Cooling system and method of operating a cooling system

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Solution Overview

Problem

In cooling systems, liquid refrigerant can interfere with compressor operation and reduce its lifetime, as not all refrigerant evaporates in the evaporator, leading to liquid entering the compressor.

Innovation Solution

A system comprising a compressor, an accumulator upstream to collect liquid refrigerant, sensors to detect temperature and pressure, and a controller to determine the rate of liquid accumulation and vaporization, implementing control commands to prevent overflow and protect the compressor by shutting it down when maximum capacity is reached.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If refrigerant is added rapidly during charging mode, then charging efficiency is improved, but liquid refrigerant may overflow the accumulator and enter the compressor

Engineering Contradiction:

Improvecharging efficiencyVSAvoidcompressor protection

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The controller predicts future liquid accumulation in the accumulator by integrating the liquid accumulation rate over time, determining whether the liquid level will reach a dangerous threshold before it actually occurs. This preliminary prediction allows the system to take preventive action (shutting down the compressor) before liquid enters the compressor, enabling rapid charging while maintaining safety.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system continuously monitors temperature and pressure of the refrigerant, calculates the liquid accumulation rate based on these measurements, and uses this feedback to update the predicted liquid level in real-time. This closed-loop feedback mechanism allows the system to adapt to changing charging conditions and maintain reliable operation during rapid charging.

Inventive Principle:

Principle #23Feedback

2Reliability

If the accumulator size is increased to prevent liquid overflow, then compressor protection is improved, but system complexity and space requirements increase

Engineering Contradiction:

Improvecompressor protectionVSAvoidaccumulator size

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces the traditional mechanical solution (oversizing the accumulator) with a computational approach (predicting liquid accumulation using sensor data and integration). Instead of physically enlarging the accumulator to handle all possible liquid influx scenarios, the system uses real-time calculations to predict when liquid levels will reach critical thresholds, enabling precise control without excessive hardware.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system dynamically adjusts operational parameters based on predicted liquid accumulation. By monitoring temperature, pressure, and calculating accumulation rates, the controller can adjust compressor operation or charging rate to prevent liquid overflow, replacing the need for a large fixed-capacity accumulator with adaptive parameter control.

Inventive Principle:

Principle #35Parameter changes

3Duration of action of moving object

If liquid refrigerant enters the compressor, then compressor operation continues, but compressor lifetime is reduced

Engineering Contradiction:

Improvecompressor operation continuityVSAvoidcompressor lifetime

Core Design Contradiction:

Duration of action of moving objectVSDuration of action of stationary object

Solution Approach 1:

The system applies preliminary anti-action by predicting liquid accumulation and shutting down the compressor before liquid can enter. The controller calculates the predicted liquid level and, upon detecting that it will reach the dangerous threshold, preemptively stops the compressor operation. This prevents the harmful liquid entry while maintaining operational continuity through timely restarts, thereby extending compressor lifetime.

Inventive Principle:

Principle #9Preliminary anti-action

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

Effectively prevents liquid from entering the compressor, thereby protecting its operation and extending its lifetime by ensuring that the accumulator does not overflow, even during charging modes where refrigerant is added rapidly.

Implementation Method 1

an accumulator upstream from the compressor. The accumulator is operable to collect liquid from the refrigerant

Methodology Applied

Scientific EffectPhase separation: Two-Phase Flow

Implementation Method 2

A sensor is located upstream from the accumulator. The sensor is operable to detect information including a temperature and a pressure of the refrigerant

Methodology Applied

Scientific EffectTemperature detection: Thermocouple

Implementation Method 3

The controller is operable to determine a rate of vaporization of the liquid in the accumulator

Methodology Applied

Scientific EffectVaporization: Evaporation

Data Source

PatentUS11835275B2Cooling system and method of operating a cooling system

Publication Date: 2023.12.05 CARRIER CORP

AI summary

A cooling system includes a compressor operable to compress refrigerant, an accumulator upstream from the compressor. The accumulator is operable to collect liquid from the refrigerant. A sensor is located upstream from the accumulator. The sensor is operable to detect information including a temperature and a pressure of the refrigerant. The controller is in communication with the sensor. The controller is operable to determine a rate of accumulation of liquid in the accumulator based on the information from the sensor. A method of operating a cooling system is also disclosed.