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Re: [TRNSYS-users] Modelling a Greenhouse in TRNSYS (Vegetation)



Hello,

You are on the right track concerning modelling greenhouse vegetation. As you suggest, you can create a Type for the vegetation and use outputs of heat transfer rate (kJ/hr) and water vapor flow rate (kg/hr) as inputs to a Gain in Type 56. Model equations can be found for example in this PhD thesis:

Hendrik Feije de Zwart, 1996: "Analyzing energy-saving potensials in a greenhouse cultivation using a simulation model". PhD. Dissertation, Landbouwuniversiteit, Wageningen.

Hope this helps.

Kind regards,

Knut Erik Enerstvedt


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From: Tammo Bruinsma <tammo.bruinsma@me.queensu.ca>
To: "trnsys-users@cae.wisc.edu" <trnsys-users@cae.wisc.edu>
Cc: 
Date: Wed, 21 May 2014 15:52:44 +0000
Subject: [TRNSYS-users] Modelling a Greenhouse in TRNSYS (Vegetation)
Hello,

I am currently working on a model of a greenhouse in TRNSYS. I have gotten as far as crating the 3D model in Google Sketchup and importing it into TRNBuild Type 56. The temperature and humidity control for the greenhouse will be handled by an external liquid desiccant unit that I am still in the process of creating. 

I am more concerned about the internal characteristics of the greenhouse. I have created a structure with mostly windows and although I have not yet been able to apply a double polyethylene type to them this shouldn't pose too much of a problem. I read somewhere that the Type 56 does not account for radiation that crosses through parallel windows and back out of the greenhouse, has anyone found a solution for this? 

Another puzzling process is the transpiration and respiration of the plant vegetation. I am aware of the equations that model these factors but do not know how to apply them to the system. One possibility might be to create an external type for the vegetation and use the necessary outputs as input variables into the Type 56 Building. Or possibly adding a "Gain" in TRNBuild that might account for the added humidification and CO2 levels, although I am not sure how this would work.

I was hoping someone might be able to shed some light on these issues and if there are any working models around I would very much appreciate taking a look at one.

Sincerely,

Tammo Bruinsma