Expansion Valve Feedback for Refrigerant Charge Detection
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Solution Overview
Problem
Existing refrigeration circuits face inefficiencies and potential damage due to incorrect refrigerant charge levels, which are often only detected during maintenance or as faults, leading to prolonged reduced efficiency or system damage.
Innovation Solution
The method involves using a network of temperature and pressure sensors to monitor and control the refrigeration circuit, specifically measuring overheating and subcooling differences to automatically adjust the electronic expansion valve's degree of opening, determining the correct refrigerant amount by comparing measured and target settings, and triggering warnings or shutdowns based on deviations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If refrigerant charge levels are not monitored in real-time, then the refrigeration circuit operates with reduced efficiency or potential damage over longer periods, but implementing continuous monitoring increases device complexity and cost
Solution Approach 1:
The patent implements continuous feedback monitoring by measuring overheating and subcooling values in real-time, comparing them against predetermined thresholds, and automatically generating warnings or shutdown signals when deviations are detected. This closed-loop feedback system enables reliable detection of refrigerant charge levels without requiring complex manual inspection procedures.
Solution Approach 2:
The system performs self-diagnosis by automatically monitoring its own operational parameters (overheating and subcooling values) and detecting anomalies that indicate incorrect refrigerant charge levels. The control unit continuously assesses system health status and triggers appropriate responses without external intervention, enabling the system to monitor itself.
2Loss of time
If refrigerant charge levels are detected only during maintenance or faults, then detection time is delayed, but continuous monitoring increases energy consumption and system complexity
Solution Approach 1:
The system performs preliminary detection by continuously monitoring overheating and subcooling values before critical faults develop. The control unit compares measured values against predetermined thresholds in advance, enabling early warning of incorrect refrigerant charge levels before they lead to system damage or require maintenance intervention.
3Reliability
If continuous monitoring and automatic shutdown functions are implemented, then system reliability improves, but device complexity and control system requirements increase
Solution Approach 1:
The control unit continuously receives feedback from temperature and pressure sensors, compares measured overheating and subcooling values against predetermined thresholds, and automatically generates warnings or shutdown signals when deviations are detected. This feedback mechanism enables reliable detection with minimal additional complexity.
Solution Approach 2:
The patent replaces complex mechanical monitoring systems with electronic sensing and control. Temperature and pressure measurements are converted into electrical signals processed by a control unit that automatically determines refrigerant charge status, substituting mechanical complexity with electronic control simplicity.
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 enables real-time detection and correction of refrigerant levels, preventing inefficiencies and damage by ensuring optimal operation and maintaining the correct refrigerant charge, thus enhancing system performance and reliability.
Implementation Method 1
a first temperature sensor (11) between condenser (2) and expansion valve (4), a second temperature sensor (13) and a third temperature sensor (9) between compressor (1) and condenser 2
Implementation Method 2
a first pressure sensor (10) between compressor (1) and condenser (2), a second pressure sensor (12) between evaporator (3) and compressor (1)
Implementation Method 3
The task of condenser 2 is to deheat (cool down) the overheated refrigerant vapor flowing from compressor (1), to liquefy it and thereby liquefy it to transfer the enthalpy to the heating water
Implementation Method 4
In the evaporator (3), the liquid refrigerant coming from the expansion valve (4) is evaporated. The necessary evaporation enthalpy is extracted from the brine circuit
Implementation Method 5
The electronic expansion valve (4) has the task of expanding the supercooled refrigerant with the inlet temperature T EI from the condensation pressure p c back to the evaporation pressure p 0
Data Source
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AI summary
1. In a method for automatically detecting refrigerant charge levels in refrigeration circuits (8), preferably a heat pump, with a compressor (1), a condenser (2), an expansion valve (4) with a variable cross section and detection of the degree of opening, an evaporator (3) , a first pressure sensor (10) between compressor (1) and expansion valve (4), a first temperature sensor (11) between condenser (2) and expansion valve (4), a second pressure sensor (12) and a second temperature sensor (13) between evaporator (3) and compressor (1), the overheating ΔTO is determined from the pressure determined by means of the second pressure sensor (12) and the temperatures of the second temperature sensor (13), the variable cross section of the expansion valve (4) is changed until a specified Superheat ΔTo,soll sets, whereupon one or both of the following checks are carried out: a) the degree of opening of the expansion valve (4) at a specified superheat ung ΔTO,setpoint is determined from a stored map or algorithm, a target degree of opening of the expansion valve (4) is determined for the overheating ΔTo,setpoint, the difference between the measured degree of opening and the target degree of opening of the expansion valve (4) is determined, b) from the means of the first pressure sensor (10) and the temperatures of the first temperature sensor (11), the subcooling ΔTU is determined, from a stored map or algorithm a target subcooling ΔTU,setpoint is determined for the overheating ΔTo,soll, the difference between the measured subcooling ΔTU and Target subcooling ΔTU,setpoint is determined, with a specified deviation between the detected opening degree and the target opening degree of the expansion valve (4) and/or a specified deviation between the measured subcooling ΔTU and the target subcooling ΔTU,setpoint, indicating a lack of refrigerant or excess refrigerant .