Predictive control for greenhouse temperature and humidity and energy optimization by improved NMPC objective function algorithm

Persistent low temperatures in autumn and winter have a huge impact on crops,and greenhouses rely on solar radiation and heating equipment to meet the required indoor temperature.But the energy cost of frequent operation of the actuators is exceptionally high.The relationship between greenhouse environmental control accuracy and energy consumption is one of the key issues faced in greenhouse research.In this study,a non-linear model predictive control method with an improved objective function was proposed.The improved objective function used tolerance intervals and boundary constraints to optimize the objective evaluation.The nonlinear model predictive control(NMPC)controller design was based on the wavelet neural network(WNN)data-driven model and applied the interior point method to solve the optimal solution of the objective function control,thus balancing the contradiction between energy consumption and control precision.The simulation results showed that the improved NMPC method reduced energy consumption by 21.02%and 9.54%compared with the model predictive control and regular NMPC,which proved the method achieved good results in a low-temperature environment.This research can provide an important reference for the field as it offers a more efficient approach to managing greenhouse climates,potentially leading to substantial energy savings and enhanced sustainability in agricultural practices.

The viability of using gasoline-integrated biodiesel-diesel mixtures in engines as a solution to greenhouse gas emissions:a review

The implementation of alternative fuels,such as biodiesel,in engines has been shown to be a feasible strategy to control greenhouse gas(GHG)emissions.The blending of biodiesel with diesel can reduce emissions of carbon monoxide(CO)and carbon dioxide and reduce soot formation.Nonetheless,biodiesel combustion comes with low thermal efficiency,elevated emissions of nitrogen oxides(NOx)and carbon deposition issues.Recently,the addition of gasoline to diesel-biodiesel blends has been proposed to compensate for the downsides of biodiesel combustion.In the current review,the viability of using this ternary fuel blend in engines is thoroughly reviewed.The review first assesses the environmental and health issues caused by conventional fuels,mitigation schemes to control GHG emissions and alternative fuels as a decarbonizing technology.The combustion and emissions characteristics of diesel-bio-diesel-gasoline mixtures are discussed in detail.Finally,the status,challenges and prospects of applying the alternative fuel mixture in engines are appraised.This work has revealed that the mixing of gasoline with diesel-biodiesel blends brings about elongated ignition delay,increased heat release rate and in-cylinder pressure at high loads.Additionally,by adding gasoline,the combustion duration is shortened and soot,CO and unburned hydrocarbon emissions are suppressed,while NOx emissions are slightly increased.Combustion stability is found to be partially disrupted in the presence of gasoline whereas fuel economy(at medium and high loads)is improved by the addition of gasoline.To support the wider deployment and commercialization of this fuelling strategy in the transportation sector,favourable legislation and/or fiscal incentives are needed in countries around the world.This would encourage researchers,fuel producers and engine manufacturers alike to solve challenges such as biodiesel feedstock costs,fuel quality,fuel storage management and engine warranty issues.

A modeling framework for the integration of electrical and thermal energy systems in greenhouses

Greenhouse horticulture is associated to a significant energy consumption in temperate countries,mainly for lighting and for heating.Interestingly,the potential for energy optimization and energy savings is high but requires detailed models capable of considering various system configurations and control systems.This paper provides an open-source modeling framework capable of simulating and optimizing the design and the control of both the greenhouse and the generation systems covering all energy needs.The proposed model is composed of sub-models from different scientific fields:a greenhouse climate model,a crop yield model,a large number of energy generation and storage units models and different rule-based control strategies.The association of such state-of-the-art models in a single framework provides a powerful tool for optimization purposes and allows the definition of completely customized systems by means of an object-oriented interface.In this work,various control strategies are defined and simulated,thus demonstrating the capabilities of the proposed model.Results indicate that,by performing minor changes to the control of the thermal screen,heating consumption can be reduced by 3%without any loss in crop yield.The control of heat-generation units also has a significant impact on the operational costs,which vary by up to 17%when self-consumption levels are accounted for in the control strategy.

Fuel poverty and low carbon emissions: a comparative study of the feasibility of the hybrid renewable energy systems incorporating combined heat and power technology

Fuel poverty is most prevalent in North East England with 14.4%of fuel poor households in Newcastle upon Tyne.The aim of this paper was to identify a grid connected renewable energy system coupled with natural gas reciprocating combined heat and power unit,that is cost-effective and technically feasible with a potential to generate a profit from selling energy excess to the grid to help alleviate fuel poverty.The system was also aimed at low carbon emissions.Fourteen models were designed and optimized with the aid of the HOMER Pro software.Models were compared with respect to their economic,technical,and environmental performance.A solution was proposed where restrictions were placed on the size of renewable energy components.This configuration consists of 150 kW CHP,300 kW PV cells,and 30 kW wind turbines.The renewable fraction is 5.10%and the system yields a carbon saving of 7.9%in comparison with conventional systems.The initial capital investment is$1.24 million which enables the system to have grid sales of 582689 kWh/a.A conservative calculation determined that 40%of the sales can be used to reduce the energy cost of fuel poor households by$706 per annum.This solution has the potential to eliminate fuel poverty at the site analyzed.