Air Conditioner Expansion Valve Control via Saturated Liquid Pressure Calculation
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Solution Overview
Problem
Air conditioners described in existing patents lack sensors to measure refrigerant state upstream and downstream from the indoor expansion valve, leading to difficulties in precisely controlling the expansion valves and insufficient reduction of refrigerant passage sound.
Innovation Solution
An air conditioner with a refrigerant circuit, including sensors to measure pressure and temperature at various points, and a controller that calculates the pressure of refrigerant as a saturated liquid and adjusts the expansion valve opening based on calculated differences to maintain the refrigerant in a liquid state at the inlet and a gas-liquid two-phase at the outlet.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If no sensor measures refrigerant state upstream and downstream from the indoor expansion valve, then the device complexity is reduced, but the manufacturing precision of expansion valve control deteriorates
Solution Approach 1:
The patent introduces an intermediary calculation approach where the controller computes the refrigerant state at the expansion valve inlet by using saturation temperature and pressure relationships as a mediator, rather than directly measuring it. This allows precise control without adding physical sensors at the expansion valve location.
Solution Approach 2:
The patent replaces the mechanical sensor measurement system with a computational model that uses thermodynamic relationships (saturation temperature-pressure curves) to determine refrigerant state. This substitution maintains precision while reducing device complexity.
2Device complexity
If expansion valve opening is not precisely controlled, then the device complexity is reduced, but the object-generated harmful factors increase
Solution Approach 1:
The patent implements a feedback control mechanism where the controller continuously monitors refrigerant temperature and pressure, compares them with saturation values, and adjusts the expansion valve opening accordingly. This feedback loop ensures precise control to minimize refrigerant passage sound without excessive system complexity.
Solution Approach 2:
The patent controls the expansion valve by dynamically adjusting its opening degree based on calculated refrigerant state parameters (temperature and pressure deviations from saturation). This parameter-based control effectively reduces passage sound while maintaining manageable system complexity.
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 effectively reduces the generation of passage sound of the refrigerant passing through the expansion valve by ensuring the refrigerant is in the correct phase states, enhancing the air conditioner's operational efficiency.
Implementation Method 1
a first sensor that measures a pressure of the refrigerant compressed by the compressor and yet to be expanded by the expansion valve
Implementation Method 2
a second sensor that measures a temperature of the refrigerant supercooled by the supercooling device and yet to be expanded by the expansion valve
Implementation Method 3
a third sensor that measures a pressure or a temperature of the refrigerant expanded by the expansion valve and yet to be compressed by the compressor
Implementation Method 4
the controller calculates a value of a pressure of the refrigerant when the refrigerant is a saturated liquid at a value of the temperature measured by the second sensor
Implementation Method 5
an expansion valve to expand the refrigerant that has passed through the supercooling device
Implementation Method 6
a compressor to compress a refrigerant
Implementation Method 7
a condenser to condense the refrigerant ejected from the compressor
Implementation Method 8
a supercooling device to supercool the refrigerant condensed by the condenser
Implementation Method 9
an evaporator to evaporate the refrigerant expanded by the expansion valve
Data Source
AI summary
In an air conditioner, a controller calculates a value of a pressure of a refrigerant when the refrigerant is a saturated liquid at a value of a temperature measured by a second sensor, calculates, based on a value of a pressure or a temperature measured by a third sensor, a value of a pressure at an outlet of an expansion valve, calculates a difference dP1 between a value of a pressure measured by a first sensor and the calculated value of the pressure of the saturated liquid and a difference dP2 between the calculated value of the pressure of the saturated liquid and the value of the pressure at the outlet of the expansion valve, and adjusts, based on a proportion of the calculated difference dP2 to the calculated difference dP1, a degree of opening of the expansion valve.