Dual Compressor Chiller Pressure Equalization for Series-Flow Efficiency

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Solution Overview

Problem

Traditional single chiller systems are less efficient compared to series flow chillers, which require additional components and space, making them costly and impractical for many facilities, thus necessitating a method to achieve series flow efficiency with a single chiller.

Innovation Solution

A refrigeration system with a divided evaporator and condenser, utilizing pressure equalization valves and configurations like two-pass flow, allows each chamber to operate at different pressures, mimicking the efficiency benefits of series flow chillers without the need for multiple units, and includes features like baffles and subcoolers to manage pressure differentials.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If series flow chiller configuration is used, then system efficiency is improved, but device complexity and cost increase due to additional evaporators, condensers and conduits

Engineering Contradiction:
Improvesystem efficiencyVSAvoiddevice complexity
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

The patent divides a single chiller into two separate chambers (first chamber and second chamber), each with its own evaporator and condenser sections. This segmentation allows the single chiller to operate with two different refrigerant circuits that can function in series flow configuration, thereby achieving improved system efficiency without requiring multiple complete chiller units. The division creates distinct high-pressure and low-pressure zones within the same device.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent combines multiple functional elements into a single integrated chiller unit. Specifically, it merges two evaporators, two condensers, and two refrigerant circuits into one chiller housing with shared components such as the compressor and control systems. This merging achieves the efficiency benefits of series flow configuration while reducing device complexity and cost compared to using separate chiller units.

Inventive Principle:
Principle #5Merging (Combining)

2Loss of energy

If series flow chiller configuration is used, then system efficiency is improved, but space requirements increase making it impractical for facilities with limited space

Engineering Contradiction:
Improvesystem efficiencyVSAvoidspace requirements
Core Design Contradiction:
Loss of energyVSArea of stationary object

Solution Approach 1:

By segmenting the chiller into two chambers within a single unit, the patent achieves series flow efficiency without the space requirements of multiple separate chillers. The compact integration of high-pressure and low-pressure zones in one housing reduces the footprint while maintaining the functional benefits of staged refrigeration.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent employs a nested arrangement where the second refrigerant circuit is integrated within the same chiller housing as the first circuit. The chambers are arranged concentrically or adjacently within the single unit, allowing one system to be nested within or alongside another, thereby achieving series flow configuration in a compact space that would not accommodate two complete chiller units.

Inventive Principle:
Principle #7Nested doll (Nesting)

3Loss of energy

If pressure differences between chambers are increased, then compressor head is reduced improving efficiency, but structural integrity may be compromised

Engineering Contradiction:
Improvecompressor headVSAvoidstructural integrity
Core Design Contradiction:
Loss of energyVSStrength

Solution Approach 1:

The patent optimizes the pressure differential parameter to achieve the optimal balance between efficiency and structural integrity. By carefully controlling the pressure difference between the high-pressure and low-pressure chambers, the system maximizes compressor head reduction for improved efficiency while maintaining pressure levels that do not compromise the structural strength of the chiller housing and internal components.

Inventive Principle:
Principle #35Parameter changes

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 compressor capacity and enhances system efficiency by maintaining pressure differentials within structural limits, allowing for reduced power consumption and operational flexibility while maintaining the efficiency of series flow systems.

Implementation Method 1

a pressure equalization valve in fluid communication with both the high-pressure side and the low-pressure side of the chiller system to equalize the pressure between the high-pressure side and the low-pressure side

Methodology Applied
Scientific EffectPressure equalization: Pressure Gradient

Implementation Method 2

the process fluid is cooled by an evaporator which absorbs heat from the process fluid through evaporating refrigerant

Methodology Applied
Scientific EffectEvaporation: Evaporation

Implementation Method 3

an evaporator which absorbs heat from the process fluid through evaporating refrigerant

Methodology Applied
Scientific EffectHeat absorption: Absorption (physical)

Implementation Method 4

The refrigerant may then be compressed in a compressor and transferred to a condenser

Methodology Applied
Scientific EffectCompression: Compression

Implementation Method 5

In a liquid cooled condenser, the refrigerant is generally cooled by a second process fluid, causing the refrigerant to condense into a liquid

Methodology Applied
Scientific EffectCondensation: Condensation

Implementation Method 6

the refrigerant is generally cooled by a second process fluid, causing the refrigerant to condense into a liquid

Methodology Applied
Scientific EffectHeat transfer: Heat Exchanger

Implementation Method 7

The liquid refrigerant may then be transferred back to the evaporator, to begin another refrigeration cycle

Methodology Applied
Scientific EffectPressure reduction: Pressure Drop

Data Source

PatentEP2449321B1System for limiting pressure differences in dual compressor chillers
Publication Date: 2018.08.22 JOHNSON CONTROLS TECHNOLOGY CO
  • EP2449321B1 patent drawingFigure 1
  • EP2449321B1 patent drawingFigure 2~4
  • EP2449321B1 patent drawingFigure 5~10

AI summary

Systems for limiting pressure differences in dual compressor chillers are provided. To achieve the efficiency benefits of series flow chillers within a single unit, an evaporator (22) and/or a condenser (24) may be partitioned into separate chambers by a baffle (36, 38). Process fluid may then flow through one chamber of the evaporator and/or condenser prior to entering the other. This configuration creates a pressure differential between chambers which may reduce compressor head and result in greater chiller efficiency. However, to maintain the structural integrity of the evaporator and/or condenser baffle, a system for limiting this pressure differential may be employed. This system may include an evaporator pressure equalization valve (40), a common liquid line (32), or an equalizing line (46) between separate liquid lines. Methods of operating dual compressor chillers using these systems are also provided.