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In general, the thermodynamic power cycle of a mini-truck diesel engine has a thermal efficiency of less than 40%. During operation, its cooling system needs to transfer around 60% of the generated heat to air at the radiator. Nowadays, diesel engines have high performance, producing a large amount of mechanical power, which inevitably leads to a large amount of heat being rejected. Thus, the radiator demands a higher air flow rate. Additionally, fan efficiency is also important since the fan itself draws the power from the engine. Therefore, both performance and efficiency are critical parameters to be considered for the cooling fan. In Thailand, there is another consideration concerning the country's hot and humid environment with its frequent traffic jams in urban areas. This paper presents computational fluid dynamics (CFD) simulations of a mini-truck engine cooling fan operating at two rotational speeds. The resulting fan static pressures and flow rates are compared with (limited) experimental data. The pressure values are roughly 11% different from the experimental data due to the pressure measuring locations. For the flow rates, the difference between the simulations and the experimental data are about 48%. The large differences are due to differences between the experimental method from the fan testing standard and the simplified simulation setup as well as possibly deviations in the 3D model of the fan geometry from the actual piece. Nevertheless, the performance trends from the simulations are consistent. For example, the ratio of the flow rates at the two operating conditions is close to that from the experimental data. Thus, the simulation methods as set up in this work have potential to be used in the design process of engine cooling fans. [ABSTRACT FROM AUTHOR]

A mechanical ventilator is an automatic medical device that replaces or augments patient's lung for respiration. During operation, air pressure, volume flow rate, air volume and cycle duration must be set to meet a patient's needs. This can be achieved by designing and controlling the blower, which is the main turbomachinery of the device. Therefore, it is crucial to appropriately design the blower so that the ventilator can be operated as physicians direct. Recently when the coronavirus spread rapidly, there were many research works concerning mechanical ventilators. However, the design process has not been discussed. Hence, this paper presents a systematic design process for a blower in a mechanical ventilator. First, the initial operating point is determined by a conventional turbomachinery design process known as Cordier analysis, which can roughly identify the suitable machine type, size, and expected performance. Next, the Euler's turbomachine equation and the velocity diagram are used to calculate the rotor-to-fluid energy transfer. The process eventually results in a blade shape with the desired performance. Then, Computational Fluid Dynamics (CFD) simulations are employed to verify the performance of the designed blower. In the case study, the designed ventilator blower has maximum static pressure of 11,000 Pa, flow rate of 0.0022 m3s−1 and rotating speed of 120,000 rpm. The computed performance curves are also presented in this work. [ABSTRACT FROM AUTHOR]