Tuning eQUEST for Plastic Shell Greenhouses with Dirt Floors
Michael Stiles,
Brendan Kelly
Issue:
Volume 12, Issue 2, March 2023
Pages:
22-28
Received:
26 April 2023
Accepted:
18 May 2023
Published:
5 June 2023
Abstract: As growers expand year-round crop production in cold climates, considerable attention is being directed towards the energy performance of plastic shell greenhouses where crops grow in the native soil. A fundamental aspect of these structures is their temperature response in the absence of HVAC equipment. A review of the technical literature shows an absence of studies that reconcile thermal modeling of plastic greenhouses with actual field performance. Modeling studies typically emphasize parameters concerned only with the energy-saving performance of isolated components or systems like electric lighting or thermal curtains. The more fundamental parameters are unstated and presumably assume the default settings of the simulation tool. This paper investigates the implications of these modeling practices with respect to the passive temperature response of these structures. A set of criteria for reconciling modeled passive temperature response with field data-based performance has been developed previously for this type of greenhouse. Using the industry-standard simulation tool eQUEST as an example, we show that default parameters for the shell and for ground coupling do not reproduce key features of actual temperature response of these structures to ambient conditions. This paper reports work-arounds and parameter-tunings for eQUEST that produced a simulation that met the reconciliation criteria. These results call into question the suitability of present modeling approaches for baselining this type of greenhouse in simulations of active HVAC. Recommendations include revisiting the source files of published past simulations and directing the attention of industry stakeholders to these issues.
Abstract: As growers expand year-round crop production in cold climates, considerable attention is being directed towards the energy performance of plastic shell greenhouses where crops grow in the native soil. A fundamental aspect of these structures is their temperature response in the absence of HVAC equipment. A review of the technical literature shows a...
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Determination of the Characteristic Parameters of a Pump for the Irrigation of Large Surfaces
Monsieur Moussa Cheikh Mall,
Amadou Seidou Maiga,
Ndongo Mamoudou
Issue:
Volume 12, Issue 2, March 2023
Pages:
29-35
Received:
25 April 2023
Accepted:
26 May 2023
Published:
20 June 2023
Abstract: From human motricity, to electric motricity, moving on to animal and mechanical motricity, man has always sought to satisfy his water needs while using appropriate technologies. To meet its needs, equipment is installed that will transport water from one intake point to another recovery point with a certain speed. Having chosen the type of hydraulic structure (well, borehole or body of water) and the mode of consumption (human, animal or plant), the sizing of suitable equipment is necessary for optimal use of water. Plant water consumption is governed by heat exchanges between the ambient air and the surface of the water and then from the latter to the subsoil. Thus the nature of the ecosystem (subsoil, surface of the water, the plant, the immediate atmosphere, the geographical area, etc.) will be decisive in calculating the water needs of the plant. As much, it can be said that the water height also obeys the laws of fluid dynamics, particularly the equation of the Bernoulli theorem applied under specific conditions in this article. Among its aforementioned technologies, photovoltaic solar pumping is increasingly becoming the most advanced in the context of climate change and sustainable development in regions where sunshine and insolation are not restrictive. Usually, an electric pump coupled with solar panels via an inverter is used to pump water from a source through a reservoir or into a distribution network. In general, in small scale and/or deep water irrigation the characteristic parameters of the pump are determined from pumping tests, whereas in large scales the capacity of the pumping system is determined from the meteorological conditions of the site. In this article, our calculations are made under specific conditions (drainage on surface water, centrifugal pump, high-flow irrigation.) to determine the characteristics of the pump flow rate (Q) and total head (HMT).
Abstract: From human motricity, to electric motricity, moving on to animal and mechanical motricity, man has always sought to satisfy his water needs while using appropriate technologies. To meet its needs, equipment is installed that will transport water from one intake point to another recovery point with a certain speed. Having chosen the type of hydrauli...
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