In cooling tower unit two phases of water and air come in a direct contact to transfer mass and energy. Processes such as humidification, dehumidification, and gas/liquid cooling can be studied in this unit. Cooling of hot water by air and cooling of hot air by water is studied in this unit. Both air and water streams are heated up to reach to the desired temperature and then is cooled down by another stream in a counter-current contact. Liquid and gas distribution in the tower is carried out using a packed bed that causes an appropriate flow pattern. Water flow rate is measured by rotameter and air flow rate is measured by orifice meter.