All issues
Volume 13 (1996)
- Issue 3 Pages 217-
- Issue 2 Pages 121-
- Issue 1 Pages 1-
Volume 13, Issue 2
Displaying 1-9 of 9 articles from this issue
- |<
- <
- 1
- >
- >|
Review Article
-
Haruo OHNISHI1996 Volume 13 Issue 2 Pages 121-131
Published: 1996
Released on J-STAGE: October 11, 2011
JOURNAL FREE ACCESSThere is urgent need to develop alternative refrigerants following the amendments to the Fourth Montreal Protocol regarding the regulation for HCFC's that is effective from January 1, 1996, and eventual the phase out of HCFC's production, currently scheduled for the year 2030.
These alternative refrigerant shave less affect to ward the global environment, but are required to meet many conditions such as safety, thermal characteristics, stability, price, energy efficiency, behavior with lubricants and materials and so on.
This report explains the current status of evaluation of candidates, and suggest about what is the best way to choice the best alternative refrigerant for the Air-conditioners, including the environmentally acceptability and safety.
And explain the development for technologies to make good use of new HFC refrigerants and issues for them.View full abstractDownload PDF (613K)
Paper
-
1th Report : Analysis of Controlled Factors for Uniform Air Velocity ProfileAtsushi TAKAHASHI, Chol Nam KONG, Hiroshi NAKATANI, Seiji OHWASE1996 Volume 13 Issue 2 Pages 133-141
Published: 1996
Released on J-STAGE: October 11, 2011
JOURNAL FREE ACCESSRecently, a lower type free-access floor system which realizes improved ease of walking and less sense of confinement has been attracting attention. However, it is known that the lower the design of the air supply chamber, the larger the non-uniformity of the supplied air velocity at each diffuser and the greater the deterioration in room temperature distribution. In this report, an analytical model is proposed for predicting the non-uniformity of supplied air velocity at the design stage. The validity of the analytical model was confirmed by the good-coincidence of results obtained in scale model tests. It was found that the limit of the floor height at which a uniform supplied air velocity is obtained was 50 mm. Moreover, a relation was found whereby the inverse of coefficient of resistance at a diffuser up to a value of 1 is proportional to the maximum non-uniformity. This indicates the possibility that design work aimed at constructing a pressurized type under floor air-conditioning system with a uniform supplied air velocity profile may be readily performed from parameters of the coefficient of resistance at a diffuser by utilizing this relation.View full abstractDownload PDF (426K) -
Etsuro NAITO, Yasutaka NAGANO1996 Volume 13 Issue 2 Pages 143-153
Published: 1996
Released on J-STAGE: October 11, 2011
JOURNAL FREE ACCESSA numerical investigation has been conducted to study the effect of body force on forced-convection of air upward-flow in the thermal entrance region between vertical parallel plates with the constant wall temperature. The governing equations based on the usual Boussinesq approximation are solved for two thermal conditons of parallel plates: one wall cooled with the other wall insulated; and both walls cooled in the same uniform states. The results are discussed in conjunction with those of uniform irrotational velocity. Numerically predicted friction factors and local Nusselt numbers are compared with their counterparts for pure forced convection. For use in practical applications, correlation equations are developed for the friction factors and the local Nusselt numbers.View full abstractDownload PDF (481K) -
Akira KAWAMOTO, Mamoru OZAWA, Fuki ARIKAWA, Masaki KATAOKA1996 Volume 13 Issue 2 Pages 155-166
Published: 1996
Released on J-STAGE: October 11, 2011
JOURNAL FREE ACCESSLinearized model of the acoustic characteristics in a resonance-tube refrigerator was developed with taking into account the fluid friction and the heat transfer at the wall. The validity of the model was examined through the comparison with experimental results obtained under various system parameters including resonance-tube configurations, the position of the stack and thermophysical properties of working fluids. The resonance frequency is well predicted by introducing a correction factor on the inertance at the open end of the tube. This correction factor was a function of the tube configuration and the position of the stack, and was determined independently on thermophysical properties of the fluid. The amplitude and the phase of the acoustic pressure showed qualitative agreement with the experimental data.View full abstractDownload PDF (611K) -
Tsutomu YAMAMOTO, Tethuya YAMAMOTO, Yasuhiko SIMIZU, Yoshinori NAKAYAM ...1996 Volume 13 Issue 2 Pages 167-173
Published: 1996
Released on J-STAGE: October 11, 2011
JOURNAL FREE ACCESSA refrigeration test employing HFC-134a and polyol ester oil was carried out in order to make clear the causes of the sludge formation in the capillary tube. Compressors used were two types: a hermetic reciprocating compressor and a rotary compressor. Installed dryer contained desiccant of the compound zeolite type.
The results showed that the amount of capillary sludge increased as the compressor temperature rose. The capillary sludge was determined to consist of desiccant and metal dust for the reciprocating compressor, and of tar-like substance for the rotary compressor. Thermal stability test which was used to check the degree of deterioration of the ester oil, suggested that the presence of desiccant and high compressor temperature might produce tar-like substance by the break down and polymerization of the ester oil. In addition, it was confirmed that factors affecting the sludge formation were the dirtiness of the refrigeration circuit for the reciprocating compressor, and the presence of desiccant, for the rotary compressor.View full abstractDownload PDF (2894K) -
Mitsuhiro FUKUTA, Tadashi YANAGISAWA, Takashi SHIMIZU, Hisashi DATE, Y ...1996 Volume 13 Issue 2 Pages 175-186
Published: 1996
Released on J-STAGE: October 11, 2011
JOURNAL FREE ACCESSLeakage flow through a narrow clearance in refrigerant compressors is a flow of refrigeration oil mixed with refrigerant. Its characteristics are very complicated because there is a possibility of a separation of vapor refrigerant from the oil according to a change of refrigerant solubility with pressure drop in the clearance. In this study, we studied the flow characteristics of refrigerant-oil miture through the narrow clearance experimentally and theoreticalIy. At first we investigated the characteristics of the two-phase flow through the narrow clearance by using a two-phase analytical model. The characteristics were also analyzed by a single phase model and the limitation of the homogeneous model was discussed by comparing results of the both models. On the other hand, the flow characteristics were measured by using an experimental channel having the narrow clearance. The followings were clarified. (1) The separation of vapor refrigerant from the liquid mixture in the channel does not progress according to the change of saturation solubility and the condition of the flowing liquid is in a super saturated condition. (2) The diverging shape of the channel induces the vapor separation. (3) The vapor separation decreases flow rate of the liquid mixture through the clearance, and the flow rate can be estimated by the analysis with an appropriate separation ratio.View full abstractDownload PDF (722K) -
1st Report : The Experimental Investigation about the Characteristics of Absorption Refrigerator Driven by Steam and Hot WaterShinji KIMIJIMA, Shisei WARAGAI, Tsuneo UEKUSA, Masaki NAKAO, Sunao KA ...1996 Volume 13 Issue 2 Pages 187-197
Published: 1996
Released on J-STAGE: October 11, 2011
JOURNAL FREE ACCESSIn recent years, co-generation system with fuel cell occupies the attention of the world from a standpoint of the environmental protection and the effective utilization of the energy. Since the waste heat of phosphoric acid fuel cell is recovered in two forms of steam (0.6 [MPa]) and hot water (65∼90 [°C]), this type of absorption refrigerator is driven by two heat sources.
In this paper, we inquire the result of the experiment intented for this absorption refrigerator the standard cooling capacity of which is 35[kW]. It is recognized that there is a mutual intervention when the supply condition of steam pressure is changed. Also the effects of hot water temperature, cooling water temperature and chilled water temperature for the performance of this absorption refrigerator is clarified. As a result, the effectiveness of using steam and hot water simultaneously in year-round operation is shown. Furthermore, it is clarified that the utilization of the low boiling temperature medium as the heat transfer medium for air-conditioner is effective.View full abstractDownload PDF (633K) -
Takashi MATSUNAGA, Suguru YOSHIDA, Ryutarou MORI, Akira YONEMARU1996 Volume 13 Issue 2 Pages 199-205
Published: 1996
Released on J-STAGE: October 11, 2011
JOURNAL FREE ACCESSBoiling heat transfer coefficient was measured for refrigerant liquid with oil contained. The liquid flowed in film on a horizontal heating surface with the vapor flowing in the upper part of a rectangular duct at different liquid flow rates, vapor flow rates, heat fluxes and oil mass fractions. Whenever the refrigerant contained the oil, the flow with foaming action was observed. The heat transfer coefficient was always decreased with increasing oil mass fraction. In order to investigate the influence of oil on the heat transfer, a dimensional correlation of the heat transfer coefficient was tentatively developed, as the sum of contributions by nucleate boiling and forced convection to the heat transfer. Based on this correlation, it was found that the reduction of the heat transfer coefficient with increasing oil mass fraction, especially until the oil mass fraction up to 20 percent, was attributed mainly to the rapid reduction of contribution by the nucleate boiling, and that the ratio of the heat transfer rate by the nucleate boiling to the total rate was decreased as the oil mass fraction was increased, because of much less reduction of the heat transfer rate by the forced convectionView full abstractDownload PDF (344K) -
Kazuhiro ENDOH, Hiroaki MATSUSHIMA, Masayuki NONAKA1996 Volume 13 Issue 2 Pages 207-216
Published: 1996
Released on J-STAGE: October 11, 2011
JOURNAL FREE ACCESSHFC zeotropic refrigerant mixture R-407C is one of the promising alternatives for HCFC-22. We have found that the coefficient of performance (COP) of the refrigeration cycle using R-407C is improved by installing a temperature glide shift heat exchanger (TGSX) which takes advantage of zeotropic characteristics to an air-conditioner. We obtained the characteristics of a refrigeration cycle of experimental apparatus with comparison to those of a fundamental refrigeration cycle based on the refrigerant thermodynamic properties. We concluded that the COP improvement ratio of experimental apparatus with the TGSX to that without the TGSX is greater than that ratio which is calculated from the fundamental refrigeration cycle. This proved to be caused by the pressure loss of low pressure side which is not taken into account in the fundamental refrigeration cycle.View full abstractDownload PDF (479K)
- |<
- <
- 1
- >
- >|