Refrigeration Cycle Apparatus Flow Rate Calculation Without Flowmeter
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Solution Overview
Problem
Traditional refrigeration cycle apparatuses that aim to detect flow-rate faults without using a flowmeter face instability in determining flow rate decreases and cannot grasp the absolute quantity of the flow rate.
Innovation Solution
A refrigeration cycle apparatus that includes a compressor, condenser, pressure-reducing means, evaporator, low-pressure side pressure detecting means, suction refrigerant temperature detecting means, frequency detecting means, cooling target fluid inflow and outflow temperature detecting means, and flow rate calculating means to determine the absolute flow rate of the cooling target fluid using detected values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a flowmeter or other measuring instruments are used to directly measure the flow rate of the cooling target fluid, then the flow rate measurement is accurate, but the refrigeration cycle apparatus becomes expensive
Solution Approach 1:
The patent uses refrigerant as an intermediary substance to indirectly measure the cooling target fluid flow rate. By measuring the refrigerant flow rate and using the heat exchange relationship in the evaporator, the system calculates the cooling target fluid flow rate without direct measurement, thus avoiding expensive flowmeters while maintaining measurement accuracy
Solution Approach 2:
The patent replaces the mechanical flowmeter measurement system with a thermal-based indirect measurement system. Instead of using mechanical instruments to directly measure the cooling target fluid flow, the system uses thermal relationships and refrigerant flow measurements to calculate the desired parameter
2Device complexity
If traditional methods without flowmeter are used to detect flow rate, then the apparatus cost is reduced, but the determination of flow rate decrease becomes unstable
Solution Approach 1:
The patent implements a feedback mechanism by continuously monitoring refrigerant flow rate, temperatures at various points, and using these measurements to calculate and track cooling target fluid flow rate. This continuous feedback loop enables stable and reliable flow rate determination without expensive direct measurement instruments
Solution Approach 2:
The patent changes the measurement parameters from directly measuring cooling target fluid flow to measuring refrigerant flow and thermal parameters. By monitoring multiple parameters (refrigerant flow rate, temperatures) and using their relationships, the system achieves stable flow rate determination through parameter interrelationships rather than direct measurement
3Device complexity
If traditional methods without flowmeter are used to detect flow rate, then the apparatus cost is reduced, but the absolute quantity of flow rate cannot be grasped
Solution Approach 1:
The patent creates a computational model that copies the physical relationships in the evaporator heat exchange process. By measuring refrigerant parameters and using the heat exchange equations, the system reconstructs or calculates the cooling target fluid flow rate information, obtaining absolute flow rate values without direct physical measurement of the cooling fluid
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
Enables the calculation of the absolute flow rate of the cooling target fluid without a flowmeter, providing stable and accurate determination of flow-rate faults, thus enhancing operational control and maintenance management.
Implementation Method 1
a compressor (1) that compresses a refrigerant
Implementation Method 2
a condenser (2) that condenses the refrigerant compressed by the compressor
Implementation Method 3
pressure-reducing means (3) for reducing a pressure of the refrigerant condensed by the condenser
Implementation Method 4
an evaporator (4) that causes the refrigerant with the pressure reduced by the pressure-reducing means to evaporate
Implementation Method 5
cooling target fluid sending means (5) for sending, to the evaporator (4), a cooling target fluid that exchanges heat with the refrigerant flowing in the evaporator
Data Source
AI summary
A refrigeration cycle apparatus includes low-pressure side pressure detecting means for detecting the pressure of a refrigerant being sucked by a compressor, suction refrigerant temperature detecting means for detecting the temperature of the refrigerant being sucked by the compressor, frequency detecting means for detecting the operation frequency of the compressor, cooling target fluid inflow temperature detecting means for detecting the temperature of a cooling target fluid flowing in an evaporator, cooling target fluid outflow temperature detecting means for detecting the temperature of the cooling target fluid flowing out of the evaporator, and flow rate calculating means (measuring unit, computing unit, and storage unit) for calculating the absolute quantity of the flow rate of the cooling target fluid flowing in the evaporator using a value detected by each detecting means.