<strong>CEC</strong> 20<strong>07</strong> - <strong>Abstracts</strong> <strong>CEC</strong> Sessions Tuesday, <strong>07</strong>/17/<strong>07</strong> Poster 9:00am - 10:30am C1-B JT, Magnetic and Non-Aerospace Coolers C1-B-01 Development <strong>of</strong> JT Coolers Operat<strong>in</strong>g at Cryogenic Temperatures with Non-Flammable Mixed Refrigerants A.N. Khatri, M. Boiarski, Advanced Research Systems. Inc.. Throttle cycle coolers, operat<strong>in</strong>g with mixed refrigerants (MR) have been used <strong>in</strong> applications at temperatures down to 70 K. Industrial s<strong>in</strong>gle-stage, oil lubricated compressor can be used to provide both a relatively low cost and long operational time. Application <strong>of</strong> nonflammable MR is important for safety, transportation, operation, service and ma<strong>in</strong>tenance. However, it is more difficult to provide a required refrigeration performance and long-term reliability due to properties <strong>of</strong> nonflammable MR. The paper presents experimental and model<strong>in</strong>g data for s<strong>in</strong>gle-stage coolers provid<strong>in</strong>g up to 10 W <strong>of</strong> refrigeration capacity. The selected nonflammable components to build the MR are commercially available. A comparative experimental and model<strong>in</strong>g performance data is presented for both flammable and nonflammable MR. A g<strong>as</strong> refrigerant supply (GRS) technology is used for a s<strong>in</strong>gle-stage cooler design. A m<strong>in</strong>imal achievable temperature is restricted by the freez<strong>in</strong>g po<strong>in</strong>t <strong>of</strong> MR. The GRS technology restricts a maximal refrigeration capacity. However, it allows to compromise between stable, long-term reliable operation and simplicity <strong>of</strong> equipment design with required refrigeration capacity. Stability <strong>of</strong> operation <strong>of</strong> small-scale, highly reliable MR coolers h<strong>as</strong> been proven by the data accumulated over long-term test<strong>in</strong>g. C1-B-02 Experimental Investigations on Mixed Refrigerant Joule-Thomson (MR J-T) Cryocooler N.S. Walimbe, M.D. Atrey, Indian Institute <strong>of</strong> Technology Bombay, Mumbai,India; K.G. Narayankhedkar, Veermata Jijabai Technological Institute, Mumbai,India. Mixed Refrigerant Joule Thomson (MR J-T) cryoocoolers have obvious advantages, such <strong>as</strong> low cost, high reliability, higher cool<strong>in</strong>g effect at 80 K, low vibrations and simplicity <strong>in</strong> design layout. As a result <strong>of</strong> this, their use for different applications h<strong>as</strong> become a major threat to conventional cryocoolers. The performance <strong>of</strong> the MR J-T cryocooler, <strong>in</strong> terms <strong>of</strong> cool<strong>in</strong>g power at low temperatures, depends significantly on the components <strong>of</strong> the g<strong>as</strong> mixture and their concentration. An experimental set up h<strong>as</strong> been developed <strong>in</strong> our laboratory to analyse various g<strong>as</strong> mixtures. An efficient counter flow heat exchanger, Hampson type, h<strong>as</strong> been fabricated and tested <strong>in</strong> the set up. The present paper gives experimental results for various g<strong>as</strong> mixtures so <strong>as</strong> to get maximum cool<strong>in</strong>g effect for a given temperature. The paper also presents the effect <strong>of</strong> work<strong>in</strong>g pressure <strong>of</strong> the optimized g<strong>as</strong> mixture on the performance <strong>of</strong> the cooler. C1-B-03 Performance <strong>of</strong> a mixed refrigerant Nitrogen g<strong>as</strong> cooler M. Siva Sankar, G. Venkatarathnam, Indian Institute <strong>of</strong> Technology Madr<strong>as</strong>. Mixed refrigerant processes are widely used for the liquefaction <strong>of</strong> natural g<strong>as</strong>. J-T cryocoolers operat<strong>in</strong>g with refrigerant mixtures are also be<strong>in</strong>g developed worldwide. Mixed refrigerant processes can also be used for the liquefaction <strong>of</strong> air, nitrogen etc. A number <strong>of</strong> patents have been granted on the liquefaction <strong>of</strong> nitrogen us<strong>in</strong>g non flammable mixtures recently. Two large commercial mixed refrigerant precooled air separation plants have also been tested recently [1]. Nitrogen g<strong>as</strong> coolers operat<strong>in</strong>g with mixtures <strong>of</strong> nitrogen, methane, ethane, propane etc. are under development <strong>in</strong> our laboratory. In this paper we describe the performance <strong>of</strong> our prototype nitrogen g<strong>as</strong> cooler. The system comprises <strong>of</strong> a pre-cool<strong>in</strong>g circuit and a mixed refrigerant circuit. Tests have been carried out with different nitrogen flow rates, different refrigerant mixtures and heat exchangers. In the current prototype, nitrogen can be cooled from room temperature to about 105 K at a flow rate <strong>of</strong> 0.1 g/s. The power <strong>in</strong>put to the system is about 1200 W. The performance <strong>of</strong> our system and comparison between experimental results and simulations are also presented. References 1) Bonaquist, D..P., Prosser, N.M., and Arman, B. (2003). Advances <strong>in</strong> refrigeration for air separation --- us<strong>in</strong>g mixed refrigerant cycles toreduce cost and improve efficiency, Paper ICR0524, Proceed<strong>in</strong>gs <strong>of</strong> the International Congress <strong>of</strong> Refrigeration 2003, W<strong>as</strong>h<strong>in</strong>gton D.C., p 1-7. C1-B-04 Pressure drop and heat transfer characteristics <strong>in</strong> a helical tube <strong>of</strong> Joule Thomson refrigerator Y-J. Hong, S-J. Park, Korea Institute <strong>of</strong> Mach<strong>in</strong>ery & Materials; Y-D. Choi, Korea University. The thermodynamic performance <strong>of</strong> a m<strong>in</strong>iature Joule Thomson refrigerator is highly depends on the hydraulic and heat transfer characteristics <strong>of</strong> the recuperative heat exchanger. The typical recuperative heat exchanger h<strong>as</strong> the double helical tube and f<strong>in</strong> configuration. The <strong>in</strong>com<strong>in</strong>g high-pressure g<strong>as</strong> enters a helical tube, and expands to the cold end <strong>of</strong> the refrigerator. After the Joule- Thomson expansion, the cold g<strong>as</strong> exhausts through a complex p<strong>as</strong>sage that is enveloped by the double helical tube and f<strong>in</strong>, mandrel and <strong>in</strong>ner surface <strong>of</strong> the Dewar. The present study focuses on the pressure drop and heat transfer characteristics <strong>in</strong> the helical tube. In general way, the curvature ratio <strong>of</strong> the helical tube h<strong>as</strong> substantial <strong>in</strong>fluences on the pressure drop and heat transfer characteristics. In this study, the heat and fluid flow is studied numerically on the high pressure g<strong>as</strong> <strong>in</strong> a helical tube. To account for the thermodynamic properties <strong>of</strong> the high pressure g<strong>as</strong>, the real g<strong>as</strong> model <strong>as</strong> a function <strong>of</strong> pressure and temperature w<strong>as</strong> used. The effects <strong>of</strong> the m<strong>as</strong>s flow rate, heat flux, pitch <strong>of</strong> the tubes and curvature ratio were studied by commercial CFD packages. C1-B-05 A Study <strong>of</strong> Active Magnetic Regeneration us<strong>in</strong>g Permanent Magnets S. Kito, K. Kamiya, H. Nakagome, S. Uchimoto, Chiba University; T. Kobay<strong>as</strong>hi, A. Takah<strong>as</strong>hi Saito, S. Kaji, Toshiba Corporation. In recent years, magnetic refrigeration techniques b<strong>as</strong>ed on the magnetocaloric effect attracts attention from a viewpo<strong>in</strong>t <strong>of</strong> earth environment protection, because the magnetic refrigeration is technology with little environmental load <strong>in</strong> order not to use chlor<strong>of</strong>luorocarbons. Especially, a new type <strong>of</strong> refrigeration cycle, the active magnetic regenerator (AMR) cycle, is suitable for a room temperature region, and the AMR cycle is expected to atta<strong>in</strong> high efficiency. We developed a room temperature magnetic refrigerator with permanent magnets, and operated the AMR cycle by us<strong>in</strong>g Gd and Gd-R alloys for the magnetic refrigerant. The AMR cycle with chang<strong>in</strong>g <strong>in</strong> the magnetic field and a movement <strong>of</strong> the heat transfer fluid w<strong>as</strong> operated for various parameters such <strong>as</strong> cycle frequency, amount <strong>of</strong> the heat transfer fluid movement, etc. Page 1 <strong>of</strong> 53
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