Two-Stage Refrigerant Injection for Cooling and Heating Efficiency
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Solution Overview
Problem
Conventional refrigeration apparatuses face challenges in achieving high operating efficiency, particularly when using refrigerants like carbon dioxide that operate in a supercritical range, due to high heat radiation loss in outdoor heat exchangers and inefficient power consumption, especially during cooling operations.
Innovation Solution
The refrigeration apparatus incorporates an intermediate heat exchanger and an intermediate heat exchanger bypass tube to optimize refrigerant flow and temperature management, along with injection rate control to enhance the cooling effect and reduce heat radiation loss, while maintaining efficiency during both cooling and heating operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If intermediate heat exchanger is used to cool refrigerant during cooling operation, then heat radiation loss is reduced and operating efficiency is improved, but during heating operation the same heat exchanger would cause efficiency decrease
Solution Approach 1:
The system dynamically switches the function of the heat exchanger based on operation mode. During cooling operation, the heat exchanger cools the refrigerant to reduce heat radiation loss. During heating operation, the bypass tube allows the heat exchanger to be bypassed, preventing efficiency decrease. This dynamic configuration resolution allows the same component to serve different functions in different operational contexts.
Solution Approach 2:
The intermediate heat exchanger bypass tube acts as an intermediary element that allows the refrigerant to bypass the heat exchanger during heating operation. This intermediary pathway enables the system to avoid the negative effect of the heat exchanger during heating while maintaining its beneficial cooling effect during cooling operation.
2Productivity
If injection rate is increased to improve cooling effect, then operating efficiency during cooling operation is improved, but the system complexity increases
Solution Approach 1:
The system controls the injection rate parameter of the refrigerant returned to the second-stage compression element. By optimizing this parameter - setting the injection rate to be greater during heating operation than during cooling operation - the system achieves improved cooling effect and operating efficiency without adding complex hardware, merely through parameter optimization.
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 reduces heat radiation loss and improves operating efficiency during cooling operations and prevents efficiency decreases during heating operations by optimizing refrigerant flow and temperature control, thereby enhancing the coefficient of performance.
Implementation Method 1
an intermediate heat exchanger which functions as a cooler of refrigerant discharged from the first-stage compression element and drawn into the second-stage compression element during the cooling operation
Implementation Method 2
a heat source-side heat exchanger which functions as a radiator or evaporator of refrigerant
Implementation Method 3
a compression mechanism having a plurality of compression elements; the refrigerant discharged from the first-stage compression element is sequentially compressed by the second-stage compression element
Data Source
AI summary
A refrigeration apparatus includes a multi-stage compression mechanism, heat source-side and usage side heat exchangers each operable as a radiator/evaporator, a switching mechanism switchable between cooling and heating operation states, a second-stage injection tube, an intermediate heat exchanger and an intermediate heat exchanger bypass tube. The intermediate heat exchanger bypass tube ensures that refrigerant discharged from the first-stage compression element and drawn into the second-stage compression element is not cooled by the intermediate heat exchanger during a heating operation. Injection rate optimization controls a flow rate of refrigerant returned to the second-stage compression element through the second-stage injection tube so that an injection ratio is greater during the heating operation than during a cooling operation. The injection ratio is a ratio of flow rate of the refrigerant returned to the second-stage compression element through the second-stage injection tube relative to flow rate of the refrigerant discharged from the compression mechanism.