Absorption Chiller Step Flow Control Against Crystallization

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Solution Overview

Problem

Absorption chillers face inefficiencies and challenges such as solar field depletion, uneven evaporator and generator load balancing, and absorbent solution crystallization, which hinder their adoption and performance.

Innovation Solution

The implementation of a Step Flow (SF) control device for absorption chillers, which balances heat energy flow by adjusting load values and transmitting control signals to variable frequency drives, preventing crystallization of the lithium bromide salt and improving the coefficient of performance (COP) through efficient management of refrigerant flow and temperature/pressure differences.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If absorption cooling is used to avoid electrical compressors and utilize heat energy, then environmental friendliness and energy cost reduction are improved, but system reliability and performance stability deteriorate due to crystallization risks and inefficiencies

Engineering Contradiction:

Improveenvironmental impact and energy costVSAvoidsystem reliability

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The control device continuously monitors operating conditions of the absorption chiller and dynamically adjusts the heat input to the generator based on real-time system state, preventing crystallization by maintaining optimal operating parameters through closed-loop feedback control

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system transitions from static, fixed operation to dynamic, adaptive control where the heat input and refrigerant flow are continuously adjusted based on varying load conditions and system state, improving reliability across different operating scenarios

Inventive Principle:

Principle #15Dynamics

2Device complexity

If traditional absorption chiller operation is used, then system simplicity is maintained, but coefficient of performance deteriorates due to uneven load balancing and energy inefficiency

Engineering Contradiction:

Improvesystem simplicityVSAvoidcoefficient of performance

Core Design Contradiction:

Device complexityVSProductivity

Solution Approach 1:

The control device dynamically adjusts the heat input to the generator based on real-time load conditions and system state, optimizing the coefficient of performance by maintaining optimal operating parameters across varying conditions without requiring complex mechanical modifications to the absorption chiller

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system optimizes performance by dynamically changing operating parameters such as heat input rate and refrigerant flow conditions based on load variations, allowing the absorption chiller to maintain high efficiency across part-load and full-load operations

Inventive Principle:

Principle #35Parameter changes

3Power

If heat input to the generator is increased to meet cooling demand, then cooling capacity is improved, but absorbent solution crystallization risk increases

Engineering Contradiction:

Improvecooling capacityVSAvoidcrystallization risk

Core Design Contradiction:

PowerVSObject-affected harmful factors

Solution Approach 1:

The control device monitors system conditions including solution concentration and temperature, and dynamically adjusts heat input to the generator to maintain cooling capacity while preventing the solution from reaching crystallization conditions through real-time feedback control

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The control device proactively adjusts heat input before crystallization conditions are reached by monitoring trends in solution concentration and temperature, preventing crystallization rather than responding after it occurs

Inventive Principle:

Principle #10Preliminary 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

SF enhances the efficiency and reliability of absorption chillers by reducing crystallization risks, optimizing refrigerant circulation, and maintaining critical differential pressures and temperatures, thereby improving overall cooling system efficiency and preventing costly downtime.

Implementation Method 1

Absorption cooling is founded on well-established principals developed in the late 1700s. Instead of relying upon an electrically powered compressor, absorption cooling utilizes heat as energy to cool a building or other structure.

Methodology Applied

Scientific EffectAbsorption cooling: Absorption (physical)

Implementation Method 2

the step of generating electrical power, as found in compressor driven cooling methods, can be avoided altogether

Methodology Applied

Scientific EffectAbsorption: Absorption (physical)

Data Source

PatentUS10215466B1Step flow chiller control device and methods therefor

Publication Date: 2019.02.26 HIGGINS ROBERT

AI summary

A Step Flow control device and methods therefore provide instructions to control operation of various absorption chiller components based on measured load or temperature information. Operating an absorption chiller according to Step Flow balances the flow of heat energy through the absorption chiller to increase efficiency and prevent crystallization. The control device may be integrated into various components of an absorption chiller or may be remote therefrom. In this manner, Step Flow can be used in new absorption chiller installations or be used to retrofit existing installations.