9.0 DISCUSSIONThe experiment that was carried out using cooling tower Model HE152.The tower is made of clear arylic with square cross sectional area of 225 cm2.The packing density of tower is 110 m2/m3 for column A and 77 m2/m3 for column B. It comes with eight decks of inclined packing. A top column that fitted on the top of the tower comes with a sharp edge orifice, a droplet arrester and water distribution system. Actually,cooling tower is a device that rejects heat which removes the waste heat to the atmosphere to achieve the temperature needed. The type of heat rejection in a cooling tower is termed "evaporative" where it allows a small portion of the water being heated to evaporate then is condensed into a moving air stream to provide significant cooling to the rest of that water stream. The heat from the water stream transferred to the air stream raises the air's temperature and its relative humidity to 100%, and this air is discharged to the atmosphere. The objectives of the cooling tower experiment are to determine the correlation of water to air mass flow ratio with increasing water flow rate and to determine the cooling load effect, and the effect of different flow rates on the wet bulb approach. Another objective is to estimate the evaporation rate of water (water loss) for the tower. The experiment is varied by using one variable which is water flowrate.The correlation of water to air mass flow ratio is called r, is important to know the portion transferred by evaporation. The higher the evaporation of water, the mass flow rate of the water will be reduced which is what we actually wanted. Once the water mass flow rate is reduced, the mass flow rate of air that enters the column packing remains the same. So, there is more air that can cool the water. Hence, the effectiveness of the water to be cooled will be higher. The r value will need to be lower as possible to achieve higher portion of water evaporated. For water flow rates of 1.0 LPM, 1,5 LPM and 2.0 LPM, the r values are 49.48, 50.97 and 51.50 respectively. We can see that the water flow rate affects the r value for which the higher the water flow rate produces higher r value. . Hence, the cooling effectiveness will be higher in water flow rate of 2.0 LPM. In addition, approach is another term that used in cooling tower that tells how closely the leaving cold water temperature approaches the entering air wet bulb temperature. To be exact it is actually the temperature differences between the water leaving the cooling tower and the ambient wet-bulb temperature. Approach is the most important indicator of cooling water performance because it dictates the theoretical limit of the leaving cold water temperature and no matter the size of the cooling tower, range or heat load, it is not possible to cool the water below the wet bulb temperature of air. Hence, the leaving water temperature must be higher than the wet bulb temperature. The different air flow rates will affect the approach of the experiment. The higher the air mass flow rate, the higher the approach would be because the air that enters through the blower will decrease the wet bulb temperature so that the water leaving the tower will be higher than the wet bulb temperature. Moreover, cooling load also determine the performance of cooling tower. Cooling load is the rate at which heat is removed from the water. The higher the cooling load, the higher the heat removal from the water. Hence, the water will experience lower temperature which is actually that we wanted.. This is because the heating load is actually the power of the pump that compresses the water to increase the temperature and also pressure of the water. The higher the heating load, the higher the evaporation rate of the water. Thus, the temperature difference of the evaporated water with the temperature of air in the cooling tower will bring to great heat removal from the evaporated water. In addition, approach is another term that used in cooling tower that tells how closely the leaving cold water temperature approaches the entering air wet bulb temperature. To be exact it is actually the temperature differences between the water leaving the cooling tower and the ambient wet-bulb temperature. Approach is the most important indicator of cooling water performance because it dictates the theoretical limit of the leaving cold water temperature and no matter the size of the cooling tower, range or heat load, it is not possible to cool the water below the wet bulb temperature of air. Hence, the leaving water temperature must be higher than the wet bulb temperature. The higher the air mass flow rate, the higher the approach would be because the air that enters through the blower will decrease the wet bulb temperature so that the water leaving the tower will be higher than the wet bulb temperature. Furthermore, during the experiment there are some errors that occurred. The error is that we did not take the amount of water loss from the make-up tank every time the variables are changed. So, the errors affected the results of our experiment. Then,the error occurs is that we cannot estimate the evaporation rate of water (water loss) for the tower.