Authors: Alex Nauta, William David Lubitz, Syeda Tasnim, Shohel Mahmud
Identifier: CSBE21796
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Published in: CSBE-SCGAB Technical Conferences » 5th CIGR and AGM Quebec City 2021 » Regular Sessions

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Description: This project sought to model the energy pathways in a greenhouse located at the Guelph Center for Urban and Organic Farming. To accomplish this objective, a 1D transient lumped capacitance model was developed using Python software, which accounted for radiation, conduction and convection heat transfer within the greenhouse structure. Measurement data collected at the site from March 5th to March 10th, 2014 was used to assess model accuracy in predicting air and soil temperatures using summative heat transfer equations. Parameters unique to the greenhouse were used to define the model. A baseline scenario was developed for the model based on literature results and past measurements at the site. Due to the large variation of values in literature, one focus of the modelling investigation was evaluating the optimal emissivity of the glazing film for IR radiation. Other focuses of the study included finding the best radiant sky temperature model, and air leakage relationship. A single variable sensitivity analysis was performed on these three parameters at baseline conditions, as well as at ten randomized configurations. Heat transfer equations used in the model were sourced primarily from previous work. Energy pathways into, and out of, each layer was evaluated at each six second time step, with the summative thermal energy value being used to find the resulting temperature change for that layer.Once the simulation was completed, the results were assessed, with the mean absolute error between measurements and simulation temperatures at baseline conditions being 3.37oC and 3.46oC for soil and air temperatures, respectively.

Keywords: thermal modelling, passive greenhouse, emissivity, 1D lumped capacitance, IR radiation, polyethylene glazing, soil temperature, natural convection, conductive heat transfer
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Date: 2021-06-11
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Conference name: 5th CIGR International Conference and CSBE-SCGAB AGM 2021, Quebec City,QC, 11-14 May 2021.
Session name: Plant Systems & Posteharvest Technology 3

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Type: Text.Abstract
Publication type: Presentation
Language 1: en
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Rights: Canadian Society for Bioengineering
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