No abstract

In this work, a non-evaporative cooling system is used with an assisted thermoelectric cooler (TEC) devices module. The system was proposed as an alternative cooling system in the high temperature climate to overcome the high energy consumption of traditional air-conditioning compression cycle. The open source Open FOAM V.9 was used to solve the transient effect of 3D model of indirect non-evaporative cooling system. The primary air temperature was set to 319 . While, the air flow was tested under four different air inlet velocities: 0.75 m/s, 1 m/s, 1.25 m/s, and 1.5 m/s. the validation shows good and acceptable agreement in COP values of the system with both experimental and theoretical works from literature within an error between (12.9 % and 9.5 %). Results show that the temperate difference value on a slice through the length of the air channel starts to decrease as velocity increasing. For example, at the last timesteps of each velocity, the temperature difference reaches about (~10 oK) when velocity is (0.75 m/s) starting from the first quarter of the channel, while the same difference in temperature not reached until the half way of the channel from the channel inlet when velocity is (1.5 m/s). Revealing that even though the percentage increase in the velocity is about 50%, the change in the temperature difference value between the inlet and outlet of the channel is about 1.2%. The local Nusselt number shows that steady state heat transfer reached very quickly as the velocity increased (i.e., at 0.75 m/s at 12s while for 1.5 m/s at 4s). Notwithstanding, as the time processed the ( increases for all cases but becomes lower as the velocity increased. .

Visualization of water flow around different bluff bodies at different Reynolds number ranging (1505 - 2492) was realized by designing and building a test rig which contains an open channel capable to ensure water velocity range (4-8cm/s) in this channel. Hydrogen bubbles generated from the ionized water using DC power supply are visualized by a light source and photographed by a digital camera. Flow pattern around a circular disk of (3.6cm) diameter and (3mm) thickness, a sphere of (3.8cm) diameter and a cylinder of (3.2cm) diameter and (10cm) length are studied qualitatively. Parameters of the vortex ring generated in the wake region of the disk and the separation angle of water stream lines from the surface of the sphere are plotted versus Reynolds number. Proper empirical formulas are investigated to describe the behavior of vortex ring parameters and separation angle versus Reynolds number. Vortex growth history in the wake region of the cylinder is identified by analyzing the photographs extracted from the digital camera used for photography purposes. Water velocity measurement in the upstream region and near the edge of the disk is conducted at different Reynolds number by measuring the length of Hydrogen bubble pulse streaks generated in the upstream region of the disk using electronic pulse generator circuit. Special electronic circuit is designed and fabricated to cut off the applied DC voltage. The calibration of the designed pulse generator is conducted using the proper oscilloscope device. The pictures extracted from the digital camera are used for analyzing the generated Hydrogen pulses.