Chiller Evaporator Spillover Port for Refrigerant Level Control

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Solution Overview

Problem

HVAC systems face challenges in maintaining optimal refrigerant levels in heat exchangers, leading to inefficiencies and lubrication issues in compressors, as existing methods fail to effectively balance refrigerant distribution between condensers and evaporators, especially under varying load conditions.

Innovation Solution

The implementation of a spill over port system in evaporators, coupled with a heat exchanger and temperature sensor, allows for the regulation of refrigerant flow to maintain optimal refrigerant levels by vaporizing spill over refrigerant to a slightly superheat temperature, directing the oil-rich refrigerant back to the compressor, and using a refrigerant level measuring device to adjust condenser levels, thereby balancing refrigerant distribution based on load conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If refrigerant level in evaporator is maintained at optimal level, then operational efficiency improves, but system complexity increases due to additional control mechanisms

Engineering Contradiction:

Improveoperational efficiencyVSAvoidcontrol system complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The spill-over port creates a self-regulating system where the evaporator automatically manages its own refrigerant level by allowing excess refrigerant to escape. This self-service mechanism eliminates the need for complex level sensors and control algorithms that would otherwise be required to maintain optimal refrigerant levels, thereby improving operational efficiency without proportionally increasing system complexity.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The system monitors temperature of the spill-over refrigerant as a proxy parameter for evaporator refrigerant level. By using temperature as the control parameter instead of direct level measurement, the system achieves effective refrigerant level management with simpler sensing requirements and less complex control logic, maintaining operational efficiency while limiting complexity growth.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If spill over refrigerant is vaporized and returned to compressor, then compressor lubrication improves, but energy consumption increases

Engineering Contradiction:

Improvecompressor lubricationVSAvoidenergy consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The system converts what would normally be wasted spill-over refrigerant (a potential loss) into a beneficial lubrication source for the compressor. By capturing and vaporizing the spill-over refrigerant, the system ensures that oil-rich refrigerant is returned to the compressor for lubrication, transforming a potential efficiency loss into a reliability gain without requiring additional energy-intensive oil circulation systems.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

Instead of discarding the spill-over refrigerant or allowing it to be lost, the system recovers it by vaporizing and returning it to the compressor. This recovery process ensures that the lubricating oil contained in the spill-over refrigerant is preserved and delivered back to where it is needed, improving compressor lubrication while minimizing the net energy penalty by reusing existing refrigerant rather than introducing additional energy-consuming lubrication mechanisms.

Inventive Principle:

Principle #34Discarding and recovering

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 solution enhances operational efficiency of chiller systems by maintaining optimal refrigerant levels, ensuring proper lubrication, and detecting refrigerant leakage, while adjusting refrigerant distribution dynamically to match changing load conditions.

Implementation Method 1

the heat exchanger is configured to receive the heat source to vaporize the spilled over refrigerant in the heat exchanger

Methodology Applied

Scientific EffectVaporization: Evaporation

Implementation Method 2

the heat exchanger is configured to receive the heat source to vaporize the spilled over refrigerant in the heat exchanger; the temperature sensor is configured to measure a temperature of the spilled over refrigerant when the spilled over refrigerant departs the heat exchanger

Methodology Applied

Scientific EffectHeat transfer: Heating

Data Source

PatentUS10422559B2Refrigerant level management in heat exchangers of an HVAC chiller

Publication Date: 2019.09.24 TRANE INTERNATIONAL INC

AI summary

Methods and systems to manage refrigerant levels in a chiller system are provided. An evaporator of the chiller system may be configured to have a spill over port allowing oil containing refrigerant to spill over through the spill over port. The spill over port may be positioned at a place that corresponds to a desired refrigerant level in the evaporator. The spill over refrigerant may be directed into a heat exchanger that is configured to substantially vaporize refrigerant of the spill over refrigerant to a slightly superheat temperature. A method of maintaining a proper refrigerant level in the evaporator may include regulating a refrigerant flow to the evaporator so that the vaporized refrigerant of the spill over refrigerant is maintained at the slightly superheat temperature.