Bypass Expansion Control in Refrigeration Cycles for Stable Heating
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Solution Overview
Problem
Conventional refrigeration cycle apparatuses face inefficiencies and insufficient heating ability, especially at low outside air temperatures, due to inadequate control of the bypass expansion valve, which limits the supercooling heat exchanger's usage and results in poor operation efficiency and heating performance.
Innovation Solution
A refrigeration cycle apparatus with a bypass passage and control system that ensures the refrigerant at the bypass outlet is always in a saturated state, optimizing the bypass amount and supercooling degree at the radiator outlet by adjusting the bypass expansion valve based on temperature sensors, thereby maximizing enthalpy difference and pressure loss reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the bypass expansion valve is controlled to maintain a predetermined temperature difference between inlet and outlet of the supercooling heat exchanger, then the bypass operation can be performed, but the refrigerant state at the bypass outlet cannot be controlled to become equal to a moist state, limiting the bypass amount and supercooling heat exchanger utilization
Solution Approach 1:
The control device uses temperature sensors to detect the actual temperature of the refrigerant at the bypass outlet and compares it with the target temperature (saturation temperature or predetermined lower temperature). Based on this feedback, the control device adjusts the bypass expansion valve opening degree to minimize the temperature difference, thereby precisely controlling the refrigerant state to be moist or subcooled, which maximizes the bypass amount and supercooling heat exchanger utilization.
Solution Approach 2:
The patent replaces conventional mechanical temperature control methods with an electronic control system that uses temperature sensors and a control device to automatically adjust the bypass expansion valve. This substitution enables precise control of the refrigerant state by electronically modulating the valve opening degree based on real-time temperature feedback, achieving superior control precision compared to mechanical methods.
2Productivity
If the bypass amount is increased to maximize supercooling effect, then operation efficiency improves, but the discharge temperature rises abnormally at low outside air temperatures, reducing heating ability
Solution Approach 1:
The control device dynamically adjusts the bypass expansion valve opening degree based on real-time temperature conditions. At low outside air temperatures, the control device reduces the bypass amount to prevent abnormal discharge temperature rise, while at higher temperatures, it increases the bypass amount to maximize supercooling effect and operation efficiency. This dynamic adjustment optimizes the balance between efficiency and heating ability across different operating conditions.
Solution Approach 2:
The patent changes the operating parameters of the bypass expansion valve (opening degree) based on the detected temperature conditions. By adjusting this parameter in response to temperature changes, the system optimizes the bypass amount to maintain appropriate discharge temperature while maximizing supercooling effect when conditions permit, thereby resolving the contradiction between efficiency and heating ability.
3Reliability
If the main expansion valve pressure-reducing amount is lowered to prevent discharge temperature rise, then heating ability is maintained, but evaporation temperature must rise and efficiency deteriorates
Solution Approach 1:
The patent segments the pressure reduction function into two independent pathways: the main expansion valve for primary pressure reduction and the bypass expansion valve for secondary pressure reduction and supercooling. By dividing this function, the system can maintain heating ability through the main expansion valve while using the bypass pathway to achieve additional pressure reduction and supercooling, thereby preventing discharge temperature rise without compromising efficiency.
Solution Approach 2:
The bypass passage acts as an intermediary pathway that allows a portion of the refrigerant to be diverted for pressure reduction and supercooling before rejoining the main flow. This intermediary mechanism enables independent control of pressure reduction and temperature control, allowing the main expansion valve to maintain heating ability while the bypass pathway improves efficiency by reducing discharge temperature through additional supercooling.
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 enhances operating efficiency and ensures sufficient heating ability even at low temperatures, preventing abnormal discharge temperature rises and maintaining efficient heating operations, while optimizing the bypass amount and reducing pressure losses.
Implementation Method 1
a supercooling heat exchanger which heat-exchanges between a mainstream refrigerant and a bypassing refrigerant, and which supercools the mainstream refrigerant
Implementation Method 2
a supercooling heat exchanger which heat-exchanges between a mainstream refrigerant and a bypassing refrigerant, and which supercools the mainstream refrigerant
Data Source
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AI summary
The present invention provides a refrigeration cycle apparatus 1A. When a temperature detected by the first temperature sensor 61 is higher than a temperature detected by the first saturation temperature detecting means 51, a control device 4 operates bypass expansion means 31 such that the temperature detected by the first temperature sensor 61 comes close to the temperature detected by the first saturation temperature detecting means 51. If the temperature detected by the first temperature sensor 61 is substantially equal to the temperature detected by the first saturation temperature detecting means 51, the control device 4 operates the bypass expansion means 31 such that a temperature detected by the second temperature sensor 6 becomes lower than a temperature detected by the second saturation temperature detecting means 52 by a predetermined temperature. Therefore, it is possible to enhance the heating ability and efficiency of the refrigeration cycle apparatus 1A.