Shared Dry Cooler Chiller Layout for Low Refrigerant Charge
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Solution Overview
Problem
Traditional HVAC&R systems relying on vapor compression and free cooling assemblies face energy inefficiencies due to high refrigerant charges and excessive reliance on compressors, which can be mitigated by optimizing the use of free cooling and reducing compressor reliance.
Innovation Solution
The implementation of a modular HVAC&R system with a vapor compression assembly, a free cooling heat exchanger, and a dry cooler assembly, where the cooling fluid is routed in series through a plate frame heat exchanger and condenser, with bypass valves controlled by a controller to minimize compressor usage and maximize free cooling reliance based on ambient and operating conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional HVAC&R systems prioritize vapor compression assembly operation, then adequate cooling capacity is maintained, but refrigerant charge increases and energy efficiency deteriorates
Solution Approach 1:
The system dynamically switches between free cooling and vapor compression modes based on ambient temperature conditions. The free cooling heat exchanger is integrated into the refrigerant circuit, allowing the system to adapt its cooling source dynamically - using ambient air when cold and the compressor when warm, thereby optimizing energy efficiency while maintaining reliable cooling capacity.
Solution Approach 2:
The free cooling heat exchanger acts as an intermediary component that enables heat exchange between ambient air and the refrigerant circuit. This intermediary allows the system to leverage ambient air as a cooling source without requiring the vapor compression assembly to operate continuously, reducing energy consumption while maintaining cooling reliability.
2Reliability
If vapor compression assembly is relied upon heavily, then cooling performance is ensured, but refrigerant charge becomes excessively large
Solution Approach 1:
The cooling function is segmented into two independent pathways: free cooling through the free cooling heat exchanger and mechanical cooling through the vapor compression assembly. This segmentation allows the system to use the simpler free cooling pathway when conditions permit, avoiding the need for large refrigerant charges in the vapor compression system while maintaining cooling performance.
3Loss of energy
If free cooling assembly is used extensively, then energy consumption is reduced, but system complexity increases due to additional components and control mechanisms
Solution Approach 1:
The free cooling heat exchanger is merged into the existing refrigerant circuit of the vapor compression system, sharing common components such as the refrigerant flow path and control system. This integration approach allows the system to benefit from free cooling when available while avoiding the need for entirely separate control systems, thereby reducing overall system complexity compared to fully independent free cooling systems.
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 the refrigerant charge and energy consumption by allowing for substantial reliance on free cooling, even at higher ambient temperatures, while maintaining adequate cooling, thereby improving energy efficiency and reducing compressor load.
Implementation Method 1
a cooling fluid may be employed to cool various fluids associated with the HVAC&R system, such as the working fluid in the condenser of the vapor compression assembly
Implementation Method 2
a dry cooler assembly (or other cooling source) may be employed in the free cooling assembly to reduce a temperature of the process fluid via ambient air
Implementation Method 3
an evaporator configured to place the working fluid in a heat exchange relationship with, for example, a conditioning or process fluid (e.g., water), such that the working fluid absorbs heat from the process fluid
Implementation Method 4
A condenser of the vapor compression assembly may be employed to receive the working fluid and condense the working fluid into liquid phase
Data Source
AI summary
A heating, ventilation, air conditioning, and/or refrigeration (HVAC&R) system includes a first modular central utility plant (mCUP) including a first chiller and a first free cooling heat exchanger, and a second mCUP including a second chiller and a second free cooling heat exchanger. The HVAC&R system also includes at least one dry cooler assembly having an air cooled heat exchanger with one or more fans, wherein the at least one dry cooler assembly is shared between the first mCUP and the second mCUP