Xiang Zhang

In the actual utilization of geothermal resources, the scaling of geothermal fluids is one of the most important factors affecting the efficiency of geothermal power generation and even causing the shutdown of power generation systems. In this paper, the key factors affecting the formation of fouling of geothermal fluids in heat exchange pipelines and the characteristics of sedimentation evolution are explored, and the influence of fouling thermal resistance on system efficiency is reduced by optimizing the operating parameters of the system and adding antiscalants. In this paper, it is proposed that the power generation is maintained within the acceptable range by increasing the flow rate instead of shutdown maintenance and cleaning, and the flow rate is increased at 1, 3 and 5 days of system operation, and the system pump consumption, expansion work and net power generation of the system all surge, and then decrease with the change of time, until the dirt generation state reaches equilibrium again, and the average net power generation under increasing flow rate is greater than the power generation without changing the flow.

This work presents the experimental results of a novel, air-to-air, additively manufactured manifold-microchannel heat exchanger with straight fins on both sides. The heat exchanger was made of Inconel 718 using a direct metal laser sintering technique. The overall core size of the heat exchanger was 94 mm × 87.6 mm × 94.4 mm, with a fin thickness of 0.220 mm on both the hot and cold sides. The heat exchanger was tested with pressurized nitrogen gas at 300 °C and 340 kPa for the hot side, while air at an ambient condition was used for the cold side. An overall heat transfer of 276 W/m²K was obtained for Reynolds number values of 132 and 79 for the cold and hot sides, respectively. A gravimetric heat transfer density (Q/m∆T) of 4.7–6.7 W/kgK and a volumetric heat transfer density (Q/V∆T) of 6.9–9.8 kW/m³K were recorded for this heat exchanger with a coefficient of performance value that varied from 42 to 52 over the operating conditions studied here. The experimental pressure drop results were within 10% of the numerical values, while the corresponding heat transfer results were within 17% of the numerical results, mainly due to imperfections in the fabrication process. Despite this penalty, the performance of the tested heat exchanger was superior to the conventional plate-fin heat exchangers: more than 60% of improvements in both gravimetric and volumetric heat transfer densities were recorded for the entire range of experimental data.

Compared to state-of-the-art heat exchangers, manifold-microchannel heat exchangers have shown superior heat removal density (kW/kg) at moderate pressure drops. However, manifold-microchannel heat exchangers made of Ni-based superalloys or other tough-to-machine materials can be a challenge to fabricate using conventional fabrication methods. This is mainly because of the inherently complex manifold microchannel geometry, as well as the required small feature sizes (e.g., fin thickness) that should be comparable, or smaller than state-of-the-art high-performance metallic-based heat exchangers (∼150 μm or smaller). In this study, a direct metal laser sintering (DMLS) additive manufacturing technique was used to fabricate the compact high-temperature manifold-microchannel heat exchanger reported here. The additively manufactured manifold-microchannel heat exchanger was fabricated as a single object, which significantly simplifies the fabrication process. In this work, three different additive manufacturing machines were used to study the effect of laser power, powder size, and layer thickness on the fin and channel sizes of the fabricated microchannel heat exchangers. To evaluate the minimum wall thickness for holding the required design pressures, pressure containment tests were performed. As a result, a wall thickness of 0.3 mm was shown to withstand 340 kPa and be leakage-free. A detailed analysis of different printing orientations and their effect on the manifold-microchannel heat exchanger's design was also performed. Finally, a 76 × 76 × 76 mm3 manifold microchannel heat exchanger was successfully fabricated with a fin thickness of 0.13 mm out of maraging steel. A second unit with dimensions of 94 × 87.6 × 94.4 mm3 was successfully fabricated with a fin thickness of 0.22 mm out of Inconel 718. Details of the fabrication process and key take-away results are discussed in this paper.

The purpose of this work is to provide empirical design models for low-pressure, subsonic Venturi nozzles. Experimentally validated simulations were used to determine the effect of nozzle geometry and operating conditions on the suction ratio (ratio of suction mass flow rate to motive mass flow rate) of low-pressure, subsonic Venturi nozzles, over a wide range of geometries and operating conditions, through a parametric study. The results of the parametric study were used to develop seven empirical models, each with a different range of applicability or calculating a different indicator of nozzle performance (i.e., suction ratio, momentum ratio, or dynamic pressure ratio), of the Venturi nozzles using a constrained multi-variable global optimization method. Of the seven empirical models, the best models were found to be those for low- (less than one) and high-suction ratios (greater than one), with mean absolute percentage errors of 5% and 18%, respectively. These empirical models provide a design tool for subsonic, low-pressure Venturi nozzles that is more than an order of magnitude more accurate than a governing equation approach or conventional flow head calculations. These newly-developed empirical models can be applied for initial nozzle design when precise suction ratios are required.

A New Approach to Evaluate and Optimize the Swirl Tube Demister Efficiency Authors: Kyle Anderson, Ben Reinhardt, Walead Sultani, Hannah O’ Hern, Xiang Zhang, Bahman Abbasi Affiliation: Oregon State University 1 INTRODUCTION In the United States, roughly 98% of the production water used in hydraulic fracturing operations is deposited in underground

In order to meet the increased water demand triggered by population explosion, rapid industrialization, agriculture development, and tourism, many water-stressed regions are augmenting their water supply with desalinated water. Further, in some areas such as Qatar and Kuwait, 100% of domestic and industrial water demand is supplied through desalination implying development of

The need of fresh water is a global concern that needs no introduction as it is on the rise on daily bases. A huge body of scientific research is active in producing alternative resources of potable water. In water desalination research field, a reputable body of studies was carried in the literature aiming at maximizing the throughput of the process by investigating the