Effect of greenhouse design parameters on conservation of energy for greenhouse environmental control

2003 ◽  
Vol 44 (2) ◽  
pp. 115
2003 ◽  
Vol 40 (1-3) ◽  
pp. 153-177 ◽  
Author(s):  
G.D. Pasgianos ◽  
K.G. Arvanitis ◽  
P. Polycarpou ◽  
N. Sigrimis

2020 ◽  
Author(s):  
Chia-Hui Hsu ◽  
Angela Huang ◽  
Fi-John Chang

<p>Maintaining stable crop production is the main benefit of greenhouses, which, however, would consume additional resources to control the indoor environment, as compared to open field cultivation. In consideration of Water-Food-Energy Nexus (WFE Nexus) management, it’s important to build an integrated methodology to estimate and optimize the crop production and resources consumption of greenhouses. Since the crop production of greenhouses is predictable if the indoor environment is well controlled, the main thing we should consider is how to reduce the water and energy consumption as much as possible during the environmental control process for greenhouses. For this purpose, we first build a machine learning-based model to predict indoor environment, including air temperature, relative humidity (RH), and soil water content, for a greenhouse that grows crops. Then according to the suitability criteria of the crop, the predicted values are utilized for environmental control if the values violate the criteria. Under such circumstance, an estimation model is established to determine which type and level of control mechanisms upon water and energy should be activated for meeting the suitability criteria to maintain stable crop production. The study area is a cherry tomato greenhouse located at the farm in Changhua County, Taiwan, where a total of 44,310 datasets were recorded by Internet of Things (IoT) from 2018 to 2019 at a 10-minute temporal resolution. This study also evaluates the efficiency of greenhouses under different scenarios of climatic conditions. The results are expected to contribute to the automatic greenhouse environmental control for stimulating the synergies of the WEF Nexus management toward sustainable development.</p><p>Keywords: Water-Food-Energy Nexus (WFE Nexus); Greenhouse; Machine learning; Internet of Things (IoT)</p>


Author(s):  
Rahim K. Jassim ◽  
Badr A. Habeebullah ◽  
Abdulraof S. Habeebullah

Energy recovery devices can have substantial impact on process efficiency and their relevance to the problem of conservation of energy resources is generally recognised to be beyond dispute. One type of such a device, which is commonly used in fossil fired and air conditioning systems, is the rotary regenerator in which a stream of hot waste gas exchanges heat with fresh atmospheric air through the intermediate agency of a rotating matrix. As there are gas streams involved in the heat transfer and mixing processes, then there are irreversibilities, or exergy destruction, due to chemical reaction, pressure losses I˙ΔP and due to temperature gradients I˙ΔT . These principle components of total process irreversibility are not independent and there is a trade-off between them. Therefore the purpose of this research paper is to demonstrate the importance of the use of exergy analysis in the minimisation of carryover leakage irreversibilities of a symmetric balanced rotary regenerator. The chemical exergy E˙o and physical exergy E˙ph are calculated and the ratio of chemical and physical irreversibilities has been evaluated for a rotary regenerator used for air preheating in a coal-fired power plant. A numerical finite difference technique has been used to calculate the fluid and matrix temperature distributions effect on the regenerator performance. The effects of variation of the principal design parameters on the irreversibilities and on the regenerator effectiveness are examined and recommendations are made for the selection of the most appropriate parameters.


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