| Author | Sok Kunthy |
| Call Number | AIT Thesis no.AE-96-04 |
| Subject(s) | Pumping machinery
|
| Note | A thesis submitted in partial fulfilment of the requirements for the degree of Master of
Engineering |
| Publisher | Asian Institute of Technology |
| Abstract | Irrigation is a prerequisite for improving agricultural production. Where gravity irrigation is not possible, water lifting devices fulfil the requirement. In Takeo province, in most cases, it was found that the low efficiency is caused by improper selection of components, installation, mis-matching of pump and engine, unnecessary fittings, poor repair and maintenance, and unreasonable design of pumps. Among theses devices, low lift pump comes nearest to meeting the high discharge requirement of most rice production areas. A local made low lift irrigation pump of 12 cm diameter and 3 m long discharge pipe was evaluated for the performance under six different speeds from 1250 to 2500 rpm and three total static heads of 1, 1.5 and 2 m. The maximum efficiency was found 49.2, 47.l and 44.3 % at speed 2250 rpm for all total static heads. Then discharge was 23.5, 21.9 and 20.21 l/s, the power input was 1.34, 1.60 and 1.75 kW and total head 2.86, 3.52 and 3.91 m respectively. When the total static head increased the total head and power input were increased by 33.1 and 28.4 %, however, the discharge and efficiency were decreased by 52.7 and 43 .1 % respectively. When the speed increased the maximum percentage increase in total head and power input were found at maximum speed and shutoff condition, but the maximum increase in efficiency was found at speed of 2250 rpm for all total static heads. The mechanical power loss was found as high as 45.01 % of power input at speed of 2200 rpm. The high mechanical loss was due to high friction between drive shaft and nylon and wooden support bearing. Deflection, misalignment and corrosion of drive shaft were significant factors affecting mechanical loss. Total power loss was accounted for 60 % of power input. A new hollow carbon steel drive shaft with outside diameter of 25 mm and inside diameter of 12.4 mm was developed to obtain lower mechanical power loss and freedom from torsional vibrations. It is made of a hollow steel shaft in order to reduce weight and increase the stiffness of the shaft. It rotated up to 3000 rpm satisfactorily. Compared to the original shaft the test results show that power requirement of newly developed drive shaft is reduced by 27.06 and 47.83 % at speed 1250 and 3000 rpm respectively. The economic effect of developed pump was analysis based on fixed and variable cost at ~ total static head one meter and speed of 2250 rpm. The total fixed cost per year of original and developed pumps were US$ 95.25 and 92.89 and the variable cost per hectare were US$ 82.25 and 41.3. If all used pumps are replaced with developed low lift irrigation pump it can save the economic of Takeo province by about US$ 1,673, 355 per year. |
| Year | 1996 |
| 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) | Gupta, C.P.; |
| Examination Committee(s) | Murty, V.V.N.;Wickramanayake, B.W.E.; |
| Scholarship Donor(s) | SIDA (Swedish International Development Cooperation Agency); |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 1996 |