• Proceedings of the SAREK Conference
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• 2005.11a
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• pp.564-569
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• 2005

Recently, from the viewpoint of global wanning, natural gas CO2 is considered as a main refrigerant for hot water system. The characteristics of CO2 is not toxic, not flammable, high pressure, and high refrigerating capacity. Also it is widely available as a byproduct of industrial processes. This paper describes the performance analysis program of the swash plate type compressor using CO2 refrigerant. Estimates of the refrigerant flow rate, compression work, discharge temperature and volumetric, compressor efficiencies of the CO2 swash plate type compressor are obtained from the various design parameter such as the inclination angle of the swash plate, discharge hole area and suction hole area.

• Transactions of The Korea Fluid Power Systems Society
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• v.8 no.1
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• pp.10-18
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• 2011

In the beginning of this study, pressure in a cylinder and flow rate from a cylinder of a rotating-cam and fixed-cylinder type radial piston pump are investigated through numerical simulations, so that the simulation results might be utilized as basements for examining physical phenomena occurring in the pump assembly. Then, for supplying basic knowledge on pump design, pressure, flow and leakage characteristics of the pump assembly under the variations of major design parameters are investigated through numerical simulations. At the end, key design parameters influencing upon volumetric efficiency of the pump are listed.

• Journal of Aquaculture
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• v.16 no.4
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• pp.203-209
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• 2003

Nitrification efficiency of fixed film biofilters with sand, loess bead, and styrofoam bead in biofilter columns of 1-m height and 30 cm width was studied. Synthetic wastewater was continuously supplied to the culture tank to maintain total ammonia nitrogen (TAN) concentration in the inflow water at around 8 mg/L. The hydraulic loading rate was set at 200 ㎥/$m^2$/day. TAN conversion was stabilized after about 90 day conditioning for all the selected filter media but with net accumulations of nitrite. On the volumetric basis, conversion rates of TAN and nitrite were the highest in styrofoam bead filter. Mean volumetric TAN conversion rates in the final samples were 682, 269, and 79 g TAN/㎥/day in the styrofoam bead, sand and loess bead filters, respectively. Low gravity and cost of styrofoam bead render the handling easier and more cost-effective.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.7
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• pp.181-186
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• 1999

The objective of present work is to investigate the performance characteristics of three-lobe Roots type supercharger for the applications of low-compression and high-expansion ration gasoline engine. A performance test was conducted to obtain the drive power, volumetric efficiency, adiabatic efficiency and the influence of performance factors of supercharger . In order to analyze the supercharging characteristics, the experiments are made on operating parameters such as the supercharger speed, pressure ration and inlet temperature on the supercharging performance of the Roots type supercharger . Based on experimental results, the drive power and flow rate of supercharger increased with supercharger speed.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.10
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• pp.1380-1391
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• 1997

A 150 m$^{3}$/hr, 30 kg/cm$^{2}$, air-cooled 3-stage reciprocating air compressor is designed to be used in starting large diesel engines. A basic design procedure is presented to meet the targeted pressure and flow rate, and especially the volumetric efficiency. Temperature and stress analyses of the cylinder are performed using FEM modelings. The dynamics of valve system is analyzed and stress at the valve seat due to valve impact is evaluated. To reduce friction loss and wear at the compressor engine system, tribological design practices are suggested. Fin-type coolers are designed to dissipate generated compression heat at each stage. Finally, a prototype is manufactured and performance test is carried out utilizing an air tank. Performance results are compared to the design targets, other foreign specifications, and some quality standards.

• Nuclear Engineering and Technology
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• v.55 no.9
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• pp.3320-3325
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• 2023

The scaled water-cooled Reactor Cavity Cooling System (RCCS) experimental facility reproduces a passive safety feature to be implemented in Generation IV nuclear reactors. It keeps the reactor cavity and other internal structures in operational conditions by removing heat leakage from the reactor pressure vessel. The present work uses Flownex one-dimensional thermal-fluid code to model the facility and predict the experimental thermal-hydraulic behavior. Two representative steady-state cases defined by the bulk volumetric flow rate are simulated (Re = 2,409 and Re = 11,524). Results of the cavity outlet temperature, risers' temperature profile, and volumetric flow split in the cooling panel are also compared with the experimental data and RELAP system code simulations. The comparisons are in reasonable agreement with the previous studies, demonstrating the ability of Flownex to simulate the RCCS behavior. It is found that the low Re case of 2,409, temperature and flow split are evenly distributed across the risers. On the contrary, there's an asymmetry trend in both temperature and flow split distributions for the high Re case of 11,524.

• Journal of Korean Society for Atmospheric Environment
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• v.20 no.1
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• pp.99-110
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• 2004

In order to investigate the performance of carbon dioxide PSA over zeolite adsorbent, the present study showed results of isotherm measurement, cyclic operation of 3-bed apparatus, and the corresponding numerical simulation. The experiment data of bed temperature, purity, recovery were matched well with that of numerical simulation. Purity of both gas and adsorbent phase increased rapidly with rinse rate but the degree of increase was retarded for large rinse rate The total amount of adsorbed increased only 10% even if rinse rate was enlarged to 4 times. Optimal rinse rate was 7N㎥/hr in this study. The heating rinse led to augments in recovery and productivity, possibly thanks to ease of description resulting from increased volumetric rinse rate and temperature rise in the column.

• Journal of Environmental Health Sciences
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• v.29 no.3
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• pp.59-64
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• 2003

This study was conducted to investigate anoxic-RBC-anoxic-RBC process and its application to remove biologically organics and nitrogen. BOD and total-nitrogen(T-N) removal efficiencies were decreased as volumetric loading rate increased. But, the removal efficiency changes of T-N were little, as compared to BOD. Increase of internal recycle rate had few affect of BOD and T-N removal rates. Also, influent allocation(to 2nd anoxic reactor) had few affect of BOD removal efficiency rate. However, when the influent allocation rate was 30%, T-N removal efficiency was increased to 84.1 %. BOD/N ratio applied to 2nd anoxic reactor was increased to range of 3.65-4.37 as influent allocation rate increased to range 20∼35%. But, it might also cause adverse effect such as decrease of denitrification rate in excessive influent allocation rate.

• Journal of Microbiology and Biotechnology
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• v.23 no.10
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• pp.1445-1453
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• 2013

The scale-up criterion of constant oxygen mass transfer coefficient ($k_La$) was applied for the production of itaconic acid (IA) in a 50 L pilot-scale fermentor by the fungal cells of Aspergillus terreus. Various operating conditions were examined to collect as many $k_La$ data as possible by adjusting the stirring speed and aeration rate in both 5 L and 50 L fermentor systems. In the fermentations performed with the 5 L fermentor, the highest IA production was obtained under the operating conditions of 200 rpm and 1.5 vvm. Accordingly, we intended to find out parallel agitation and aeration rates in the 50 L fermentor system, under which the $k_La$ value measured was almost identical to that ($0.02sec^{-1}$) of the 5 L system. The conditions of 180 rpm and 0.5 vvm in the 50 L system turned out to be optimal for providing almost the same volumetric amount of dissolved oxygen (DO) into the fermentor, without causing shear damage to the producing cells due to excessive agitation. Practically identical fermentation physiologies were observed in both fermentations performed under those respective operating conditions, as demonstrated by nearly the same values of volumetric ($Q_p$) and specific ($q_p$) IA production rates, IA production yield ($Y_{p/s}$), and specific growth rate (${\mu}$). Specifically, the negligible difference of the specific growth rate (${\mu}$) between the two cultures (i.e., $0.029h^{-1}$ vs. $0.031h^{-1}$) was notable, considering the fact that ${\mu}$ normally has a significant influence on $q_p$ in the biosynthesis of secondary metabolites such as itaconic acid.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.9
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• pp.847-854
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• 2013

The objective of this study is to experimentally investigate the mixed flow and oxygen transfer characteristics of a horizontally injected aeration process using an annular nozzle ejector. The flow rate ratio, pressure ratio and ejector efficiency are calculated using the measured flow rate and pressure with the experimental parameters of the ejector pitch and primary flow rate. The visualization images of mixed flow issuing from the ejector are analyzed qualitatively, and the volumetric oxygen transfer coefficients are calculated using the measured dissolved oxygen concentration. The mixed flow behaves like a buoyancy jet or horizontal jet owing to the momentum of primary flow and air bubble size. The buoyancy force of the air bubble and the penetration of mixed flow are found to be important parameters for the oxygen transfer rate owing to the contact area and time of two phases.