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The heat exchanger, which connects the Earth with the air, dramatically streamlines the process of heating and cooling buildings while conserving energy. This study quantitatively examines an Earth-Air Heat Exchanger (EAHE) natural ventilation system that serves the dual purpose of heating and cooling. The study's objective was to investigate the potential impact of varying thicknesses of disturbed soil on the efficiency of (EAHE) under varied pipe lengths and flow velocities. The study was conducted at Nasiriya, a city in southern Iraq, utilizing computational fluid dynamics (CFD) to analyze the meteorological conditions. The study findings revealed that, about the pipe diameter, if it exceeds a specific threshold, variations in wall temperature do not have any additional impact on it. While at 0D thickness, it was found that at high speeds with varying lengths, the air temperature inside the pipe increases due to the lack of sufficient time to exchange heat with the undisturbed soil. However, at low speeds, the air temperature inside the pipe begins to decrease as the length of the pipe increases due to the longer period of air remaining inside the pipe. The wall temperature remains constant at low speeds regardless of variations in flow velocity and pipe length at the soil thickness from 1D to 6D Due to the increased thickness of the soil, which is considered disturbed soil, affected by the ocean temperature. The wall temperature equals the soil temperature, but the higher speed amplifies the differential and causes the wall temperature to deviate from the soil temperature. Although the soil on the wall is shallow, the temperatures in such locations correspond to the temperature of the soil. [ABSTRACT FROM AUTHOR]

Electrokinetic micropumps receive increasing attention due to their applications in pumping of biological and chemical fluids; such as blood, DNA, and saline PBSs. In this paper, the electroosmotic flow in square microchannels has been numerically investigated by developing a model from the basic governing equations (continuity, momentum, energy, Laplace and Poisson- Boltzmann equations). These equations were numerically solved by CFD program for two fluids (water and PBS). The study considered the external applied electric field and zeta potential to interrogate their potential effects on electroosmotic flow. Thermal characteristics of electroosmotic flow have been also studied by calculating the temperature distribution through electroosmosis micropump region. The results confirm the considerable effect of applied electric field, concentration of electrolyte fluid and zeta potential on microflow velocity and flow rate. The PBS gave higher velocity and flow rate values compared with water, and there was only a slight increase in temperature due to Joule heating effect. [ABSTRACT FROM AUTHOR]