Refrigerant Pump Priming Using Flow Control for Startup Reliability
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Solution Overview
Problem
HVAC and refrigeration systems face challenges in ensuring appropriate refrigerant flow and pressure differential during startup, which can lead to inadequate lubrication and cooling of moving parts, potentially causing damage and inefficiency, especially when multiple chillers are involved and condenser water pump shutdown is not practical.
Innovation Solution
The system employs a refrigerant cooling and lubrication assembly that decouples condenser operation using flow control devices like source valves to prime the refrigerant pump by sourcing liquid refrigerant from the evaporator, establishing an appropriate pressure differential before starting the compressor, allowing for lubrication and cooling without shutting off the condenser water pump.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the condenser water pump is shut off to prime the refrigerant pump, then liquid refrigerant can be sourced from the evaporator to establish appropriate pressure differential, but this is not practical in systems with multiple chillers as it impacts other areas of the system
Solution Approach 1:
The system is divided into multiple independent refrigerant sourcing paths: one from the evaporator and another from the condenser. The flow control device allows selective activation of these paths, enabling the refrigerant pump to be primed from the evaporator without requiring shutdown of the condenser water pump, thus maintaining system flexibility while ensuring reliable priming.
Solution Approach 2:
The system dynamically switches between different refrigerant sourcing modes based on operational requirements. During startup, the flow control device directs refrigerant from the evaporator to prime the pump. During normal operation, it can source from the condenser, allowing the system to adapt its refrigerant supply strategy to maintain both reliability and operational flexibility.
2Reliability
If liquid refrigerant is not properly sourced to the compressor at startup, then the moving parts such as bearings and motor may be damaged due to inadequate lubrication and cooling, but ensuring proper pressure differential requires complex pump priming procedures
Solution Approach 1:
The flow control device is pre-configured to direct refrigerant flow from the evaporator to the refrigerant pump during startup conditions. This preliminary configuration ensures that the pump is automatically primed with liquid refrigerant before the compressor starts, establishing the necessary pressure differential and ensuring adequate lubrication and cooling without requiring complex manual priming procedures.
Solution Approach 2:
The flow control device acts as an intermediary component that automatically manages refrigerant flow distribution. It mediates between the evaporator/condenser and the refrigerant pump, ensuring proper priming and pressure differential establishment through automatic flow direction based on operational conditions, thereby protecting the compressor without adding significant complexity.
3Reliability
If the flow control device directs refrigerant from the evaporator during startup, then appropriate pressure differential is established for refrigerant pump operation, but the condenser operation must be decoupled which may impact system efficiency
Solution Approach 1:
The flow control device dynamically adjusts refrigerant flow paths based on operational phase. During startup, it decouples the condenser and directs flow from the evaporator to establish pressure differential. During normal operation, it reconnects the condenser path to maintain system cooling efficiency, allowing the system to optimize between reliable refrigerant flow establishment and overall productivity at different operational stages.
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 approach ensures reliable refrigerant flow and lubrication during startup and operation, preventing damage to moving parts and maintaining system efficiency across various operating conditions, including startup, restart, full load, and partial load, without disrupting the overall cooling tower and heat rejection side.
Implementation Method 1
there can be an issue of whether the refrigerant pump is primed with a suitable and appropriate pressure differential so as to confirm a refrigerant flow through the refrigerant pump
Implementation Method 2
liquid refrigerant can be used as a lubricant for components with moving parts... for cooling moving parts that may be part of the compressor, for example the compressor motor and the compressor bearings
Implementation Method 3
Lubricants, such as oil, are commonly used in the HVAC or refrigeration system to lubricate the moving parts... liquid refrigerant can be used as a lubricant for components with moving parts
Data Source
AI summary
Apparatuses, systems, and methods are disclosed to prime a refrigerant pump by decoupling the condenser from the refrigerant pump and the refrigerant pump line or shielding from a condenser operation prior to startup of the system, so that liquid refrigerant can be appropriately sourced from the condenser and/or the evaporator using flow control device(s) such as a source valve on a source line of the condenser and/or on a source line of the evaporator and the control of such valve(s).