Compressor Oil Reservoir Heating to Prevent Refrigerant Dissolution

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Solution Overview

Problem

The refrigeration cycle apparatus experiences oil exhaustion in the compressor due to refrigerant dissolution in the oil reservoir, leading to decreased oil concentration, reliability issues, and reduced refrigerant volume, causing performance and overflow problems.

Innovation Solution

A refrigeration cycle apparatus with a heater that heats the refrigeration oil separated by the oil separator to prevent refrigerant dissolution, maintaining oil concentration and preventing overflow, and includes a controller to regulate the oil returning process based on temperature and compressor operation frequency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the oil reservoir container is provided to store surplus oil, then oil exhaustion during normal operation is prevented, but refrigerant dissolves in the oil during non-operational periods, decreasing oil concentration and causing oil exhaustion

Engineering Contradiction:
Improvecompressor reliabilityVSAvoidoil concentration
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The patent changes the temperature parameter of the refrigeration oil by introducing a heating mechanism. The heating device raises the oil temperature during non-operational periods, reducing refrigerant solubility in the oil and preventing refrigerant dissolution. This parameter change (temperature increase) directly addresses the contradiction by maintaining oil concentration while still allowing oil storage in the reservoir container.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent applies preliminary action by heating the refrigeration oil before refrigerant dissolution occurs. The heating device is activated during non-operational periods to preemptively prevent refrigerant from dissolving in the stored oil, thereby maintaining oil concentration before the problem can arise.

Inventive Principle:
Principle #10Preliminary action

2Quantity of substance

If the refrigerant is dissolved in the refrigeration oil within the oil reservoir container, then the volume of the oil increases, but overflow is caused in the oil reservoir container

Engineering Contradiction:
Improverefrigerant volumeVSAvoidoil reservoir container volume
Core Design Contradiction:
Quantity of substanceVSVolume of stationary object

Solution Approach 1:

The patent changes the temperature parameter to reduce refrigerant solubility in the oil. By heating the refrigeration oil during non-operational periods, the refrigerant is prevented from dissolving in the oil, thereby preventing volume increase and overflow in the oil reservoir container.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent implements feedback control through the controller that monitors system conditions and activates the heating device when refrigerant dissolution is detected or anticipated. The controller regulates the heating based on operational status, creating a feedback loop that prevents overflow while managing refrigerant volume.

Inventive Principle:
Principle #23Feedback

3Quantity of substance

If the amount of refrigerant sealed in the refrigerant circuit is increased to maintain appropriate refrigerant amount, then refrigerant dissolution is compensated, but the device complexity and initial charge requirement increase

Engineering Contradiction:
Improverefrigerant amountVSAvoidrefrigerant circuit complexity
Core Design Contradiction:
Quantity of substanceVSDevice complexity

Solution Approach 1:

Instead of increasing refrigerant amount, the patent changes the temperature parameter of the refrigeration oil to prevent refrigerant dissolution. This alternative approach maintains the original refrigerant charge while using thermal control to manage oil concentration, avoiding the need for additional refrigerant and the associated complexity.

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

The solution effectively prevents oil exhaustion, maintains optimal oil concentration, reduces refrigerant volume, and enhances compressor reliability by heating the refrigeration oil, thereby improving the refrigeration cycle's performance and preventing overflow.

Implementation Method 1

a heater configured to heat the refrigeration oil separated by the oil separator

Methodology Applied
Scientific EffectHeating: Heating

Implementation Method 2

The oil reservoir container is disposed below the oil separator. The oil reservoir container is configured to allow the refrigeration oil separated by the oil separator to flow thereinto via the oil inflow pipe due to its weight.

Methodology Applied
Scientific EffectGravitational separation: Gravitation

Data Source

PatentEP3722700B1Refrigeration cycle device
Publication Date: 2023.10.18 MITSUBISHI ELECTRIC CORP
  • EP3722700B1 patent drawingFigure 1
  • EP3722700B1 patent drawingFigure 2
  • EP3722700B1 patent drawingFigure 3

AI summary

A refrigeration cycle apparatus (200) includes a refrigerant circuit (30) in which refrigerant circulates in the order of a compressor (1), an oil separator (2), a first heat exchanger (3), a decompressing apparatus (4), and a second heat exchanger (5) and returns to the compressor (1). The refrigeration cycle apparatus (200) further includes: an oil reservoir (6) configured to store refrigeration oil; a first pipe (21) that connects the oil separator (2) and the oil reservoir (6), the first pipe (21) being configured to send the refrigeration oil separated by the oil separator (2) to the oil reservoir (6); a second pipe (22) that connects the oil reservoir (6) and a suction side of the compressor (1); a third pipe (23) that connects the oil reservoir (6) and the suction side of the compressor (1) at a position lower than a position at which the second pipe (22) is connected to the oil reservoir (6); and a heater (10) configured to heat the refrigeration oil separated by the oil separator (2).