Air Conditioner Compressor Control for Oil Viscosity at Part Load

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Solution Overview

Problem

Air conditioners and refrigeration systems face inefficiencies and reliability issues when operating at part load due to fluctuations in temperature and pressure, leading to decreased oil viscosity and potential oil dilution, which affects compressor performance.

Innovation Solution

The system manages compressor operations by controlling oil viscosity, temperature differentials, and suction pressure through adjustments to fan speeds, compressor operations, and crankcase heater management, maintaining these parameters within predetermined ranges to inhibit oil migration and dilution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If air conditioners operate at part load, then energy consumption is reduced, but oil viscosity decreases and compressor performance deteriorates

Engineering Contradiction:

Improveenergy consumptionVSAvoidcompressor performance

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The system dynamically adjusts operating parameters (fan speeds, compressor capacity, crankcase heater operation) to maintain oil viscosity within acceptable ranges during part load operation, resolving the contradiction between energy savings and compressor performance

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The controller continuously monitors oil temperature, suction pressure, and superheat conditions, and adjusts system operations based on feedback to prevent oil dilution and maintain reliable compressor operation at part load

Inventive Principle:

Principle #23Feedback

2Use of energy by moving object

If air conditioners operate at part load, then energy consumption is reduced, but temperature and pressure fluctuations increase

Engineering Contradiction:

Improveenergy consumptionVSAvoidtemperature and pressure stability

Core Design Contradiction:

Use of energy by moving objectVSStability of the object's composition

Solution Approach 1:

The system employs dynamic control of fan speeds and compressor capacity to adapt to varying load conditions while maintaining stable operating parameters, allowing energy-efficient part load operation without excessive temperature and pressure fluctuations

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

By adjusting operational parameters such as fan speeds and compressor capacity based on real-time conditions, the system maintains temperature and pressure stability during part load operation

Inventive Principle:

Principle #35Parameter changes

3Reliability

If fan speeds are reduced to lower suction pressure, then oil viscosity is maintained, but cooling capacity decreases

Engineering Contradiction:

Improveoil viscosity maintenanceVSAvoidcooling capacity

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The system separately controls different components (compressor capacity, fan speeds, expansion valve) to independently manage oil viscosity and cooling capacity, allowing optimization of both parameters without direct trade-off

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system adjusts multiple parameters simultaneously (compressor capacity, fan speeds, expansion valve position) to maintain oil viscosity while preserving cooling capacity through coordinated control

Inventive Principle:

Principle #35Parameter changes

4Reliability

If compressor operations are restricted to maintain oil temperature, then oil viscosity is maintained, but system efficiency decreases

Engineering Contradiction:

Improveoil viscosity maintenanceVSAvoidsystem efficiency

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The system uses periodic or conditional activation of crankcase heaters rather than continuous operation, maintaining oil viscosity during critical periods while minimizing energy consumption during stable operating conditions

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The system dynamically adjusts crankcase heater operation and compressor capacity based on real-time oil temperature and load conditions, maintaining oil viscosity while optimizing system efficiency through conditional parameter changes

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 approach enhances the performance, reliability, and cost efficiency of air conditioners by maintaining optimal oil viscosity and preventing oil issues during varying operating conditions.

Implementation Method 1

crankcase heater management, maintaining these parameters within predetermined ranges to inhibit oil migration and dilution

Methodology Applied

Scientific EffectHeating: Heating

Implementation Method 2

adjustments to fan speeds, compressor operations, and crankcase heater management

Methodology Applied

Scientific EffectFan: Fan

Data Source

PatentUS9482454B2Compressor operation management in air conditioners

Publication Date: 2016.11.01 LENNOX IND INC

AI summary

In various implementations, compressor operation in an air conditioner may be managed by maintaining oil viscosity, a temperature differential, compressor sump temperature, and/or suction pressure. Properties of the air conditioner or portions thereof, such as the compressor, may be determined. To manage compressor operations, operation(s) of the air conditioner may be adjusted based on one or more of the determined properties.