Parallel Heat Exchanger Valve Control for Stable Refrigerant Saturation
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Solution Overview
Problem
In refrigeration apparatuses, it is challenging to rapidly regulate valve openings to adjust for changes in refrigerant temperature differences across heat exchangers, leading to unstable temperature control and inefficient heat energy utilization.
Innovation Solution
A heat source unit with motor-operated valves and temperature sensors connected in parallel, where the valve openings are controlled based on discharge temperature and refrigerant temperature measurements to maintain stable refrigerant flow rates and achieve saturation states accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the valve opening is regulated based on the temperature difference of refrigerant at heat exchanger outlets, then the degree of superheating can be kept constant, but the temperature control becomes unstable and slow to respond due to the gas state refrigerant's high thermal inertia
Solution Approach 1:
The patent implements feedback control by measuring the discharge temperature of the compressor and using it to regulate the valve openings of multiple heat exchangers. The valve opening controller continuously adjusts the valve positions based on the discharge temperature feedback, creating a closed-loop control system that rapidly responds to temperature changes and maintains stable operation.
Solution Approach 2:
The patent regulates the valve openings before significant temperature fluctuations occur by using discharge temperature as an early indicator. The controller proactively adjusts the refrigerant flow to prevent large temperature deviations, rather than reacting after the outlet temperature has already changed significantly.
2Productivity
If multiple heat exchangers are connected in parallel with individual flow-rate-regulating valves, then heat exchange capability is enhanced, but the system complexity increases making rapid valve regulation difficult
Solution Approach 1:
The patent merges the control functions of multiple heat exchangers into a single integrated control system. The valve opening controller receives discharge temperature information and simultaneously regulates all motor-operated valves based on this common feedback, simplifying the control architecture while maintaining the parallel heat exchange capability.
Solution Approach 2:
The discharge temperature sensor serves as a universal measurement point that provides critical feedback for controlling all heat exchangers in the system. This single sensor enables the controller to coordinate multiple valves and manage the entire parallel heat exchange system through a unified control strategy.
3Use of energy by moving object
If the refrigerant at heat exchanger outlets is in a gas state with superheating, then heat energy is obtained as sensible heat, but the heat energy utilization efficiency is reduced compared to two-phase state refrigerant
Solution Approach 1:
The patent dynamically changes the refrigerant flow parameters by adjusting the motor-operated valve openings based on discharge temperature. This enables the system to optimize the refrigerant state and flow distribution across heat exchangers, improving heat energy utilization by preventing excessive superheating and maintaining more efficient two-phase or saturated vapor conditions.
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 solution enables stable regulation of valve openings, ensuring efficient heat exchange performance and rapid saturation of refrigerant, thereby enhancing the capability of both heat exchangers and reducing temperature fluctuations.
Implementation Method 1
The first motor-operated valve (26) regulates the amount of refrigerant that flows to the first heat exchanger (24) when the first heat exchanger (24) functions as a refrigerant evaporator
Implementation Method 2
The first temperature sensor (81) measures the temperature of refrigerant that flows from the first motor-operated valve (26) to the first heat exchanger (24)
Implementation Method 3
a first heat exchanger (24) and a second heat exchanger (25), wherein the second heat exchanger (25) is connected in parallel to the first heat exchanger (24)
Implementation Method 4
a compressor (21), wherein the compressor (21) compresses low-temperature low-pressure refrigerant that has undergone heat exchange in the heat exchangers (24, 25) into high-temperature high-pressure refrigerant
Implementation Method 5
the refrigerant in a gas-liquid two-phase state in which the heat energy is consumed in order to cause the liquid refrigerant to be evaporated as latent heat of vaporization
Data Source
AI summary
A heat source unit includes a compressor, first and second heat exchangers connected in parallel, first and second motor-operated valves regulating amounts of refrigerant that flow to the first and second heat exchangers, first and second temperature sensors measuring temperatures of refrigerant flowing from the first and second motor-operated valve to the first and second heat exchangers, a discharge temperature sensor measuring temperature of refrigerant discharged from the compressor, and a valve opening controller. The controller regulates valve openings of the first and second motor-operated valves based on the discharge temperature, refrigerant temperature detected by the first temperature sensor and refrigerant temperature detected by the second temperature sensor.