Abstract

BELLON HERNANDEZ, Oscar; AMADOR SOTO, Humberto  and  RODRIGUEZ LOZANO, Erika. Design and simulation of a discrete time controller for regulating temperature in a scale greenhouse. Prospect. [online]. 2016, vol.14, n.1, pp.80-88. ISSN 1692-8261.  https://doi.org/10.15665/rp.v14i1.646.

This paper describes the design process of a temperature controller working in discrete time to keep the inside greenhouse against destructive effect of climate night freeze. Specific heat capacity and speed of airflow at a greater temperature than the outside one were used as manipulated variables not simultaneously. First, a dynamic model was analytically deduced involving mentioned input variables along with the temperature inside the greenhouse as the output variable. The validation procedure was based on the input thermal power step response of the system and thermal behavior in steady state. A factorial design was implemented to determine other parameters generated by the inclusion of the inflow speed variable. This result was the starting point for simulating assessment tests of performance controller obtained in scenarios where the outside temperature in the greenhouse was configured to represent two situations: outside environmental temperature at the freezing point and temperature behavior during the course of a climate night freeze by radiation. Such simulated situations showed that the controller kept the system without risk of frost damage.

Keywords : Discrete time controller; Regulating temperature; Greenhouse modeling; Freeze; Thermal power; Inflow speed.

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