• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.12
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• pp.1132-1138
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• 2005

Recently, production and use of freon substances are restrained due to depletion of ozone layer and global warming. In this aspect of environmental problems, the best solution is to use the natural refrigerant such as ammonia. Thus, this study is to find the optimal operating conditions by comparing the performance between the shell and tube type and shell and disk type heat exchangers using the ammonia refrigerant, and to verify the superiority of the shell and disk type heat exchanger that is not used in field of refrigeration and air conditioning. Finally, this study shows that the shell and disk type heat exchanger is applicable to the ammonia refrigeration system, and this system minimizes the refrigerant charge and installation space.

• Solar Energy
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• v.17 no.1
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• pp.3-15
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• 1997

The goal of this paper is to measure and compare the performance of solar heat pump for school classroom heating. To accomplish the goal, solar heat pump with alumium roll bond type evaporator and indoor heat exchanger(condenser) was built and fully instrumented with thermocouples and pressure transducers etc. The test results showed that the COP and capacity of R-134a($CF_3CH_2F$) were higher than those of R-12($CF_2Cl_2$). The solar heat pump system for room heating was designed to show the best efficiency that the room temperature make $18{\sim}20^{\circ}C\;and\;23{\sim}25^{\circ}C$ in Seoul during November, December, and January.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2008.04a
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• pp.199-205
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• 2008

In this study, a system to measure continuously the fuel concentration in a steady flow rig on the basis of Rayleigh scattering is presented. The system can be employed to measure both the temporal and the spatial distribution. Also, it is possible to calibrate the system for the measurement of accurate absolute concentration. Firstly, the system was tested at a calibration chamber for the determination of scattering cross section from propane, butane, acetylene, Freon-12 and Genetron 143a. After this, the system was adapted to a steady flow rig to measure the temporal and spatial fuel concentration. The rig is composed of cylinder head, intake manifold, injector, and transparent cylinder which can simulate internal combustion engine. To cope with the problem of Mie scattering interference, a software filter was developed, which is based on the rise time and the time constant of the photomultiplier-amplifier system. The results show that LRS can provide useful informations about concentration field and the software filter is very effective method to remove Mie interference.

• Journal of the Korean Physical Society
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• v.80
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• pp.1-12
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• 2022

Over the past few decades, tetrafluoroethane (TFE, R134a Freon)-based gases have been widely used in the operation of phenolic resistive plate chambers (RPCs) in many high-energy experiments. However, TFE has a high global warming potential (GWP); therefore, a search for new eco-friendly gases to replace traditional TFE-based ones is now unavoidable. In this research, we present cosmic-ray test results of a prototype RPC for the SHiP (search for hidden particles) experiment using 1.6- and 1.4-mm-thick RPC electrodes containing mixtures of various gases, including 1,3,3,3-tetrafluoropropene (HFO1234ze), CO₂, iC₄H₁₀ and SF₆. We compare the performance data gathered with these new gas mixtures with those gathered with a traditional TFE-based gas used for RPCs in compact muon solenoid (CMS) and a toroidal LHC apparatus (ATLAS) experiments. The addition of CO₂ to the HFO1234ze-based gas was found to be fairly effective in reducing the working-point high voltage (HVWP) for RPC operation. The results of our experiments lead us to the conclusion that adding 40% CO₂ or less, when combined with HFO1234ze-based gas, is conducive to reliable detector performance for SHiP single-gap phenolic RPCs.

• Journal of Energy Engineering
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• v.17 no.4
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• pp.189-197
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• 2008

In this study, a system to measure continuously the fuel concentration in a steady flow rig on the basis of Rayleigh scattering is presented. The system can be employed to measure both the temporal and the spatial distribution. Also, it is possible to calibrate the system for the measurement of accurate absolute concentration. Firstly, the system was tested at a calibration chamber for the determination of scattering cross section from propane, butane, acetylene, Freon-12 and Genetron 143a. After this, the system was adapted to a steady flow rig to measure the temporal and spatial fuel concentration. The rig is composed of cylinder head, intake manifold, injector, and transparent cylinder which can simulate internal combustion engine. To cope with the interference of Mie scattering, which is main obstacle of the measuring concentration with Rayleigh scattering, a hardware filter was installed for reducing the number density of particles. Furthermore a software filter was developed, which is based on the rise time and the time constant of the photomultiplier-amplifier system. In addition, background noisy was reduced by adjusting the optical array and applying the pin hall and beam trap. The results show that LRS can provide useful information about concentration field and the software filter is very effective method to remove Mie interference.