A theoretical and experimental investigation was carried out to study the behavior of a two-phase closed thermosyphon loop (TPCTL) during steady-state operation using different working fluids. Three working fluids were investigated, i.e., distilled water, methanol, and ethanol. The TPCTL was constructed from an evaporator, condenser, and two pipelines (riser and downcomer). The driving force is the difference in pressure between the evaporator and condenser sections and the fluid returns to the heating section by gravity. In this study, the significant parameters used in the experiments were filling ratios (FR%) of 50%, 75%, and 100% and heat-input range at the evaporator section of 215-860.2 W. When the loop reached to the steady-state, the wall-temperature was recorded at various positions along the thermosyphon loop. Results showed that the thermal performance with water was better than methanol and ethanol with same condition. The experimental values of the heat transfer coefficient at the evaporator section were measured for the three working fluids. The results were estimated with the nucleate boiling correlation using engineering equation solver (ESS) program. In addition, a comparison between the experimental ( ) and theoretical ( values of heat transfer coefficient in the evaporator section showed good agreement with a maximum difference of 16%.

The survival ability and development of the free living stages of Dictyocaulus. filaria larvae were studied to understand the epidemiology of this parasite in irrigation system . Galvanised iron boxes were planted and containated at subsequent times by faeces containing the larvae. Then faecal , soil and pasture samples were examined weekly, climatic conditions were recorded in  Baghdad area.  The results showed that the free living larvae survived and migrated from the faeces to the soil and pasture in the squares of the 2 nd group of boxes which has been contaminated in January for a longer period in comparison with other groups. The larvae survived until the 1 st week of April in their faecal , soil and pasture samples. On the other hand , no larvae could be recovered after one week of contamination in the fifth group of boxes which has been contaminated in July. In the other groups of boxes, the larvae survived for (98) days in the 1 st group , (49) days in the 3 rd group and for (21) days in the 4 th group, however, the number of larvae in the soil and pasture in all groups was lower than that in the faeces, and the presence of larvae in the soil was recovered for short time  The climatic condition during December , January , Febreuary and March had good influence on the survivability and moulting of the larvae in comparison with the adverse effect of other months . *Part of his M.Sc. Thesis.