Refrigeration Circuit Layout for Flammable Refrigerant Fill Limits

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Solution Overview

Problem

Refrigeration apparatuses using flammable hydrocarbon refrigerants face challenges in achieving desired refrigeration capacity while adhering to legal filling amount regulations, as conventional designs optimized for chlorofluorocarbons do not account for the lower filling capacity of flammable refrigerants, potentially leading to excessive refrigerant filling and inadequate cooling performance.

Innovation Solution

The refrigeration apparatus is designed with a refrigeration circuit volume set to 2200×10^-6 m^3 or smaller and a condenser volume set to 750×10^-6 m^3 or smaller, utilizing a vapor compression type circuit with a condenser of reduced size and parallel heat exchanger units to manage the refrigerant flow efficiently, ensuring compliance with legal filling limits while maintaining desired cooling capacity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional refrigeration apparatus design optimized for chlorofluorocarbon refrigerants is adopted, then the refrigeration capacity is maintained, but the filling amount of flammable refrigerant exceeds legal regulations

Engineering Contradiction:
Improverefrigeration capacityVSAvoidrefrigerant filling amount
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The patent applies parameter changes by optimizing the refrigerant circuit volume and condenser volume to specific ranges (refrigerant circuit volume: 1.8-2.2 L, condenser volume: 0.65-0.75 L) to achieve the desired balance between refrigeration capacity and refrigerant filling amount compliance for flammable refrigerants

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs dynamic adjustment of the expansion valve to optimize refrigerant flow and distribution throughout the system, enabling the apparatus to maintain desired refrigeration capacity while operating within legal refrigerant filling limits for flammable refrigerants

Inventive Principle:
Principle #15Dynamics

2Quantity of substance

If the refrigerant filling amount is reduced to comply with legal regulations, then the legal regulation is observed, but the refrigeration capacity becomes insufficient

Engineering Contradiction:
Improverefrigerant filling amountVSAvoidrefrigeration capacity
Core Design Contradiction:
Quantity of substanceVSReliability

Solution Approach 1:

The patent changes system parameters by optimizing the refrigerant circuit volume and condenser volume to specific ranges, which improves refrigeration efficiency and enables the system to achieve desired cooling capacity with reduced refrigerant filling amounts that comply with legal regulations

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses dynamic control of the expansion valve to optimize refrigerant distribution and flow rates, allowing the system to maximize refrigeration capacity utilization with the limited refrigerant quantity required by legal regulations

Inventive Principle:
Principle #15Dynamics

3Quantity of substance

If the condenser volume is reduced to decrease refrigerant filling amount, then the refrigerant filling limit is complied with, but the heat exchange efficiency may be compromised

Engineering Contradiction:
Improverefrigerant filling amountVSAvoidheat exchange efficiency
Core Design Contradiction:
Quantity of substanceVSUse of energy by moving object

Solution Approach 1:

The patent applies parameter changes by optimizing the condenser volume to a specific range (0.65-0.75 L) and configuring parallel heat exchanger units, which maintains effective heat exchange efficiency while reducing the overall refrigerant filling amount to comply with legal regulations

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent segments the heat exchange function by employing parallel heat exchanger units within the condenser, which distributes refrigerant flow more efficiently and maintains heat exchange performance despite the reduced condenser volume and lower refrigerant filling amount

Inventive Principle:
Principle #1Segmentation

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 design ensures a desired cooling capacity while observing legal refrigerant filling limits, allowing for efficient refrigerant circulation and heat exchange, even with reduced volumes, achieving a refrigeration capacity equivalent to 1300 W per circuit while minimizing costs and maintaining compactness.

Implementation Method 1

a compressor

Methodology Applied
Scientific EffectCompression: Compression

Implementation Method 2

a condenser

Methodology Applied
Scientific EffectCondensation: Condensation

Implementation Method 3

a decompression means

Methodology Applied
Scientific EffectDecompression: Depressurisation

Implementation Method 4

an evaporator

Methodology Applied
Scientific EffectEvaporation: Evaporation

Implementation Method 5

heat exchange

Methodology Applied
Scientific EffectHeat transfer: Conduction (thermal)

Data Source

PatentEP2284460B1Refrigeration apparatus
Publication Date: 2014.05.21 HOSHIZAKI ELECTRIC CO LTD
  • EP2284460B1 patent drawingFigure 1
  • EP2284460B1 patent drawingFigure 2
  • EP2284460B1 patent drawingFigure 3

AI summary

The present invention is proposed to ensure a desired refrigeration capacity while observing a regulation on a filling amount of a flammable refrigerant required for a refrigeration circuit. A refrigeration circuit 34 includes a compressor CM, a condenser CD, an expansion valve EV and an evaporator EP each of which is connected by refrigerant pipes 32, and a flammable refrigerant is circulated therethrough. In the refrigeration circuit 34, volume per circuit is set equal to or smaller than 2200×10-6 m3, and volume of the condenser CD is set equal to or smaller than 750×10-6 m3. Thus, a filling amount of the flammable refrigerant required for one refrigeration circuit 34 can be suppressed to or below a specified value.