Two-Stage Refrigeration Control for Discharge Temperature Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing refrigeration apparatuses of two-stage compression type do not effectively manage the discharge temperature of refrigerant during cooling operations, leading to inefficiencies when the utilization-side heat exchanger functions as an evaporator, as they lack specific strategies to handle excessive discharge temperatures.
Innovation Solution
A refrigeration apparatus with a control unit that adjusts the cooling capacity of the intermediate cooler and the refrigerant flow rate of the economizer circuit to optimize operation efficiency by prioritizing the intermediate cooler over the economizer circuit when the discharge temperature exceeds a certain threshold, and vice versa, using a cooling fan to adjust airflow and control capacities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the refrigerant flow rate of the economizer circuit is increased to reduce discharge temperature, then the discharge temperature is reduced, but the operation efficiency deteriorates due to excessive refrigerant bypassing the evaporator
Solution Approach 1:
The patent applies dynamic control by making the refrigerant flow rate of the economizer circuit variable based on discharge temperature conditions. The control unit dynamically adjusts the expansion valve opening degree to optimize the balance between discharge temperature reduction and maintaining operation efficiency, rather than using a fixed flow rate.
Solution Approach 2:
The patent changes the operational parameters of the economizer circuit based on discharge temperature thresholds. When discharge temperature exceeds the first threshold, the system increases the refrigerant flow rate through the economizer circuit; when it falls below the second threshold, the system decreases the flow rate, thereby adapting system performance to real-time conditions.
2Temperature
If the cooling capacity of the intermediate cooler is increased to reduce discharge temperature, then the discharge temperature is reduced, but the device complexity increases due to additional control requirements
Solution Approach 1:
The patent implements feedback control by using the control unit to continuously monitor discharge temperature and automatically adjust the intermediate cooler's cooling capacity and economizer circuit's refrigerant flow rate. This closed-loop feedback mechanism manages the complexity by automating the control process based on real-time temperature data.
Solution Approach 2:
The control unit acts as an intermediary that coordinates between the intermediate cooler and economizer circuit. It processes temperature information and determines the appropriate control actions for both components, simplifying the overall control architecture by centralizing the decision-making logic.
3Productivity
If the refrigerant flow rate of the economizer circuit is decreased to improve operation efficiency, then the operation efficiency is improved, but the discharge temperature excessively rises
Solution Approach 1:
The system dynamically adjusts the refrigerant flow rate through the economizer circuit based on discharge temperature conditions. When discharge temperature is within the acceptable range (below the first threshold), the system reduces the flow rate to improve operation efficiency; when temperature rises above the threshold, the flow rate is increased to control temperature, creating a dynamic optimization strategy.
4Productivity
If the cooling capacity of the intermediate cooler is decreased to improve operation efficiency, then the operation efficiency is improved, but the discharge temperature excessively rises
Solution Approach 1:
The control unit uses feedback from discharge temperature measurements to automatically adjust the intermediate cooler's cooling capacity. When discharge temperature rises above the first threshold, the control unit increases the cooling capacity; when temperature drops below the second threshold, it decreases the cooling capacity, thereby maintaining operation efficiency while preventing excessive temperature rise.
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 improves operation efficiency by effectively managing discharge temperatures, ensuring the refrigeration apparatus operates efficiently even under varying conditions by strategically utilizing the intermediate cooler and economizer circuit based on temperature thresholds.
Implementation Method 1
an intermediate cooler (17) configured to cool the refrigerant discharged from the lower stage-side compression unit (22, 23)
Implementation Method 2
an economizer circuit (38) configured to decompress and evaporate a part of the refrigerant flowed out of the heat source-side heat exchanger (13) or utilization-side heat exchanger (64)
Implementation Method 3
a heat source-side heat exchanger (13); a utilization-side heat exchanger (64)
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A refrigeration apparatus (1) is of a two-stage compression type for compressing a refrigerant to a supercritical region. The refrigeration apparatus (1) includes a lower stage-side compression unit (22, 23), a higher stage-side compression unit (21), an intermediate cooler (17), a heat source-side heat exchanger (13), a utilization-side heat exchanger (64), an economizer circuit (38), and a control unit (100). During a first operation in which the heat source-side heat exchanger (13) functions as a radiator and the utilization-side heat exchanger (64) functions as an evaporator, in a case where a discharge temperature (Td) which is a temperature of the refrigerant discharged from the higher stage-side compression unit (21) is more than a first temperature, the control unit (100) increases a cooling capacity of the intermediate cooler (17) without increasing a refrigerant flow rate (Q) of the economizer circuit (38) on condition that the intermediate cooler (17) does not reach a maximum cooling capacity.