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المستخلص Energy conservation is a major concern in the vapor compression refrigeration cycle especially in areas of hot weather (such as in the middle east countries, where the temperature may exceed 50°C) where air conditioning systems are used for long periods causing high energy consumption. In such a weather condition, the performance of the air-cooled condensers decreases sharply and the electrical power consumption increases excessively. Such a problem led to many research programs in order to improve the performance of these condensers by making some modifications aiming in enhancing the heat transfer from them. The common forms of condensers may be classified on the basis of the cooling medium into (1) air-cooled condensers, (2) water-cooled condensers, and (3) evaporative condensers.The evaporative condenser will be the subject of this research. The evaporative condensers-as air cooled and water cooled ones- reject heat from the condensing vapor into the cooling medium. In the evaporative condenser, superheated high pressure vapor, coming from the compressor discharge, flows through a banks of tubes. The external surface of the tubes is continually kept wet by a water distribution system. On the other hand, air is drawn around the condenser tubes. Absorbing heat from the refrigerant, some of the water on the tubes evaporates in the air. Consequently, the refrigerant vapor gives up its heat and condenses.Evaporative condensers have an advantage over the water cooled condensers which is the reduction of water pumping and chemical treatment requirements associated with the cooling tower/refrigerant condenser systems. They also have an advantage over the air cooled condensers which is the lower iv coil surface area and air flow requirements to reject the same amount of heat, hence greater operating efficiencies may be obtained by operating at lower condensing temperature.The evaporative condenser operates at a lower condensing temperature than the air cooled condenser which is limited by the ambient dry bulb temperature, while the evaporative condenser is limited by the ambient wet bulb temperature and it is well known that the ambient wet bulb temperature is usually lower than the ambient dry bulb temperature by 8-14 °C, which makes the evaporative condenser operate at a lower condensing temperature. Therefore, these systems are usually energy efficient compared to those using an air cooled condenser. Furthermore, the initial cost of the evaporative condenser is lower than that of the water cooled condenser due to reduced space and number of components.In this research, a theoretical analysis is adopted to calculate the amount of heat transfer to both water and air flows using the enthalpy potential difference. In this method, the control surface was taken as the condenser plus the two sections before and after it.An experimental investigation is also conducted using hot water flowing under a high flow rate in an evaporative condenser. This investigation aims to determine and study the factors affecting the performance of the evaporative condenser. For this purpose, a test rig was designed, constructed and installed in the refrigeration laboratory. Many experiments were conducted by varying the hot water temperature, the air flow rate and the injection water flow. |