Adaptive Heat Exchanger Flow Control for HVAC ΔT Efficiency

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Solution Overview

Problem

HVAC systems operate inefficiently at high fluid flow rates, consuming excessive energy with minimal additional heat transfer and requiring inefficient chiller sequencing, due to the need for manual setting of threshold flow and ΔT settings by users or technicians.

Innovation Solution

An adaptive flow limit controller determines an optimal threshold flow rate using an adaptive model that adjusts based on temperature difference and flow rate measurements, prioritizing energy consumption and occupant comfort, and automatically controls the flow rate to maintain efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the threshold flow rate is manually set by users or technicians, then the system can enforce flow limits, but the system requires specialized knowledge and manual configuration which reduces ease of operation

Engineering Contradiction:

Improveease of operationVSAvoiddevice complexity

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The controller automatically determines the threshold flow rate by monitoring system parameters and calculating the gradient of temperature difference with respect to flow rate, eliminating the need for manual configuration by users or technicians. The system self-adjusts based on real-time measurements, making operation simpler while maintaining sophisticated control capabilities.

Inventive Principle:

Principle #25Self-service

2Reliability

If the threshold flow rate is manually set by users or technicians, then the system can enforce flow limits, but incorrect settings lead to inefficient operation

Engineering Contradiction:

ImprovereliabilityVSAvoidease of operation

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The controller continuously monitors temperature difference and flow rate, calculates the gradient, and automatically adjusts the threshold flow rate setting based on real-time system conditions. This closed-loop feedback ensures optimal settings are maintained without requiring manual intervention, improving both reliability and ease of operation.

Inventive Principle:

Principle #23Feedback

3Productivity

If fluid flow rate increases through a heat exchanger, then more heat transfer capacity is available, but energy consumption increases with diminishing returns

Engineering Contradiction:

ImproveproductivityVSAvoiduse of energy

Core Design Contradiction:

ProductivityVSUse of energy by moving object

Solution Approach 1:

The system dynamically adjusts the threshold flow rate based on the calculated gradient of temperature difference with respect to flow rate. When the gradient becomes too shallow (indicating diminishing returns), the system automatically reduces the flow rate threshold, preventing operation in the inefficient high-flow region and optimizing the balance between productivity and energy consumption.

Inventive Principle:

Principle #15Dynamics

4Productivity

If fluid flow rate increases through a heat exchanger, then heat transfer capacity increases, but temperature difference across the coil decreases

Engineering Contradiction:

ImproveproductivityVSAvoidtemperature difference

Core Design Contradiction:

ProductivityVSTemperature

Solution Approach 1:

The controller continuously monitors the temperature difference across the heat exchanger and uses this feedback to calculate the gradient with respect to flow rate. When the temperature difference becomes too small (indicating inefficient operation), the system automatically adjusts the flow rate threshold downward, maintaining optimal temperature difference while preserving adequate heat transfer capacity.

Inventive Principle:

Principle #23Feedback

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 adaptive flow limit controller optimizes energy consumption and occupant comfort by automatically determining the threshold flow rate, reducing energy waste and improving HVAC system efficiency without requiring manual settings.

Implementation Method 1

heat exchangers to transfer energy between liquid and air

Methodology Applied

Scientific EffectHeat conduction: Conduction (thermal)

Implementation Method 2

transfer energy between liquid and air

Methodology Applied

Scientific EffectConvection: Convection

Implementation Method 3

flow rate sensor that measures a flow rate of the fluid through the heat exchanger

Methodology Applied

Scientific EffectFlow measurement:

Implementation Method 4

temperature sensors that measure a temperature difference of the fluid across the heat exchanger

Methodology Applied

Scientific EffectThermal detection:

Data Source

PatentUS11519631B2HVAC control system with adaptive flow limit heat exchanger control

Publication Date: 2022.12.06 TYCO FIRE & SECURITY GMBH

AI summary

An adaptive flow limit controller for controlling a flow rate of a fluid through a heat exchanger includes a processing circuit. The processing circuit is configured to use an adaptive model to determine a threshold flow rate of the fluid through the heat exchanger at which a gradient of a temperature difference of the fluid across the heat exchanger with respect to the flow rate of the fluid through the heat exchanger has a threshold gradient value. The processing circuit is configured to operate a flow control device to maintain the flow rate of the fluid of through the heat exchanger at less than or equal to the threshold flow rate.