Effect of different mesh-sized cladding materials on a naturally ventilated greenhouse-microclimate | |
| Author | Soni, Peeyush |
| Call Number | AIT Thesis no.AE-03-04 |
| Subject(s) | Nets Greenhouses -- Climate Microclimatology |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. AE-03-04 |
| Abstract | Nets and screening materials are often used by greenhouse industry in tropics to obstruct the insect inclusion. A wide range of such claddings are available with different mesh-openings. Experiments were conducted in four greenhouses with tomato crop inside, to study the spatial distribution of air-temperature and specific-humidity under naturally ventilated condition. Both, absolute and relative stress-gradients of temperature and humidity were observed for vertical (z) and horizontal (x and y) direction with x as semi-minor axis of 3 m x 6 m greenhouse structure. A real-time comparison was made among greenhouses with 53, 34, 33 and 19% porosity meshes for two plant maturity stages and two plant density levels. Shorter plants occupied 5% of gutter height while taller statured 50%; plant density doubled from 1.7 plant/m2 to 3.3 plants/m2 with three and five rows kept parallel toy axis, respectively. Air temperature gradients were 14% (z) that increased with vegetation; decreasing porosity increased these vertical gradients from 5% to 10%. Horizontal (x) locations exhibited 12% temperature gradient that was found insensitive to vegetation but, lowering porosity increased gradients from 8% to 12%. There was 10% temperature gradients observed in horizontal (y) locations, which decreased with decreasing vegetation (especially height). Specific humidity gradients in vertical (z) direction increased with vegetation and were 30%. Lowering porosity increased (z) humidity gradient. Horizontal (x) locations claimed 25% humidity gradients that increased with vegetation but decreased on decreasing porosity. About 30% horizontal (y) humidity gradient was noted, which decreased with vegetation but, lowering porosity increased it from 10% to 25%. Horizontal gradients of both temperature and humidity responded considerably slow towards plant density rather, they found to be more sensitive against plant height. Plant density on the other hand, altered their peak absolute values. Both, inward and outward heat-gradients were highest across the least porous net (-0.9 °c and +6 °C). Doubling density reported significantly higher gradients while heat envelope remained un-respondent towards plant height. Difference in soil temperature at 5 cm and 10 cm depths was lesser in less porous net greenhouse. Increasing the both, plant density and plant height lowered the difference. With matured plants inside, less porous greenhouses evidenced lesser evapotranspiration values. |
| Year | 2003 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. AE-03-04 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Food, Agriculture and Natural Resources (Former title: Department of Food Agriculture, and BioResources (DFAB)) |
| Academic Program/FoS | Agricultural and Food Engineering (AE) |
| Chairperson(s) | Salokhe, Vilas M.; |
| Examination Committee(s) | Jayasuriya, H.P. W. ;Chaiyaphol Kaewprakaisaengkul ;Achilles, Thomas; |
| Scholarship Donor(s) | Government of the Netherlands; |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 2003 |