A 2 dimensional Hammerstein model for heating and ventilation control of conceptual thermal zones

The research behind this article aims to reduce the operational costs and energy consumption of closed-environment growing systems, or grow-cells. Essentially a sealed building with a controlled environment, and insulated from outside lighting, grow-cells are configured to suit the particular crop being produced. The article briefly reviews the concept and preliminary work in relation to a prototype being developed by the authors and collaborating industry partner. Here, limitations in the temperature control system can lead to significant thermal gradients and poor efficiency. In this regard, the main focus of the article concerns a novel approach to thermal modelling that includes quantitative identification of spatial zones with similar thermal characteristics and the estimation of steady state temperature functions based on the heater and fan input voltages. These are combined with either a linear or a state-dependent parameter model, to represent the transient response. This approach yields a Hammerstein type model which, in this article, is optimised and evaluated using experimental data collected from 30 ther-mocouples distributed around an environmental test chamber.