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Volume 25 (1994 - 199･･･
- Issue 4 Pages 175-
- Issue 3 Pages 125-
- Issue 2 Pages 59-
- Issue 1 Pages 3-
Volume 25, Issue 1
Displaying 1-5 of 5 articles from this issue
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Naoki TATSUZAWA, Takaaki MAEKAWA1994 Volume 25 Issue 1 Pages 3-9
Published: June 25, 1994
Released on J-STAGE: September 05, 2011
JOURNAL FREE ACCESSA new computer-controller sampling device used to measure methane emission from paddy soils for short times was constructed. It is possible to automatically collect the gas sample under natural conditions, since the chamber pressure is measured with a small difference of pressure step by step using a differencial pressure sensor.
As a result of 15 different air sampling tests, the measured value was underestimated by -9.6% for the theoretical value of flow meter. The underestimation factor was mainly a decrease in the flow of air because of the orifice resistance set up in this sensing device. As a result of the gas sampling measurement for sampled soils in the laboratory, a very small quantity of methane was detected. In comparison with the new method using chamber 2, the calculated error of the method for chamber 1, a controlled experiment, was underestimated by -10.46%. The pressure of chamber 2 was variable because of the influence of the outer temperature change, however this problem is able to be solved by selecting the suitable range of pressure sensor and referencing to the data of chamber pressure based on the changes of outer temperature.View full abstractDownload PDF (742K) -
Structural design and heat collecting performanceSeishu TOJO, Kengo WATANABE, Fusakazu AI, Allen C. CHAO1994 Volume 25 Issue 1 Pages 11-19
Published: June 25, 1994
Released on J-STAGE: September 05, 2011
JOURNAL FREE ACCESSA proposed solar system for drying agricultural waste sludge was tested on its collecting performance of solar thermal energy. The system has a simple solar housing and a rotating drum inside the housing, and its manufacturing cost is very cheap. One of the characteristics of the proposed system is that it collects solar heat in the solar housing and drying operation is run in the housing simultaneously. The experiments on collecting solar thermal energy brought the following results.
1. Hot air about 40-50°C is obtained for 6 hours on a fine day in the summer. There is a temperature gradient in the solar housing. The air temperature on the floor is lower than that of exhaust air and the air warmer than the exhaust air remains above the rotating drum inside the housing.
2. The collecting characteristic of solar heat is described with a state model. The exhaust air temperature is simulated approximately by the state differential equation which has a system heat capacity and two variables, solar radiation and inlet air temperature.
3. The collected solar heat is influenced with exhaust/inlet air flow rate. The more the exhaust air flows, the lower the air temperature increases, however, the higher the total collecting efficiency becomes.
4. Simulation results show that about 5°C warmer air was obtained in winter noon time of Tokyo in case of the exhaust air rate 0.02m3/s than in case of the exhaust air rate 0.06m3/s, but they induced almost same removed water by drying.View full abstractDownload PDF (2815K) -
The Circulating and Mixing Characteristics of Rice Particles in a Twin-shell MixerShengwu CHANG, Yelian MIAO, Shigeru YOSHIZAKI1994 Volume 25 Issue 1 Pages 21-27
Published: June 25, 1994
Released on J-STAGE: September 05, 2011
JOURNAL FREE ACCESSThe study was aimed to optimize the rice-mixing operation by the dynamic analysis of the mixing process of rice particles in a batch mixer.
In this work, the variation in concentration of the components shown from the surface of flowing down particles was observed dynamically by optical measurement using a CCD video camera. The circulating and mixing characteristics of rice particles in a twin-shell mixer were investigated.
The following conclusions were obtained from the present work:
(1) Operating the mixer at a charge ratio of 0.3 with a running speed of mixer between 15-60rpm, the resulting product of the elapse time of one circulation and the running speed of mixer was almost constant. The same result was obtained with the product of the final mixing time and the running speed of mixer.
(2) Operating the mixer at a running speed of 20rpm with a charge ratio of feed to vessel between 0.2-0.3, the resulting elapse time of one circulation did not change significantly at 11 seconds while the final mixing time increased from 30 to 37.5 seconds. At charge ratio between 0.3-0.4, the elapse time of one circulation decreased from 11 to 9 seconds and the final mixing time did not change significantly at 37.5 seconds.
(3) The final degree of mixing, which was about 90%, did not change significantly with the running speed of mixer and the charge ratioView full abstractDownload PDF (755K) -
Michihiro NAKAJIMA, Hiroshi MORISHIMA, Yasuhisa SEO, Yasuyuki SAGARA1994 Volume 25 Issue 1 Pages 29-37
Published: June 25, 1994
Released on J-STAGE: September 05, 2011
JOURNAL FREE ACCESSTo utilize the wet-bulb temperature as a monitoring or controlling factor of a vacuum cooling process, the morphological improvements of a wet-bulb sensor have been carried out with an experimental vacuum cooler, and it's applicability has been investigated by setting it in vacuum chambers of some commercial plants. The procedures and results obtained are summarized as follows;
1) The changing characteristics of wet-bulb temperatures measured with some types of sensors, which were originally mounted in the vacuum chambers of commercial plants, indicated that the wet-bulb temperature was more useful than a chamber pressure to monitor the product temperature during after a flash point of cooling process, and also morphological improvements of the sensor were required to detect the flash point as the controlling factor of the plant.
2) The necessary conditions for the morphology of wet-bulb sensor, using a thermocouple as well as a water-bottle, to detect both flash point and product temperature during cooling processes were presented;
This is (a) The measuring point of thermocouple should be set at the point separated more than 2cm above the top of water-bottle while keeping the distance of 10-15cm between the measuring point and the free surface of water in the bottle.
(b) The initial temperature of water in the bottle should be lower than that of the product.
3) By installing an improved sensor in the vacuum chamber of practical plant, we verified that the wet-bulb temperature could be used stably as a controling factor of cooling process for commercial vacuum plants.View full abstractDownload PDF (986K) -
Fandamental Heating Characteristics of Long Wave Infrared RadiationKazuhiko ITOH, Chung Su HAN1994 Volume 25 Issue 1 Pages 39-45
Published: June 25, 1994
Released on J-STAGE: September 05, 2011
JOURNAL FREE ACCESSWe identified the heating characteristics of longwave infrared radiation and the heater employing in order to establish a drying system for agricultural products.
The emissivity of two major types of longwave infrared radiation heaters on the market were 0.9 or larger when the range of wavelength was 3-15μm. It was clear that the surface temperature of a heater changes in proportion to the voltage and that the surface temperature of a panel heater differs largely according to its position. The absorption value of longwave infrared radiation didnot change when the relative humidity of the air was changed.
We also measured the quantity of heat absorbed by the heatreceiving plates of different hues. In the case of longwave infrared radiation, hue and especially color lightness did not affect the quantity. On the contrary, when an infrared radiationlamp was used, the quantity decreased as colorlightness increased.
The result of measurement of the decomposition rates of β-carotene and chlorophyll-a showed thatthe rate is lower when heated by longwave infrared radiation than when heated by solar or infrared radiation lamp.View full abstractDownload PDF (745K)
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