Heat source unit and refrigeration device
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Solution Overview
Problem
Existing refrigeration apparatuses do not effectively prevent liquid compression at the heat source-side unit during compressor startup, which can lead to damage and inefficiencies.
Innovation Solution
Incorporating a control unit that manages the operation of a two-stage compression system with an intermediate heat exchanger functioning as an evaporator at startup, bypassing the lower-stage compression element to evaporate refrigerant before it enters the higher-stage compression, thereby preventing liquid compression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the lower-stage compression element is operated at startup, then the compression unit can compress refrigerant, but liquid refrigerant may be sucked in causing liquid compression
Solution Approach 1:
The system performs preliminary action by operating the higher-stage compression element and intermediate heat exchanger before startup to evaporate liquid refrigerant and raise suction pressure to a predetermined level, ensuring refrigerant is in gaseous state before the lower-stage compression element starts, thus preventing liquid compression
Solution Approach 2:
The intermediate heat exchanger acts as an intermediary device that receives liquid refrigerant from the utilization-side unit and evaporates it through heat exchange, transforming it into gaseous state before it enters the higher-stage compression element, thereby preventing liquid compression in the compression system
2Reliability
If the higher-stage compression element operates alone at startup, then liquid compression is prevented, but compression efficiency is reduced
Solution Approach 1:
The system implements periodic action by first operating only the higher-stage compression element during the startup period to prevent liquid compression, then transitioning to operate both compression elements together after suction pressure reaches the predetermined level, thus achieving both protection and efficiency
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 effectively suppresses liquid compression at startup, ensuring efficient operation and extending compressor lifespan by ensuring refrigerant is in a gaseous state before compression, thus preventing damage and improving system efficiency.
Implementation Method 1
an intermediate heat exchanger (17) disposed on a refrigerant path between the lower-stage compression element (23) and the higher-stage compression element (21) and configured to cause the refrigerant to exchange heat with a heating medium
Data Source
Figure 1
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Figure 3
AI summary
A heat source-side unit (10) includes a heat source-side circuit (11). The heat source-side circuit (11) includes a compression unit (20) including a lower-stage compression element (23) and a higher-stage compression element (21), an intermediate heat exchanger (17) disposed on a refrigerant path between the lower-stage compression element (23) and the higher-stage compression element (21), and a bypass passage (23c) connected to a suction pipe (23a) and a discharge pipe (23b) each connected to the lower-stage compression element (23). At startup of the compression unit (20), a first action is performed for stopping the lower-stage compression element (23) and operating the higher-stage compression element (21). This configuration thus suppresses occurrence of liquid compression at startup of a compressor.