Refrigerant Composition for Liquid Chiller Systems

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Solution Overview

Problem

Refrigerants with temperature glide in liquid chiller systems for electric vehicles face performance penalties in cross-flow arrangements, leading to suboptimal cooling capacity and energy efficiency compared to those without glide.

Innovation Solution

The use of a refrigerant composition comprising 1,1-difluoroethylene (R-1132a) and optional components like difluoromethane (R-32) and 2,3,3,3-tetrafluoropropene (R-1234yf) in liquid chiller systems with counter-flow heat exchangers, which exploits temperature glide to enhance performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a non-azeotropic refrigerant with temperature glide is used in a cross-flow heat exchanger arrangement, then the refrigerant can provide cooling capacity, but the temperature glide causes performance penalties due to mismatched temperature profiles between refrigerant and air streams

Engineering Contradiction:

Improvecooling capacityVSAvoidenergy efficiency

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The patent inverts the conventional cross-flow heat exchanger arrangement by switching to a counter-flow configuration. This inversion allows the refrigerant temperature profile to align properly with the air stream temperature profile, eliminating the performance penalty caused by temperature glide. The counter-flow arrangement enables the cold air to exit at a lower temperature and the hot air to exit at a higher temperature, maximizing the temperature difference across the heat exchanger and improving both cooling capacity and energy efficiency.

Inventive Principle:

Principle #13The other way round (Inversion)

2Productivity

If the refrigerant evaporation temperature is lowered to increase cooling capacity in the evaporator, then more heat can be extracted, but the temperature difference between refrigerant and air becomes too small to maintain effective heat exchange

Engineering Contradiction:

Improvecooling capacityVSAvoidtemperature difference

Core Design Contradiction:

ProductivityVSTemperature

Solution Approach 1:

The patent utilizes the dynamic temperature glide property of non-azeotropic refrigerants in a counter-flow heat exchanger configuration. As the refrigerant evaporates, its temperature gradually increases along the heat exchanger length, dynamically matching the temperature profile of the air stream. This dynamic adaptation allows the system to maintain an optimal temperature difference throughout the heat exchange process, enabling lower average evaporation temperatures while preserving effective heat exchange and maximizing cooling capacity.

Inventive Principle:

Principle #15Dynamics

3Stability of the object's composition

If a single-component or azeotropic refrigerant is used, then the refrigerant maintains constant temperature during phase change, but the system cannot exploit temperature glide to improve performance in counter-flow heat exchangers

Engineering Contradiction:

Improvetemperature stabilityVSAvoidrefrigeration performance

Core Design Contradiction:

Stability of the object's compositionVSProductivity

Solution Approach 1:

The patent changes the fundamental parameter of refrigerant composition from single-component or azeotropic to non-azeotropic mixture. This parameter change introduces temperature glide during phase change, which is then exploited through the counter-flow heat exchanger configuration. The temperature glide allows the refrigerant temperature to vary along the heat exchanger length, matching the air stream temperature profile and maximizing the temperature difference, thereby significantly improving refrigeration performance while maintaining stable composition throughout the system.

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 composition exhibits superior refrigeration performance, higher coefficient of performance (COP), and increased volumetric cooling capacity compared to R-1234yf or binary mixtures like R-454C, particularly in counter-flow heat exchanger geometries, while maintaining low flammability and Global Warming Potential (GWP).

Implementation Method 1

heat is rejected outside the vehicle by flowing external air in cross-flow over the tubes of the condenser and condensing refrigerant inside the tubes

Methodology Applied

Scientific EffectHeat transfer: Conduction (thermal)

Implementation Method 2

the refrigerant evaporates inside the tubes of the evaporator

Methodology Applied

Scientific EffectEvaporation: Evaporation

Implementation Method 3

heat is rejected outside the vehicle by flowing external air in cross-flow over the tubes of the condenser and condensing refrigerant inside the tubes

Methodology Applied

Scientific EffectHeat transfer: Conduction (thermal)

Implementation Method 4

condensing refrigerant inside the tubes

Methodology Applied

Scientific EffectCondensation: Condensation

Implementation Method 5

the heat exchangers for moving heat between refrigerant in the chiller system and the hot and cold liquids will be arranged so that the fluids are in counter-current flow

Methodology Applied

Scientific EffectHeat exchange: Heat Exchanger

Data Source

PatentUS20230072663A1Refrigerant compositions and use thereof

Publication Date: 2023.03.09 MEXICHEM FLUOR S A DE CV

AI summary

The use as a refrigerant of a composition comprising 1,1-difiuoroethyiene in a liquid chiller system.