Refrigeration Valve Control for Flexible Unit Placement
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Solution Overview
Problem
Refrigeration apparatuses face constraints in placing utilization units relative to heat source units due to height differences and pipe lengths, leading to increased pressure on expansion valves and potential refrigerant insufficiency, which can result in reduced capacity and efficiency.
Innovation Solution
The refrigeration apparatus includes a heat source unit and utilization unit connected through a refrigerant circuit, with a valve control system that adjusts the degree of opening of expansion valves to maintain pressure within predetermined limits and ensures sufficient refrigerant flow, even with large height differences, by using a heat-source-side valve opening control means and utilization-side valve opening control means to manage pressure and subcooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the height difference between heat source unit and utilization unit is increased, then placement flexibility is improved, but liquid head pressure on expansion valve increases causing potential valve failure
Solution Approach 1:
The patent applies dynamics by making the expansion valve opening degree adjustable rather than fixed. The control device dynamically adjusts the opening degree of the expansion valve based on the height difference between units, allowing the system to adapt to different installation scenarios while maintaining safe operating pressures
Solution Approach 2:
The patent changes the operating parameters of the expansion valve by adjusting its opening degree. When height difference exceeds a predetermined threshold, the control device reduces the opening degree to compensate for increased liquid head pressure, thereby maintaining reliable operation despite greater height differences
2Adaptability or versatility
If the height difference between heat source unit and utilization unit is increased, then placement flexibility is improved, but refrigerant flow to utilization unit decreases causing capacity loss
Solution Approach 1:
The system dynamically adjusts the expansion valve opening degree based on height difference. When the utilization unit is placed at a greater height, the control device increases the opening degree to compensate for reduced refrigerant flow, thereby maintaining the required capacity and productivity
Solution Approach 2:
The control device uses feedback from the height difference information to automatically adjust the expansion valve opening degree. This feedback mechanism ensures that refrigerant flow is optimized for the specific installation configuration, maintaining capacity despite varying height differences
3Adaptability or versatility
If the pipe length between heat source unit and utilization unit is increased, then placement flexibility is improved, but pressure loss increases causing refrigerant insufficiency
Solution Approach 1:
The expansion valve opening degree is dynamically adjusted based on pipe length. When the pipe length exceeds a predetermined threshold, the control device increases the opening degree to compensate for pressure loss, ensuring sufficient refrigerant quantity reaches the utilization unit
Solution Approach 2:
The system changes the expansion valve opening parameter in response to pipe length variations. By increasing the opening degree for longer pipes, the system compensates for pressure losses and maintains adequate refrigerant flow and quantity
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 allows for increased height differences between units, reduces the risk of expansion valve failure, and maintains refrigerant flow and capacity, thereby alleviating placement constraints and enhancing the apparatus's efficiency and reliability.
Implementation Method 1
the heat-source-side heat exchanger (44) functions as a condenser
Implementation Method 2
the utilization-side heat exchanger (41) functions as an evaporator
Implementation Method 3
a heat-source-side expansion valve (36)... and a utilization-side expansion valve (51)
Data Source
AI summary
For cooling operation, a refrigeration apparatus includes a heat-source-side valve opening controller for controlling a degree of opening of a heat-source-side expansion valve so that pressure of a refrigerant flowing into the utilization-side expansion valve in the cooling operation becomes equal to or lower than a predetermined reference pressure value. For heating operation, the refrigeration apparatus includes a utilization-side valve opening controller for performing, when a low-quantity utilization unit in which a quantity of the refrigerant falls below a quantity of the refrigerant required for delivering capacity of the utilization unit is found among a plurality of the utilization units in the heating operation, valve opening reducing operation of reducing a degree of opening of the utilization-side expansion valve of the utilization unit except for the low-quantity utilization unit.