Modelling and optimal climate control of the crop production process in Chinese solar greenhouses

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Sun, W, 2024. Modelling and optimal climate control of the crop production process in Chinese solar greenhouses. PhD, Nottingham Trent University.

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Abstract

The Chinese solar greenhouse (CSG), known for its low cost of operation, is a prevalent greenhouse type in Northern China. Climate control of CSG is required for efficient crop production with high yield and quality at low energy and resource costs. However, current heuristic control schemes have limited success in maximising the net revenue of CSG cultivation. Optimal control presents a promising method for improving efficiency of greenhouse production, but few optimal CSG climate control systems have been developed. On the one hand, a well-designed and thoroughly validated integrated model of CSG climate and crop growth, which serves as a basis for optimal control, is unavailable. On the other hand, a user-friendly optimal control algorithm for climate management of a standard CSG without the local controller is currently unavailable. This project aims to model the crop production process and generate an applicable optimal climate control approach for standard CSGs. Firstly, this study developed a lettuce growth model that describes the effects of a broad range of greenhouse climates, including air temperature with extreme conditions, humidity, CO2 concentration, and shortwave radiation on dynamics of the single state variable, structural crop dry weight. Secondly, we developed and evaluated a CSG climate model to predict indoor radiation, temperature, humidity, and CO2 based on external weather, greenhouse structure, crops, and controls. Thirdly, the two developed models were synthesized into an integrated CSG climate-crop growth model, which was validated and then smoothed for control purposes. Fourthly, an optimal control system for CSG climate management using event-driven receding horizon design incorporated with real-time feedback was designed and evaluated. Performance comparisons were conducted among ideal optimal control, open loop optimal control, closed loop optimal control, and control supervised by growers. This study provides system models and an optimisation framework for implementing optimal control theory in practical CSG cultivation.

Item Type:	Thesis
Creators:	Sun, W.
Contributors:	Name Role NTU ID ORCID Lu, C. Thesis supervisor ARE3LUC https://orcid.org/0000-0002-0064-4725 Coules, A. Thesis supervisor MBC3COULEA UNSPECIFIED
Date:	May 2024
Rights:	The copyright in this work is held by the author. You may copy up to 5% of this work for private study, or personal, non-commercial research. Any re-use of the information contained within this document should be fully referenced, quoting the author, title, university, degree level and pagination. Queries or requests for any other use, or if a more substantial copy is required, should be directed to the author.
Divisions:	Schools > School of Animal, Rural and Environmental Sciences
Record created by:	Melissa Cornwell
Date Added:	28 Jan 2025 16:39
Last Modified:	28 Jan 2025 16:39
URI:	https://irep.ntu.ac.uk/id/eprint/52939