All issues
Volume 14 (1997)
- Issue 3 Pages 213-
- Issue 2 Pages 105-
- Issue 1 Pages 1-
Volume 14, Issue 2
Displaying 1-10 of 10 articles from this issue
- |<
- <
- 1
- >
- >|
Papers
-
Noriaki NAKAZAWA, Takeshi SAKO, Takashi NAKANE, Akira SEKIYA, Mitsutak ...1997 Volume 14 Issue 2 Pages 105-112
Published: 1997
Released on J-STAGE: October 11, 2011
JOURNAL FREE ACCESSThe liquid densities of thirteen fluorinated ethers which are expected as promising candidates of CFC alternatives were measured at temperatures from 278 K to 323 K and atmospheric pressure. The fluorinated ethers used in this study are 1-difluoromethoxy-1,1, 2- trifluoroethane, 1-methoxy-1, 1,2,2-tetrafluoroethane, 1-methoxy-2,2 ,3 ,3- tetrafluoropropane, 1-methoxy-1-trifluoromethy1-2,2 ,2- trifluoroethane, 1-methoxy-1,1,2,2, 3-hexafluoropropane,1-difluoromethoxy-2,2, 3, 3 -tetrafluoropropane, 1-methoxy-heptafluoropropane,1-difluoromethoxy-2, 2, 3, 3, 3-pentafluoropropane, 1- (2, 2, 2-trifruoroethoxy) -1, 1, 2,2-tetrafluoroethane, 1-pentafluoroethoxy-1, 1, 2, 2-tetrafluoroethane,2-trifluoromethoxy-1, 1, 1,2-tetrafluorobutane, 1-proxynonafluorobutane, and 1-ethoxy-undecafluoropentane.
The liquid density has been measured by the vibrating tube densitometer (ANTON PARR, DMA 602) within an error of 0.07%.
The liquid densities decrease monotonically with increase of temperature.View full abstractDownload PDF (364K) -
-The Utilization Effect of Unused Thermal Heat-Hiroshi KOJIMA, Atsushi AKISAWA, Takao KASHIWAGI1997 Volume 14 Issue 2 Pages 113-124
Published: 1997
Released on J-STAGE: October 11, 2011
JOURNAL FREE ACCESSRecently the energy conservation is expected from the global environment protection view point. In this study, a new concept of a compound gas cooling system using treated sewage water combining a gas engine heat pump and an absorption heat pump is proposed. In this system, the absorption heat pump is driven by the waste heat from the gas engine. In this paper, first, the best absorption cycle for this absorption heat pump is selected for the cooling and heating mode. And finally the simulation model of the two-stage absorption heat pumps for heating mode is demonstrated and the static characteristics are clarified.View full abstractDownload PDF (490K) -
(1st Report : Reduction of Noises caused by Resonance of each Scroll Compressor Element)Kiyoshi SANO, Sadao kAWAHARA, Noriyuki FUJIWARA, Noriaki ISHII1997 Volume 14 Issue 2 Pages 125-136
Published: 1997
Released on J-STAGE: October 11, 2011
JOURNAL FREE ACCESSSilent operation of domestic-use air-conditioners is a strong requirement from users. Therefore, noise reduction in a hermetic-type compressor used for air-conditioners is quite significant as an element technology in air-conditioner field. The noise sources in the hermetic-type compressor can be categorized into the three types ; the first is a solid-.borne noise caused by resonance of each compressor construction material, which is excited by vibrations and transmitted to the hermetic shell ; the second is an air-borne noise caused by compressor inner cavity resonance of refrigerant gas, which comes outside through the hermetic shell ;the third is a solid-vibration noise caused by whole compressor vibration at low speed operation. This paper presents detailed analyzes for the noise and vibration causes in scroll-type compressor first, which will make possible a low noise and low vibration design of scroll-type compressor. Secondly, proposed varoius devices for further reduction of noise caused by resonance of each compressor element are presented with noise reduction data.View full abstractDownload PDF (790K) -
(2nd Report : Noises due to Cavity Resonance in Various Compressor Spaces)Kiyoshi SANO, Sadao KAWAHARA, Noriyuki FUJIWARA, Noriaki ISHII1997 Volume 14 Issue 2 Pages 137-148
Published: 1997
Released on J-STAGE: October 11, 2011
JOURNAL FREE ACCESSThe scroll-type compressor features lower noise, due to less pulsation of gas pressure, than that of the rotary-type compressor. Nevertheless, at high rotation speed, the pulsation of gas pressure produces a significantly larger influence on total noise. In the present report, the author clarifies the relationship between noise and gas pressure pulsation is generated in the inner spaces of the hermetic shell in the scroll-type compressor as well as the relationship between acoustic characteristics and the pulsation of gas pressure. Experimental analysis and FEM analysis for acoustic field are performed and experiments for a scroll-type compressor with various newly-devised discharging mufflers and with a Helmholtz resonator near the discharging port for reduction of the compressor noises are presented.View full abstractDownload PDF (708K) -
(3rd Report : Electro-magnetic Noise for Inverter Driven Compressor)Kiyoshi SANO, Sadao KAWAHARA, Teruyuki AKAZAWA, Noriaki ISHII1997 Volume 14 Issue 2 Pages 149-158
Published: 1997
Released on J-STAGE: October 11, 2011
JOURNAL FREE ACCESSA brushless DC motor with a permanent magnet rotor has been adopted for a scroll compressor for domestic-use air-conditioners because of a demand for compressor high efficiency. A waveform of the driving voltage in the inverter power supply unit is chopped by the PWM signal. Its duty ratio is increased/decreased to control the DC voltage in order to provide a wide range of rotation frequencies for the compressor. The driving voltage includes the carrier frequency and its harmonic components, which produce an electro-magnetic force in the moter, resulting in high electro-magnetic noise. In the present report, the author clarifies the relationships between the noise and the waveform of driving voltage and frequency response function of the motor. A method to improve the frequency response function by changing the stator shape in order to reduce electro-magnetic noise is presented. Subsequently, the influence on electro-magnetic noise from the waveform of driving voltage is examined. Furthermore, the electro-magnetic noises during inverter driving of an induction motor are presented.View full abstractDownload PDF (574K) -
Toshiyoshi MIYAZAWA, Koichi ICHIMIYA1997 Volume 14 Issue 2 Pages 159-167
Published: 1997
Released on J-STAGE: October 11, 2011
JOURNAL FREE ACCESSEffective thermal conductivity and permeability of a porous medium were examined as a function of porous diameter at constant porosity. If the porous diameter increases at constant porosity, the number of pore should reduce and as the result the contact area to solid material also decreases. Effect of solid material becomes large and effective thermal conductivity increases. This tendency was experimentally confirmed by using three kinds of ceramic material (porous diameter df=1.3mm, 2.0mm and 4.2 mm, porosity &epsilon = 87%). In addition, permeability was determined experimentally for various porous diameters by using Ergun's equation including viscous term and kinetic term.View full abstractDownload PDF (368K) -
Koichi ICHIMIYA, Hiroshi MATSUMOTO, Hiromichi FUKUMOTO, Toshiyoshi MIY ...1997 Volume 14 Issue 2 Pages 169-177
Published: 1997
Released on J-STAGE: October 11, 2011
JOURNAL FREE ACCESSThe numerical estimation was performed on the effects of Grashof number and Prandtl number in a single circular impinging jet with confined insulated wall. Numerical values were obtained for the Reynolds number Re = 100 and 500, the Prandtl number Pr = 0.01 ∼ 1,000, the Grashof number Gr = O∼10,000 and the dimensionless distance between nozzle and impingement surface H=1.0. In the case of a normal jet, a recirculated flow was generated on the insulated upper wall and the local heat transfer was improved with increase of Grashof numbers because of a flow accerelation near the impingement surface. However, in the case of a jet inverse to gravity direction, the local heat transfer was depressed because a recirculated flow region by the buoyancy was generated on the impingement surface. Effects of Prandtl number were also examined. The characteristics of average Nusselt numbers along various Prandtl numbers were divided into three regions.View full abstractDownload PDF (315K) -
Takehiro YAZAKI, Seiji OKAWA, Akio SAITO1997 Volume 14 Issue 2 Pages 179-190
Published: 1997
Released on J-STAGE: October 11, 2011
JOURNAL FREE ACCESSMolecular dynamics simulation studies of the ice crystal growth from its surface were performed, and the temperature dependence of the growth rate of crystal and the melting temperature of the system including ice-water interface wer investigated. Distinction between ice crystal and liquid water was obtained using the method based on the mobility of water molecules, and the growth rate of ice crystal was estimated from it. The corresponding results were also obtained from the time variation of total enthalpy, density profile along the direction normal to the interface and configuration of molecules. The results show that the crystal growth occurred in the limited region of temperature, which range is about 30K, and the temperature dependence of the growth rate of ice crystal has the maximum around 275K. When the temperature is higher than around 295K, the ice crystal facing to the liquid water began to melt. The melting temperature of the system including the ice-water interface was slightly lower than the result obtained from the melting simulation using the bulk ice crystal.View full abstractDownload PDF (782K) -
Fumio KURIYAMA1997 Volume 14 Issue 2 Pages 191-200
Published: 1997
Released on J-STAGE: October 11, 2011
JOURNAL FREE ACCESSThis paper reports an analysis of the refrigeration power of basic and orifice pulse tube refrigerators. The enthalpy flow rates in pulse tubes are explained and compared with the same way for the two types of the refrigerators. The heat transfer between the gas and the wall of a pulse tube causes phase shifts of the mass flow rate and temperature oscillations of the gas. The relationship of the pressure, mass flow rate and temperature oscillations in the pulse tube with the heat transfer is obtained. The enthalpy flow rates in the pulse tube with the heat transfer are explained with an equation for both basic and orifice pulse tube refrigerators. The equation expresses the generation of enthalpy flow and the heat transfer influence on the enthalpy flow.View full abstractDownload PDF (332K) -
1st Report : Basic Cycle AnalysisHiroshi KOJIMA, Atsushi AKISAWA, Takao KASHIWAGI1997 Volume 14 Issue 2 Pages 201-212
Published: 1997
Released on J-STAGE: October 11, 2011
JOURNAL FREE ACCESSEnergy conservation is becoming important for global environmental protection. New simple techniques of more efficiently using the waste heat of gas co-generation systems for refrigeration are required. This paper proposes a new method of using low temperature waste heat below 100°C for refrigeration. In the new method, the low temperature waste heat is fed into the weak solution line of the double effect absorption cycle directly via an auxiliary heat exchanger. In this paper, first, the location of the auxiliary waste heat recovery heat exchanger on the solution line was studied for each solution flow type of double effect absorption cycle. Then six promising methods of recovering waste heat were selected, and moreover, the basic model was constructed and the effect of input of the low temperature waste heat was investigated for each selected method.View full abstractDownload PDF (492K)
- |<
- <
- 1
- >
- >|