• International Journal of Aeronautical and Space Sciences
• /
• v.12 no.4
• /
• pp.379-384
• /
• 2011

This paper performs numerical prediction of fuel temperature in the fuel tanks of unmanned air vehicles for both ground static non-operating and in flight transient conditions. The calculation is carried out using a modified Dufort-Frankel scheme. For this calculation, it is assumed that a non-operating vehicle on the ground is subjected to repeating daily cycles of ambient temperature with solar radiation and wind under 1%, with a 20% probability of hot day conditions. The energy conservation equation is used as the governing equation to calculate heat transfer between the fuel tank surface and the ambient environment. Results of the present analysis may be used as the estimated initial values of fuel temperatures in a vehicle's fuel tank for the purpose of analyzing transient fuel temperatures during various flight missions. This research also demonstrates that the fuel temperature of the front tank is higher than that of the rear tank, and that the difference between the two temperatures increases in the later phases of flight due to the consumption of fuel.

• Asian-Australasian Journal of Animal Sciences
• /
• v.27 no.7
• /
• pp.1050-1056
• /
• 2014

This study investigated the main factors influencing digester temperature and methods to reduce heat losses during the cold season in the subtropics. Four composite digesters (two insulated and two uninsulated) were buried underground to measure their internal temperature ($^{\circ}C$) at a depth of 140 cm and 180 cm, biogas production and methane ($CH_4$) concentration in biogas from August to February. In parallel the temperature of the air (100 cm above ground), in the slurry mixing tank and in the soil (10, 100, 140, and 180 cm depth) was measured by thermocouple. The influent amount was measured daily and the influent chemical composition was measured monthly during the whole experimental period. Seasonal variations in air temperature significantly affected the temperature in the soil, mixing tank and digester. Consequently, biogas production, which is temperature dependent, was influenced by the season. The main factors determining the internal temperature in the digesters were insulation with Styrofoam, air temperature and temperature of slurry in the mixing tank. Biogas production is low due to the cold climate conditions in winter in Northern Vietnam, but the study proved that storing slurry in the mixing tank until its temperature peak at around 14:00 h will increase the temperature in the digester and thus increase potential biogas production. Algorithms are provided linking digester temperature to the temperature of slurry in the mixing tank.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.59 no.2
• /
• pp.155-163
• /
• 2023

This study deals with the maximum thermal load analysis and optimal capacity determination method of tank culture system for applying seawater source heat pump to save energy and realize zero energy. The location of the fish farm was divided into four sea areas, and the heat load in summer and winter was analyzed, respectively. In addition, two representative methods, the flow-through aquaculture system and the recirculation aquaculture system were reviewed as water treatment methods for fish farms. In addition, the concept of the exchange rate was introduced to obtain the maximum heat load of the fish farms. Finally, power consumption for heat pumps was analyzed in the view point of sea areas, tank capacity, and exchange rate based on the calculated maximum thermal load.

• Journal of the Korea Safety Management & Science
• /
• v.18 no.3
• /
• pp.71-80
• /
• 2016

This study is on safety improvement measures through analysis of accident cases during plant storage tank construction. Storage tank is a general term for artificial ground facility constructed to store oil, water, gas, and other chemicals. Some companies have clustered storage tanks (tank farm). The construction methods vary according to the component and types of fluids. Because most of the construction procedures include lifting heavy weight materials using heavy construction equipment and are carried out at high places, storage tank construction contains more risk factors than normal aerial construction. Recently, major accidents such as storage tank collapse have occurred often, and cost many lives due to the characteristics of the structure. In this study we would like to analyze the cause of these accidents and propose measures to improve safety.

• International Journal of Naval Architecture and Ocean Engineering
• /
• v.7 no.4
• /
• pp.670-690
• /
• 2015

In this paper, numerical investigations for tank sloshing, based on commercial CFD package FLUENT, are performed to study effects of boundary layer grid, liquid viscosity and compressible air on sloshing pressure, wave height and rising time of impact pressure. Also, sloshing experiments for liquids of different viscosity are carried out to validate the numerical results. Through comparison of numerical and experimental results, a computational model including boundary layer grid can predict the sloshing pressure more accurately. Energy dissipation due to viscous friction leads to reduction of sloshing pressure and wave elevation. Sloshing pressure is also reduced because of cushion effect of compressible air. Due to high viscosity damping effect and compressible air effect, the rising time of impact pressure becomes longer. It is also found that liquid viscosity and compressible air influence distribution of dynamic pressure along the vertical tank wall.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
• /
• v.3 no.1
• /
• pp.10-12
• /
• 1974

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.24 no.6
• /
• pp.444-451
• /
• 2014

The signal patterns of slosh noise produced by the fuel tank of a passenger vehicle are characterized by analyzing vehicle interior noise, fuel tank vibration, and near-field noise radiated from the fuel tank. This paper also shows the noise transfer path analysis results performed from the fuel tank to the vehicle inside. On top of them, physical index is described, demonstrating a good correlation with subjective feeling of slosh noise. It is essential to identify the main noise transfer paths for redesigning of the fuel tank system aiming at reducing slosh noise and also helpful to apply physical index in evaluating and reducing this noise. It is found that structure-borne path is the main root of slosh noise and a value reveals a good correlation with subjective feeling.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.22 no.12
• /
• pp.845-851
• /
• 2010

This study was experimentally performed to find the effects of refrigerant subcooling in the refrigeration system and to propose how to get the efficient use of energy. A refrigerant-subcooling refrigeration system consisted of a typical single vapor-compression refrigeration cycle, a subcooler, and an ice storage tank. The degree of subcooling at the exit of the condenser can be increased by the heat transfer between the subcooler and the ice storage tank. The cold heat in the ice storage tank was stored by using the refrigeration cycle during night time and then used to absorb the heat from the subcooler during daytime. The cooling capacity and COP of this system were higher than those of the conventional system due to the increase in the degree of subcooling. Typically, the refrigerant-subcooling system showed superior performance to the conventional refrigeration system and would also contribute to load leveling.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.28 no.1
• /
• pp.15-20
• /
• 2016

Phase change materials (PCM) are able to store a large amount of latent heat, and can be applied to thermal energy storage systems. In a PCM, it takes a long time to store heat in the storage system because of the low thermal conductivity. In this study, a finned-tube-in-tank heat exchanger was applied to a PCM thermal energy storage system to increase heat transfer efficiency. The effects of geometric and operating parameters were investigated, and the results were compared with those of the tube-in-tank heat exchanger. The finned-tube-in-tank heat exchanger showed higher heat transfer effectiveness than the tube-in-tank heat exchanger. The heat exchange effectiveness of the storage tank was determined as a function of the average NTU.

• Journal of the Korean Institute of Gas
• /
• v.10 no.1 s.30
• /
• pp.7-12
• /
• 2006

The quantity of gas which can be supplied by LPG storage tank become a standard of selection. In the absence of the maximum evaporation rates from LPG storage tanks by tank capacity, continuation using time, air temperature, it is in a problem for the dissemination of LPG Storage tanks. In this paper, we showed the maximum evaporation rates from LPG storage tanks by tank capacity, air temperature, continuous using time and remaining level.