured to circulate refrigerant transitioning to a supercritical state at a high-pressure side; a pressure detector configured to detect refrigerant pressure in a part of the main circuit 10 between the compressor 11 and the gas cooler 12; and a pulsation suppression unit configured to suppress pulsation of the refrigerant pressure to be detected by the pressure detector.