Centrifugal Chiller Layout for Low-Pressure Refrigerant Flow Control
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Solution Overview
Problem
Centrifugal chillers using low-pressure refrigerants face issues with heat loss and poor controllability due to heat exchange between components with different temperature levels, and insufficient pressure differences, especially in low load areas, when integrating vessel walls for compactness.
Innovation Solution
The integration of the condenser and economizer with shared vessel walls, along with strategically positioned base surfaces and the use of expansion valves in refrigerant piping outside the devices, allows for reduced heat loss, stable refrigerant flow, and improved controllability by avoiding direct heat exchange between the condenser and evaporator and securing elevation differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the condenser, economizer, and evaporator are integrated via shared walls to make the chiller more compact, then the device size is reduced, but heat loss occurs due to heat exchange between the condenser and evaporator which have extremely different temperature levels
Solution Approach 1:
The patent segments the refrigerant flow paths within the integrated vessel by providing partition walls that separate the condenser, economizer, and evaporator sections. This segmentation prevents direct heat exchange between components with different temperature levels while maintaining the compact integrated structure, thus reducing heat loss without sacrificing space efficiency.
Solution Approach 2:
The economizer acts as an intermediary component positioned between the condenser and evaporator. By routing refrigerant through the economizer with controlled flow paths and using it as a thermal buffer zone, the patent prevents direct thermal coupling between the high-temperature condenser and low-temperature evaporator, thereby reducing parasitic heat loss while maintaining system integration.
2Device complexity
If a fixed orifice is provided inside the economizer as a decompression mechanism, then the device structure is simplified, but controllability deteriorates particularly in low load areas
Solution Approach 1:
The patent replaces the fixed orifice with a dynamic expansion valve that can adjust its opening degree based on operating conditions. This dynamic component allows the system to maintain optimal refrigerant flow control across varying load conditions, particularly improving performance in low load areas where a fixed orifice would be insufficient, while adding only moderate structural complexity.
3Object-affected harmful factors
If the refrigerant is a low-pressure refrigerant, then environmental impact is reduced, but a pressure difference cannot be sufficiently secured in low compression area, causing deterioration in refrigerant flow and refrigeration capability
Solution Approach 1:
The patent introduces gravitational potential energy as an additional dimension to drive refrigerant flow. By positioning the economizer at a lower elevation than the condenser and the evaporator at a lower elevation than the economizer, the system creates elevation differences that generate hydrostatic pressure head. This gravitational assistance compensates for the insufficient pressure difference in low-pressure refrigerant systems, ensuring reliable refrigerant flow and maintaining refrigeration capability without compromising environmental benefits.
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 enhances the compactness of the centrifugal chiller, reduces heat loss, stabilizes expansion valve control, and ensures reliable refrigerant flow across varying operating conditions, even under low pressure differences.
Implementation Method 1
heat exchange between the condenser and the evaporator, and also, a fixed orifice functioning as a decompression mechanism is provided inside the economizer
Implementation Method 2
a base surface of the economizer is positioned below a base surface of the condenser, and above a base surface of the evaporator
Data Source
AI summary
A centrifugal chiller in which a closed-cycle refrigeration cycle is formed by connecting a compressor, a condenser, an economizer and decompression means forming a multi-stage compression cycle, and an evaporator, with the refrigeration cycle being charged with a low-pressure refrigerant. The condenser and the economizer are integrated with each other by having a portion of their vessel walls form a shared wall, with the base surface of the economizer being positioned below the base surface of the condenser and above the base surface of the evaporator.