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1.
A flow controller for refrigerant expansion is reported. Devices are fabricated using a micromolding technique that is developed for thick nickel electrodeposition. The device consists of a short-tube restrictor with an integrated normally open valve, which, when actuated, presents a controllable blockage into the flow passage to obstruct the flow. Fabricated devices are evaluated with compressed air, with up to 22% reduction in mass flow rate at maximum actuation of the restrictor. The devices are also evaluated in an R134a vapor compression system of 1.5-2 kW, with the ability to control mass flow that is found to be greatly influenced by the vapor compression cycle's operational parameters. After the inlet pressure, the level of subcooling proved to be the most important parameter. For a cycle operating between 29 deg C and 4 deg C , saturation temperatures in the condenser and evaporator, respectively, actuation of the device reduced the refrigerant mass flow rate by 3.5% with 0.6 oC subcooling and up to 10.8 % with 5 deg C subcooling. 相似文献
2.
Jan Weszka Marian Domanski Bozena Jarzabek Jan Jurusik Jan Cisowski Anna Burian 《Thin solid films》2008,516(10):3098-3104
Thin films of poly(1,4-phenylenemethilidynenitrilo-1,4-phenylenenitrilomethilidyne) (PPI) have been prepared by chemical vapor deposition in the horizontal geometry using gaseous argon as a transport agent. PPI thin films have been grown by polycondensation of para-phenylene diamine (PPDA) and terephtal aldehyde (TPA). Fourier Transform Infrared spectra confirm formation of PPI layers without end groups. The strongest absorption band with discernible vibronic progression has been found to be due to superposition of 2.64, 2.82 and 3.03 eV bands corresponding to interband transitions connecting electronic ground state and vibrational levels of electronic excited state. A feature seen at about 2.6 eV in the spectra of PPI films prepared at higher temperatures of PPDA and TPA sources are attributed to excitons connected with the π-π? gap. Shoulder at 3.31 eV is attributed to interband transitions between delocalized states, while a peak at 4.2 eV is attributed to excitons formed by localized holes and delocalized electrons and vice versa and interband transitions connecting delocalized and localized bands, with the binding energy of about 0.8 eV. Thin films prepared at low temperatures of monomers consist of randomly distributed PPI chains weakly bound together. 相似文献
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R-22的替代现状 总被引:9,自引:2,他引:9
张建君 《制冷与空调(北京)》2005,5(1):62-69
1背景 R~22于1928年最初被人们所认可,并于1936年开始商业化生产使用.迄今为止,R-22已经在很多系统中得到应用,从最小型的窗式空调到最大型的冷水机组和热泵,也包括那些区域性的冷却和加热系统.使用这种通用型制冷剂的单个设备的制冷功率在2 kW与30 MW之间(0.5冷吨到9,500冷吨).R-22的使用装置包括:旋转式活塞、往复式活塞、涡旋式、螺杆和离心式压缩机,在实验中还包括吸收循环装置.没有一种制冷剂能够像R-22这样有如此大的产量和如此广的应用范围. 相似文献
5.
Daniela Domanski Guillermina Urretavizcaya Facundo J. Castro Fabiana C. Gennari 《Journal of the American Ceramic Society》2004,87(11):2020-2024
MgAl2 O4 spinel was successfully synthesized using a mechanochemical route that avoided the formation and calcination of its precursors at high temperatures. The method involved a single step in which γ-Al2 O3 –MgO, AlO(OH)–MgO, and α-Al2 O3 –MgO mixtures were milled at room temperature under air atmosphere. The formation of MgAl2 O4 occurred faster with γ-Al2 O3 than with AlO(OH) or α-Al2 O3 . After 140 h, the mechanochemical treatment of the γ-Al2 O3 –MgO mixture yielded 99% of MgAl2 O4 . 相似文献
6.
This paper described in general a computer model for simulation of steady-state performance of a split, residential, air-to-air heat pump. Organization of the model is discussed and approach to modelling of main heat pump components is explained. The modelling effort emphasis was on the local phenomena to be described by fundamental thermodynamic, heat transfer and fluid mechanic relationships. The model has been verified in a wide range of operating conditions from high temperature cooling to low temperature heating. 相似文献
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This paper described in general a computer model for simulation of steady-state performance of a split, residential, air-to-air heat pump. Organization of the model is discussed and approach to modelling of main heat pump components is explained. The modelling effort emphasis was on the local phenomena to be described by fundamental thermodynamic, heat transfer and fluid mechanic relationships. The model has been verified in a wide range of operating conditions from high temperature cooling to low temperature heating. 相似文献
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Anthony R. de Souza Michael R. Greenberg Ben-chieh Liu Karol J. Krotki Sallie A. Marston Ashok K. Dutt Yuk Lee David F. Batten Timothy J. Finan J. H. Holmes Brenton M. Barr Ryszard Domanski Victoria A. Lawson Dean M. Hanink Clarence G. Ray Saleem Mohammad Clyde Weaver Richard E. Caves Luis Suarez-Villa Dean Forbes Brenda J. Moscove Leland R. Pederson Nolin Masih Thomas A. Reiner Noel D. Uri Sidney R. Jumper Charles G. Schmidt James J. Parsons James T. Peach W. Donald McTaggart Daniel J. Fairbanks Peggy Evans Rutherford H. Platt 《The Annals of Regional Science》1987,21(3):126-187