In this study, the modelling of power transformer with (250 kVA) by using (AN-SYS17.1/FLUENT) code program was done. The power transformer was connected with earth air heat exchanger to decrease the temperature of (oil, core, and coils) of transformer which will increase its efficiency for preventing the damage and/or failure. The case study used the weather conditions of Nasiriya city, Iraq, at July 1 st with 50 °C as maximum ambient temperature and full electrical load of the power transformer. In addition to different pipe diameter, length of earth air heat exchanger and different air velocity entering to pipe. The results showed the temperature of (oil, core, and coils) for power transformer decreased with increase the pipe length and earth air heat exchanger depth underground. The air velocities inlet to earth air heat exchanger that used in the study were (2, 4 , and 6 m/s, respectively) and the results showed the increasing of air velocity inlet to earth air heat exchanger should decrease the temperature of (oil, core, and coils) for power transformer and increase the thermal conductivity of oil. The study concluded when using earth air heat exchanger in the power transformer and performance of power transformer will be increasing and led to decrease the temperature of oil about (18.5 °C).The results showed a significant convergence with previous researches.
Reducing electric power consumption is a critical issue, especially in areas with elevated temperatures such as Iraq. In Basra city, the electric power consumption, due to the air conditioning units (ACU), is extremely high. In this work, an evaporative cooling unit (ECU) is fabricated and tested, being retrofitted with the condenser part of a splittype air conditioner. The experimental procedure is done in Basra Engineering Technical College. The present work is categorized with two cases. In case one, the system runs without using the ECU, while in Case Two the system is tested with the ECU. Results show that decreasing the inlet air temperature to the condenser will reduce the condensation and evaporation temperatures. Furthermore, it decreases the compression pressure ratio and increases the refrigerant mass flow rate. With this modification, it is found that the consumption power is decreased by 26% and the COP increased by 90% compared with case one. The second law analysis of the modified system shows that using an ECU will decrease most of the exergy destruction and losses in the components. Only exergy destruction in the evaporator is increased. The second law system efficiency is improved by 69.5%.
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