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Volume 19 (2002)
- Issue 4 Pages 301-
- Issue 3 Pages 211-
- Issue 2 Pages 101-
- Issue 1 Pages 1-
Volume 19, Issue 4
Displaying 1-10 of 10 articles from this issue
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The System Driven by the Exhaust Gas of Micro Gas TurbineHitoshi ASANO, Terushige FUJII, Xiao WANG, Takafumi ORIGANE, Masatoshi ...2002 Volume 19 Issue 4 Pages 301-312
Published: 2002
Released on J-STAGE: March 14, 2012
JOURNAL FREE ACCESSAbsorption refrigerators are very efficient as a heat recovery unit in a co-generation system.In order to design an absorption refrigerator for an arbitrary heat source properly, it is important to consider not only quantity but also quality of heat flow. The evaluation of exergy loss in each component is also effective for the improvement of system. This paper deals with the exergy analysis on a LiBr-water absorption refrigerator consisted of a single-and a double-effect cycle driven by the exhaust gas of the micro gas turbine with the output power of about 30 kW. Moreover, exergy loss in absorption process was eva1uated. As a result, it was shown that 80% of the exergy loss in an absorber was caused in absorption process, and the exergy loss decreased with decreasing the change in solution concentration in absorber. In these calculated results,the maximum cooling load of 77.8 kW was obtained from the exhaust gas with the temperature of 2900°C by utilizing both a single-and a double-effect cycles in combination. The energy and exergy efficiency of the system was 88.0% and 25.6%, respectively.View full abstractDownload PDF (707K) -
Shixue WANG, Yoshio UTAKA2002 Volume 19 Issue 4 Pages 313-320
Published: 2002
Released on J-STAGE: March 14, 2012
JOURNAL FREE ACCESSThe condensation heat transfer characteristic curves for ternary vapor mixture of water, ethanol and air (or nitrogen) under the ethanol mass fraction of 0.01, 0.07, 0.25, 0.45 and relatively low concentrations of air (or nitrogen) were measured.The effect of air (or nitrogen) as a non-condensable gas on several different domains in the Marangoni condensation characteristic curves was discussed. It was shown that the effect of non-condensable gas in the domains controlled by the diffusion resistance and the filmwise condensation was not notable but in the domain dominated by the condensate resistance of dropwise mode was remarkable. Moreover, the variations of the several characteristic points representing the characteristic curves caused by the change in non-condensable gas concentration were discussed. The deteriorations of the maximum heat transfer coefficient and the maximum heat flux for low ethanol concentration and low concentration of non-condensable gas, in which the excellent heat transfer characteristics were exhibited, were more remarkable.View full abstractDownload PDF (515K) -
Michio YANADORI, Masao IMANARI2002 Volume 19 Issue 4 Pages 321-328
Published: 2002
Released on J-STAGE: March 14, 2012
JOURNAL FREE ACCESSWe examined the pressure drop and heat transfer of a heat transportation system equipped with a fan coil unit using surfactant solution as heat medium. We found that the total pressure drop of the system using surfactant solution was about less 50% than that of one using water. The total heat transfer rate of the fin-tube heat exchanger in the fan coil unit of surfactant solution system was less 16-19% than that of the water system.View full abstractDownload PDF (500K) -
Masao FUJII, Yu SESHIMO2002 Volume 19 Issue 4 Pages 329-338
Published: 2002
Released on J-STAGE: March 14, 2012
JOURNAL FREE ACCESSA new enhanced surface for forced-air convection heat transfer effective in the range of Reynolds number lower than 3000 was invented.This technique is called “breathing effect”. The surface has many perforations and is bent to form a trapezoidal shape. A heat exchanger constructed with these surfaces has enlargement and contraction parts alternately along the flow passages. The mechanism of the heat transfer enhancement is due to the secondary flow induced by the suction and injection through the perforations, and to the frequent boundary layer interruption at each contraction part. The invented process of the breathing effect and its applications are presented in order to spread the practical application of the breathing effect.View full abstractDownload PDF (594K) -
Takeo KOMATSUBARA, Takasi SUNAGA, Yasuki TAKAHASI2002 Volume 19 Issue 4 Pages 339-348
Published: 2002
Released on J-STAGE: March 14, 2012
JOURNAL FREE ACCESSR134a was selected as the alternative refrigerant for R12 because of the similar thermodynamic properties with R12. But refrigeration oil for R12 couldn't be used for R134a because of the immiscibility with R134a. To solve this problem we researched miscible oil with R134a and selected polyol ester oil (POE) as refrigeration oil. But we found sludge deposition into capillary tube after life test of refrigerator with POE and detected metal soap, decomposed oil and alkaline ions by analysis of sludge. This results was proof of phenomena like oil degradation, precipitation of process materials and wear of compressor. Therefore we improved stability and lubricity of POE, reevaluated process materials and contaminations in refrigerating circuit. In this paper we discuss newly developed these technologies and evaluation results of it by life test of refrigerator.View full abstractDownload PDF (580K) -
Effects of Plate Thickness and Surface MaterialTetsuo HIRATA, Masaaki ISHIKAWA, Yuzuru HANYUDA2002 Volume 19 Issue 4 Pages 349-355
Published: 2002
Released on J-STAGE: March 14, 2012
JOURNAL FREE ACCESSExperimental studies for ice removal phenomena of ethylene glycol solution on a horizontal polyvinyl-chloride plate have been performed. The effects of plate thickness and surface material on the ice removal phenomena are examined. It is shown that the optimum plate thickness for the ice removal exists and that the onset value of cooling heat flux is the largest for the plates of 1.O-1.5mm in thickness. It is found that the ice removal phenomena can occur on the metallic surface. However, the value of the onset of cooling heat flux becomes small for the metallic surface, because the ice forms in the shape of large sheet due to the large thermal conductivity. It is also found that plate material, which can maintain local temperature difference on plate surface, is preferable for the ice removal phenomena.View full abstractDownload PDF (414K) -
Investigation of Heat Exchanger Materials and Heat Exchanger TypeYoshinari ODA, Shinji NAKAGAWA, Masashi OKADA, Koji MATSUMOTO, Tetsuo ...2002 Volume 19 Issue 4 Pages 357-365
Published: 2002
Released on J-STAGE: March 14, 2012
JOURNAL FREE ACCESSDynamic-type of ice-making cold thermal energy storage systems using water-silicone oil emulsion with an additive, (C2H50)3SiC3H6NH2, has been proposed. Two kinds of heat exchanger were examined and the performances were compared with each other. One type of heat exchanger was a spiral tube and it was immersed in a low temperature thermostatic bath. The other was coil-shaped double tube heat exchanger using two tubes. The emulsion was circulated to make ice continuously. These systems were operated under various cooling conditions (flow rates of the emulsion and brine temperatures). The effects of the tube materials (fluororesin and non-fluororesin) and thickness were also examined. Slurry ice was formed continuously without adhesion of ice to the cooling wall under certain conditions. Using the fluororesin tube prevented ice from the adhesion and it enlarged the range of the cooling conditions under which slurry ice was formed continuously. Furthermore, by making thickness of the tube thinner and increasing the heat transfer coefficient on the outside of the tube, ice was made continuously without lowering the rate of ice formation at a higher brine temperature.View full abstractDownload PDF (607K) -
Akira AKAHIRA, K.C.Amanul Alam, Yoshinori HAMAMOTO, Atsushi AKISAWA, T ...2002 Volume 19 Issue 4 Pages 367-374
Published: 2002
Released on J-STAGE: March 14, 2012
JOURNAL FREE ACCESSThe study aims at clarifying the performance of silica gel-water adsorption refrigeration cycle with mass recovery process.Two kinds of heat exchanger were examined and the performances were compared with each other. One type of heat exchanger was a spiral tube and it was immersed in a low temperature thermostatic bath. The other was coil-shaped double tube heat exchanger using two tubes. The emulsion was circulated to make ice continuously. These systems were operated under various cooling conditions (flow rates of the emulsion and brine temperatures). The effects of the tube materials (fluororesin and non-fluororesin) and thickness were also examined. Slurry ice was formed continuously without adhesion of ice to the cooling wall under certain conditions. Using the fluororesin tube prevented ice from the adhesion and it enlarged the range of the cooling conditions under which slurry ice was formed continuously. Furthermore, by making thickness of the tube thinner and increasing the heat transfer coefficient on the outside of the tube, ice was made continuously without lowering the rate of ice formation at a higher brine temperature.View full abstractDownload PDF (494K) -
Gab-Soo DO, Yasuyuki SAGARA, Mizuho TABATA, Ken-ichi KUDOH, Toshiro HI ...2002 Volume 19 Issue 4 Pages 375-380
Published: 2002
Released on J-STAGE: March 14, 2012
JOURNAL FREE ACCESSMicro-Slicer Image Processing System (MSIPS) has been developed for measuring the three-dimensional(3-D) structure and distribution of ice crystals formed in biological materials. The system has functions to reconstruct the 3-D image based on the image data of exposed cross sections obtained by multi-slicing of a frozen sample with the minimum thickness of 1μm and to display the internal structure as well as an arbitrary cross section of the sample choosing observation angles. The effects of freezing conditions on the morphology and distribl1tion of ice crystals were demonstrated quantitatively from the observations of raw beef stained by fluorescent indicator. The 3-D image of the sample demonstrated that the growth of ice columns was restricted by the intrinsic structure of muscle fibers. The proposed method provided a new tool to investigate the effects of freezing conditions on the size, morphology and distribution of ice crystals.View full abstractDownload PDF (2925K) -
Shigeaki UENO, Gab-Soo DO, Yasuyuki SAGARA, Ken-ichi KUDOH, Toshiro HI ...2002 Volume 19 Issue 4 Pages 381-387
Published: 2002
Released on J-STAGE: March 14, 2012
JOURNAL FREE ACCESSA Micro-Slicer Image Processing System (MSIPS) has been applied to observe the ice crystal structure formed in frozen dilute solutions three-dimensionally. Several parameters were also proposed to investigate three-dimensional (3-D) morphology and distribution of ice crystals quantitatively, based on reconstructed images obtained by multi-slicing of a frozen sample with the thickness of 5μm. The equivalent diameter of ice crystals were in the range of 85μm up to 169μm, and then decreased exponentially in increasing freezing rate at the freezing temperature of -20°C to -80°C. The 3-D morphology of ice crystal was found to be a bundle of continuous columns at any freezing temperature under the usual freezing conditions except supercooling.View full abstractDownload PDF (599K)
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