A CFD Study of the Fluid Flow through Air Distribution Hoses in a Greenhouse

The indoor climate of a greenhouse provides the plants with favorable growing conditions that can result in faster growth and higher yields. Important parameters to control in a greenhouse are the temperature, the humidity, and the level of CO2 concentrations. In southern Europe, both heating and cooling are required to control the greenhouse temperatures throughout the year. In this study, Computational Fluid Dynamics (CFD) simulations is employed to study the fluid flow through air distribution hoses (ADHs) in a research greenhouse in Bucharest, Romania. The ADHs are part of a novel, energy-efficient concept at the greenhouse, comprised of an integrated heat pump system, air handling units (AHUs), a dry cooler, and borehole thermal energy storage. The heat pump system provides both heating and cooling, while the greenhouse humidity is controlled by the AHUs. CO2-enrichment to the greenhouse is provided from installed CO2 tanks. The CO2-enriched air is circulated from the AHUs to the ADHs, which have a series of perforated holes along their lengths. In these preliminary simulations, different configurations of the perforated holes are simulated to optimize the mixing of the climate-controlled air with the greenhouse air. Both the diameters of the holes and the opening of the ADH outlet are varied to study the mass flow rates out of the holes. The CFD simulations provide suitable design criteria for the installation of ADHs in a greenhouse environment and for optimizing the efficiency of ADHs. Copyright © 2023, AIDIC Servizi S.r.l.A CFD Study of the Fluid Flow through Air Distribution Hoses in a GreenhousepublishedVersio

Assessment of heating and cooling demands of a glass greenhouse in Bucharest, Romania

In southern parts of Europe, a balanced use of both heating and cooling is required to control the greenhouse temperatures throughout the year. Especially, with climate change and increasingly hot summers, the need for efficient greenhouse cooling and humidity control has become more and more important. In this work, we investigate the heating and cooling demands of a glass greenhouse located in Bucharest, Romania (latitude 44 N, longitude 26 E). The IDA Indoor Climate and Energy (IDA ICE) software is applied for the assessment of the energy demands, with weather data supplied using the integrated International Weather for Energy Calculations (IWEC) file for Bucharest. With a 2-degree wide deadband, the temperatures of the greenhouse compartments are set to 25°C and 19°C for day and night, respectively. The simulation gives an annual heating demand of 1,715 MWh for the greenhouse, corresponding to 638 kWh/m . The annual cooling demand is 1739 MWh, corresponding to 647 kWh/m . The maximum daily cooling load averages about 730 kW during the hottest summer months, while the maximum heat load averages about 590 kW for the coldest winter months. A novel, energy-efficient concept to be installed at the greenhouse, comprising an integrated heat pump system, air handling units, dry coolers, and the utilization of borehole thermal energy storage (BTES), is discussed in terms of the main principles and the required capacities of the system.Assessment of heating and cooling demands of a glass greenhouse in Bucharest, RomaniapublishedVersio

Organic fertilizer effect on lettuce (Lactuca sativa L.) cultivated in nutrient film technology

The survey was carried out in the Research Centre for the study of food products quality “HORTINVEST” between 2014-2015 using the Nutrient Film Technology (NFT) for the cultivation of lettuce. Three lettuce cultivars were used: Markies, Lollo bionda and Lollo rosa, together with three types of fertilizers: two organic fertilizers and a chemical one. Biometrical measurements on lettuce growth were conducted; also at the end of the cultivation cycle biochemical measurements were performed in order to assess plant quality. Also correlations between various biometrical parameters and influencing vegetal factors were settled. The results led towards gains in the plant growth rate, in the development of the leaf number and eventually in the production growth. For all lettuce varieties under research the total plant mass was higher due to organic fertilizers in comparison with plants under chemical fertilizer treatment. The plants organically fertilized proved to be superior as to the biochemical quality. Research was carried out in order to assess the quantitative and qualitative feedback of lettuce cultivated in Nutrient Film Technology (NFT) to various organic fertilizers which might replace chemical fertilizers

RESEARCH ON THE PRESENCE OF THE OROBANCHE CUMANA PARASITIC PLANT IN SUNFLOWER CULTURE

The economic importance of sunflower in Braila County has been the main motivation in the study of the Orobanche cumana attack and the concern to offer a wide range of hybrids to the growers in this area and to provide information on their reaction under similar conditions to those analyzed. The research was carried out in Braila county in the years 2015-2016. Six sunflower hybrids were studied. Observations were made on the frequency, intensity and degree of attack at the end of flowering and before harvesting were determined by counting the parasite on each plant. Formula for the degree of attack: F × I / 100 (%), where F = attack frequency (%) I = attack intensity (%). The number of sunflower plants per plot, plant height, calatidian diameter, number of broomrape attack plants, average number of broomrape stems per host plant and plot production at harvest were recorded. The results of the research on the parasitic-host plant system studied under natural infestation conditions depend on the homogeneity of experimental infestation on the field and on the studied genetic material. Infestation with Orobanche cumana was lifted during the two years of research

Physio-chemical properties of two cherry tomato varieties in relation to the greenhouse environmental factors

To prevail on the agricultural market, greenhouse grown cherry tomatoes need to meet certain quality standards. The quality can be assessed by determining several chemical and physical characteristics. The aim of the current study is to analyse such parameters of two cherry tomato varieties (Cheramy and Flaviola) in relation to their flowering stage and to the growing conditions within the greenhouse: air temperature, relative humidity and CO2 concentration. The soluble solids, titratable acidity and dry matter were determined. Furthermore, the β-carotene, lycopene and ascorbic acid contents were analysed. Tomato fruit size and firmness were also assessed. The current study illustrates a limited correlation between the environmental factors and the quality parameters. Thus, future research should be pursued for a better understanding of the effect of these climatic conditions on greenhouse grown tomatoes.publishedVersio