http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Effect of heat exchanger materials on the performance of adsorption chiller
Ngoc Vi Cao,Xuan Quang Duong,Woo Su Lee,Moon Yong Park,JAE DONG CHUNG,Hiki Hong 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.5
The effect of adsorber heat exchanger (adHEX) material on the system performance of a silica gel-water, fin-tube type adsorption chiller was investigated for three typical materials, aluminum (Al), copper (Cu) and stainless steel (SS), following both the first and second laws of thermodynamics. High thermal conductivity was expected to shorten switching time and prolong adsorption/desorption period, and consequently result in a larger amount of water vapor, and lower thermal mass. In other words, since the product of density and heat capacity increases the heat supplied to the system, higher thermal performance was expected for Cu. However, preliminary calculations failed to confirm the expectation. This study examined the causes by artificially changing the Al thermo-physical properties to those of the Cu and SS. Above a threshold thermal conductivity, the main cause was found to be the material’s density, and below the threshold, thermal conductivity was most important. The Al adHEX showed 0.518 of COP, 221 W/kg of SCP and 0.115 of η e , which were 6.85 % and 6.53 % higher in COP and exergy efficiency than the Cu adHEX.
Ngoc Vi Cao,Xuan Quang Duong,Woo Su Lee,JAE DONG CHUNG 대한설비공학회 2019 International Journal Of Air-Conditioning and Refr Vol.27 No.2
A three-dimensional numerical analysis was conducted to examine the effect on performance of un-balanced heating/cooling water supply and nonuniform pressure distribution in the beds, issues observed in an experiment by our colleague during the development of a 35 kW prototype finned-tube type adsorption chiller. Case studies were conducted with reference values of v=1m/s, Pc=4144 Pc=4144Pa and Pe=1447 Pa, and the differences in Δv=0.25 Δv=0.25m/s, Δ c =415 ΔPc=415Pa and ΔP e =145 ΔPe=145Pa. A remarkable increase in COP was found for the cases of un-balanced heating water supply and nonuniform pressure distribution when the bed was connected to the evaporator. However, after integration of multi-modules, the effect was smoothed out, which removed the worry about the degradation in the overall COP. The effect of un-balanced cooling water supply and nonuniform pressure distribution when the bed was connected to the condenser was not discernible. In all cases, the change in SCP was negligible.
Heat Recovery Time of Adsorption Cooling System
Xuan Quang Duong,Ngoc Vi Cao,JAE DONG CHUNG 대한설비공학회 2018 International Journal Of Air-Conditioning and Refr Vol.26 No.2
In this study, a two-dimensional numerical model of finned-tube type adsorbers was developed and used to examine heat recovery time to improve the performance of an adsorption cooling system. The optimal heat recovery time, which resulted in the highest COP, was determined for a range of heat source temperatures (60–90 ∘ C) and cycle times (600–1200 s). The introduced heat recovery process enhanced COP, but also reduced SCP. This penalty became more serious when the hot water temperature was low and cycle time was short, which serves as a guideline for when heat recovery should be adopted in a given operating condition.
소형 이륜자동차의 머플러 배기압력 특성에 관한 실험적 연구
이중섭(C. S Vi),최석천(S. C. Choi),배재영(J. Y. Bae),정한식(H. S. Chung),정효민(H. M. Jeong),서정세(J. S. Suh) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.11
In this study, a experiment has been developed for measuring the exhaust pressure of muffler at inlet and outlet. The main experimental parameters were a engine speed and sound absorbing material in the muffler. The muffer sound absorbing material tested a steel wool and glass wool. The exhaust pressure was measured with pressure sensor. The phase of exhaust pressure with high speed was moved according to increasing engine speed comparing with exhaust pressure w1th low speed. Also, the distribution of exhaust pressure at the model-1, 2 and 3 are similar with distribution of exhaust pressure at muffler inlet.
Studies on the Optimum Models of the Dairy Product Kou Woan Lao Using Response Surface Methodology
Weng, Wei-Lien,Liu, Vi-Chung,Lin, Chin-Wen Asian Australasian Association of Animal Productio 2001 Animal Bioscience Vol.14 No.10
Kou Woan Lao is an oriental-style dairy product, which is coagulated by milk-clotting enzyme from the culture filtrate of lao-chao. The product appears smooth, sweet, slightly wine flavour, and the flavour differs from yogurt. The aim of this study was to search for the optimum model to shorten the period of manufacture, and to improve the quality of Kou Woan Lao. A response surface design was used for studying the effects of addition of carrageenan, locust bean gum, and culture filtrate from lao-chao on the curd firmness, viscosity, and syneresis. Results indicated that the best rheological property, preservative quality and acceptability of Kou Woan Lao could be obtained by the combination of 0.22% carrageenan, 0.21 % locust bean gum and 12% culture filtrate from lao-chao. The curd firmness, viscosity and syneresis of resultant product were 29.3 g, 21,347.7 cps, and 8.92%, respectively and the microstructure of the curd revealed a relatively complete three-dimensional spider web-like structure.