HVAC Airflow Inversion Control for Target Thermal Distribution

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Solution Overview

Problem

Current HVAC systems face challenges in accurately predicting building energy consumption and optimizing performance due to limitations in building energy simulation models, which assume well-mixed indoor air and neglect stratified airflow and complex boundary conditions, leading to inaccurate thermal comfort and energy efficiency.

Innovation Solution

A control system that uses an airflow dynamics model to estimate thermal state distribution in the environment by reversing the control framework, where the thermal state of outputted air is the primary objective, and determines the necessary HVAC actuator states to achieve a target thermal state distribution, optimizing performance and energy consumption by adjusting boundary conditions related to HVAC system outputs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If building energy simulation models assume well-mixed indoor air to simplify computation, then computational complexity is reduced, but accuracy of thermal comfort and energy consumption predictions deteriorates due to neglecting stratified airflow and non-uniform heat loads

Engineering Contradiction:

Improvecomputation complexityVSAvoidprediction accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The indoor space is segmented into multiple thermal zones with different temperature levels, allowing the model to capture vertical stratification effects while maintaining computational efficiency through zone-based rather than fully continuous spatial discretization

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The control framework is inverted by treating thermal state distribution as the primary objective and HVAC actuator states as secondary, reversing the conventional approach where actuator control is primary and thermal outcomes are secondary byproducts

Inventive Principle:

Principle #13The other way round (Inversion)

2Measurement precision

If CFD models are used to predict airflow dynamics and temperature distribution, then accuracy of thermal state prediction is improved, but computational complexity increases and sophisticated boundary conditions cannot be accounted for

Engineering Contradiction:

Improvethermal state prediction accuracyVSAvoidmodel complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

An intermediary control layer is introduced that translates between simplified energy simulation models and detailed CFD airflow models, allowing accurate thermal predictions without directly solving complex CFD equations while still capturing stratified airflow effects

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The model merges the strengths of both BES and CFD approaches by integrating zone-based energy simulation with simplified airflow dynamics to capture thermal stratification without the full computational burden of complete CFD modeling

Inventive Principle:

Principle #5Merging (Combining)

3Ease of operation

If conventional HVAC control focuses on meeting set points through actuator states, then thermal comfort is achieved, but energy efficiency optimization is lost as thermal state of outputted air becomes a secondary byproduct

Engineering Contradiction:

Improvethermal comfort achievementVSAvoidenergy efficiency

Core Design Contradiction:

Ease of operationVSUse of energy by moving object

Solution Approach 1:

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The system implements feedback control by continuously monitoring actual thermal state distribution and adjusting HVAC actuator states to minimize the difference between predicted and measured thermal conditions, optimizing both comfort and energy efficiency

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS11162701B2Controlling HVAC system by inversing airflow dynamics

Publication Date: 2021.11.02 MITSUBISHI ELECTRIC RESEARCH LABORATORIES INC

AI summary

A control system for controlling an operation of a heating ventilation and air conditioning (HVAC) system is provided. The control system comprises an input interface configured to accept data indicative of a target distribution of thermal state in an environment, and a memory configured to store an airflow dynamics model (ADM) and an HVAC model. The control system further comprises a processor configured to inverse the ADM to estimate values of boundary conditions for inlet locations defining target thermal state at the inlet locations that result in the target distribution of thermal state in the environment; determine, using the HVAC model, target control parameters of actuators of the HVAC system resulting in the target thermal state at the inlet locations; and submit control commands to the HVAC system to operate the actuators of the HVAC system according to the control parameters.