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RISS 인기검색어
- 검색키워드
- 저자 : Keishi Kariya (검색결과 3 건)
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Mohammad Sultan Mahmud,Keishi Kariya,AKIO MIYARA 대한설비공학회 2017 International Journal Of Air-Conditioning and Refr Vol.25 No.1
In the present study, local condensation heat transfer coefficients of the R1234ze(E) inside a vertical plate heat exchanger (PHE) were investigated experimentally. In the experiment, three vertical flow channels are formed in the test section where refrigerant flows downward in the middle channel and cooling water flows upward in other two channels. The test section consists of eight plates: two of them form a channel of chevron type PHE for refrigerant flow channel, other two flat plates are set for heat transfer measurements, and another consist on cooling water flow channel. Down flow of the condensing refrigerant R1234ze(E) in the center channel releases heat to other channels of cooling water. In order to measure local heat transfer characteristics, a total of 60 thermocouples were set at middle of flow direction and also in the right and left sides of plates in test section. Experiments were conducted for mass fluxes ranging from 10kg/m2s to 50kg/m2s. The measurement results show that local heat transfer coefficients decrease with increase of wetness with different values in horizontal direction. Further, characteristics of local heat flux and wall temperature distribution as a function of distance from inlet to outlet of refrigerant channel were explored in detail.
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M. Mostaqur Rahman,Keishi Kariya,AKIO MIYARA 대한설비공학회 2017 International Journal Of Air-Conditioning and Refr Vol.25 No.3
Experiments on condensation heat transfer and adiabatic pressure drop characteristics of R134a were performed inside smooth and microfin horizontal tubes. The tests were conducted in the mass flux range of 50 kg/m2s to 200 kg/m2s, vapor quality range of 0 to 1 and saturation temperature range of 20 ∘ C to 35 ∘ C. The effects of mass velocity, vapor quality, saturation temperature, and microfin on the condensation heat transfer and frictional pressure drop were analyzed. It was discovered that the local heat transfer coefficients and frictional pressure drop increases with increasing mass flux and vapor quality and decreasing with increasing saturation temperature. Higher heat transfer coefficient and frictional pressure drop in microfin tube were observed. The present experimental data were compared with the existing well-known condensation heat transfer and frictional pressure drop models available in the open literature. The condensation heat transfer coefficient and frictional pressure drop of R134a in horizontal microfin tube was predicted within an acceptable range by the existing correlation.
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FUEL CELL WASTE HEAT POWERED ADSORPTION COOLING SYSTEMS
SEUNG TAEK OH,BIDYUT BARAN SAHA,KEISHI KARIYA,YOSHINORI HAMAMOTO,HIDEO MORI 대한설비공학회 2013 International Journal Of Air-Conditioning and Refr Vol.21 No.2
In the present paper, the e®ect of desorption temperature on the performance of adsorption cooling systems driven by waste heat from fuel cells was analyzed. The studied adsorption cooling systems employ activated carbon ¯ber (ACF) of type A-20ethanol and RD type silica gelwater as adsorbentrefrigerant pairs. Two di®erent temperature levels of waste heat from polymer electrolyte fuel cell (PEFC) and solid oxide fuel cell (SOFC) are used as the heat source of the adsorption cooling systems. The adsorption cycles consist of one pair of adsorptiondesorption heat exchanger, a condenser and an evaporator. System performance in terms of speci¯c cooling capacity (SCC) and coe±cient of performance (COP) are determined and compared between the studied two systems. Results show that silica gelwater based adsorption cooling system is preferable for e®ective utilization of relatively lower temperature heat source. At relatively high temperature heat source, COP of ACFethanol based adsorption system shows better performance than that of silica gelwater based adsorption system.
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